Neural evidence for advantaged representation of first items in memory

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Brain Imaging

Background:

• The primacy effect, an advantage for recalling early information, is well-established but its neural basis remains unclear.
• Visual cortex activity patterns can maintain memory representations without external stimuli.
• Serial position may modulate memory representation during delay periods.

Purpose of the Study:

• To investigate the neural mechanisms underlying the behavioral primacy effect.
• To determine if enhanced neural representation of the first item during memory delay contributes to the primacy effect.

Main Methods:

• Human functional magnetic resonance imaging (fMRI) task with sequential encoding of two stimuli.
• Multivariate decoding to differentiate stimulus categories (faces vs. landscapes) during encoding and post-encoding periods.
• Behavioral analysis of recall speed to assess the primacy effect.

Main Results:

• Participants showed a behavioral primacy effect, recalling first items faster.
• Greater neural "reactivation" of first versus second items was observed in the ventral occipito-temporal cortex during the post-encoding delay.
• The neural advantage for the first item predicted the strength of the behavioral primacy effect.

Conclusions:

• Enhanced neural reinstatement in the ventral occipito-temporal cortex plays a key role in the primacy effect.
• These findings suggest that unique neural processing of the first item contributes to its mnemonic advantage.
• The study illuminates potential neural mechanisms for memory advantages of early presented information.