The neocortical circuit: themes and variations

• Published in: Nature neuroscience Vol. 18; no. 2; pp. 170 - 181
• Main Authors: Harris, Kenneth D, Shepherd, Gordon M G
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.02.2015; Nature Publishing Group
• Subjects: 13/51; 631/378/3920; 64/60; 9/74; Animal Genetics and Genomics; Animals; Behavioral Sciences; Biological Techniques; Biomedicine; Brain mapping; Brain research; Humans; Interneurons - physiology; Medical examination; Neocortex; Neocortex - cytology; Neocortex - physiology; Nerve Net - cytology; Nerve Net - physiology; Neural circuitry; Neurobiology; Neurosciences; Physiological aspects; review-article
• ISSN: 1097-6256; 1546-1726
• DOI: 10.1038/nn.3917

Harris and Shepherd review our knowledge of input and output patterns for different classes of cortical cells. They propose that cortex, like other parts of the body, has a serially homologous organization, featuring area- and species-specific variations on a basic theme, that allows different types of function to emerge. Similarities in neocortical circuit organization across areas and species suggest a common strategy to process diverse types of information, including sensation from diverse modalities, motor control and higher cognitive processes. Cortical neurons belong to a small number of main classes. The properties of these classes, including their local and long-range connectivity, developmental history, gene expression, intrinsic physiology and in vivo activity patterns, are remarkably similar across areas. Each class contains subclasses; for a rapidly growing number of these, conserved patterns of input and output connections are also becoming evident. The ensemble of circuit connections constitutes a basic circuit pattern that appears to be repeated across neocortical areas, with area- and species-specific modifications. Such 'serially homologous' organization may adapt individual neocortical regions to the type of information each must process.