Temporal structure in neuronal activity during working memory in macaque parietal cortex


Many cortical structures have elevated firing rates during working memory, but it is not known how the activity is maintained. To investigate whether reverberating activity is important, we studied the temporal structure of local field potential (LFP) activity and spiking from area LIP in two awake macaques during a memory-saccade task. Using spectral analysis, we found spatially tuned elevated power in the gamma band (25–90 Hz) in LFP and spiking activity during the memory period. Spiking and LFP activity were also coherent in the gamma band but not at lower frequencies. Finally, we decoded LFP activity on a single-trial basis and found that LFP activity in parietal cortex discriminated between preferred and anti-preferred direction with approximately the same accuracy as the spike rate and predicted the time of a planned movement with better accuracy than the spike rate. This finding could accelerate the development of a cortical neural prosthesis.

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Figure 1: The memory-saccade task.
Figure 2: LFP spectrograms averaged across trials during saccades to either the preferred or anti-preferred direction.
Figure 3: Tuning of spiking and LFP activity.
Figure 4: Spike spectrum.
Figure 5: Spike spectrograms.
Figure 6: Spike-triggered average potential from a single cell at a single site.
Figure 7: Coherency of spiking and LFP activity across time.
Figure 8: Single-trial decoding of a movement plan.


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This work was supported by the DARPA grant MDA972-00-1-0029, NIH grants EY05522-21 and MH62528-01, ONR grant N00014-94-0412, the Keck Foundation, the McKnight Foundation, the Sloan-Swartz Foundation, the Center for Neuromorphic Systems Engineering at Caltech and the Workshop for the Analysis of Neural Data (http://www.vis.caltech.edu/~WAND).

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Correspondence to Richard A. Andersen.

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Pesaran, B., Pezaris, J., Sahani, M. et al. Temporal structure in neuronal activity during working memory in macaque parietal cortex. Nat Neurosci 5, 805–811 (2002). https://doi.org/10.1038/nn890

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