Hierarchical computation in the canonical auditory cortical circuit.
Sensory cortical anatomy has identified a canonical microcircuit underlying computations between and within layers. This feed-forward circuit processes information serially from granular to supragranular and to infragranular layers. How this substrate correlates with an auditory cortical processing hierarchy is unclear. We recorded simultaneously from all layers in cat primary auditory cortex (AI) and estimated spectrotemporal receptive fields (STRFs) and associated nonlinearities. Spike-triggered averaged STRFs revealed that temporal precision, spectrotemporal separability, and feature selectivity varied with layer according to a hierarchical processing model. STRFs from maximally informative dimension (MID) analysis confirmed hierarchical processing. Of two cooperative MIDs identified for each neuron, the first comprised the majority of stimulus information in granular layers. Second MID contributions and nonlinear cooperativity increased in supragranular and infragranular layers. The AI microcircuit provides a valid template for three independent hierarchical computation principles. Increases in processing complexity, STRF cooperativity, and nonlinearity correlate with the synaptic distance from granular layers.
Atencio
Craig A
CA
University of California, San Francisco/University of California, Berkeley Bioengineering Graduate Group, W. M. Keck Foundation Center for Integrative Neuroscience, and Coleman Memorial Laboratory, Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, CA 94143, USA.
Sharpee
Tatyana O
TO
Schreiner
Christoph E
CE
D000200:Action Potentials; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D002415:Cats