Freiburg Neuroscience Lecture Series |
"Brain-wide patterns of neural activity underlying a visual decision task"
by Prof Kenneth Harris (University College London)
Behavior arises from neuronal activity patterns, but whether the relevant activity is concentrated in a small number of regions or distributed across the brain remains unknown.
We studied how mice perform a visually-guided perceptual decision task. Subjects were trained to give one of three responses (choose left, right, or neither) depending on the relative contrast of two simultaneously presented visual stimuli. Widefield imaging of dorsal cortex revealed that after stimulus presentation, activity progressed from primary visual cortex to secondary visual areas, secondary motor cortex, and finally primary motor cortex. Optogenetic inactivation of visual cortex and secondary motor cortex impaired task performance, with the critical time-window for inactivation being earlier in visual cortex. Inactivating primary motor cortex, however, did not impair performance.
We used Neuropixels electrodes to record the activity of >20,000 neurons across the brain during task performance. These arrays span ~4 mm of tissue and thus record simultaneously across diverse brain regions, including sensory, parietal, frontal, and motor isocortex; thalamic nuclei; hippocampus; striatum; superior colliculus; and multiple midbrain structures. Neurons responding to visual stimuli or predicting decisions were localized to specific brain regions, but neurons with correlates of ongoing movement or recent reward were widespread. Visually responsive neurons were found in superficial superior colliculus, visual cortex, and striatum.
Neurons that predicted the animal’s choice substantially prior to movement (~100ms) were found in deep superior colliculus and the mesencephalic reticular formation. However, activity concurrent with action execution and following reward delivery were observed in nearly every region we recorded.
We suggest that when animals perform this task, visual information flows through visual and secondary motor cortices and striatum, to the midbrain where a behavioral choice is selected. By contrast, corollary information about ongoing movements and rewards is represented globally including in primary motor cortex, but this activity is not required for task execution.
Further information: www.neuro.uni-freiburg.de/events
DATES AND VENUE
Tuesday, April 09, 2019 | 12:15 PM to 01:15 PM
Institute of Biology I | Lecture Hall | First Floor