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Biomedical subjects

C L Colby

Publications and source records attributed to C L Colby.

6 recordsLinked to original sources
PubMed1992

The updating of the representation of visual space in parietal cortex by intended eye movements.

Every eye movement produces a shift in the visual image on the retina. The receptive field, or retinal response area, of an individual visual neuron moves with the eyes so that after an eye movement it covers a new portion of visual space. For some parietal neurons, the location of the receptive field is shown to shift transiently before an eye movement. In addition, nearly all parietal neurons respond when an eye movement brings the site of a previously flashed stimulus into the receptive field. Parietal cortex both anticipates the retinal consequences of eye movements and updates the retinal coordinates of remembered stimuli to generate a continuously accurate representation of visual space.

Animals↗
PubMed1992

Oculomotor control and spatial processing.

In the past year research in the oculomotor system has concentrated on some hitherto neglected areas, and also caused a re-evaluation of several long-standing concepts. Careful studies of the translational (otolith) vestibulo-ocular reflex and the torsional system have demonstrated their importance. A re-evaluation of the role of the superior colliculus in the generation of saccades has provided evidence for its participation in the feedback process. New studies of the interaction of eye movements and visual processing have shown that the brain can compensate for the visual effects of eye movements and maintain a retinotopic representation of visual space for the saccadic system.

Animals↗
PubMed1991

Heterogeneity of extrastriate visual areas and multiple parietal areas in the macaque monkey.

The definition of visual areas remains a key problem in the effort to elucidate cortical functions. Visual areas vary along a number of dimensions and are increasingly difficult to define according to traditional criteria at higher levels of the hierarchy. Three recently discovered areas in monkey parietal association cortex illustrate a new approach to this problem. Their definition depends on assessment of neuronal response properties in the alert, behaving animal combined with precise reconstruction of recording sites. This approach permits recognition of functionally distinct areas in the absence of retinotopic maps.

Animals↗
PubMed1991

The neuroanatomy and neurophysiology of attention.

Attention is a distributed process. The activity of neurons in many brain structures can be modulated by the attentional state of the animal. Attention directed toward a particular external stimulus is often reflected in an enhancement of the sensory response to that stimulus. Enhancement is spatially selective for neurons in many areas and explicitly eye-movement related in most. Attention directed toward the internal representation of a stimulus may be associated with a prolongation of neural activity. These modulations of neuronal responsiveness underscore the dynamic nature of neural processing. Competition between left- and right-brain structures in the control of attention is common. While attention is perceived as a unitary process, it is subserved by many brain structures. Given the wide distribution of attentional processes, it is not surprising that children diagnosed as having attentional deficits show considerable diversity in symptoms and etiology.

Animals↗