Anatomical Organization of Macaque Monkey Striate Visual Cortex

Abstract

I hope that this review of the internal anatomy of the monkey primary visual cortex makes clear the high degree of specialization that exists in each of the cortical laminae and their constituent neurons. Each lamina is driven by different patterns of relays from the LGN and by different patterns of intrinsic interlaminar projections. The elaborate laminar and intralaminar segregation of efferent neuron arrays suggests that the extraordinary precision of inter- and intralaminar connectivity provides a unique functional role for each set of efferent neurons. The organization of aspinous (presumed inhibitory) local circuit neurons suggests that they are highly specialized, and within each lamina and via interlaminar relays each variety may only accomplish a single, particular task. The cortex neuropil does not give the immediate impression of "random" networks, and if such exist, they must surely be between very tightly determined subgroups of neurons. Clearly a very detailed physiological exploration of V1 is still needed, with new consideration of thalamic axon function, of efferent neuron characteristics, of laminar differences, and of spatial organization of properties within laminae, in order to match known anatomical detail with function. The concept of columnar organization in cortical organization of V1 may eventually be redefined in more complex terms that accurately describe the anatomical and functional parcellation evident in cortical depth and perhaps may link it to a means by which a correlation of different aspects of the visual image is achieved.