New research- Schizophrenia

'Noisy' memory in schizophrenia

Date:

July 14, 2014

Source:

Elsevier

Summary:

The inability to ignore irrelevant stimuli underlies the impaired working memory and cognition often experienced by individuals diagnosed with schizophrenia, reports a new study. 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 schizophrenia may be related in part to a problem with this filtering process, which medical researchers have recently studied.

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 schizophrenia 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 working memory -- 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 irrelevant information, 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 healthy volunteers. 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."

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Story Source:
The above story is based on materials provided by Elsevier. Note: Materials may be edited for content and length.

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Journal Reference:

1. Teal S. Eich, Derek Evan Nee, Catherine Insel, Chara Malapani, Edward E. Smith. Neural Correlates of Impaired Cognitive Control over Working Memory in Schizophrenia. Biological Psychiatry, 2014; 76 (2): 146 DOI: 10.1016/j.biopsych.2013.09.032

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BPS new research

Neurosurgeons find small brain region that turns consciousness on and off, like the key in a car's ignition

The 54-year-old epilepsy patient - her name remains concealed to protect her privacy - was lying on the operating table while surgeons explored inside her brain with electrodes. They were looking for the source of her epileptic seizures. Suddenly, after they applied electricity to a small region, buried deep, near the front of the brain, the woman froze and her eyes went blank. She was awake, but entirely unresponsive.

The precise area the surgeons had zapped included a sliver of tissue known as the claustrum, which is part of a network that supports awareness. Mohamad Koubeissi and his colleagues state that nobody has ever examined the effects of stimulating this specific brain region before, despite this kind of surgical procedure having been performed for decades. Just as geographers still surprise us with reports of having discovered previously unchartered parts of the earth, it takes one aback to hear of unexplored areas of neural terrain.

Intrigued by the woman's response to the stimulation of this specific brain region, the surgeons investigated further. Ten further stimulations, and on every occasion zapping the claustrum had the same effect. By contrast, zapping an area just 2.7mm away did not.

Perhaps the woman was simply paralysed by the electrical stimulation? The effects are more intriguing than that. If given an instruction prior to the stimulation, such as words to utter or movements to make, she continued this for a few seconds after the stimulation began, but then descended into still, unresponsive stupor. It was also striking to observe that as soon as the stimulation ended, the woman regained consciousness. However, she had no memory of the preceding moments during the stimulation period.

The researchers also examined the synchronisation of activity across the brain during the stimulation of the claustrum. They found that it increased synchronisation across the brain, possibly to a debilitating level. If so, this would match the situation observed in epileptic seizures that trigger loss of consciousness.

Caution is required - after all, this is a single case study, and the patient in question was missing part of one hippocampus, removed during earlier treatment for epilepsy. Nonetheless this is an intriguing finding. "... [T]he disruption of consciousness that we herein describe has never been precipitated by electrical stimulation of any other site in the human brain," the researchers said.

Speaking to New Scientist magazine, lead author Koubeissi likened the claustrum to a car's ignition. While both the brain and the car are made up of many functioning parts, "...there's only one spot where you turn the key and it all switches on and works together," he told them. "So while consciousness is a complicated process created by many structures and networks - we may have found the key." If these results can be replicated, the hope is that stimulation of the claustrum may offer a way to treat disorders of consciousness associated with epileptic seizures.

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Mohamad Z. Koubeissia, Fabrice Bartolomei, Abdelrahman Beltagy, Fabienne Picard. (2014). Electrical stimulation of a small brain area reversibly disrupts consciousness.  Epilepsy & Behavior Volume 37, August 2014, Pages 32–35

BPS New research- What happens to the cool kids?

BPS new research -What happens to the cool kids?
"Cool kids", according to a new study, are those early teens (aged 13 to 15) who want to be popular, and try to impress their peers by acting older than their years. They have precocious romantic relationships, commit relatively minor acts of bad behaviour (such as sneaking into the cinema without paying), and surround themselves with good-looking friends. These teenagers attract respect from their peers at first, but what's the story by the time they reach early adulthood?

Joseph Allen and his colleagues made contact with 184 thirteen-year-olds (98 girls) from a diverse range of backgrounds, living in the Southeastern United States. They interviewed them at that age, and then again when they were aged 14 and 15. The researchers also contacted some of their close friends and peers. Finally, the sample and their friends were followed up again a decade later, when they were aged 21 to 23.

There were short-term advantages to being a cool kid - these teens tended to be popular when they were in early adolescence. However, this popularity began to fade through teenhood. And ten years later, the cool kids were at greater risk for alcohol and drug problems, more serious criminal behaviour, and, according to their friends, they struggled with their platonic and romantic relationships. As adults, cool kids also tended to blame their recent relationship break ups on their partner not thinking they were popular enough - as if they were still viewing life through the immature lens of cool.

Allen's team said their results show that "early adolescent attempts to gain status via pseudomature behaviour are not simply passing annoyances of this developmental stage, but rather may signal movement down a problematic pathway and away from progress toward real psychosocial competence." They think cool kids' preoccupation with being precocious and rebellious gets in the way of them developing important socialisation skills. It's also likely that as they get older, cool kids feel the need to engage in ever greater acts of rebellion to command respect from their peers.

Is it possible that the researchers were simply measuring a propensity to deviance and criminality in early adolescence, making their longitudinal findings unsurprising? They don't think so. They point out that serious criminality, and alcohol and cannabis use, in early adulthood were more strongly correlated with being a cool kid in early adolescence (i.e. as measured by desire for popularity; precious romantic relationships; minor deviance; and surrounding oneself with good-looking friends) than with alcohol and drug use, and criminality at that time.

The study is not without limitations - for example, cool kids were found to lose their popularity through adolescence, but this was based on a measure of their peers' desire to be with them, not on their status. It's also possible they retained or earned popularity with teens older than them. Nonetheless, Allen and his team said their findings are novel and show that the "seemingly minor behaviours" associated with being a cool kid "predict far greater future risk than has heretofore been recognised."

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Allen JP, Schad MM, Oudekerk B, & Chango J (2014). What Ever Happened to the "Cool" Kids? Long-Term Sequelae of Early Adolescent Pseudomature Behavior. Child development PMID: 24919537