% % This file was created by the Typo3 extension % sevenpack version 0.7.14 % % --- Timezone: CEST % Creation date: 2013-05-21 % Creation time: 20-26-38 % --- Number of references % 54 % @Book { 1088, title = {Primate Audition: Ethology and Neurobiology}, year = {2002}, month = {8}, pages = {312}, abstract = {Like speech, the species-specific vocalizations or calls of non-human primates mediate social interactions, convey important emotional information, and in some cases refer to objects and events in the caller's environment. These functional similarities suggest that the selective pressures which shaped primate vocal communication are similar to those that influenced the evolution of human speech. As such, investigating the perception and production of vocalizations in extant non-human primates provides one avenue for understanding the neural mechanisms of speech and for illuminating the substrates underlying the evolution of human language. Primate Audition: Ethology and Neurobiology is the first book to bridge the epistemological gap between primate ethologists and auditory neurobiologists. It brings together the knowledge of world experts on different aspects of primate auditory function. Leading ethologists, comparative psychologists, and neuroscientists who have developed new experimental approaches apply their methods to a variety of issues dealing with primate vocal behavior and the neurobiology of the primate auditory system. With the advent of new signal processing techniques and the exponential growth in our knowledge of primate behavior, the time has arrived for a neurobiological investigation of the primate auditory system based on principles derived from ethology. The synthesis of ethological and neurobiological approaches to primate vocal behavior presented in Primate Audition: Ethology and Neurobiology is likely to yield the richest understanding of the acoustic and neural bases of primate audition and possibly shed light on the evolutionary precursors to speech.}, department = {Department Logothetis}, web_url = {http://www.crcnetbase.com/isbn/9781420041224}, publisher = {CRC Press}, address = {Boca Raton, FL, USA}, series = {Methods and new frontiers in neuroscience}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, ISBN = {978-0-8493-0956-4}, author = {Ghazanfar, AA} } @Article { 5274, title = {Integration of Bimodal Looming Signals through Neuronal Coherence in the Temporal Lobe}, journal = {Current Biology}, year = {2008}, month = {7}, volume = {18}, number = {13}, pages = {963-968}, abstract = {The ability to integrate information across multiple sensory systems offers several behavioral advantages, from quicker reaction times and more accurate responses to better detection and more robust learning [1]. At the neural level, multisensory integration requires large-scale interactions between different brain regions—the convergence of information from separate sensory modalities, represented by distinct neuronal populations. The interactions between these neuronal populations must be fast and flexible, so that behaviorally relevant signals belonging to the same object or event can be immediately integrated and integration of unrelated signals can be prevented. Looming signals are a particular class of signals that are behaviorally relevant for animals and that occur in both the auditory and visual domain [2], [3] and [4]. These signals indicate the rapid approach of objects and provide highly salient warning cues about impending impact. We show here that multisensory integration of auditory and visual looming signals may be mediated by functional interactions between auditory cortex and the superior temporal sulcus, two areas involved in integrating behaviorally relevant auditory-visual signals [5] and [6]. Audiovisual looming signals elicited increased gamma-band coherence between these areas, relative to unimodal or receding-motion signals. This suggests that the neocortex uses fast, flexible intercortical interactions to mediate multisensory integration.}, department = {Department B{\"u}lthoff}, web_url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6VRT-4SVCR03-1-1\&_cdi=6243\&_user=29041\&_orig=browse\&_coverDate=07\%2F08\%2F2008\&_sk=999819986\&view=c\&wchp=dGLbVlz-zSkWz\&md5=142e0fb30c2ef24b02ac40f4ed665c4a\&ie=}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1016/j.cub.2008.05.043}, author = {Maier, JX and Chandrasekaran, C and Ghazanfar, AA} } @Article { 5838, title = {Interactions between the Superior Temporal Sulcus and Auditory Cortex Mediate Dynamic Face/Voice Integration in Rhesus Monkeys}, journal = {Journal of Neuroscience}, year = {2008}, month = {4}, volume = {28}, number = {17}, pages = {4457-4469}, department = {Department Logothetis}, web_url = {http://www.jneurosci.org/cgi/reprint/28/17/4457}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1523/JNEUROSCI.0541-08.2008}, author = {Ghanzafar, AA and Chandrasekaran, C and Logothetis, NK} } @Article { 5837, title = {Category-specific responses to faces and objects in primate auditory cortex}, journal = {Frontiers in Systems Neuroscience}, year = {2008}, month = {3}, volume = {1}, number = {2}, pages = {1-8}, abstract = {Auditory and visual signals often occur together, and the two sensory channels are known to infl uence each other to facilitate perception. The neural basis of this integration is not well understood, although other forms of multisensory infl uences have been shown to occur at surprisingly early stages of processing in cortex. Primary visual cortex neurons can show frequency-tuning to auditory stimuli, and auditory cortex responds selectively to certain somatosensory stimuli, supporting the possibility that complex visual signals may modulate early stages of auditory processing. To elucidate which auditory regions, if any, are responsive to complex visual stimuli, we recorded from auditory cortex and the superior temporal sulcus while presenting visual stimuli consisting of various objects, neutral faces, and facial expressions generated during vocalization. Both objects and conspecifi c faces elicited robust fi eld potential responses in auditory cortex sites, but the responses varied by category: both neutral and vocalizing faces had a highly consistent negative component (N100) followed by a broader positive component (P180) whereas object responses were more variable in time and shape, but could be discriminated consistently from the responses to faces. The face response did not vary within the face category, i.e., for expressive vs. neutral face stimuli. The presence of responses for both objects and neutral faces suggests that auditory cortex receives highly informative visual input that is not restricted to those stimuli associated with auditory components. These results reveal selectivity for complex visual stimuli in a brain region conventionally described as non-visual “unisensory” cortex.}, department = {Department Logothetis}, web_url = {http://www.frontiersin.org/systemsneuroscience/paper/10.3389/neuro.06/002.2007/pdf/}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.3389/neuro.06.002.2007}, author = {Hoffman, KL and Ghanzafar, AA and Gauthier, I and Logothetis, NK} } @Article { 4441, title = {Looming Biases in Monkey Auditory Cortex}, journal = {Journal of Neuroscience}, year = {2007}, month = {4}, volume = {27}, number = {15}, pages = {4093-4100}, abstract = {Looming signals (signals that indicate the rapid approach of objects) are behaviorally relevant signals for all animals. Accordingly, studies in primates (including humans) reveal attentional biases for detecting and responding to looming versus receding signals in both the auditory and visual domains. We investigated the neural representation of these dynamic signals in the lateral belt auditory cortex of rhesus monkeys. By recording local field potential and multiunit spiking activity while the subjects were presented with auditory looming and receding signals, we show here that auditory cortical activity was biased in magnitude toward looming versus receding stimuli. This directional preference was not attributable to the absolute intensity of the sounds nor can it be attributed to simple adaptation, because white noise stimuli with identical amplitude envelopes did not elicit the same pattern of responses. This asymmetrical representation of looming versus receding sounds in the lateral belt auditory cortex suggests that it is an important node in the neural network correlate of looming perception.