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The role of the superior colliculus in visually guided behavior

1965; Elsevier BV; Volume: 11; Issue: 1 Linguagem: Inglês

10.1016/0014-4886(65)90026-9

1090-2430

James M. Sprague, Thomas H. Meikle,

Spatial Neglect and Hemispheric Dysfunction

Unilateral lesions in the superior colliculus of the cat which do not involve the tegmentum result in two major behavioral signs: an homonymous field defect with complete or relative neglect of stimuli in the visual fields contralateral to the lesion, seen particularly in extinction of the contralateral response when rival stimuli are used; and a motor deficit in appropriate movements of eyes, head and body, expressed in ipsiversive forced circling and an heightened compulsive response to ipsilateral stimuli. These signs are not related to changes in pupils or in accommodation. Associated with these are abnormal responses to contralateral acoustic, tactile and sometimes nociceptive stimuli, appearing primarily as inappropriate localization of the stimuli rather than as changes in sensory threshold. The two major deficits are separable by means of smaller lesions in various parts of the afferent and efferent tectal pathways. Lesions of the tectospinal tract result in the motor deficit without the visual neglect. Involvement of the brachium of the superior colliculus and of parts of the tectothalamic system yield a contralateral visual neglect without the motor deficit. Bilateral collicular lesions result in apparent initial blindness and enduring deficits in visual following, in localization of stationary stimulus objects, in a disability to look up and in poor localization to tactile stimulation of the hind legs. We conclude that the functions of the superior colliculus include that of visual attention and perception as well as the classically accepted control of the movements of head and eyes.