Cortex最新文献

Current models of face perception and the face-processing network suggest that acquired prosopagnosia may not be a single disorder but rather a family of variants differing in mechanism. It has been proposed that tests of face perception and face imagery can probe component processes to support apperceptive, associative, and amnestic distinctions. However, validating this proposal is hampered by the rarity of this condition. Here we report observations gathered over two-and-a-half decades on the perception of facial shape and the imagery for famous faces of twenty-three patients. Patients with lesions limited to the occipitotemporal lobes had an apperceptive profile, with impaired perception of facial shape but no or mild deficits for face imagery. The apperceptive defect affected not just configuration but also feature size and external contour, especially in the upper face, and was more severe when subjects attended to multiple aspects of the face. An amnestic profile, with severely impaired imagery and minimally affected perception, was seen in two patients, one with right and one with bilateral anterior temporal damage. Four patients had an apperceptive/amnestic combination, all with bilateral occipitotemporal and right anterior temporal damage. Right anterior temporal damage alone often caused only mild imagery deficits: along with their relatively intact face perception, these subjects came closest to meeting proposed exclusionary criteria for an associative variant, i.e., relative preservation of both imagery and perception. These results confirm a link between apperceptive prosopagnosia and occipitotemporal lesions. Damage to the right anterior temporal lobe was common to all with a severe amnestic deficit, but often requiring additional damage.

Poor performance on cognitive assessment tasks may indicate a selective 'impairment'. However, it is unclear whether such difficulties separate the individual from the general population qualitatively (i.e., they form a discrete group) or quantitatively (i.e., they represent the lower end of a continuous distribution). Taxometric methods address this question but have rarely been applied to cognitive disorders. This study examined the latent structure of developmental prosopagnosia (DP) - a relatively selective deficit in face recognition that occurs in the absence of neurological injury. Multiple taxometric procedures were applied to dominant diagnostic indices of face recognition ability across two independent datasets. All analyses supported a categorical outcome, even for mild cases of DP, suggesting that it is a qualitatively distinct condition. This finding has significant implications for our understanding of DP given it has traditionally been viewed as a continuous impairment. In particular, existing (arbitrary) diagnostic cut-offs may be too conservative, underestimating prevalence rates and prohibiting big-data approaches to theoretical study. More broadly, these conclusions support application of the taxometric method to many other cognitive processes where weaknesses are predominantly assumed to reside on a continuous distribution.

Based on historic observations that children with reading disabilities were disproportionately both male and non-right-handed, and that early life insults of the left hemisphere were more frequent in boys and non-right-handed children, it was proposed that early focal neuronal injury disrupts typical patterns of motor hand and language dominance and in the process produces developmental dyslexia. To date, these theories remain controversial. We revisited these earliest theories in a contemporary manner, investigating demographics associated with reading disability, and in a subgroup with and without reading disability, compared structural imaging as well as patterns of activity during tasks of verb generation and non-word repetition using magnetoencephalography source imaging. In a large group of healthy aging adults (n = 282; average age 72.3), we assessed reading ability via the Adult Reading History Questionnaire and found that non-right-handedness and male sex significantly predicted endorsed reading disability. In a subset of participants from the larger cohort who endorsed reading disability (n = 14) and a group who denied reading disability (n = 22), we compared structural and functional imaging data. We failed to detect structural differences in volumetric brain morphometry analyses, however we observed decreased neural activity on magnetoencephalography within the reading disability group. The detected differences were largely restricted to left hemisphere ventral occipito-temporal and posterior-lateral temporal cortices, the visual word form area and middle temporal gyrus, regions implicated in developmental dyslexia. Moreover, these observed disruptions occurred in a focal, network-specific manner, preferentially disturbing the ventral/sight reading recognition pathway, resulting in a pattern of regional anomalous lateralization of function that distinguished the reading disability cohort from normal readers. Collectively, the results presented here align with old theories regarding the etiology of developmental dyslexia and highlight how results from investigating neurodevelopmental differences in healthy aging individuals can powerfully contribute towards our overall understanding of neurodevelopment and neurodiversity.