}, department = {Department B{\"u}lthoff}, web_url = {http://www.jneurosci.org/cgi/reprint/27/15/4093}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1523/JNEUROSCI.0330-07.2007}, author = {Maier, JX and Ghazanfar, AA} } @Article { 4406, title = {Vocal-Tract Resonances as Indexical Cues in Rhesus Monkeys}, journal = {Current Biology}, year = {2007}, month = {2}, volume = {17}, number = {5}, pages = {425-430}, abstract = {Vocal-tract resonances (or formants) are acoustic signatures in the voice and are related to the shape and length of the vocal tract. Formants play an important role in human communication, helping us not only to distinguish several different speech sounds [1], but also to extract important information related to the physical characteristics of the speaker, so-called indexical cues. How did formants come to play such an important role in human vocal communication? One hypothesis suggests that the ancestral role of formant perception—a role that might be present in extant nonhuman primates—was to provide indexical cues 2, 3, 4 and 5. Although formants are present in the acoustic structure of vowel-like calls of monkeys 3, 4, 5, 6, 7 and 8 and implicated in the discrimination of call types 8, 9 and 10, it is not known whether they use this feature to extract indexical cues. Here, we investigate whether rhesus monkeys can use the formant structure in their “coo” calls to assess the age-related body size of conspecifics. Using a preferential-looking paradigm 11 and 12 and synthetic coo calls in which formant structure simulated an adult/large- or juvenile/small-sounding individual, we demonstrate that untrained monkeys attend to formant cues and link large-sounding coos to large faces and small-sounding coos to small faces—in essence, they can, like humans [13], use formants as indicators of age-related body size.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6VRT-4N3XDTT-2-5\&_cdi=6243\&_user=29041\&_orig=browse\&_coverDate=03\%2F06\%2F2007\&_sk=999829994\&view=c\&wchp=dGLbVtz-zSkzS\&md5=078468b88abc6937d407705fd4194b66\&ie=/sdarticle.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1016/j.cub.2007.01.029}, author = {Ghazanfar, AA and Turesson, HK and Maier, JX and Dinther, RV and Patterson, RD and Logothetis, NK} } @Article { 3819, title = {Eye movements of monkey observers viewing vocalizing conspecifics}, journal = {Cognition}, year = {2006}, month = {1}, volume = {101}, number = {3}, pages = {515-529}, abstract = {Primates, including humans, communicate using facial expressions, vocalizations and often a combination of the two modalities. For humans, such bimodal integration is best exemplified by speech-reading – humans readily use facial cues to enhance speech comprehension, particularly in noisy environments. Studies of the eye movement patterns of human speech-readers have revealed, unexpectedly, that they predominantly fixate on the eye region of the face as opposed to the mouth. Here, we tested the evolutionary basis for such a behavioral strategy by examining the eye movements of rhesus monkeys observers as they viewed vocalizing conspecifics. Under a variety of listening conditions, we found that rhesus monkeys predominantly focused on the eye region versus the mouth and that fixations on the mouth were tightly correlated with the onset of mouth movements. These eye movement patterns of rhesus monkeys are strikingly similar to those reported for humans observing the visual components of speech. The data therefore suggest that the sensorimotor strategies underlying bimodal speech perception may have a homologous counterpart in a closely related primate ancestor.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6T24-4J5C802-1-K\&_cdi=4908\&_user=29041\&_orig=search\&_coverDate=10\%2F31\%2F2006\&_sk=998989996\&view=c\&wchp=dGLbVzz-zSkzS\&md5=44ee60f125ff59f612771fae32e6f567\&ie=/sdarticle.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1016/j.cognition.2005.12.007}, author = {Ghazanfar, AA and Nielsen, KJ and Logothethis, NK} } @Article { 3824, title = {Monkeys match the number of voices they hear to the number of faces they see}, journal = {Current Biology}, year = {2005}, month = {6}, volume = {15}, number = {11}, pages = {1034-1038}, abstract = {Convergent evidence demonstrates that adult humans possess numerical representations that are independent of language [ [1], [2], [3], [4], [5] and [6]]. Human infants and nonhuman animals can also make purely numerical discriminations, implicating both developmental and evolutionary bases for adult humans’ language-independent representations of number [ [7] and [8]]. Recent evidence suggests that the nonverbal representations of number held by human adults are not constrained by the sensory modality in which they were perceived [9]. Previous studies, however, have yielded conflicting results concerning whether the number representations held by nonhuman animals and human infants are tied to the modality in which they were established [ [10], [11], [12], [13], [14] and [15]]. Here, we report that untrained monkeys preferentially looked at a dynamic video display depicting the number of conspecifics that matched the number of vocalizations they heard. These findings suggest that number representations held by monkeys, like those held by adult humans, are unfettered by stimulus modality.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science/article/pii/S0960982205004823}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1016/j.cub.2005.04.056}, author = {Jordan, KE and Brannon, EM and Logothetis, NK and Ghazanfar, AA} } @Article { 3361, title = {Multisensory integration of dynamic faces and voices in rhesus monkey auditory cortex}, journal = {Journal of Neuroscience}, year = {2005}, month = {5}, volume = {25}, number = {20}, pages = {5004-5012}, abstract = {In the social world, multiple sensory channels are used concurrently to facilitate communication. Among human and nonhuman primates, faces and voices are the primary means of transmitting social signals (Adolphs, 2003; Ghazanfar and Santos, 2004). Primates recognize the correspondence between species-specific facial and vocal expressions (Massaro, 1998; Ghazanfar and Logothetis, 2003; Izumi and Kojima, 2004), and these visual and auditory channels can be integrated into unified percepts to enhance detection and discrimination. Where and how such communication signals are integrated at the neural level are poorly understood. In particular, it is unclear what role ''unimodal'' sensory areas, such as the auditory cortex, may play. We recorded local field potential activity, the signal that best correlates with human imaging and event-related potential signals, in both the core and lateral belt regions of the auditory cortex in awake behaving rhesus monkeys while they viewed vocalizing conspecifics. We demonstrate unequivocally that the primate auditory cortex integrates facial and vocal signals through enhancement and suppression of field potentials in both the core and lateral belt regions. The majority of these multisensory responses were specific to face/voice integration, and the lateral belt region shows a greater frequency of multisensory integration than the core region. These multisensory processes in the auditory cortex likely occur via reciprocal interactions with the superior temporal sulcus.