Multi-lesion analysis of the cortico-collicular attention network of the cat brain M Zavaglia, C C Hilgetag |
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Department of Computational Neuroscience, University Medical Center Eppendorf Hamburg, Germany
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| Spatial attention is a prime example for distributed network functions of the brain. Lesion studies in animal models have been used to investigate attentional mechanisms and perspectives for rehabilitation. We analyzed systematic data from cooling deactivation and permanent lesion experiments in the cat where unilateral deactivation of posterior middle suprasylvian cortex (pMS) or superior colliculus (SC) caused a severe neglect in the contralateral hemifield. Surprisingly, additional deactivation of structures in the opposite hemisphere reversed the deficit. Using these data, we employed Multi-perturbation Shapley-value Analysis (MSA) to compute causal contributions of bilateral pMS and SC to visual attention. MSA is a game-theoretical method for inferring functional contributions and interactions from behavioral performance. Brain regions are considered players and each coalition of non-lesioned regions has a performance score, here, for orienting to the left visual field. Regions pMSr and SCr made the strongest positive contributions, while pMSl and SCl had negative contributions, implying that their perturbation may reverse the effects of contralateral lesions or improve normal function. Strong negative interactions existed between regions within each hemisphere, while all interhemispheric interactions were positive. It is a challenge to reconcile these causal interactions with the known physiological network for attention in the cat brain. |
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