minicolumns

Minicolumns are vertical clusters of neurons in the cerebral cortex that extend from the pial surface down toward the white matter and are considered a fundamental structural and functional unit of cortical processing. They were described as a repeated modular organization of the cortex by Vernon Mountcastle in the mid-20th century. A minicolumn typically has a diameter of about 30 to 50 micrometers and spans multiple cortical layers, containing tens to a few hundred neurons, including excitatory pyramidal cells and inhibitory interneurons. The neurons within a minicolumn are strongly interconnected along the vertical axis, with connections that descend and ascend through layers, while horizontal connections link neighboring columns to form larger networks. Groups of minicolumns form macrocolumns or cortical modules, which are thought to process specific types of information such as sensory features or motor plans.

Functional roles attributed to minicolumns include the encoding and propagation of localized information and the coordination of activity across layers to support pattern recognition, feature binding, and timing. The modular arrangement supports parallel processing and integration within larger cortical circuits that receive input from the thalamus and project to higher cortical areas.

Developmentally, minicolumns arise from radial migration of neurons and subsequent synaptic refinement; their density and spacing differ by cortical region and species. Clinically, atypical minicolumn organization has been reported in several neurodevelopmental and psychiatric disorders, including autism spectrum disorders and schizophrenia, though findings vary and interpretation remains debated.

See also: Cortical column, Macrocolumn.