}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/ghazanfar05_JN_3361[0].pdf}, department = {Department Logothetis}, web_url = {http://www.jneurosci.org/cgi/reprint/25/20/5004}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1523/JNEUROSCI.0799-05.2005}, author = {Ghazanfar, AA and Maier, JX and Hoffman, KL and Logothetis, NK} } @Article { 2727, title = {Primate brains in the wild: the sensory bases for social interactions}, journal = {Nature Reviews Neuroscience}, year = {2004}, month = {8}, volume = {5}, number = {8}, pages = {603-616}, abstract = {Each organism in the animal kingdom has evolved to detect and process a specific set of stimuli in its environment. Studies of an animal's socioecology can help us to identify these stimuli, as well as the natural behavioural responses that they evoke and control. Primates are no exception, but many of our specializations are in the social domain. How did the human brain come to be so exquisitely tuned to social interactions? Only a comparative approach will provide the answer. Behavioural studies are shedding light on the sensory bases for non-human primate social interactions, and data from these studies are paving the way for investigations into the neural bases of sociality.}, department = {Department Logothetis}, web_url = {http://www.nature.com/nrn/journal/v5/n8/pdf/nrn1473.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1038/nrn1473}, author = {Ghazanfar, AA and Santos, LR} } @Article { 2726, title = {Multisensory integration of looming signals by rhesus monkeys}, journal = {Neuron}, year = {2004}, month = {7}, volume = {43}, number = {2}, pages = {177-181}, abstract = {Looming objects produce ecologically important signals that can be perceived in both the visual and auditory domains. Using a preferential looking technique with looming and receding visual and auditory stimuli, we examined the multisensory integration of looming stimuli by rhesus monkeys. We found a strong attentional preference for coincident visual and auditory looming but no analogous preference for coincident stimulus recession. Consistent with previous findings, the effect occurred only with tonal stimuli and not with broadband noise. The results suggest an evolved capacity to integrate multisensory looming objects.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WSS-4CX5R56-7-7\&_cdi=7054\&_user=29041\&_orig=browse\&_coverDate=07\%2F22\%2F2004\&_sk=999569997\&view=c\&wchp=dGLbVlW-zSkWA\&md5=b23d613101fbf15fdc259ef8b7177130\&ie=/sdarticle.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1016/j.neuron.2004.06.027}, author = {Maier, JX and Neuhoff, JG and Logothetis, NK and Ghazanfar, AA} } @Article { 2129, title = {Neuroperception: Facial expressions linked to monkey calls}, journal = {Nature}, year = {2003}, month = {6}, volume = {423}, number = {6943}, pages = {937-938}, abstract = {The perception of human speech can be enhanced by a combination of auditory and visual signals1, 2. Animals sometimes accompany their vocalizations with distinctive body postures and facial expressions3, although it is not known whether their interpretation of these signals is unified. Here we use a paradigm in which 'preferential looking' is monitored to show that rhesus monkeys (Macaca mulatta), a species that communicates by means of elaborate facial and vocal expression4, 5, 6, 7, are able to recognize the correspondence between the auditory and visual components of their calls. This crossmodal identification of vocal signals by a primate might represent an evolutionary precursor to humans' ability to match spoken words with facial articulation.}, department = {Department Logothetis}, web_url = {http://www.nature.com/nature/journal/v423/n6943/full/423937a.html}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1038/423937a}, author = {Ghazanfar, AA and Logothetis, NK} } @Article { 1931, title = {Auditory looming perception in rhesus monkeys}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, year = {2002}, month = {11}, volume = {99}, number = {24}, pages = {15755-15757}, abstract = {The detection of approaching objects can be crucial to the survival of an organism. The perception of looming has been studied extensively in the visual system, but remains largely unexplored in audition. Here we show a behavioral bias in rhesus monkeys orienting to “looming” sounds. As in humans, the bias occurred for harmonic tones (which can reliably indicate single sources), but not for broadband noise. These response biases to looming sounds are consistent with an evolved neural mechanism that processes approaching objects with priority.}, department = {Department Logothetis}, web_url = {http://www.pnas.org/content/99/24/15755.full.pdf+html}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1073/pnas.242469699}, author = {Ghazanfar, AA and Neuhoff, JG and Logothetis, NK} } @Article { 1087, title = {Temporal cues in the perception of long calls by cotton-top tamarins.}, journal = {Animal Behaviour}, year = {2002}, volume = {64}, pages = {427-438}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Smith-Rohrberg, D and Pollen, AA and Hauser, MD} } @Article { 1091, title = {The auditory behaviour of primates: a neuroethological perspective}, journal = {Current Opinion in Neurobiology}, year = {2001}, month = {12}, volume = {11}, number = {6}, pages = {712-720}, abstract = {The ethological approach has already provided rich insights into the auditory neurobiology of a number of different taxa (e.g. birds, frogs and insects). Understanding the ethology of primates is likely to yield similar insights into the specializations of this taxa's auditory system for processing species-specific vocalisations. Here, we review the recent advances made in our understanding of primate vocal perception and its neural basis.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science/article/pii/S0959438801002744}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1016/S0959-4388(01)00274-4}, author = {Ghazanfar, AA and Hauser, MD} } @Article { 38, title = {Role of cortical feedback in the receptive field structure and nonlinear response properties of somatosensory thalamic neurons.}, journal = {Experimental Brain Research}, year = {2001}, volume = {141}, pages = {88}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Krupa, DJ and Nicolelis, MAL} } @Article { 1090, title = {The role of temporal cues in conspecific vocal recognition: rhesus monkey orienting asymmetries to reversed calls.}, journal = {Brain, Behavior and Evolution}, year = {2001}, volume = {58}, pages = {163-172}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Smith-Rohrberg, D and Hauser, MD} } @Article { 1093, title = {The structure and function of dynamic cortical and thalamic receptive fields.}, journal = {Cerebral Cortex}, year = {2001}, volume = {11}, pages = {183-193}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Nicolelis, MAL} } @Article { 1092, title = {Units of perception in the antiphonal calling behavior of cotton-top tamarin (Saguinus oedipus): playback experiments with long calls.}, journal = {Journal of Comparative Physiology A}, year = {2001}, volume = {187}, pages = {27-35}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Flombaum, JI and Miller, CT and Hauser, MD} } @Article { 1094, title = {Encoding of tactile stimulus location by somatosensory thalamocortical ensembles.}, journal = {Journal of Neuroscience}, year = {2000}, volume = {20}, pages = {3761-3775}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Stambaugh, CR and Nicolelis, MAL} } @Article { 1097, title = {Immediate thalamic sensory plasticity depends on cortical feedback.