Memory Deficits in Schizophrenia Explored: Disturbances Appear Isolated in the Dorsolateral Region of Prefrontal Cortex, Data from MRIs Show

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CHICAGO -- Disturbances in the dorsolateral region of the prefrontal cortex are associated with both working and episodic memory deficits in schizophrenia, Deanna M. Barch, Ph.D., said at the annual meeting of the Society for Psychophysiological Research.

Data from a series of functional magnetic resonance imaging studies revealed that disturbances in cognitive task-related prefrontal activation in schizophrenia are relatively isolated to the dorsolateral region of the prefrontal cortex.

These disturbances are associated with both working memory and episodic memory deficits, and are equally severe for both verbal and nonverbal materials, said Dr. Barch of the department of psychology at Washington University, St. Louis.

Researchers have long suggested that disturbances in the function of the prefrontal cortex contribute to cognitive deficits in schizophrenia, particularly problems with working memory.

Dr. Barch's work adds to a growing body of evidence that suggests prefrontal disturbances may actually contribute to deficits in several domains besides working memory, including attention, inhibition, episodic memory, and emotional regulation.

Dr. Barch hypothesized that one of the specific roles of the dorsolateral prefrontal cortex (DLPFC) is the representation and maintenance of contextual information, and that disturbances of the DLPFC lead to deficits in cognitive behavior processing, which in turn contribute to disturbances in a wide array of other cognitive domains.

Contextual representations are important to a wide variety of cognitive domains such as language processing and semantic representation, and are used to guide subsequent behavior or responses.

For example, if a person reads the word "pen" in a sentence following a description of a farmer and his chickens, contextual representation allows the reader to more easily access the less common meaning of pen as an enclosure. Such an interpretation would be contextually appropriate to the sentence.

Dr. Barch and her colleagues used a variation on the classic continuous task test to examine contextual processing. Thirty-eight of the individuals had in 38 schizophrenia, and 48 people were healthy controls.

The study participants were shown a series of letters on a screen and asked to respond to the target letter "X," but only when it followed the letter "A. …