November 6, 2010

Long-term Memories The Good, the Bad, and the Ugly

From The Dana Foundation

Editor’s note: Traumatic memories haunt the lives of people suffering from post-traumatic stress disorder, or PTSD, and other illnesses. Fortunately, recent research into the changeability of long-term memories may someday develop into treatments for such individuals. But before this can happen, writes Cristina Alberini, Ph.D., of Mount Sinai School of Medicine, researchers must determine just how effectively the fear associated with older memories—especially those involved in PTSD—can be reduced and for how long. Researchers must also address the ethical issues that go hand in hand with modifying memory.

For more than a century, clinicians, psychologists, and biologists have worked to understand the mechanisms underlying the formation and storage of long-term memories. Recently, scientists found that when a stored memory is recalled, it becomes sensitive to disruption for a limited time.1,2 This finding indicates that it might be possible to weaken or even erase memories of traumatic experiences that become uncontrollably intrusive in post-traumatic stress disorder (PTSD). This possibility has drawn great interest from scientific and clinical communities, as well as from nonscientists, who became interested in its potential clinical applications; furthermore, it raised ethical concerns.

Many ethical questions and debates about treatments designed to weaken memories may reflect the still poor understanding of how memory recall or reactivation results in memory fragility and the many unknowns surrounding its temporal boundaries. Whereas the study of animal models and healthy humans has provided some knowledge about post-recall memory disruption, data on the use of such disruption to treat PTSD symptoms are still conflicting. The strengthening of memory with the passage of time, the resilience of strong memories to disruption, and the specific aspects of memory that become sensitive to disruption raise questions about the limitations of this approach and warrant more research. Here, we will look at how we form memories of an emotional event and how these memories become fragile after recall. That will help us consider the potential, limitations, and ethics of disrupting memories of emotion.

Read the entire article

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October 28, 2010

The Vegetative State and the Science of Consciousness

Article in British Journal for the Philosophy of Science

N. Shea, T. Bayne

Abstract

Consciousness in experimental subjects is typically inferred from reports and other forms of voluntary behaviour. A wealth of everyday experience confirms that healthy subjects do not ordinarily behave in these ways unless they are conscious. Investigation of consciousness in vegetative state patients has been based on the search for neural evidence that such broad functional capacities are preserved in some vegetative state patients. We call this the standard approach. To date, the results of the standard approach have suggested that some vegetative state patients might indeed be conscious, although they fall short of being demonstrative. The fact that some vegetative state patients show evidence of consciousness according to the standard approach is remarkable, for the standard approach to consciousness is rather conservative, and leaves open the pressing question of how to ascertain whether patients who fail such tests are conscious or not. We argue for a cluster-based ‘natural kind’ methodology that is adequate to that task, both as a replacement for the approach that currently informs research into the presence or absence of consciousness in vegetative state patients and as a methodology for the science of consciousness more generally.

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October 22, 2010

What research paradigms have cognitive psychologists used to study “False memory,” and what are the implications of these choices?

K. Pezdek, S. Lam
Article in Consciousness and Cognition

Abstract
This research examines the methodologies employed by cognitive psychologists to study “false memory“, and assesses if these methodologies are likely to facilitate scientific progress or perhaps constrain the conclusions reached. A PsycINFO search of the empirical publications in cognitive psychology was conducted through January, 2004, using the subject heading, “false memory.” The search produced 198 articles. Although there is an apparent false memory research bandwagon in cognitive psychology, with increasing numbers of studies published on this topic over the past decade, few researchers (only 13.1% of the articles) have studied false memory as the term was originally intended—to specifically refer to planting memory for an entirely new event that was never experienced in an individual’s lifetime. Cognitive psychologists interested in conducting research relevant to assessing the authenticity of memories for child sexual abuse should consider the generalizability of their research to the planting of entirely new events in memory.

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January 30, 2008

God on the brain

From BBC (and read exciting transcript): Rudi Affolter and Gwen Tighe have both experienced strong religious visions. He is an atheist; she a Christian. He thought he had died; she thought she had given birth to Jesus. Both have temporal lobe epilepsy.

Like other forms of epilepsy, the condition causes fitting but it is also associated with religious hallucinations. Research into why people like Rudi and Gwen saw what they did has opened up a whole field of brain science: neurotheology.

The connection between the temporal lobes of the brain and religious feeling has led one Canadian scientist to try stimulating them. (They are near your ears.) 80% of Dr Michael Persinger’s experimental subjects report that an artificial magnetic field focused on those brain areas gives them a feeling of ‘not being alone’. Some of them describe it as a religious sensation.

