Strategic Manipulations for Associative Memory and the Role of Verbal Processing Abilities in Schizophrenia

Abstract

Individuals with schizophrenia demonstrate episodic memory (EM) deficits and abnormal EM-related brain activity. Experimental encoding manipulations significantly benefit memory performance in schizophrenia, suggesting that a strategic processing deficit may contribute to memory impairment. However, few studies have investigated the combined effects of encoding and retrieval strategies on EM in schizophrenia. The current study examined the impact of encoding and retrieval strategies on associative memory and brain activity in schizophrenia. We also assessed the role of verbal processing ability in response to strategic memory interventions in schizophrenia. Behavioral and functional neuroimaging data were collected from 23 participants with schizophrenia and 24 comparison subjects while performing associative memory encoding and recall tasks. Behaviorally, both schizophrenia participants and controls benefited from memory strategies and showed significant associations between verbal processing ability and recall. Additionally, among schizophrenia participants, encoding strategy use was associated with enhanced brain activity in multiple brain areas. Schizophrenia participants also demonstrated significant associations between verbal processing ability and encodingrelated brain activity in prefrontal cortex. Findings suggest that memory performance and brain activity in schizophrenia can be enhanced via strategic manipulations, and individual differences in cognitive abilities in schizophrenia can affect behavioral and neurobiological responses to strategic memory interventions. (JINS, 2011, 17, 796-806)

Cognitive correlates of verbal memory and verbal fluency in schizophrenia, and differential effects of various clinical symptoms between male and female patients

“…These findings suggest that the repeated learning of the first semantically-organisable list induced differences in the strategy implemented to learn the interference list, with stronger reliance upon the use of semantic organisation. The contribution of semantic organisation to recall efficiency corroborates what was observed in several previous studies, and suggests that verbal memory performance in these patients could be improved by encouraging effective encoding strategies (Bonner-Jackson and Barch, 2011).…”

Contributions of Feature Binding During Encoding and Functional Connectivity of the Medial Temporal Lobe Structures to Episodic Memory Deficits Across the Prodromal and First-Episode Phases of Schizophrenia

“…Prior studies have shown that patients do not naturally make use of strategies such as encoding and rehearsing items based on semantic content (Iddon, McKenna, Sahakian, & Robbins, 1998), although when such strategies are overtly suggested to patients, they appear able to use the strategies to improve memory performance (Ragland et al, 2003; Ragland et al, 2009). The fact that patients in the present study showed enhanced MTL–visual cortex connectivity patterns at recognition testing suggests that these regions are able to become functionally active but did not do so during the critical moment of learning, thereby supporting the notion that encoding strategy may affect associative memory deficits (Bonner-Jackson & Barch, 2011). …”

Cognition in schizophrenia: core psychological and neural mechanisms

“…Consistent with this hypothesis, a number of studies suggest that individuals with schizophrenia are impaired in their ability to generate effective mnemonic strategies (for review, see [36]). However, when provided with strategies that promote successful episodic encoding, individuals with schizophrenia are typically able to benefit as much as controls from these strategies [e.g., 72, 73, 74], and can even show intact item recognition when provided with support for effective encoding [75]. Further, a meta-analysis of brain activity alterations during episodic memory performance in schizophrenia showed consistent evidence for reduced activation in both ventrolateral and DLPFC, but did not find consistent evidence for altered hippocampal activity [76].…”