RT Journal Article
SR Electronic
T1 Decoding the time course of spatial information from spiking and local field potential activities in the superior colliculus
JF eneuro
JO eNeuro
FD Society for Neuroscience
SP ENEURO.0347-22.2022
DO 10.1523/ENEURO.0347-22.2022
A1 Heusser, Michelle R.
A1 Bourrelly, Clara
A1 Gandhi, Neeraj J.
YR 2022
UL http://www.eneuro.org/content/early/2022/11/11/ENEURO.0347-22.2022.abstract
AB Place code representation is ubiquitous in circuits that encode spatial parameters. For visually guided eye movements, neurons in many brain regions emit spikes when a stimulus is presented in their receptive fields and/or when a movement is directed into their movement fields. Crucially, individual neurons respond for a broad range of directions or eccentricities away from the optimal vector, making it difficult to decode the stimulus location or the saccade vector from each cell’s activity. We investigated whether it is possible to decode the spatial parameter with a population-level analysis, even when the optimal vectors are similar across neurons. Spiking activity and local field potentials (LFP) in the superior colliculus were recorded with a laminar probe as monkeys performed a delayed saccade task to one of eight targets radially equidistant in direction. A classifier was applied offline to decode the spatial configuration as the trial progresses from sensation to action. For spiking activity, decoding performance across all eight directions was highest during the visual and motor epochs and lower but well above chance during the delay period. Classification performance followed a similar pattern for LFP activity too, except the performance during the delay period was limited mostly to the preferred direction. Increasing the number of neurons in the population consistently increased classifier performance for both modalities. Overall, this study demonstrates the power of population activity for decoding spatial information not possible from individual neurons.SIGNIFICANCE STATEMENTWe make countless goal-directed eye movements each day. Individual neurons that signal for the appearance of a visual stimulus and/or the execution of a rapid eye movement often fire at comparable levels for very different spatial parameters. We recorded both spiking activity and local field potential (LFP) signals across many channels simultaneously and asked whether the spatial parameter of target or saccade direction can be decoded across a broad range of the visual field. Applying simple categorical classifiers to ‘populations’ of neurons, we found that both spiking and LFP activity were informative of direction early on, starting at the initial visual response and continuing through movement initiation. This investigation demonstrates the advantage of a population-level framework over traditional approaches.