Direct brain recordings reveal occipital cortex involvement in memory development

Abstract:

Processing of low-level visual information shows robust developmental gains through childhood and adolescence. However, it is unknown whether low-level visual processing in the occipital cortex supports age-related gains in memory for complex visual stimuli. Here, we examined occipital alpha activity during visual scene encoding in 24 children and adolescents, aged 6.2–20.5 years, who performed a subsequent memory task while undergoing electrocorticographic recording. Scenes were classified as high- or low-complexity by the number of unique object categories depicted. We found that recognition of high-complexity, but not low-complexity, scenes increased with age. Age was associated with decreased alpha power and increased instantaneous alpha frequency during the encoding of subsequently recognized high- compared to low-complexity scenes. Critically, decreased alpha power predicted improved recognition of high-complexity scenes in adolescents. These findings demonstrate how the functional maturation of the occipital cortex supports the development of memory for complex visual scenes.

Authors:

• Qin Yin

• Elizabeth L Johnson

• Lingfei Tang

• Kurtis I Auguste

• Robert T Knight

• Eishi Asano

• Noa Ofen

Date: 2020

DOI: https://doi.org/10.1016/j.neuropsychologia.2020.107625

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Attention and interference in the processing of global and local information: effects of unilateral temporal-parietal junction lesions

Authors:

• Michele Lazzara

• Lynn C. Robertson

• Robert T. Knight

Date: 1988

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Abstract:

The processing of hierarchical stimuli was examined in patients with lesions in the temporal-parietal junction. In separate blocks of trials, subjects were instructed to identify the letter at the local or the global level of a hierarchical stimulus. Consistent with previous findings, reaction times for controls were faster in the globally than in the locally directed condition and reaction times to the local level were longer when the letters at the two levels were different (e.g. local "S"s forming a global "H") than when they were the same (e.g. local "S"s forming a global "S"). In other words, controls exhibited interference when locally directed. Patients with lesions centered in the rostral inferior parietal lobe (IPL) showed interference effects similar to controls. In contrast, patients with lesions centered in the posterior superior temporal gyrus and adjacent caudal inferior parietal lobe (STG) showed no interference. The data suggest that the posterior superior temporal plane and adjacent caudal inferior parietal lobe plays an important role in the integration of and/or attention to local and global level information.

Right-sided neglect in a left-hander: Evidence for reversed hemispheric specialization of attention capacity

Abstract

Severe hemi-spatial neglect, anosognosia, contralateral hypokinesia, aprosodia, and visual-spatial constructive difficulties—typically seen in right-handers with right hemisphere lesions—were observed in a left-handed patient with an acute left frontal cortical and subcortical infarct. There was no evidence of accompanying aphasia and the neglect syndrome gradually resolved over a 2-week period. The assumption by the left hemisphere of a classic right hemisphere attention, visuo-spatial and prosodic superiority may represent a case of reversed hemispheric specialization.

Authors

• Nina F. Dronkers

• Robert T. Knight

Date: 1985

DOI: 10.1016/0028-3932(89)90118-8

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Reversed hemispheric organization in a left-hander

Authors:

• Dean C. Delis

• Robert T. Knight

• Gregory V. Simpson

Date: 1983

PubMed: 6843812

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Abstract:

For left-handers, cognitive functions are organized in the brain similarly to right-handers or they are more diffusely represented. In this study, we report a left-handed patient with a focal right temporal-parietal lesion who evidenced a lasting Wernicke's aphasia and visual-spatial functioning typical of a right-hander with left-hemisphere in involvement. The patient's performance on other tasks (e.g. praxis, singing) as well as observed behavioral changes also resembled those of a right-hander with left-hemisphere compromise. This case suggests that it is possible for cognitive functions to be inversely represented in the two hemispheres.