His work raises the prospect that we are programmed to believe in god, that faith is a mental ability humans have developed or been given. And temporal lobe epilepsy (TLE) could help unlock the mystery.

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January 9, 2008

Cheap drugs against aggression don’t work

Study shows placebos as good as antipsychotics for the intellectually disabled.

Scientists have discovered that taking a sugar pill is more effective than routine medications in treating aggression in people with intellectual disabilities. Until now, patients with intellectual disabilities have been prescribed antipsychotic drugs — normally given to people with a psychiatric disease like schizophrenia — to treat aggressive behaviour such as head banging. But evidence for the drugs’ effectiveness has been thin.

“Antipsychotic drugs are widely used because they are cheap and at high doses they sedate people,” says Eric Emerson at Lancaster University, an expert in the behaviour of intellectually disabled people.

Peter Tyrer, based at Imperial College London, led an international research project looking at 86 people with intellectual disability at clinics across England, Wales and at one centre in Australia. Patients being treated for aggressive behaviour randomly received one of two antipsychotic drugs — respiridone or haloperidol — or a placebo.

Nature News

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January 4, 2008

Altered emotional response in bipolar mania

abnormal states,neuroimaging,psychiatry — thomasr @ 11:20 am

Psychiatric illnesses are often good models for testing the functional relationship between specific regions of the brain. At the same time, one may gain insight into the neurocognitive mechanisms behind a specific disease.

This is the case in a recently published study in Psychiatry Research by Foland et al.:

Evidence for deficient modulation of amygdala response by prefrontal cortex in bipolar mania.
Foland LC, Altshuler LL, Bookheimer SY, Eisenberger N, Townsend J, Thompson PM.

Several studies have implicated the involvement of two major components of emotion regulatory networks, the ventrolateral prefrontal cortex (VLPFC) and amygdala, in the pathophysiology of bipolar disorder. In healthy subjects, the VLPFC has been shown to negatively modulate amygdala response when subjects cognitively evaluate an emotional face by identifying and labeling the emotion it expresses.

The current study used such a paradigm to assess whether the strength of this modulation was altered in bipolar subjects when manic. During functional magnetic resonance imaging (fMRI), nine manic subjects with bipolar I disorder and nine healthy subjects either named the emotion shown in a face by identifying one of two words that correctly expressed the emotion (emotion labeling task) or matched the emotion shown in a face to one of two other faces (emotion perception task). The degree to which the VLPFC regulated amygdala response during these tasks was assessed using a psychophysiological interaction (PPI) analysis.

Compared with healthy subjects, manic patients had a significantly reduced VLPFC regulation of amygdala response during the emotion labeling task. These findings, taken in context with previous fMRI studies of bipolar mania, suggest that reductions in inhibitory frontal activity in these patients may lead to an increased reactivity of the amygdala.

Psychiatry Res. 2008 Jan 15;162(1):27-37.

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May 24, 2007

Visual hallucinations? Draw it!

epilepsy_brain.jpgVisual (and other non-visual) hallucinations sometimes occur during epileptic seizures. A relatively straightforward but little used method to describe these experiences is to ask the sufferer to draw the hallucinations — even as they occur.

According to G.D. Schott, in an article in the latest issue of Brain, such descriptions not only not only serve as tools to understand the sufferer and symptoms; they can also be used for differential diagnosis. 

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April 5, 2007

An artificial sixth sense

abnormal states — virgil @ 2:16 pm

Wired has a story about new sensory prosthetics giving people a sense of magnetic north, “tactile vision”, etc. Subjects report that they even dream in their new senses.

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March 7, 2007

Out-of-body experiences may be caused by arousal system disturbances in brain

abnormal states,altered states — thomasr @ 3:40 pm

astral-projection.jpgNear death, sleep-wake transition have same likelihood of correlating to out-of-body experiences

Having an out-of-body experience may seem far-fetched to some, but for those with arousal system disturbances in their brains, it may not be a far off idea that they could sense they were really outside their own body watching themselves. In previous studies of more than 13,000 Europeans, almost 6 percent said they have had such an out-of-body experience.

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December 21, 2006

Functional neuroimaging in unconscious states

mri.jpegSteven Laureys and colleagues ask whether functional imaging methods such as fMRI and PET can be used to detect consciousness in individual patients. Recent studies have showed activation patterns in a vegetative patient that are comparable to helahty subjects. One pertinent question is therefore whether we can move from group studies towards individual scans. Here, Laureys et al. still have reservations, saying that “[published] data are insufficient to make recommendations for or against any of the neurorehabilitative treatments in vegetative state and minimally conscious state patients.”

