Network-selectivity and stimulus-discrimination in the primary visual cortex: cell-assembly dynamics

• Published in: The European journal of neuroscience 2016-01, Vol.43 (2), p.204-219
• Main Authors: Bharmauria, Vishal, Bachatene, Lyes, Cattan, Sarah, Brodeur, Simon, Chanauria, Nayan, Rouat, Jean, Molotchnikoff, Stéphane
• Format: Article
• Language: English
• Subjects: Action Potentials; Animals; assembly-dynamics; cat; Cats; Female; functional connection; Male; network-selectivity; Neurons - physiology; Photic Stimulation; primary visual cortex; stimulus-discrimination; Visual Cortex - physiology; Visual Perception - physiology
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/ejn.13101

Visual neurons coordinate their responses in relation to the stimulus; however, the complex interplay between a stimulus and the functional dynamics of an assembly still eludes neuroscientists. To this aim, we recorded cell assemblies from multi‐electrodes in the primary visual cortex of anaesthetized cats in response to randomly presented sine‐wave drifting gratings whose orientation tilted in 22.5° steps. Cross‐correlograms revealed the functional connections at all the tested orientations. We show that a cell‐assembly discriminates between orientations by recruiting a ‘salient’ functional network at every presented orientation, wherein the connections and their strengths (peak‐probabilities in the cross‐correlogram) change from one orientation to another. Within these assemblies, closely tuned neurons exhibited increased connectivity and connection‐strengths compared with differently tuned neurons. Minimal connectivity between untuned neurons suggests the significance of neuronal selectivity in assemblies. This study reflects upon the dynamics of functional connectivity, and brings to the fore the importance of a ‘signature’ functional network in an assembly that is strictly related to a specific stimulus. It appears that an assembly is the major ‘functional unit’ of information processing in cortical circuits, rather than the individual neurons. A ‘salient’ functional network is activated within an assembly of layer II/III neurons (area 17) in the cat primary visual cortex that is contingent upon the specific orientation of the sine‐wave drifting grating. We suggest that network‐selectivity in an assembly is inevitable for stimulus‐discrimination. This study reflects upon the importance of a ‘signature’ functional network in an assembly that is exclusively related to a particular input.