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Front Neurosci. 2019 Sep 11;13:961. doi: 10.3389/fnins.2019.00961. eCollection 2019.

Sex, Age, and Handedness Modulate the Neural Correlates of Active Learning.

Author information

1
Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, United States.
2
Department of Psychology, The University of Alabama at Birmingham, Birmingham, AL, United States.
3
Department of Pediatrics, Division of Neurology, Cincinnati Children's Hospital Medical Center, Pediatric Neuroimaging Research Consortium, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
4
Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom.

Abstract

Background:

Self-generation of material compared to passive learning results in mproved memory performance; this may be related to recruitment of a fronto-temporal encoding network. Using a verbal paired-associate learning fMRI task, we examined the effects of sex, age, and handedness on the neural correlates of self-generation.

Methods:

Data from 174 healthy English-speaking participants (78M, 56 atypically handed; ages 19-76) were preprocessed using AFNI and FSL. Independent component analysis was conducted using GIFT (Group ICA fMRI Toolbox). Forty-one independent components were temporally sorted by task time series. Retaining correlations (r > 0.25) resulted in three task-positive ("generate") and three task-negative ("read") components. Using participants' back-projected components, we evaluated the effects of sex, handedness, and aging on activation lateralization and localization in task-relevant networks with two-sample t-tests. Further, we examined the linear relationship between sex and neuroimaging data with multiple regression, covarying for scanner, age, and handedness.

Results:

Task-positive components identified using ICA revealed a fronto-parietal network involved with self-generation, while task-negative components reflecting passive reading showed temporo-occipital involvement. Compared to older adults, younger adults exhibited greater task-positive involvement of the left inferior frontal gyrus and insula, whereas older adults exhibited reduced prefrontal lateralization. Greater involvement of the left angular gyrus in task-positive encoding networks among right-handed individuals suggests the reliance on left dominant semantic processing areas may be modulated by handedness. Sex effects on task-related encoding networks while controlling for age and handedness suggest increased right hemisphere recruitment among males compared to females, specifically in the paracentral lobe during self-generation and the suparmarginal gyrus during passive reading.

Implications:

Identified neuroimaging differences suggest that sex, age, and handedness are factors in the differential recruitment of encoding network regions for both passive and active learning.

KEYWORDS:

age; associate learning; fMRI; handedness; sex; verbal memory

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