The superior colliculus subserves interhemispheric neural summation in both normals and patients with a total section or agenesis of the corpus callosum

被引:60
作者
Savazzi, S [1 ]
Marzi, CA [1 ]
机构
[1] Univ Verona, Dept Neurol & Visual Sci, I-37134 Verona, Italy
关键词
superior colliculus; redundant target effect; neural summation; probabilistic summation; callosal section; callosal agenesis;
D O I
10.1016/j.neuropsychologia.2004.04.011
中图分类号
B84 [心理学]; C [社会科学总论]; Q98 [人类学];
学科分类号
03 ; 0303 ; 030303 ; 04 ; 0402 ;
摘要
To verify the possibility that the superior colliculus (SC) subserves interhemispheric neural summation, we presented single or double white visual targets to one or both hemifields in normal participants and in patients lacking the corpus callosum (one with total callosotomy and one with callosal agenesis). Simple reaction time was typically faster with double than single stimuli, a phenomenon known as the redundant target effect (RTE); moreover, confirming previous results, we found a larger RTE in patients without callosum than in normals. In both groups, the redundancy gain was related to neural coactivation rather than to probability summation. The novel finding was that, when using monochromatic purple stimuli that are invisible to the SC, we found a similar redundancy gain in both groups; moreover, this redundancy gain was probabilistic rather than neural. Control experiments with monochromatic red stimuli yielded a RTE of the neural type similar to that with white stimuli and this confirmed that the probabilistic RTE found was specific for purple stimuli. In conclusion, visual input to the SC is necessary for interhemispheric neural summation in both normals and in individuals without the corpus callosum while probabilistic summation can occur without a collicular contribution. (C) 2004 Elsevier Ltd. All rights reserved.
引用
收藏
页码:1608 / 1618
页数:11
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