Fast Oscillations in Cortical Circuits, by Roger D. Traub, John G. R. Jefferys and Miles A. Whittington

It is a frustrating fact in the sociology of science: new ideas often only become acceptable and credible when advertised by previously orthodox practitioners. Such is the case with the discovery and nascent functional imputations of the cortical neuronal population oscillations greater than 30 Hz — also known as gamma (γ) oscillations. These oscillations were first observed by Lord Adrian, studied in detail for over 40 years by Walter Freeman (the third) — first in the olfactory bulb of the rabbit and later in cats and humans, and then “popularized” by Charlie Gray (previously a Ph.D. student of Walter Freeman’s) and Wolf Singer (a respected single cell neurophysiologist) in a series of reports commencing in 1987 and culminating, in what is regarded, even by their detractors, as a landmark communication for the newly emerging field of brain dynamics, in a paper in Nature in 1989. This paper concerned the existence of gamma band neuronal population oscillations in the visual cortex (40–60 Hz) of the cat and the conditions under which they became phase synchronized in space in response to visual stimulation. In acknowledgment of the pioneering work of Freeman such oscillations went under the cognomen of “the visual sniff”. Gray and Singer proposed that such synchronization may be indicative of a mechanism for the global association of contiguous and non-contiguous elements of a visual scene by the establishment of distributed cell assemblies that are characterized by the frequency and phase of their oscillation. Here, apparently, was strong experimental evidence for a solution to the “binding problem” — how atomic sense percepts are assembled into a meaningful perceptual whole — as articulated by von der Malsberg and Schneider.