'Noisy' memory in schizophrenia

July 14, 2014, Elsevier
Functional magnetic resonance imaging (fMRI) and other brain imaging technologies allow for the study of differences in brain activity in people diagnosed with schizophrenia. The image shows two levels of the brain, with areas that were more active in healthy controls than in schizophrenia patients shown in orange, during an fMRI study of working memory. Credit: Kim J, Matthews NL, Park S./PLoS One.

The inability to ignore irrelevant stimuli underlies the impaired working memory and cognition often experienced by individuals diagnosed with schizophrenia, reports a new study in the current issue of Biological Psychiatry.

Our brains are usually good at focusing on the information that we are trying to learn and filtering out the "noise" or thoughts that aren't relevant. However, memory impairment in may be related in part to a problem with this filtering process, which Dr. Teal Eich at Columbia University and her colleagues studied.

"Our assumption was that understanding the impairments in the component processes of – the ability to hold and manipulate information in the mind – among patients with schizophrenia could be fundamental to understanding not only cognitive function in the disorder, which is widespread and has debilitating consequences, but also the disorder itself," Eich explained.

The researchers recruited patients with schizophrenia and a control group of healthy volunteers to complete an item recognition task in the laboratory while undergoing a functional magnetic resonance imaging scan. In particular, they focused on analyzing potential activation differences in the ventro-lateral prefrontal cortex (VLPFC), a region of the brain implicated in working memory.

The design of the task allowed for the assessment of the various components of working memory: 1) maintaining the memory itself, 2) inhibiting or ignoring , and 3) during memory retrieval, controlling the interference of irrelevant information.

While simply maintaining the memory, both groups showed a similar degree of activation in the VLPFC. During the inhibition phase, VLPFC activity is expected to decrease, which was indeed observed in the healthy group, but not in the patients. Finally, during interference control, patients performed worse and showed increased VLPFC activation compared to the . Overall, the patients showed altered VLPFC functioning and significant impairments in their ability to control working memory.

"Our findings show that these patients have a specific deficit in inhibiting information in working memory, leading to impaired distinctions between relevant and irrelevant thoughts," said Eich. "This result may provide valuable insights into the potential brain mechanisms underlying the reasons why these affected individuals are unable to control or put out of mind certain thoughts or ideas."

This study adds to a growing literature suggesting that cognitive functions require both the activation of one set of regions and the inhibition of others. The failure to suppress activation may be just as disruptive to cortical functions as deficits in cortical activation.

Many years ago, the pioneering scientist Patricia Goldman-Rakic and her colleagues showed that the inhibition of regional prefrontal cortical activity was dependent upon the integrity of the GABA (gamma-aminobutyric acid) system in the brain, a chemical system with abnormalities associated with schizophrenia.

"We need to determine whether the cortical inhibitory deficits described in this study can be attributed to particular brain chemical signaling abnormalities," said Dr. John Krystal, Editor of Biological Psychiatry. "If so, this type of study could be used to guide therapeutic strategies to enhance working memory function."

Explore further: Shedding light on memory deficits in schizophrenic patients and healthy aged subjects

More information: The article is "Neural Correlates of Impaired Cognitive Control over Working Memory in Schizophrenia" by Teal S. Eich, Derek Evan Nee, Catherine Insel, Chara Malapani, and Edward E. Smith (DOI: 10.1016/j.biopsych.2013.09.032). The article appears in Biological Psychiatry, Volume 76, Issue 2 (July 15, 2014)

Related Stories

Shedding light on memory deficits in schizophrenic patients and healthy aged subjects

February 23, 2012
Working memory, which consists in the short-term retention and processing of information, depends on specific regions of the brain working correctly. This faculty tends to deteriorate in patients with schizophrenia, as it ...

Tickling the brain with magnetic stimulation improves memory in schizophrenia

March 12, 2013
Cognitive impairments are disabling for individuals with schizophrenia, and no satisfactory treatments currently exist. These impairments affect a wide range of cognition, including memory, attention, verbal and motor skills, ...

Altered brain activity responsible for cognitive symptoms of schizophrenia

March 20, 2013
Cognitive problems with memory and behavior experienced by individuals with schizophrenia are linked with changes in brain activity; however, it is difficult to test whether these changes are the underlying cause or consequence ...

Inflammation and cognition in schizophrenia

November 1, 2012
There are a growing number of clues that immune and inflammatory mechanisms are important for the biology of schizophrenia. In a new study in Biological Psychiatry, Dr. Mar Fatjó-Vilas and colleagues explored the impact ...

Motor excitability predicts working memory

December 23, 2013
Humans with a high motor excitability have a better working memory than humans with a low excitability. This was shown in a study conducted by scientists from the Transfacultary Research Platform at the University of Basel. ...

Regulating brain activity to improve attention

June 4, 2014
(Medical Xpress)—Researchers from The University of Nottingham have found that balanced activity in the brain's prefrontal cortex is necessary for attention.

Recommended for you

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

Recording a thought's fleeting trip through the brain

January 17, 2018
University of California, Berkeley neuroscientists have tracked the progress of a thought through the brain, showing clearly how the prefrontal cortex at the front of the brain coordinates activity to help us act in response ...

Midbrain 'start neurons' control whether we walk or run

January 17, 2018
Locomotion comprises the most fundamental movements we perform. It is a complex sequence from initiating the first step, to stopping when we reach our goal. At the same time, locomotion is executed at different speeds to ...

Miles Davis is not Mozart: The brains of jazz and classical pianists work differently

January 16, 2018
Keith Jarret, world-famous jazz pianist, once answered in an interview when asked if he would ever be interested in doing a concert where he would play both jazz and classical music: "No, that's hilarious. [...] It's like ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.