A Differential Circuit via Retino Colliculo Pulvinar Pathway Enhances Feature Selectivity in Visual Cortex through Surround Suppression
In the mammalian visual system, information from the retina streams into parallel bottom up pathways. It remains unclear how these pathways interact to contribute to contextual modulation of visual cortical processing. By optogenetic inactivation and activation of mouse lateral posterior nucleus (LP) of thalamus, a homolog of pulvinar, or its projection to primary visual cortex (V1) we found that LP contributes to surround suppression of layer (L) 2/3 responses in V1 by driving L1 inhibitory neurons. This results in subtractive suppression of visual responses and an overall enhancement of orientation, direction, spatial, and size selectivity. Neurons in V1 projecting LP regions receive bottom up input from the superior colliculus (SC) and respond preferably to non patterned visual noise. The noise dependent LP activity allows V1 to "cancel" noise effects and maintain its orientation selectivity under varying noise background. Thus, the retina SC LP V1 pathway forms a differential circuit with the canonical retino geniculate pathway to achieve context dependent sharpening of visual representations.
Neuron