Abstract
Two-photon imaging studies in mouse primary visual cortex (V1) consistently report that around half of the neurons respond to oriented grating stimuli. However, in cats and primates, nearly all neurons respond to such stimuli. Here we show that mouse V1 responsiveness and selectivity strongly depends on neuronal depth. Moving from superficial layer 2 down to layer 4, the percentage of visually responsive neurons nearly doubled, ultimately reaching levels similar to what is seen in other species. Over this span, the amplitude of neuronal responses also doubled. Moreover, stimulus selectivity was also modulated, not only with depth but also with response amplitude. Specifically, we found that orientation and direction selectivity were greater in stronger responding neurons, but orientation selectivity decreased with depth whereas direction selectivity increased. Importantly, these depth-dependent trends were found not just between layer 2/3 and layer four but at different depths within layer 2/3 itself. Thus, neuronal depth is an important factor to consider when pooling neurons for population analyses. Furthermore, the inability to drive the majority of cells in superficial layer 2/3 of mouse V1 with grating stimuli indicates that there may be fundamental differences in the micro-circuitry and role of V1 between rodents and other mammals.
Significance Statement Studies frequently pool responses of neurons from different cortical depths in population analyses. Here we show that population neuronal response characteristics in mouse primary visual cortex vary dramatically across depth planes separated by just 50 μm. We also demonstrate that the stimulus selectivity of neuronal responses varies with both cortical depth and the response amplitude of neurons. These findings highlight the importance of considering cell depth and response amplitude as important factors contributing to the overall characteristics of neurons in sensory cortex.
Footnotes
Authors report no conflict of interest.
R01MH111447 and R21AA022168
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