Subjective Difficulty in a Verbal Recognition-based Memory Task: Exploring Brain-behaviour Relationships at the Individual Level in Healthy Young Adults

TL;DR

This study investigates how subjective difficulty influences brain activity during a verbal recognition memory task, revealing individual differences and sex effects that are often overlooked in traditional fMRI analyses.

Contribution

It introduces a method to analyze individual-level brain-behavior relationships in memory tasks, accounting for subjective difficulty and sex differences.

Findings

Sex differences in brain activity patterns across load levels

Individual brain activity maps better predict response times than group maps

Subjective difficulty modulates brain-behavior relationships in memory tasks

Abstract

The vast majority of fMRI studies of task-related brain activity utilize common levels of task demands and analyses that rely on the central tendencies of the data. This approach does not take into account perceived difficulty nor regional variations in brain activity between people. The results are findings of brain-behavior relationships that weaken as sample sizes increase. Participants of the current study included twenty-six healthy young adults evenly split between the sexes. The current work utilizes five parametrically modulated levels of memory load centered around each individual’s predetermined working memory cognitive capacity. Principal components analyses (PCA) identified the group-level central tendency of the data. After removing the group effect from the data, PCA identified individual-level patterns of brain activity across the five levels of task demands. Expression of the group effect significantly differed between the sexes across all load levels. Expression of the individual level patterns demonstrated a significant load by sex interaction. Furthermore, expressions of the individual maps make better predictors of response time behavior than group-derived maps.