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D B Bender

Publications and source records attributed to D B Bender.

26 records · Page 2Linked to original sources
PubMed1978

Localization and detection of visual stimuli following superior colliculus lesions in rhesus monkeys.

Rhesus monkeys were trained to fixate a central stimulus and to detect and localize a 50 msec light flash presented 6-80 degrees on either side of the central stimulus. Following large lesions of the superior colliculus, they showed persistent deficits in localizing flashes presented 43-80 degrees from the fixation stimulus. However, they were not consistently impaired when the flashes were presented more centrally, and their performance with peripheral stimuli improved when the stimulus duration was 1 sec. Thus, the superior colliculus appears to be necessary for the localization of brief visual stimuli in the far periphery.

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PubMed1977

Contributions of the corpus callosum and the anterior commissure to visual activation of inferior temporal neurons.

Most neurons in the inferior temporal cortex of the rhesus monkeys have visual receptive fields that extend across the vertical meridian well into both the contralateral and ipsilateral visual half-fields. We examined the role of different portions of the forebrain commissures in providing the ipsilateral input with the following results. (1) Combined section of the splenium and anterior commissure eliminated visual activation from the ipsilateral visual half-field. (2) Section of the splenium, with sparing of the anterior commissure, reduced the incidence of ipsilateral activation by about one-half. (3) Section of the anterior commissure, with sparing of the splenium, did not alter the incidence of ipsilateral activation. (4) Section of the non-splenial portions of the corpus callosum had no effect on the laterality of the receptive fields. Thus, both the splenium and the anterior commissure but not the non-splenial callosum can provide information from the ipsilateral visual field to neurons in inferior temporal cortex. These results are interpreted as suggesting that the converging input from the two visual half-fields onto single inferior temporal neurons provided by the forebrain commissures may mediate interhemispheric transfer of visual habits.

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PubMed1976

A visual deficit after superior colliculus lesions in monkeys.

The superior colliculus has been implicated in visual orientation and localization in several mammalian species. To examine this possibility in rhesus monkeys, we trained monkeys to respond to one of six locations signaled by a small light of 5 s duration that was turned off immediately before they were allowed to respond. The locations were directly behind the light. After tectal lesions they continued to perform this task normally, but showed a severe deficit when the duration of the signal was reduced to 1 s. However, when the stimulus remained on throughout the trial and the site of the stimulus and response were further separated, performance of the animals with tectal lesions was normal. We suggest that this deficit in the accuracy of reaching guided by a transient visual stimulus may be related to the role of the superior colliculus in the control of eye movements.

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PubMed1975

Visual activation of neurons in inferotemporal cortex depends on striate cortex and forebrain commissures.

Neurons in inferotemporal cortex respond only to visual stimuli and a majority have receptive fields that extend well into both visual half-fields. After bilateral removal of striate cortex, no inferotemporal neurons responded to visual stimuli. After unilateral removal of striate cortex, inferotemporal neurons in both hemispheres responded only to stimuli in the hemifield contralateral to the intact striate cortex. After section of the corpus callosum and anterior commissure, inferotemporal neurons in both hemispheres responded only to stimuli in the hemifield contralateral to the recording site. These results indicate that inferotemporal cortex visual information from striate cortex and that the pathway from striate cortex to the contralateral inferotemporal cortex includes the forebrain commissures. This same striate-temporal pathway is also necessary for normal discrimination learning. We suggest that the converging input onto single inferotemporal neurons from widely separated retinal areas may provide a mechanism for stimulus equivalence over different parts of the visual field, and it may be the absence of such a mechanism that contributes to the visual discrimination deficit that follows inferotemporal lesions.

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PubMed1969

Visual receptive fields of neurons in inferotemporal cortex of the monkey.

Neurons in inferotemporal cortex (area TE) of the monkey had visual receptive fields which were very large (greater than 10 by 10 degrees) and almost always included the fovea. Some extended well into both halves of the visual field, while others were confined to the ipsilateral or contralateral side. These neurons were differentially sensitive to several of the following dimensions of the stimulus: size and shape, color, orientation, and direction of movement.

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