}, journal = {Proceedings of the National Academy of Sciences, USA}, year = {1999}, volume = {96}, pages = {8200-8205}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Krupa, DJ and Ghazanfar, AA and Nicolelis, MAL} } @Article { 1096, title = {Spatiotemporal properties of layer V neurons in the rat primary somatosensory cortex.}, journal = {Cerebral Cortex}, year = {1999}, volume = {9}, pages = {384}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Nicolelis, MAL} } @Article { 1095, title = {The neuroethology of primate vocal communication: substrates for the evolution of speech.}, journal = {Trends in Cognitive Science}, year = {1999}, volume = {3}, pages = {377-384}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Hauser, MD} } @Article { 1098, title = {Simultaneous encoding of tactile information by three primate cortical areas}, journal = {Nature Neuroscience}, year = {1998}, month = {11}, volume = {1}, number = {7}, pages = {621-630}, abstract = {We used simultaneous multi-site neural ensemble recordings to investigate the representation of tactile information in three areas of the primate somatosensory cortex (areas 3b, SII and 2). Small neural ensembles (30−40 neurons) of broadly tuned somatosensory neurons were able to identify correctly the location of a single tactile stimulus on a single trial, almost simultaneously. Furthermore, each of these cortical areas could use different combinations of encoding strategies, such as mean firing rate (areas 3b and 2) or temporal patterns of ensemble firing (area SII), to represent the location of a tactile stimulus. Based on these results, we propose that ensembles of broadly tuned neurons, located in three distinct areas of the primate somatosensory cortex, obtain information about the location of a tactile stimulus almost concurrently.}, web_url = {http://www.nature.com/neuro/journal/v1/n7/pdf/nn1198_621.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1038/2855}, author = {Nicolelis, MAL and Ghazanfar, AA and Stambaugh, CR and Oliveira, LMO and Laubach, M and Chapin, JK and Nelson, RJ and Kaas, JH} } @Article { 1108, title = {Distributed neural substrates and the evolution of speech production.}, journal = {Behavioral and Brain Sciences}, year = {1998}, volume = {21}, pages = {516-517}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Katz, DB} } @Article { 1099, title = {The effects of estradiol on gonadotropin-releasing hormone neurons in the developing mouse brain.}, journal = {General \& Comparative Endocrinology}, year = {1998}, volume = {112}, pages = {356-363}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Grober, MS and Winterstein, G and Ghazanfar, AA and Eroschenko, V} } @Article { 1100, title = {Hebb\&\#8217;s dream: the resurgence of cell assemblies.}, journal = {Neuron}, year = {1997}, volume = {19}, pages = {219-221}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Nicolelis, MAL and Fanselow, EE and Ghazanfar, AA} } @Article { 1102, title = {Non-linear processing of tactile information by thalamocortical ensembles.}, journal = {Journal of Neurophysiology}, year = {1997}, volume = {78}, pages = {506-510}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Nicolelis, MAL} } @Article { 1101, title = {Reconstructing the engram: simultaneous, multi-site, many single neuron recordings.}, journal = {Neuron}, year = {1997}, volume = {18}, pages = {529-537}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Nicolelis, MAL and Ghazanfar, AA and Faggin, B and Votaw, S and Oliveira, LMO} } @Inbook { 2374, title = {Acoustic communication}, year = {2004}, pages = {334-343}, department = {Department Logothetis}, editor = {Bekoff, M.}, publisher = {Greenwood Press}, address = {Westport, CT, USA}, booktitle = {Encyclopedia of Animal Behavior}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, ISBN = {0-313-32746-7}, author = {Ghazanfar, AA and Miller, CT} } @Inbook { 1089, title = {Primates as auditory specialists}, year = {2002}, month = {8}, pages = {1-12}, department = {Department Logothetis}, web_url = {http://www.crcpress.com/product/isbn/9780849309564}, editor = {Ghazanfar, A.A.}, publisher = {CRC Press}, address = {Boca Raton, FL, USA}, booktitle = {Primate Audition: Ethology and Neurobiology}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, ISBN = {978-0-8493-0956-4}, DOI = {10.1201/9781420041224.ch1}, author = {Ghazanfar, AA and Santos, LR} } @Inbook { 1105, title = {Meaningful acoustic units in nonhuman primate vocal behavior.}, year = {2002}, pages = {265-273}, publisher = {MIT Press, Cambridge, MA}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Miller, CT and Ghazanfar, AA} } @Inbook { 1104, title = {Specialized processing of primate facial and vocal expressions: evidence for cerebral asymmetries.}, year = {2002}, pages = {480-530}, publisher = {Cambridge University Press}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weiss, DJ and Ghazanfar, AA and Miller, CT and Hauser, MD} } @Inbook { 1103, title = {The space-time continuum in mammalian sensory pathways.}, year = {2000}, pages = {97-130}, publisher = {Hardwood Press, Sidney}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA and Nicolelis, MAL} } @Poster { HoffmanTGL2009, title = {Phase coding of faces and objects in the superior temporal sulcus}, journal = {Frontiers in Systems Neuroscience}, year = {2009}, month = {3}, volume = {Conference Abstract: Computational and Systems Neuroscience 2009}, abstract = {Phase coding - stimulus coding by the timing of spikes with respect to the phase of local oscillations - is an alternative, complementary coding strategy to that of rate coding. One neocortical mechanism for phase coding posits that rhythmic inhibition in the gamma frequency range may interact with stimulus-evoked excitation, producing spikes earlier in an oscillatory cycle for preferred than non-preferred stimuli (Fries et al. 2007). Thus, the enhanced response for preferred stimuli commonly seen in the slowly-evolving rate code may also be coded through differences in spike timing within a single gamma cycle. Theoretically, this would provide a downstream target with a faster readout than would be possible with rate coding. Evidence for phase coding of visual stimuli was demonstrated recently in V1 of the anesthetized macaque (Montemurro et al. 2008), but only for lower frequencies (<12 Hz). Another study of spike-field phase coding in the secondary somatosensory cortex of the awake monkey also failed to find phase coding in the gamma frequency range (Ray et al. 2008). To address the generality and frequency-dependence of phase coding, we tested whether phase coding would be observed in an object-selective brain region in the awake macaque. Two monkeys passively viewed images of faces, clip-art objects, and computer-generated 'greebles' during broadband recordings from the upper bank superior temporal sulcus (STS; N=13 sessions). For all stimulus-responsive single units, trials were grouped according to the stimulus category presented and spiking was compared to the phase of the frequency components of the local field potential on that trial. For the majority of these cells (N=15), the phase at which firing occurred differed across stimulus categories. The category-selective phase differences were most common in two frequency bands: below 20Hz and in the gamma range (60-80Hz). The phase differences were not sustained throughout the image presentation, but rather were limited to roughly the first 200ms following stimulus onset, with no difference in the time course across frequencies. These results suggest that the visual category displayed can be extracted from the oscillatory phase when firing occurs. This holds not only for primary cortical areas known for their precise spike timing, but also for cells in association cortex, such as the upper-bank of the STS. Unlike previous studies, we found evidence of phase coding in the gamma frequency range, suggesting that there may be a regional specificity to the coding strategies used. The superior temporal sulcus receives highly-processed signals from multiple modalities, via projections from widespread cortical areas. As such, cells in STS may be less strictly driven by any given sensory input than are cells in early sensory cortical areas. Timing with respect to an internal gamma 'clock' may be one means by which such association areas maintain precise codes, as has been demonstrated previously for other cortical association areas such as the hippocampus (e.g., Buzsaki \& Chrobak 1995). The phase coding observed in STS may indicate one role for intrinsic rhythms in the coding of extrinsic - or stimulus-driven - inputs.