title: Lateral neglect in a head movement task: more impairment with unilateral than bilateral lesions of the superior colliculus in the rat.
abstract: Unilateral lesions of the superior colliculus produce contralateral neglect. This study determined if bilateral lesions would impair head orientation in a way expected from the summation of two contralateral neglects. Rats were trained to make various head movements to get water at a 3 x 3 array of holes, each with a recessed water-baited dipper. On each of 20 trials in a session, a water-deprived subject approached and sampled the array by orienting its head and inserting its snout in the holes in a self-determined sequence. The measures recorded for each position and for each trial were: the order in which a baited position was sampled (selection order), the number of times it was not sampled (misses), and the number of times it was sampled when dry (perseverations). Radio-frequency lesions were made and testing was resumed after 3 days. Large unilateral lesions of the superior colliculus produced a neglect of contralateral positions and increased perseverations to ipsilateral positions. Center positions were also neglected but to a lesser extent. Bilateral lesions of the superior colliculus produced only a moderate increase in lateral misses and no increase in lateral perseverations. Bilateral lesions did produce a neglect of upper positions on both sides. The results indicate that a major contributor to contralateral neglect produced by a unilateral lesion is an antagonistic process that promotes orientation to the side ipsilateral to the lesion.
authors: Laboratory of Neuropsychology, Wesleyan University, Middletown, CT 06457.
authors: H M
authors: HM
authors: Sinnamon
authors: E J
authors: EJ
authors: Garcia
mesh_terms: D000818:Animals; D001931:Brain Mapping; D007839:Functional Laterality / Q000502:physiology*; D006257:Head / Q000502:physiology*; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013477:Superior Colliculi / Q000502:physiology*