Reduced Functional Connectivity in Brain Networks Underlying Paired Associates Memory Encoding in Schizophrenia

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Relational episodic memory encoding deficits are a key feature of schizophrenia (SZ).
• Previous whole-brain multivariate analyses of these deficits are lacking.
• Task-based fMRI data from open science initiatives have not been fully utilized to study SZ-related memory encoding impairments.

Purpose of the Study:

• To conduct the first network-level investigation of impaired relational episodic encoding in SZ using previously unpublished task fMRI data.
• To examine functional network differences between individuals with SZ and healthy controls during paired associate encoding.

Main Methods:

• Utilized fMRI data from 40 individuals with SZ and 40 healthy controls.
• Employed an associative semantic strategy for verbal paired associate encoding.
• Applied constrained principal component analysis to identify functional networks involved in encoding.

Main Results:

• Identified three distinct functional networks: responding, linguistic processing/attention, and default mode networks.
• Observed aberrant activity in all three networks in the SZ group during successful encoding, including hypoactivation in the linguistic processing/attention network.
• Found that stronger anticorrelation between linguistic processing/attention and default mode networks predicted successful retrieval, independent of group.

Conclusions:

• Aberrant activity in language and default mode networks may underlie difficulties in employing deep semantic strategies for relational episodic encoding in SZ.
• Findings suggest that abnormalities in networks representing language and meaning contribute to memory deficits in schizophrenia.
• Highlights the potential of network-level analysis for understanding cognitive impairments in SZ.