}, department = {Department Logothetis}, web_url = {http://www.frontiersin.org/10.3389/conf.neuro.06.2009.03.170/event_abstract}, event_place = {Salt Lake City, UT, USA}, event_name = {Computational and Systems Neuroscience Meeting (COSYNE 2009)}, DOI = {10.3389/conf.neuro.06.2009.03.170}, author = {Hoffman, K and Turesson, H and Ghazanfar, AA and Logothetis, NK} } @Poster { 5130, title = {Whose voice is that? In pursuit of an animal model of vocal recognition}, year = {2008}, month = {4}, department = {Department Logothetis}, department2 = {Research Group Kayser}, web_url = {http://www.ccg.unam.mx/en/news/days_molecular_medicine_2008}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {Stockholm, Sweden}, event_name = {Days of Molecular Medicine 2008}, language = {en}, author = {Petkov, C and Kayser, C and Patterson, R and Ghazanfar, AA and Logothetis, N} } @Poster { GhazanfarCL2006, title = {Coherence in auditory cortical activity is modulated by face/voice integration in rhesus monkeys}, year = {2006}, month = {10}, volume = {36}, number = {799.13}, abstract = {We are investigating how auditory and visual information are integrated in the neocortex by recording single units and local field potential (LFP) activity with multiple electrodes in the lateral belt (LB) region of auditory cortex. Rhesus monkeys performed a task where they were required to maintain their fixations within the video frame for the duration of conspecific vocalization stimuli. The stimuli were presented as Face+Voice, Voice alone \& Face alone conditions. Our initial study demonstrated that raw LFP power reflects integration of face/voice signals in the form of both enhancement and suppression. While this LFP modulation was evident in the majority of LB cortical sites (89\%), parallel modulation in the analog multiunit firing rates was not as consistently apparent (40\% of sites). This suggests that the integrative effects are masked in multiunit activity. This may be because LFP modulations affect the firing reliability of particular cells--not necessarily through firing rate, but via the probability that they will fire for a given ensemble pattern of synaptic activity. In the present study, an analysis of 18 vocalization-sensitive single units revealed that 5 show some form of multisensory integration via firing rate (\verb=~=28\%). Although preliminary, this proportion of multisensory LB neurons is roughly equivalent to that reported for the superior temporal sulcus (STS). The notion that multisensory processes in LB auditory cortex may be reflected in the cooperation of neural signals receives support from our LFP analyses. LFP coherence measured across 27 pairs of LB cortical sites revealed modulations in the gamma band (40-80 Hz) and lower frequencies (5-30 Hz) that were greater for bimodal versus unimodal conditions. In a subset of experiments, we recorded STS in parallel with LB. Coherence between LB and STS (20 pairs) showed the greatest strength in the bimodal condition for low frequencies, but in the gamma range both the Face+Voice and Face alone conditions showed an equivalent increase in gamma band activity relative to the Voice alone condition. Our data suggest that firing rates may be less relevant to the integration of information than the temporal structure of neural activity and its effects on small neural networks.}, department = {Department Logothetis}, web_url = {http://www.sfn.org/index.aspx?pagename=abstracts_ampublications}, event_place = {Atlanta, GA, USA}, event_name = {36th Annual Meeting of the Society for Neuroscience (Neuroscience 2006)}, author = {Ghazanfar, AA and Chandrasekaran, CF and Logothetis, NK} } @Poster { ChandrasekaranvPLG2006_2, title = {Representation of Formants \& Fundamental Frequencies of Coo Calls in Rhesus Monkey Auditory Cortex}, year = {2006}, month = {10}, number = {4}, department = {Department Logothetis}, web_url = {http://www.apan.jhu.edu/Program_APANIV.htm}, event_place = {Atlanta, GA, USA}, event_name = {Tucker-Davis Symposium on Advances and Perspectives in Auditory Neurophysiology (APAN IV)}, author = {Chandrasekaran, CF and van Dinther, R and Patterson, RD and Logothetis, NK and Ghazanfar, AA} } @Poster { ChandrasekaranvPLG2006, title = {Representation of formants and fundamental frequencies of coo calls in rhesus monkey auditory cortex}, year = {2006}, month = {10}, volume = {36}, number = {799.12}, abstract = {Vocal tract resonances (or formants) are acoustic signatures in the voice related to the shape and length of the vocal tract. Formants play a role in both human and monkey vocal communication, allowing listeners to extract important information related to the physical characteristics of the speaker, such as age, sex and/or body size. We investigated the neural representation of this acoustic cue in rhesus monkey auditory cortex using parametric manipulations of synthetic coo calls. The synthesis procedure allowed us to generate 4 different fundamental frequencies and 4 different vocal tract lengths (generating a large set of formant frequencies) independently, allowing us to explore whether auditory cortex is differentially sensitive to one cue or the other. Duration of the call was also a variable, as the original vocalizations were from 4 different monkey callers. Spiking activity (multiunit clusters and single units) and local field potential (LFPs) were recorded from the core (44 sites) and lateral belt fields (33 sites) of two passively listening monkeys. Responses to these coo stimuli were complex, often multi-peaked. As expected for vocal stimuli, response amplitudes were greater in the belt than the core. Using multiple regression, with fundamental frequency, formant frequencies and duration as factors, we analyzed spikes and LFPs pooled across cortical sites in a given auditory area. For both types of neuronal signals, formants and duration explained a significant portion of the variance for belt and core regions. The fundamental frequency explained a much smaller proportion of the variance. The coefficient of regression was higher for the belt region compared to the core region. Removing formants, but not fundamental frequencies, drastically reduced the coefficient, demonstrating that the belt region may respond to the formant frequencies in vocalizations better than the core region. These cortical differences, revealed with the use of parametrically-manipulated, ethologically-relevant sounds, hint at the functional organization of auditory cortex for real world events.