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B M Dow

Publications and source records attributed to B M Dow.

28 records · Page 2Linked to original sources
PubMed1980

Behavioral enhancement of visual responses of prestriate neurons of the rhesus monkey.

Neurons in the superior colliculus, striate cortex, frontal eye fields, and posterior parietal cortex of the monkey respond to visual stimuli. Many of these cells discharge more intensely to a stimulus when it is to be the target for a saccadic eye movement than when fixation is maintained. We have demonstrated that such enhancement of the visual response is also present for cells in prestriate cortex. The prestriate effect is a modulation of the visual response and not a concomitant of oculomotor activity. It is present for eye movements away from as well as into the visual receptive field and is thus similar to that seen in striate cortex and different from that studied in the superior colliculus, frontal eye fields, and posterior parietal cortex. The visual responses of many prestriate cells habituate with repeated stimulation. When the monkey makes saccadic eye movements to a stimulus that is eliciting only a habituated response, the enhancement acts as a dishabituation which persists throughout the eye movement trials.

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PubMed1976

Central mechanisms of vision: parallel processing.

Despite repeated attempts by several laboratories to discover increasingly complex "feature detector" neurons in higher visual centers of mammals, there has been little convincing evidence for the existence of such neurons. What had been reported instead is that many neurons in higher centers show less rather than more specificity when compared with cells in areas 17, 18 and 19. Studies in mammalian retina have revealed multiple processing systems apparently operating in parallel at the level of the ganglion cells. Striate cortex receives at least two different kinds of visual input from the lateral geniculate, and sends at least two different parallel outputs to other brain regions. Within striate cortex there is some segregation of different functional cell types in separate layers. The accumulated evidence suggests the existence of parallel visual processing mechanisms beginning in mammalian retina and extending through striate cortex to higher cortical centers. The notion of separate processing systems for the detection of different features in the visual world recalls earlier work by Lettvin, Maturana, McCulloch and Pitts concerning visual processing in the frog retina and optic tectum.

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