Pyramidal cells ensheathed by perineuronal nets in human motor and somatosensory cortex.

This study presents data concerning the distribution of chondroitin sulphate proteoglycan-immunoreactive perineuronal nets in sensorimotor areas (Brodmann's areas 3, 1, 2 and 4) of the human cerebral cortex. In addition to previously described subpopulations of nonpyramidal neurons in neocortical areas, many large or medium-sized pyramidal cells in layers III and V, including Betz cells in the motor cortex, were shown to be net-associated and constitute about one-third of all net-associated cells. Such widespread occurrence of perineuronal nets around subpopulations of pyramidal cells is known from macaque monkeys but not from the cortex of myomorph rodents. Thus it appears that a certain proportion of net-associated pyramidal cells distinguishes individual cortical areas in highly evolved primates. This ratio may vary also with respect to species-dependent organization principles in nonprimate mammals.