}, department = {Department Logothetis}, web_url = {http://www.sfn.org/index.aspx?pagename=abstracts_ampublications}, event_place = {Atlanta, GA, USA}, event_name = {36th Annual Meeting of the Society for Neuroscience (Neuroscience 2006)}, author = {Chandrasekaran, C and van Dinther, R and Patterson, RD and Logothetis, NK and Ghazanfar, AA} } @Poster { MaierLG2005, title = {Looming versus receding signals in rhesus monkey auditory cortex}, year = {2005}, month = {11}, volume = {35}, number = {616.16}, abstract = {A key survival strategy of animals is the detection and adaptive response to rapidly approaching danger. Accordingly, behavioral experiments have shown that animals have a bias towards approaching motion signals as opposed to receding signals in both the visual [e.g., Schiff et al., 1962 Science 136:982] and auditory [e.g., Ghazanfar et al., 2002 PNAS 99:15755] domain. In the auditory domain, primates (including humans) appear to detect approaching motion using dynamic intensity cues. Dynamic intensity can also give information about behaviorally-relevant variables such as the time-to-contact of approaching sound sources, independent of absolute intensity. In the present study, we investigated the representation of looming and receding sounds in rhesus monkey auditory cortex. We recorded local field potential (LFP) activity in the auditory cortex of an awake, behaving monkey while the subject was presented with amplitude modulated complex tones either unimodally or in combination with visual motion-in-depth signals. Auditory stimuli were rising and falling intensity complex tones, 1, 2 or 4 seconds in duration, simulating sound sources moving in depth at a constant velocity. Visual stimuli were expanding/contracting black disks. We independently varied strength and speed of the simulated source. Preliminary spectral analysis of LFP data shows a bigger sustained increase in gamma band (30-50 Hz) activity in response to rising intensity sounds compared to falling intensity sounds in 10 out of 19 cortical sites. This response is not triggered by the stimulus reaching an absolute intensity threshold. Because of the close link between auditory intensity and distance, and the behavioral relevance for detecting approaching motion, we hypothesize that dynamic auditory intensity is encoded as dynamic distance for the following reasons: 1) responses were biased towards rising intensity, in parallel with known behavioral biases; 2) responses were independent of absolute intensity; and 3) responses were enhanced when auditory stimuli were paired with congruent but not incongruent visual motion-in-depth signals.}, department = {Department B{\"u}lthoff}, department2 = {Department Logothetis}, web_url = {http://www.sfn.org/absarchive/}, event_place = {Washington, DC, USA}, event_name = {35th Annual Meeting of the Society for Neuroscience (Neuroscience 2005)}, author = {Maier, J and Logothetis, NK and Ghazanfar, AA} } @Poster { MaierLG2005_2, title = {Multisensory processing of looming signals in primates}, year = {2005}, month = {6}, volume = {6}, number = {31}, abstract = {The world is full of rapidly approaching danger. In order to survive in such a dynamic and dangerous environment, one must perceive and respond appropriately such events. Looming signals are those sensory cues that indicate the rapid approach of objects. Many animal species possess behavioral biases toward visual and auditory looming signals. However, the ability to integrate looming signals across modalities has not been directly studied and is the subject of the presented work. First, using a preferential looking paradigm, we found that rhesus monkeys naturally integrate auditory-visual looming signals, using simple motion-in-depth cues (dynamic intensity change and visual expansion/contraction). Second, in a psychophysical study in humans, we found that humans also spontaneously integrate auditory-visual motion-in-depth signals. Finally, to investigate the neural correlates of this integration, we recorded local field potential (LFP) activity in the monkey temporal lobe while the subject was presented with auditory, visual and bimodal looming and receding signals. Preliminary analysis of LFP signals shows multisensory effects in auditory cortex, and increased coherence between simultaneously recorded LFP signals in auditory cortex and STS during bimodal stimulation. These results might suggest that the brain integrates information across modalities by synchronizing activity from different sensory areas.}, department = {Department B{\"u}lthoff}, department2 = {Department Logothetis}, web_url = {http://imrf.mcmaster.ca/IMRF/2005/}, event_place = {Trento, Italy}, event_name = {6th International Multisensory Research Forum (IMRF 2005)}, author = {Maier, J and Logothetis, NK and Ghazanfar, A} } @Poster { HoffmanGGL2004, title = {Category-specific responses for faces and objects in the superior temporal sulcus and beyond}, year = {2004}, month = {10}, volume = {34}, number = {525.3}, abstract = {Single unit responses in the lower bank of the superior temporal sulcus and inferotemporal cortex show selectivity for faces and objects; however, the degree of selectivity beyond these unimodal visual areas is not well understood. Simultaneous recordings were collected from electrodes placed in multisensory regions of the upper bank of the superior temporal sulcus (uSTS), and in the lateral belt of auditory cortex, which is heavily interconnected with uSTS. The monkey passively viewed three classes of static images: monkey faces, various clip-art objects, and Greebles, an artificial set of homogeneous stimuli. Electrodes in auditory cortex as well as those in uSTS showed local field potential response profiles which differed for faces than for either Greebles or objects. The ‘face’ response in both recorded regions was characterized by a peak negativity around 100ms after stimulus onset. Multiple- and single-unit activity in uSTS revealed a variety of response selectivities to the three stimulus categories, but the most common was an enhanced response for the face stimuli. Discriminatory responses began as early as 50-70ms after stimulus onset. Taken together, these results indicate that 1. faces and objects elicit differentiable neural responses, even outside of unimodal visual areas, 2. Greeble responses are more closely associated with object than with face responses, and 3. category discrimination can occur at early latencies even in multisensory ‘association’ cortex.}, web_url = {http://www.sfn.org/absarchive/}, event_place = {San Diego, CA, USA}, event_name = {34th Annual Meeting of the Society for Neuroscience (Neuroscience 2004)}, author = {Hoffman, KL and Ghazanfar, AA and Gauthier, I and Logothetis, NK} } @Poster { HoffmanGGL2004_2, title = {Differential responses for faces and objects in auditory cortex and superior temporal sulcus}, year = {2004}, month = {6}, volume = {5}, number = {133}, abstract = {Behavioral and neural evidence suggests that faces are represented as a distinct class from other objects. Face-selective single unit reponses are most commonly found in unimodal visual areas such as the lower bank of superior temporal sulcus and the contiguous inferotemporal region. We investigated 1) the degree to which such face/object classifications occur beyond unimodal visual areas and 2) whether Greebles, an artificial set of homogeneous stimuli, elicit responses from sites that are also face-responsive. Simultaneous electrode recordings were collected from auditory cortex and the upper bank of the superior temporal sulcus (uSTS). The monkey passively viewed three classes of static images: monkey faces, various clip-art objects, and Greebles. The local field potential (LFP) response to faces was characterized by a peak negativity around 100ms after stimulus onset in both auditory cortex and uSTS. Both regions responded to objects and Greebles; however, their LFPs typically had a longer latency to peak, and a different response profile when compared with the face response. The relationship between the LFP response and spiking activity will also be described.