With Childhood Hemispherectomy, One Hemisphere Can Support--But is Suboptimal for--Word and Face Recognition

Abstract

The left and right cerebral hemispheres are important for word and face recognition, respectively—a specialization that emerges over human development. But children who have undergone a hemispherectomy develop with only one hemisphere. The question is whether this preserved hemisphere, be it left or right, can support both word and face recognition. Here, a large sample of patients with childhood hemispherectomy and age-matched controls performed word- and face-matching tasks. Controls viewed stimuli either in one visual field (restricting initial processing to one hemisphere) or, like the patients, in central vision. Across word and face tasks, patients performed comparably to controls using primarily one hemisphere, but more poorly than controls viewing stimuli centrally with both hemispheres engaged. Additionally, patients showed deficits in low-level visual processing that may explain their word/face recognition deficits relative to controls. Altogether, the findings suggest that either hemisphere alone can support word and face recognition, albeit sub-optimally.

Unilateral Resection of Both Cortical Visual Pathways Alters Action but not Perception

“…The results from the estimation tasks are consistent with previous investigations that documented retained perceptual functions in pediatric patients with cortical resections even when the resection compromised a large portion of the ventral visual pathway (Granovetter et al, 2020; Liu et al, 2019). Our results revealed a consistently different pattern of behavior for the visuomotor task, presumably mediated by computations carried out by the dorsal pathway.…”

Beyond the Visual Word Form Area: Characterizing a hierarchical, distributed and bilateral network for visual word processing

“…These language capabilities appear to suffice for word processing following left occipitotemporal cortex resection, especially in childhood, with the RH VWFA activated by orthography in many cases Liu et al, prep). Relatedly, children with a single hemisphere (post-hemispherectomy for the management of medically resistant epilepsy) score, on average, 80 percent accuracy on a word discrimination task and this is so even with just a preserved RH (Granovetter et al, 2022). Also, in adult patients with prosopagnosia following focal damage to the RH, a moderate reading deficit, less severe than after LH damage, can be detected (Behrmann and Plaut, 2014) and, in an adult patient with (partially recovered) pure alexia, stimulation of the RH but not the LH disrupted oral reading (Coslett and Monsul, 1994).…”