How should functional imaging of patients with disorders of consciousness contribute to their clinical rehabilitation needs? Laureys S, Giacino JT, Schiff ND, Schabus M, Owen AM. 2006 Dec ; 19 (6): 520-527

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November 19, 2006

Altered cognition and emotion in depersonalization disorder

depersonal.jpgDepersonalization Disorder (DPD) is a dissociative disorder in which sufferers are affected by persistent feelings of depersonalization. The symptoms include a sense of automation, feeling a disconnection from one’s body, and difficulty relating oneself to reality. In a recent study Medford et al. reports that patients with DPD do not process emotionally salient material in the same way as healthy controls, in accordance with their subjective descriptions of reduced or absent emotional responses

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March 28, 2006

Greater control in Tourette’s

abnormal states — thomasr @ 1:21 pm

New evidence suggests that young people with Tourette’s syndrome actually exhibit a greater level of cognitive control over their movements than their non-affected peers do.

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March 16, 2006

Genes, depression and medication

abnormal states — thomasr @ 2:56 pm

Whether depressed patients will respond to an antidepressant depends, in part, on which version of a gene they inherit, a study led by scientists at the National Institutes of Health (NIH) has discovered. Having two copies of one version of a gene that codes for a component of the brain’s mood-regulating system increased the odds of a favorable response to an antidepressant by up to 18 percent, compared to having two copies of the other, more common version.

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March 5, 2006

Consciousness baffling psyhiatrists

abnormal states — thomasr @ 10:57 am

Former President Bill Clinton used to tell the public that he “felt their pain.” He may have been right—literally. Empathy has been shown to activate a brain region involved in feeling pain. A large part of a psychiatrist’s day is spent navigating the world of emotions, feelings, and consciousness. Yet what is actually known about these ephemeral mental states?

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February 28, 2006

Metamemory, delusions and schizophrenia

abnormal states — thomasr @ 12:22 pm

What causes delusions in schizophrenia? A study by Moritz et al. demonstrates that metamemory corruption appears to be a contributing factor to the formation of delusions.

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February 4, 2006

An update on anxiety

abnormal states — thomasr @ 9:04 pm

It unclear today whether anxiety states should be thought of as several distinct diagnostic entities, or as one broadly conceived syndrome with no clear boundaries between various manifestations of anxiety. In this review by Vladan Starcevic at Medscape.com both conceptual and treatment issues are presented and discussed.

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December 26, 2005

Social reasoning in schizophrenia

abnormal states — thomasr @ 9:06 pm

How do people suffering from schizophrenia think socially? In this study by Russell et al. patients were asked to verbally describe cartoons of different social complexity. The results demonstrate that patients suffering from schizophrenia show different result profiles according to their symptomalogy, and that verbal measures may be used as an indicator for social reasoning deficits in schizophrenia.

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December 21, 2005

Are emotions different in schizophrenia?

abnormal states — thomasr @ 7:01 pm

A recently published review Alemana and colleagues argue that patients suffering from schizophrenia are different in their emotional experiences. This difference is due to alterations in the functions of specific brain circuits, especially the dorsolateral prefrontal cortex and the amygdala.

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December 7, 2005

Autism May Be Linked to Enlarged Brain Region

abnormal states — thomasr @ 8:42 am

The brains of children with autism may be bigger than those of children who do not suffer from the disorder, according to a new study.

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November 25, 2005

You must be looking at me: The nature of gaze perception in schizophrenia patie

abnormal states — thomasr @ 1:02 pm

Christine Hooker and Sohee Park

Introduction

Accurately identifying gaze direction is an important component of successful social interaction. Preliminary research indicates that schizophrenia patients have deficits in gaze perception, but the nature of this deficit is still unclear. The current study investigates whether nonspecific perceptual abnormalities could explain gaze perception deficits and whether schizophrenia patients show a direct gaze bias in their judgement.

Methods

Fifteen chronic schizophrenia patients and nineteen normal control participants made a direct gaze judgement for eyes in a face, and a centre judgement for a geometric shape in a scrambled face.

Results

The data show that schizophrenia patients are as accurate as healthy control subjects at identifying direct gaze when it occurs but they are more likely to misinterpret averted gaze as directed at them. The pattern of results indicates that this tendency to endorse direct gaze is not a consequence of a perceptual deficit in judging angular displacement.

Conclusions

Schizophrenia patients have a self‐referential bias in judging the direction of gaze that could lead to the misinterpretation of another person’s intentions during the course of social interaction.

Psychology Press

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