}, department = {Department Logothetis}, web_url = {http://imrf.mcmaster.ca/IMRF/2004/}, event_place = {Barcelona, Spain}, event_name = {5th International Multisensory Research Forum (IMRF 2004)}, author = {Hoffman, K and Ghazanfar, A and Gauthier, I and Logothetis, NK} } @Poster { NielsenLG2004, title = {Eye movements of monkey perceivers during viewing of species-specific vocal signals}, year = {2004}, month = {6}, volume = {5}, number = {64}, abstract = {Primates use auditory and visual cues to process the vocal communication signals produced by members of their species. For human speech, facial cues are known to enhance perception of speech under noisy conditions. That is, if speech has to be followed at high background noise levels, the ability to see a talker’s face enhances intelligibility. Recently, studies have examined the eye movement patterns of humans while viewing talkers under varying levels of naturalistic background noise (Vatikiotis-Bateson et al. (1998) Perception \& Psychophysics 60: 926). Under all noise conditions, human perceivers mostly fixate the eye region, followed by the mouth region, but as the background noise increases, they increase their number of fixations on the mouth region. To characterize potential behavioral homologies between monkey and human vocal communication, we have been investigating the eye movement patterns of rhesus monkeys while they view digitized videos of conspecifics producing vocalizations under three different background noise levels. We are analyzing how the simultaneous presentation of a dynamic facial expression and its corresponding vocalization influences the gaze patterns of monkey observers. Such data will give us insights into the evolution of sensory and motor mechanisms used in primate vocal communication.}, department = {Department Logothetis}, web_url = {http://imrf.mcmaster.ca/IMRF/2004/}, event_place = {Barcelona, Spain}, event_name = {5th International Multisensory Research Forum (IMRF 2004)}, author = {Nielsen, KJ and Logothetis, NK and Ghazanfar, AA} } @Poster { MaierNLG2004, title = {Monkeys naturally integrate auditory-visual looming signals}, year = {2004}, month = {6}, volume = {5}, number = {65}, abstract = {Looming signals (signals that indicate the rapid approach of objects) are behaviourally relevant for primates. We investigated whether rhesus monkeys can integrate the auditory and visual signals of a simulated looming object using the preferential-looking method. Monkeys were presented with two black discs, each on a separate LCD monitor. One disk symmetrically expanded (‘visual looming’), while the other disk symmetrically contracted (‘receding’ stimulus). An auditory signal synchronized with both visual stimuli but either increasing (‘auditory looming’) or decreasing (‘receding’) in intensity was played through a centrally-located speaker (see Ghazanfar et al. (2003) PNAS 99:15755-15757). Viewing behaviour was video-taped, digitized and looking times measured. Our preliminary results reveal that all subjects looked longer at the visual looming stimulus when presented simultaneously with an auditory looming stimulus. Conversely, the effect of the receding sound had little or no influence on their viewing behaviour. Monkeys thus appear to naturally integrate auditory-visual looming signals without any explicit training. The integration of looming, but not receding stimuli, may be because of the strong behavioural relevance of approaching objects. Since many neurons in the superior temporal sulcus are polysensory and selective for looming visual stimuli, we are currently investigating whether such neurons integrate auditory-visual looming signals.}, department = {Department B{\"u}lthoff}, department2 = {Department Logothetis}, web_url = {http://imrf.mcmaster.ca/IMRF/2004/}, event_place = {Barcelona, Spain}, event_name = {5th International Multisensory Research Forum (IMRF 2004)}, author = {Maier, J and Neuhoff, J and Logothetis, NK and Ghazanfar, A} } @Poster { GhanzafarLHL2003, title = {Acoustic parameters underlying vocalization-sensitive neural responses in Rhesus monkey auditory cortex}, year = {2003}, month = {11}, volume = {33}, number = {181.14}, abstract = {The vocal behavior of macaque monkeys has been studied extensively in both field and laboratory settings. To date, however, no investigation has systematically examined the neural mechanisms underlying species-specific recognition of their vocalizations. To bridge this gap, we are investigating the auditory representation of conspecific vocalizations in the neocortex of behaving rhesus monkeys. Subjects performed a simple auditory detection task during which, on each trial, they listened to a conspecific vocalization followed by a non-vocal, target sound. The stimulus set consisted of call types familiar to our captive-bred subjects but from unknown individuals: three exemplars from each of 7 call categories. Our preliminary investigation using these natural stimuli (Ghazanfar et al, SFN 2002) revealed that \verb=~=45\% of auditory belt cortical multi-units were selective for 1 or 2 call categories. This suggests that the macaque auditory cortex is specialized to process communication sounds. To assess the degree of this specialization and the specificity of vocalization-sensitivity, we are comparing single-unit responses to vocalizations with time-reversed versions, pure-tones and band-passed noise. For each vocalization, a pure-tone and a band-passed noise stimulus were generated to match the signal’s duration, dominant frequency and average RMS power. Recordings from both core and belt cortical areas will determine whether vocalization-sensitive neurons in these regions are driven by simple features of the signal or by more complex interactions between spectral and temporal properties.}, department = {Department Logothetis}, web_url = {http://www.sfn.org/index.aspx?pagename=annualmeeting_futureandpast}, event_place = {New Orleans, LA, USA}, event_name = {33rd Annual Meeting of the Society for Neuroscience (Neuroscience 2003)}, author = {Ghanzafar, AA and Leopold, DA and Hauser, MD and Logothetis, NK} } @Poster { 1551, title = {Neural responses to species-specific vocalizations in the auditory association cortex of the awake behaving rhesus monkey}, year = {2002}, month = {11}, volume = {32}, number = {588.15}, abstract = {The design of the primate auditory system should reflect the specialized functions that it evolved to carry out. One such function is conspecific vocal recognition. Measuring the neural selectivity to vocalizations is a way to identify the mechanisms underlying this auditory specialization. Previous studies examining call selectivity in the primate auditory cortex suffered from two drawbacks: an impoverished stimulus set and/or the use of anesthetized or passive-listening paradigms. We adopted a simple behavioural task to study how neurons in the rhesus monkey auditory cortex respond to conspecific vocalizations. Two monkeys were trained to listen to sound sequences composed of one or two conspecific vocalizations (mean SPL=79.9 dB) and an artificial horn sound (frequency bandwidth: 788Hz-11kHz; 300ms in duration; SPL=69.7 dB) presented in free-field. They were rewarded if they pulled a lever within 1 sec following the horn sound. Both monkeys were able to do this task at >95\%-correct performance levels. This task requires that the monkey attend in the auditory domain without the confounds of over-training on vocalizations and the response lability that occurs during passive-listening. Our stimuli consist of 3 exemplars from each of 7 call categories (coos, pant-threats, grunts, aggressive barks, shrill barks, noisy screams and harmonic arches). Using this paradigm, we are investigating whether the responses of auditory ‘belt’ cortical neurons reflect category-level selectivity to conspecific vocalizations.