A direct pathway to anterior IPS for graspable objects: fMRI evidence from a patient with a lesion to the geniculostriate pathway
Quanjing Chen1, Colleen Schneider1,2, Emily Prentiss1, Zoe Williams3, Bogachan Sahin4, Bradford Z. Mahon1,4,5,6; 1Department of Brain and Cognitive Sciences, University of Rochester, 2Medical Scientist Training Program, University of Rochester School of Medicine and Dentistry, 3Department of Ophthalmology, University of Rochester School of Medicine and Dentistry, 4Department of Neurology, University of Rochester School of Medicine and Dentistry, 5Department of Neurosurgery, University of Rochester School of Medicine and Dentistry, 6Center for Visual Science, University of Rochester
Prior research demonstrates a primarily left-lateralized frontoparietal network is automatically engaged when participants view images of manipulable objects. However, the role of awareness, and processing in the geniculostriate pathway for dorsal action representations to be activated by manipulable objects has not been investigated. Here we study an individual with a right homonymous hemianopia caused by a stroke lesion that deafferented primary visual cortex of inputs from the lateral geniculate nucleus. Images of graspable objects (tools), fearful and emotionally neutral faces were shown in the intact and hemianopic visual fields. Replicating prior research, fearful faces differentially drive activity in the amygdala, even when the stimuli are presented in the hemianopic field. We also find that small manipulable objects continue to activate the anterior IPS. While aIPS activity for tool stimuli was present regardless of whether stimuli were presented in the visually intact or hemianopic visual fields, category-preferring effects in the ventral visual pathway were observed only when stimuli were presented in the intact visual field. These findings suggest a direct pathway to parietal grasp-related areas that bypasses processing in primary visual cortex, offering a new perspective on visual inputs to the dorsal visual pathway.
Topic Area: LONG-TERM MEMORY: Semantic