Neuronal networks for induced ‘40 Hz’ rhythms

TLDR

Gamma or 40 Hz rhythms are linked to both high‑level feature binding and low‑level phase coding, and simulations indicate they can arise from excitatory, inhibitory, or mixed neuronal networks. Experimental data show that intrinsic 40 Hz oscillators in neocortical and thalamic neurons, together with tonically excited networks of mutually inhibitory interneurons in hippocampus and neocortex, produce coherent 40 Hz rhythms. Published in Trends Neuroscience, 1996, vol.

Abstract

A fast, coherent EEG rhythm, called a gamma or a '40 Hz' rhythm, has been implicated both in higher brain functions, such as the 'binding' of features that are detected by sensory cortices into perceived objects, and in lower level processes, such as the phase coding of neuronal activity. Computer simulations of several parts of the brain suggest that gamma rhythms can be generated by pools of excitatory neurones, networks of inhibitory neurones, or networks of both excitatory and inhibitory neurones. The strongest experimental evidence for rhythm generators has been shown for: (1) neocortical and thalamic neurones that are intrinsic '40 Hz' oscillators, although synchrony still requires network mechanisms; and (2) hippocampal and neocortical networks of mutually inhibitory interneurones that generate collective 40 Hz rhythms when excited tonically. Trends Neurosci. (1996) 19, 202–208