Slower Postencoding Stimulus Reaction Time Predicts Poorer Subsequent Source Memory and Increased Midline Cortical...

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Memory

Background:

• Episodic memory, the ability to recall past personal experiences with contextual detail, varies significantly among individuals.
• The influence of trial-by-trial attention during encoding and individual differences in attention and executive functions on memory encoding and retrieval remains incompletely understood.

Purpose of the Study:

• To investigate how within-subject variations in attention (measured by reaction times) during encoding affect subsequent episodic memory retrieval.
• To examine how between-subject variations in attention and executive function abilities modulate the relationship between attention during encoding and memory performance.
• To explore the neural correlates of attention-related memory variations using functional magnetic resonance imaging (fMRI).

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to study 38 healthy young adults performing an object-location encoding task.
• Reaction times (RTs) to a central fixation cross before and after stimulus encoding were recorded to index pre- and postencoding attention.
• Mixed-effects logistic regression and trial-by-trial fMRI analyses were employed to link RTs, behavioral performance, and brain activity.

Main Results:

• Slower postencoding reaction times (RTs) were significantly associated with poorer subsequent source memory recall within individuals.
• Preencoding RTs did not predict memory success, indicating a specific role for attention immediately following stimulus presentation.
• Individual differences in task-switching ability, self-reported cognitive failures, and attention modulated the link between postencoding RTs and memory.
• Increased activity in default mode network (DMN) regions during encoding correlated with slower postencoding RTs and impaired source memory retrieval.

Conclusions:

• Attention immediately following stimulus encoding, rather than preceding it, is crucial for successful source memory.
• Individual cognitive abilities significantly influence the relationship between attention during encoding and memory outcomes.
• Default mode network activity during encoding is implicated in attention-related memory deficits, highlighting its role in memory variability.