Search Results for « Neocortex »

This is, to date, the only thorough study of the cortex of the most commonly used primate. It has a prologue, seven autonomous chapters and an epilogue. It is written in good prose, with a happy choice of words, preserving familiar terms without loss of precision. Its ninety pages of text include about fourteen pages of tables and clear line drawings schematizing the growth, size and proportion of the brain, its fissural pattern, thickness of layers, survey by serial sections, partial maps by sundry authors and diagrams of interconnections. The frontispiece, in color, conveys the distribution of distinguishable architectural areas and by its tinting suggests how these merge into one another. There is a carefully selected bibliography of some one hundred and fifty entries. But the most important portion of the volume is, as the authors state, a set of sixty-two collotype plates, each at a magnification of 100 diameters,

Although inhibition plays a major role in the function of the mammalian neocortex, the circuit connectivity of GABAergic interneurons has remained poorly understood. The authors review recent studies of the connections made to and from interneurons, highlighting the overarching principle of a high density of unspecific connections in inhibitory connectivity. Whereas specificity remains in the subcellular targeting of excitatory neurons by interneurons, the general strategy appears to be for interneurons to provide a global "blanket of inhibition" to nearby neurons. In the review, the authors highlight the fact that the function of interneurons, which remains elusive, will be informed by understanding the structure of their connectivity as well as the dynamics of inhibitory synaptic connections. In a last section, the authors describe briefly the link between dense inhibitory networks and different interneuron functions described in the neocortex.

A puzzling feature of the neocortex is the rich array of inhibitory interneurons. Multiple neuron recordings revealed numerous electrophysiological-anatomical subclasses of neocortical gamma-aminobutyric acid-ergic (GABAergic) interneurons and three types of GABAergic synapses. The type of synapse used by each interneuron to influence its neighbors follows three functional organizing principles. These principles suggest that inhibitory synapses could shape the impact of different interneurons according to their specific spatiotemporal patterns of activity and that GABAergic interneuron and synapse diversity may enable combinatorial inhibitory effects in the neocortex.