Neural correlates of the difference between working memory speed and simple sensorimotor speed: an fMRI study

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• Psychological studies show differences in processing speed between simple and complex cognitive tasks.
• Neural correlates underlying these processing speed differences remain largely unexplored.
• Working memory (WM) represents a key complex cognitive process crucial for various higher-order functions.

Purpose of the Study:

• To investigate the neural correlates of the speed differences between simple and complex cognitive processes.
• To identify brain regions and networks associated with the speed of working memory (WM) performance.
• To explore the relationship between neural structure, WM performance, and general intelligence.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed during an N-back task to measure working memory (WM) capacity and speed.
• Task parameters, including speed and memory load, were manipulated to differentiate neural activity related to simple versus complex cognitive processes.
• A 0-back task was used to estimate the neural correlates of simple cognitive processes for comparison.

Main Results:

• Significantly increased activation was observed in the right dorsolateral prefrontal cortex (DLPFC) when comparing fast WM performance to simple cognitive tasks.
• Enhanced functional connectivity was found between the right DLPFC and the right superior parietal lobe during rapid WM tasks.
• Local gray matter volume in the right DLPFC positively correlated with accuracy in fast WM tasks and with psychometric measures of intelligence.

Conclusions:

• The right DLPFC and its associated neural network are critical for the rapid execution of cognitive processes within working memory (WM).
• These findings provide a neural basis for understanding individual differences in cognitive processing speed and their relationship to intelligence.
• The study elucidates the neural mechanisms underlying the distinction between simple and complex cognitive task performance speeds.