}, department = {Department Logothetis}, web_url = {http://www.sfn.org/absarchive/}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {Orlando, FL, USA}, event_name = {32nd Annual Meeting of the Society for Neuroscience (Neuroscience 2002)}, author = {Ghazanfar, AA and Pauls, J and Leopold, DA and Hauser, MD and Logothetis, NK} } @Poster { 1198, title = {Periods of stimulus absence stabilize the perception of ambiguous patterns}, year = {2001}, month = {11}, volume = {31}, number = {165.16}, abstract = {A fundamental property of ambiguous visual patterns is the inevitability of perceptual reversal. The rate of alternation generally depends both upon the physical structure of the stimulus as well as the inherent rate of an individual. Here we present evidence that critical to the reversal process is the prolonged physical presence of the inducing stimulus. We demonstrate that when stimuli are shown only intermittently, the rate of perceptual alternation sharply declines to nearly zero in some subjects. In particular, we found that rotating three-dimensional bistable patterns with mean dominance times less than 10 seconds could be stabilized for periods lasting over ten minutes by correctly adjusting the duration of on and off periods. Since either perceptual state could be maintained in this way, this effect did not simply reflect a perceptual bias on the part of the observer. This trend was also present for other bistable patterns, including those involving geometric depth reversals and apparent motion correspondence. We systematically investigated the influence of stimulus on and off durations on the stability of such patterns, and found that minimizing the duration of the stimulus on time was the predominant factor in perceptual stabilization. We suggest that upon removal of the inducing stimulus a visual memory process retains and holds the last perceptual state, which persists and governs the perceptual interpretation during the subsequent presentation. Electrophysiological studies are currently underway to better elucidate the neural mechanisms contributing to this phenomenon.}, department = {Department Logothetis}, web_url = {http://www.sfn.org/index.aspx?pagename=abstracts_ampublications}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {San Diego, CA, USA}, event_name = {31st Annual Meeting of the Society for Neuroscience (Neuroscience 2001)}, author = {Wilke, M and Maier, A and Leopold, DA and Ghazanfar, AA and Logothetis, NK} } @Miscellaneous { 1452, title = {Book Review - Animal Experimentation: A Guide to the Issues. By Vaughan Monamy}, journal = {Animal Behaviour}, year = {2002}, month = {3}, volume = {63}, number = {3}, pages = {631-632}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science/article/pii/S0003347201919633}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1006/anbe.2001.1963}, author = {Ghazanfar, AA} } @Miscellaneous { 1110, title = {Flexible Apes - Tree of Origin: What Primate Behavior Can Tell Us about Human Social Evolution by Frans B. M. de Waal}, journal = {American Scientist}, year = {2002}, month = {1}, volume = {90}, number = {1}, pages = {90-92}, department = {Department Logothetis}, web_url = {http://www.jstor.org/stable/27857612}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA} } @Miscellaneous { 1109, title = {Hanging around with baboons}, journal = {Trends in Cognitive Science}, year = {2001}, month = {8}, volume = {5}, number = {8}, pages = {366-367}, abstract = {A Primate's Memoirs: A Neuroscientist's Unconventional Life Among the Baboons by Robert M. Sapolsky, Scribner, 2001. $25.00 (304 pages) ISBN 0 743 20247 3 I will admit from the outset that Robert Sapolsky is one of my heroes. During my junior year of college, I read his treatise ‘Stress, the Aging Brain, and the Mechanisms of Neuron Death’ 1. Twice. Although I never went on to study stress, aging or neuron death, the book made me realize that one could be both a neuroscientist and a field biologist…and be good ones. Sapolsky showed that this two-pronged approach to the study of the brain and behavior was both intellectually fertile and loads of fun. I've been trying to be like him ever since, and A Primate's Memoirs is the book I would want to write someday – the true-life adventure story of 20 or so summers studying primates in the Serengeti plains of East Africa. From these pages, we learn much about primates, both human and non-human, and about humility (and humour) in the face of adversity.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science/article/pii/S1364661300017009}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1016/S1364-6613(00)01700-9}, author = {Ghazanfar, AA} } @Miscellaneous { 1107, title = {Biomedical research and animal welfare: a delicate balance}, journal = {Nature Neuroscience}, year = {2001}, month = {3}, volume = {4}, number = {3}, pages = {227-229}, web_url = {http://www.nature.com/neuro/journal/v4/n3/full/nn0301_227.html}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1038/85055}, author = {Ghazanfar, AA} } @Miscellaneous { 1106, title = {Review of \&\#8220;Sound\&\#8221; edited by P. Kruth \& H. Stobart.}, journal = {The Physiologist}, year = {2001}, volume = {44}, pages = {50}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Ghazanfar, AA} } @Conference { MaierG2004, title = {Auditory and Multisensory Perception of Looming Signals by Rhesus Monkeys: A Naturalistic Behaviour Research}, year = {2004}, month = {8}, volume = {5}, pages = {10}, abstract = {Brains have evolved to process information that is important for the survival of animals in their natural environment. Instead of using experimental paradigms that involve artificial or arbitrary stimuli and a high degree of training and conditioning, it would therefore be better to study animals’ natural behavior and reactions using behaviourally-relevant stimuli. One of the most basic needs of animals is to be able to deal with rapidly approaching dangerous objects (predators, competitive individuals or abiotic sources). Animals across the animal kingdom show a bias for detecting looming signals --signals that indicate the rapid approach of objects-- over receding signals, in the visual domain. However, when vision fails, for example in darkness, animals must rely on their auditory system to detect looming motion. Under conditions where both visual and auditory signals can be detected, their bimodal integration can enhance detection and discriminability. We studied rhesus monkeys’ (Macaca mulatta) spontaneous behaviour in response to auditory and multisensory looming stimuli. First, using the head-orientation response, we showed that in the auditory domain, monkeys also have a bias for detecting looming signals over receding signals. We tested the effectiveness of two different auditory motion cues --dynamic intensity and pitch change-- for detecting looming sound sources. Both cues proved effective in detecting looming motion. Second, using the preferential looking paradigm, we showed that monkeys have a natural capacity for integrating auditory-visual looming, but not receding signals. This ability was dependent on the spectral structure of the sound. The results suggest an evolved bias for detecting ecologically relevant looming signals and reveal the power of using naturalistic paradigms for investigating the perception of sensory signals in primates.}, department = {Department B{\"u}lthoff}, department2 = {Department Logothetis}, talk_type = {Abstract Talk}, web_url = {http://www.neuroschool-tuebingen-nena.de/index.php?id=284}, event_place = {Oberjoch, Germany}, event_name = {5. Neurowissenschaftliche Nachwuchskonferenz T{\"u}bingen (NeNa '04)}, author = {Maier, JX and Ghazanfar, AA} }