A seminar hosted by the Bristol Neuroscience Research Network with support from the British Neuroscience Association and the Wellcome Trust Neural Dynamics Programme
Abstract: Perseveration -- repeatedly performing one action even though other choices would lead to larger rewards – is a very common animal behavior. Neither the purpose nor neuronal mechanisms of perseveration are understood. One hypothesis is that performing the same action repeatedly allows quick and efficient execution, because preparatory activity can be established in appropriate brain circuits. If so, there should exist neurons somewhere in the brain whose activity correlates with perseveration and rapid movement execution, and whose inhibition suppresses both.
We trained mice to perform a “two-armed bandit” task, responding to a tone by turning a wheel in one of two directions. Reward was more probable for one turn direction, with the optimal direction switching in blocks. Mouse behavior was best fit by learning models including both reward seeking and perseveration. Reaction times were fastest when choices were repeated. Recordings across the forebrain using Neuropixels electrodes revealed correlates of ongoing choices and rewards in many regions, but neurons whose pre-tone activity predicted upcoming choices were only found in secondary motor cortex (MOs). MOs activity built up over multiple choices to the same side, and predicted rapid reaction times. Optogenetically inhibiting MOs reduced perseveration and slowed reaction times. In contrast, inhibiting medial prefrontal cortex slowed reward-based updating of the optimal choice side but did not affect perseveration.
We hypothesise that in this task, activity in MOs subserves motor preparation. Mice plan their movement in advance of the tone, and MOs activity in the pre-tone period creates a neural state in which the tone quickly releases an action to the chosen side. This hypothesis is further supported by results in a different task, where the appropriate choice cannot be determined prior to the tone, and MOs activity does not predict upcoming choices.
Bio: Prof. Kenneth Harris (University College London). Prof. Kenneth Harris is a leader of the current large-scale recording revolution in neuroscience. Kenneth studied mathematics at Cambridge University, did a PhD in robotics at UCL, then moved to Rutgers University in the United States for postdoctoral work in neuroscience. There he performed pioneering work, in the lab of Gyorgi Buzsaki, on methods for simultaneous recording from large numbers of neurons and on the organisation of cell assemblies in the hippocampus. Before returning to UCL in 2012, he held faculty positions at Rutgers and Imperial College London. He is currently Professor of Quantitative Neuroscience at UCL and together with Prof. Matteo Carandini directs the Cortexlab. He has made seminal contributions to our understanding of cortical circuit organisation, neural population dynamics, state-dependent modulation of cortical circuits and large-scale recording methodology.
Harris profile and the Cortex Lab
To book a 1:1 with the speaker, please contact Catherine Brown. Note there are limited slots available and they will be allocated on a first-come, first-served basis.
The day before the talk BN will be hosting a journal club aimed at Early Career Researchers who will spend a few hours exploring an discussing one of the speaker's publications. Participants of the journal club are then invited to have lunch with the speaker the day of the seminar. Spaces are strictly limited! If you are an ECR, and would like to take part, please contact Seán Froudist-Walsh with your expression of interest. (please note, for this club we are now operating a waiting list)
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