New perspectives of information transformation through the auditory cortical layers

Abstract

Neurons in sensory, motor, and association areas of the mammalian neocortex usually are organized in columns of six layers, in which the layers divide by the morphology of the neurons into three major subdivisions, the granular cell layer (mainly layer IV), the supragranular layers I–III, and the infragranular layers V and VI (1–3). The types of neurons in the layers, the connections between neurons within and between the layers, and the types and patterns of input projections determine how information is transformed when it passes through the cortical layers. Because of the rather stereotyped main excitatory pathway from the thalamic input to the granular cell layer and further to the supragranular and infragranular layers (4), the information transformation through the cortical layers may follow a general, basic scheme. Local modifications of this scheme could allow for area- and field-specific adaptations to the needs of processing different sensory, motor, or associative information. The study by Atencio et al. in this issue of PNAS (5) provides a breakthrough in describing properties of a basic scheme of information transformation in the neocortex, taking the cat primary auditory cortex as an example.