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Contact

Britni Crocker

Address: 72076 Tübingen
E-Mail: britni.crocker

 

Picture of Crocker, Britni

Britni Crocker

Position: Undergraduate Research Assistant  Unit: Alumni Logothetis

Information theoretic analysis of electrophysiological signals
in the macaque prefrontal cortex

 

Neural Coding in the Lateral Prefrontal Cortex


Visual information from both dorsal and ventral streams of the cortex terminate in the lateral prefrontal cortex (lPFC), a cortical area thought to be involved in working memory, attentional control, and abstract higher-order thinking. In an effort to unravel how the lateral prefrontal cortex codes for visual information we use an information-theoretic approach to analyze neural activity in the lPFC during the presentation of dynamic visual stimuli. Studies in other brain areas have shown that local field potentials (LFP) convey information separate from and in parallel to the spiking activity of neurons [1,2]. Our aim is to determine how visual information is coded in the lPFC and whether that coding differs from the results reported in sensory areas.

 

Our Research Methods


We use multi-electrode array (MEA) recordings and functional imaging to study the fine details neural coding and spatial structure of visual information in the lPFC of the anesthetized macaque.  In particular, we record and analyze the LFP and spiking activity during the repeated presentation of dynamic visual stimuli (10 second video clips) of varying contrast.  Using the Information Breakdown ToolBox, we calculate the mutual information between these various neurophysiological signals and the visual stimuli.

 

Present Results and Next Steps


Our preliminary results have shown that LFP in the lPFC is modulated by the presentation of visual stimuli (see Figure 1), especially in the low frequencies (1-10 Hz).  Consistent with studies in other areas, the phase of the LFP signal carries more information than the amplitude – up to an order of magnitude in our data.  Interestingly, these two informative components of LFP have different spatial distributions; while LFP phase information is spread out relatively evenly across most channels, information in the LFP amplitude is the result of a few informative channels.  In addition to confirming these results, we are now analyzing the spiking activity and integrating our findings with results from functional imaging studies.

 

Figure 1:

Representative LFP signals from 2 different stimulus presentations: one with high contrast (left) and one with low contrast (right).  (Movie Contrast) The frame-by-frame movie contrast (green).  The high contrast movie has  larger fluctuations in contrast over time.  (Average Voltage) The voltage recorded by a representative channel averaged over trials (blue).  (Filtered Signal) The filtered signal from the channel in a limited frequency range, averaged over trials (red).  (Amplitude and Phase) LFP amplitude and phase in the 1-4 Hz range over time and trials for a representative channel.  Each horizontal line indicates a single trial.  For the amplitude, cool colors represent relative low amplitude and hot colors represent relative high amplitude.  For the phase, the spectrum from cold to hot colors indicates phase values between negative pi and pi.  Responses to the stimuli are more robust in the presentation of the high contrast movie than the low contrast movie and are more robust in the phase of the signal than in its amplitude.

 

Collaborators


Dr. Theofanis Panagiotaropoulos

(MPI for Biological Cybernetics, Tubingen, Germany)

Dr. Michel Besserve

(MPI for Biological Cybernetics, Tubingen, Germany)

Dr. Stefano Panzeri

(Italian Institute of Technology, Robotics, Brain and Cognitive Sciences Department, Genova, Italy)

Dr. Andreas Tolias

(Baylor College of Medicine, Department of Neuroscience, Houston, U.S.A)

Dr. Jozien Goense

(MPI for Biological Cybernetics, Tubingen, Germany)

 

References


[1] Belitski, A, A Gretton, C Magri, Y Murayama, M A Montemurro, N K Logothetis, and S Panzeri. 2008. Low-Frequency Local Field Potentials and Spikes in Primary Visual Cortex Convey Independent Visual Information. J. Neurosci. 28, no. 22 (May 28): 5696-5709.

 

[2] Kayser, C, M A Montemurro, N K Logothetis, and S Panzeri. 2009. Spike-Phase Coding Boosts and Stabilizes Information Carried by Spatial and Temporal Spike Patterns. Neuron 61, no. 4 (2): 597-608.

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Posters (3):

Besserve M Person, Panagiotaropoulos T Person, Crocker B Person, Kapoor V Person, Tolias A Person, Panzeri S Person and Logothetis NK Person (February-2012): Identifying endogenous rhythmic spatio-temporal patterns in micro-electrode array recordings, 9th Annual Computational and Systems Neuroscience Meeting (Cosyne 2012), Salt Lake City, UT, USA.
Crocker B Person, Kapoor V Person, Panzeri S Person, Logothetis NK Person and Panagiotaropoulos T Person (November-2011): Low frequency local field potentials in the inferior convexity of the macaque prefrontal cortex convey visual information during anesthesia, 41st Annual Meeting of the Society for Neuroscience (Neuroscience 2011), Washington, DC, USA.
Panagiotaropoulos T Person, Besserve M Person, Crocker B Person, Kapoor V Person, Tolias AS Person, Panzeri S Person and Logothetis NK Person (November-2011): Spatiotemporal mapping of rhythmic activity in the inferior convexity of the macaque prefrontal cortex, 41st Annual Meeting of the Society for Neuroscience (Neuroscience 2011), Washington, DC, USA.

Theses (1):

Crocker B Person: An information-theoretic analysis of neural signals in macaque ventrolateral prefrontal cortex, International Max Planck Research School Tübingen: Graduate School of Neural & Behavioural Sciences, (May-2011). Master thesis

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Last updated: Friday, 17.01.2014