Objective: Analysis of the consequences of bilateral dorso-medial pulvinar lesions

Background: Expansion of the dorsal pulvinar in humans and its anatomical connectivity suggests its involvement in higher-order cognitive and visuomotor functions. However, albeit recent studies in non-human primates suggest a contribution of dorsal pulvinar portions to visuomotor functions, the determination of its functional role in humans has been hampered by the rarity of patients with selective lesions in the dorsal pulvinar.

Methods: We conducted neurological, neurophysiological and neuropsychological examinations in a 31 year old patient with bilateral lesions in the medio-dorsal pulvinar. Reach testing was performed on a touch screen and with eye movement control with and without foveal viewing of reach targets. Structural and functional MR analyses including resting state functional connectivity were performed. Patient data in each task condition was compared to 7-14 healthy, age matched subjects.

Results: In this case-control study we examine in detail the consequences of bilateral and highly selective dorso-medial pulvinar lesions due to an atypical cerebral sarcoidosis manifestation. The patient had intact primary sensory and motor functions, normal electrophysiological examinations and did not show any spatial attention and perceptual deficits. At the same time he was unable to stand or walk, and exhibited deficits in goal-directed reaches and precision grasping that were independent of eye position. Unexpectedly, the main functional connectivity effect of the lesion on remote brain regions was not found in fronto-parietal cortices as would be suggested by the current literature but in mid posterior cingulate cortex and cerebellum. These results suggest that pulvinar function in humans goes well beyond its subscribed role in visual cognition and might be more appropriately conceived as an integrator of postural and sensory activity for the programming of voluntary movements. In addition, human specific adaptations of the medial pulvinar might have enabled bipedal locomotion and precise object manipulation with the hands.

Conclusions: These results suggest that human pulvinar function goes well beyond its subscribed role in visual cognition and might be more appropriately conceived as an integrator of postural and sensory activity for the programming of voluntary movements. 

References: Wilke, M., Kagan, I., Andersen, R.A. Effects of pulvinar inactivation on spatial decision

making between equal and asymmetric reward options. Journal of Cognitive Neuroscience.

2013. 25(8), 1270-83.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/astasia-reach-and-grasp-deficits-following-bilateral-medio-dorsal-pulvinar-lesions/