Deficits in Complex Visual Perception Following Unilateral Temporal Lobectomy

Abstract

Although human temporal cortex is known to be important for short- and long-term memory, its role in visual perception is not well understood. In this study, we compared the performance of three patients with unilateral temporal lobectomies to that of normal controls on both "simple" and "complex" visual discriminations that did not involve explicit memory components. Two types of complex tasks were tested that involved discriminations secondary to texture segmentation. These were contrasted with simple discriminations using luminance-defined stimuli. Patients showed impaired thresholds only on tasks involving texture segmentation, performing as well as controls when the targets were defined by luminance rather than texture. The minimum stimulus presentation times for threshold performance were also measured for all tasks and found to be elevated in temporal lobectomy patients relative to controls. Although the magnitude of the deficits observed was substantial, loss was equivalent in ipsi- and contra-lesional regions of the visual field. Additional control experiments showed that the patients' perceptual deficits were not due, even in part, to disturbances of basic visual capacities such as acuity and contrast sensitivity. Our results indicate that temporal lobe damage disrupts complex, but not simple, visual discriminations throughout the visual field.

Generalized deficits in visual selective attention after V4 and TEO lesions in macaques

“…These very limited effects of the lesions on acuity are in agreement with other studies in which basic visual capabilities were found to be intact after mid‐level and high‐level extrastriate lesions (e.g. Merigan, 1996; Huxlin & Merigan, 1998). In addition, a previous study with the same two monkeys (De Weerd et al ., 1999) demonstrated that grating orientation discrimination was unimpaired in lesion‐affected quadrants for contrasts as low as 2.5%.…”

Evidence of a relationship between asymmetries in tympanic membrane temperature and lateralised sensory preferences

“…Although evidence suggests a contralateral relationship between temporal lobe and visual field in some specific areas of the temporal lobe, higher-level temporal areas possess a representation of the entire central visual field in each of the two temporal lobes (Gross, Rocha-Miranda, & Bender, 1972). Huxlin and Merigan (1998) report that visual deficits produced by temporal lobectomy in humans are found in both ipsilateral and contralateral visual hemifields. Given that the location of the middle and inner ear is towards the underside of the temporal lobe, and the possibility that the temporal lobes are not contralaterally related to visual hemifields, it seems possible that eye preference (a self-report measure of preference for one eye over another) may also be related to TMT Diff, leading to:…”

“…Tympanic membrane temperature difference (TMT Diff) will be negatively correlated with eye preference However, as noted by Huxlin and Merigan (1998), the role of the human temporal cortex in vision is not well understood. As a result, the possibility of a contralateral link between eye preference and TMT Diff is relatively speculative.…”

Acuity-independent effects of visual deprivation on human visual cortex

“…ICs have garnered considerable interest because of their "inferential" nature-despite the lack of luminance edges, the visual system uses implicit configural cues to infer the presence of a contour. Finally, behavioral investigations in macaque suggest that IC perception is strongly dependent on higher visual areas, including V4 (37,38) and inferotemporal (IT) cortex (39,40).…”