A transient deficit of first- and second-order motion perception in human

Purpose: To study the neuroanatomical substrate of first- and second-order motion perception in human by analyzing the perceptual concomitants to acute topectomy of a small portion of the right lateral ocdpito-temporal cortex in 19 year old patient, SF. Method: Microsurgical resection of cortex to 5 - 6 mm largely spared white matter. Lesion locus was reconfirmed by MR imaging with 3 D cortical surface reconstruction. Computer generated random dot cinematograms (RDC) were used to assess motion perception before and after surgery. These stimuli resembled those used to assess acute motion perception deficits in primates. Results: Staining with histological markers (cell bodies, myelin, parvalbumen, AChE, and SMI 32) showed cytoarchitectural characteristics resembling those of simian area MT. Firstorder motion perception was affected in the contralateral visual field. Second-order motion perception was affected in both visual hcmifields. The post-surgical deficits resolved within weeks. Conclusions: Previously reported motion perception deficits in human have lasted months or years. The nature and quick recovery of the deficit in SF resembles the transient motion perception deficit observed in monkey following ibotenic acid lesions in area MT This provides additional evidence that humans possess a specialized conical area serving the same motion perception functions as MT in monkey. Involvement of both hemifields in secondorder motion suggests a processing mechanism with broad receptive fields that span the vertical midline.