Restoration of visual orienting into a cortically blind hemifield by reversible deactivation of posterior parietal cortex or the superior colliculus

TY - JOUR

T1 - Restoration of visual orienting into a cortically blind hemifield by reversible deactivation of posterior parietal cortex or the superior colliculus

AU - Lomber, Stephen G

AU - Payne, Bertram R

AU - Hilgetag, Claus C

AU - Rushmore, JarrettR

PY - 2002/2

Y1 - 2002/2

N2 - A contralateral hemineglect of the visual field can be induced by unilateral cooling deactivation of posterior middle suprasylvian (pMS) sulcal cortex of the posterior parietal region, and this neglect can be reversed by additional cooling deactivation of pMS cortex in the opposite hemisphere. The purpose of the present study was to test whether an enduring hemianopia induced by removal of all contiguous visual cortical areas of one hemisphere could be reversed by local cooling of pMS cortex in the opposite hemisphere. Two cats sustained large unilateral ablations of the contiguous visual areas, and cooling loops were placed in the pMS sulcus, and in contact with adjacent area 7 or posterior ectosylvian (PE) cortex of the opposite hemisphere. In both instances cooling of pMS cortex, but neither area 7 nor PE, restored a virtually normal level of orienting performance to stimuli presented anywhere in the previously hemianopic field. The reversal was highly sensitive to the extent of cooling deactivation. In a third cat, cooling deactivation of the superficial layers of the contralateral superior colliculus also restored orienting performance to a cortical ablation-induced hemianopia. This reversal was graded from center-to-periphery in a temperature-dependent manner. Neither the cortical ablation nor any of the cooling deactivations had any impact on an auditory detection and orienting task. The deactivations were localized and confirmed by reduced uptake of radiolabeled 2-deoxyglucose to be limited to the immediate vicinity of each cooling loop. The results are discussed in terms of excitation and disinhibition of visual circuits.

AB - A contralateral hemineglect of the visual field can be induced by unilateral cooling deactivation of posterior middle suprasylvian (pMS) sulcal cortex of the posterior parietal region, and this neglect can be reversed by additional cooling deactivation of pMS cortex in the opposite hemisphere. The purpose of the present study was to test whether an enduring hemianopia induced by removal of all contiguous visual cortical areas of one hemisphere could be reversed by local cooling of pMS cortex in the opposite hemisphere. Two cats sustained large unilateral ablations of the contiguous visual areas, and cooling loops were placed in the pMS sulcus, and in contact with adjacent area 7 or posterior ectosylvian (PE) cortex of the opposite hemisphere. In both instances cooling of pMS cortex, but neither area 7 nor PE, restored a virtually normal level of orienting performance to stimuli presented anywhere in the previously hemianopic field. The reversal was highly sensitive to the extent of cooling deactivation. In a third cat, cooling deactivation of the superficial layers of the contralateral superior colliculus also restored orienting performance to a cortical ablation-induced hemianopia. This reversal was graded from center-to-periphery in a temperature-dependent manner. Neither the cortical ablation nor any of the cooling deactivations had any impact on an auditory detection and orienting task. The deactivations were localized and confirmed by reduced uptake of radiolabeled 2-deoxyglucose to be limited to the immediate vicinity of each cooling loop. The results are discussed in terms of excitation and disinhibition of visual circuits.

KW - Animals

KW - Blindness, Cortical

KW - Catheter Ablation

KW - Cats

KW - Female

KW - Functional Laterality

KW - Orientation

KW - Parietal Lobe

KW - Superior Colliculi

KW - Vision, Ocular

KW - Visual Cortex

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

KW - Research Support, U.S. Gov't, Non-P.H.S.

KW - Research Support, U.S. Gov't, P.H.S.

U2 - 10.1007/s00221-001-0957-9

DO - 10.1007/s00221-001-0957-9

M3 - SCORING: Journal article

C2 - 11845242

VL - 142

SP - 463

EP - 474

JO - EXP BRAIN RES

JF - EXP BRAIN RES

SN - 0014-4819

IS - 4

ER -