Contour discrimination in a young monkey with striate cortex ablation
Affiliation:
1. University Hospital of Psychiatry, University of Bern, Bern, Switzerland;2. Translational Research Centre, University Hospital of Psychiatry, University of Bern, Bern, Switzerland;3. Institute of Diagnostic and Interventional Neuroradiology, University of Bern, Bern, Switzerland;1. Sanford-Burnham Medical Research Institute, La Jolla, CA, USA;2. University of California, San Francisco, CA, USA;1. Departments of Neurology and Stereotactic Neurosurgery, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany;2. Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany;3. German Centre for Neurodegenerative Diseases (DZNE), Otto von Guericke University, Leipziger Strasse 44, 39120 Magdeburg, Germany;4. Helen Wills Neuroscience Institute and Department of Psychology, University of California, Tolman Hall, MC 3192, Berkeley, CA 94720, USA;5. Center for Vital Longevity and School of Behavioral and Brain Sciences, University of Texas, Dallas, TX 75235, USA
Abstract:
A young (412 role=presentation style=font-size: 90%; display: inline-block; position: relative;> months old) rhesus monkey was subjected to bilateral removal of striate cortex. No striate cortex remained in post-mortem examination, but a small cluster of undegenerated cells was found in each anteroventral lateral geniculate nucleus.A series of eleven experiments, involving various types of visual discriminations, is described. It was found that no discrimination was possible when luminous flux was equated, provided certain other differences between the stimuli were not present. When, however, there was a difference in total contour length, performance was far above chance, even with flux equated. The animal could also respond to moving stimuli. It could not discriminate very effectively, however, between a flickering stimuli and a “phi” movement synchronized with the flicker, nor could it make a red-green discrimination.Various speculations are put forward concerning the nature of the residual vision, and it is suggested that this animal could discriminate the integral of all retinal ganglionic activity, whether based on the response to steady illumination, or to spatial (contour) or temporal (movement or flicker) gradients. No discrimination, however, was possible based on the distribution of such variation.
