March 29, 2011

Being rejected a real pain, brain images show

From CBC News:

The pain of rejection is more than just a figure of speech: regions of the brain that respond to physical pain overlap with those that react to social rejection, a brain imaging study shows.

The study used brain imaging on people involved in romantic breakups.

“These results give new meaning to the idea that rejection ‘hurts,”‘ wrote psychology professor Ethan Kross of the University of Michigan and his colleagues. Their findings are reported in Tuesday’s edition of Proceedings of the National Academy of Sciences.

Co-author Edward Smith of Columbia University explained that the research shows that psychological or social events can affect regions of the brain that scientists thought were dedicated to physical pain.

Click here to read the rest of the article.

Click here for full access to the study published in Proceedings of the National Academy of Sciences.

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March 10, 2011

Can Someone in a Vegetative State Communicate Thoughts?

In this short video (about 4 mins) from the New York Times, David Corcoran discusses evidence from an fMRI study that suggests that people in a vegetative state can communicate thoughts.

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February 23, 2011

Scientists look to new imaging techniques to measure metals in the brain

From the Globe and Mail:

We are metal heads. Our brains need iron, copper, manganese and zinc to function, yet there is growing evidence that these metals may play a role in Alzheimer’s disease, Parkinson’s disease multiple sclerosis and other illnesses.

Canadian scientists are developing new imaging techniques to accurately map and measure metals in the brain, a crucial step toward learning more about why they are so essential, as well as understanding the damage they can cause under some circumstances.

Click here to read the rest of the article.

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November 15, 2010

Mental Training Through Meditation Enhances Attentional Stability

A. Lutz, H. Slagter, et al.
Article in Journal of Neuroscience

Abstract
The capacity to stabilize the content of attention over timevaries among individuals, and its impairment is a hallmark ofseveral mental illnesses. Impairments in sustained attentionin patients with attention disorders have been associated withincreased trial-to-trial variability in reaction time and event-relatedpotential deficits during attention tasks. At present, it isunclear whether the ability to sustain attention and its underlyingbrain circuitry are transformable through training. Here, weshow, with dichotic listening task performance and electroencephalography,that training attention, as cultivated by meditation, can improvethe ability to sustain attention. Three months of intensivemeditation training reduced variability in attentional processingof target tones, as indicated by both enhanced theta-band phaseconsistency of oscillatory neural responses over anterior brainareas and reduced reaction time variability. Furthermore, thoseindividuals who showed the greatest increase in neural responseconsistency showed the largest decrease in behavioral responsevariability. Notably, we also observed reduced variability inneural processing, in particular in low-frequency bands, regardlessof whether the deviant tone was attended or unattended. Focusedattention meditation may thus affect both distracter and targetprocessing, perhaps by enhancing entrainment of neuronal oscillationsto sensory input rhythms, a mechanism important for controllingthe content of attention. These novel findings highlight themechanisms underlying focused attention meditation and supportthe notion that mental training can significantly affect attentionand brain function.

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October 26, 2010

The Default Network: Your Mind, on Its Own Time

From The Dana Foundation:

Studies about the brain usually focus on neural activity during the completion of a specific task—remembering a series of words, for example. But over the last 20 years, researchers have been interested in what the brain does during periods of supposed inactivity. They discovered that when someone appears to be doing nothing at all, a network of brain regions—named the default network—is hard at work, allowing for the rich inner lives inside our heads. Applying what is known about the default network to diseases like Alzheimer’s allows for new possibilities for diagnosis and evaluation of treatments.

You’re lying in a brain scanner in the dark, looking up at a small white crosshair, left alone with your thoughts for the next six minutes. What goes through your mind? Perhaps you think about why you volunteered for this, or what you’ll do with the money you earn from this experiment. Perhaps you plan out the rest of your day, or start replaying a conversation from yesterday. New techniques in neuroimaging are helping scientists understand how your brain represents such internally directed and spontaneous thoughts.

Read the entire article

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October 17, 2009

Alpha Oscillations, Attention and Consciousness

One way to describe brain activity measured by EEG or MEG is by its frequency content. Frequencies can be categorized into one of the following ranges: low, middle and high. The low frequencies include the delta and theta ranges, whereas the middle frequency range consists of the alpha and beta ranges. The gamma wave belongs to the high frequency group.

Different cognitive functions have been associated with these different frequency ranges. Specifically, alpha oscillations have been associated with the inhibition of brain regions that are not required to perform a given task. However, in a past paper, Palva and Palva summarized an accumulating body of evidence that suggested that alpha oscillations play a much larger role in cognition by contributing to mechanisms of attention and consciousness. Click here for full access to the paper.

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October 9, 2009

1/f Scaling and Emergent Pattern Formation in Complex Systems

1/f scaling (or 1/f noise) refers to a scaling relation followed by fluctuations that have been widely observed in nature. 1/f fluctuations have been observed ubiquitously across different disciplines of science (e.g. chemistry, psychology, biology). In specific relation to cognitive neuroscience, 1/f scaling has been observed widely in fMRI measurement series and treated, generally, as noise to work around as opposed to an object of study. The challenge is that since 1/f fluctuations seem to be present throughout the brain, they do not help localize specific cognitive functions to specific areas of the brain. However, studies have shown that the appearance of 1/f fluctuations in fMRI measurements change as a function of cognitive variables.

Whereas some researchers argue that 1/f scaling is a byproduct of processes that are irrelevant to theories of cognition, others argue that 1/f fluctuations reflect a general and essential principle of emergent pattern formation in complex systems, including cognitive systems.

In a past study Kello, Beltz, Holden and Van Orden examined the relevance of 1/f scaling to cognitive function in four experiments using simple and choice response tasks. (For full access to the paper, click here.) The results of this study supported the emergent coordination argument and the researchers concluded that “the generality of 1/f scaling in cognitive performance is evidence that cognitive functions are universally formed as emergent patterns of physiological and behavioral activity”.

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October 5, 2009

Lucid Dreaming: A State of Consciousness with Features of Both Waking and Non-Lucid Dreaming

U. Voss, R. Holzmann, I. Tuin, J.A. Hobson
Article in Sleep

Abstract
Study Objectives: The goal of the study was to seek physiological correlates of lucid dreaming. Lucid dreaming is a dissociated state with aspects of waking and dreaming combined in a way so as to suggest a specific alteration in brain physiology for which we now present preliminary but intriguing evidence. We show that the unusual combination of hallucinatory dream activity and wake-like reflective awareness and agentive control experienced in lucid dreams is paralleled by significant changes in electrophysiology.

Design: 19-channel EEG was recorded on up to 5 nights for each participant. Lucid episodes occurred as a result of pre-sleep autosuggestion.

Setting: Sleep laboratory of the Neurological Clinic, Frankfurt University.

Participants: Six student volunteers who had been trained to become lucid and to signal lucidity through a pattern of horizontal eye movements.

Measurements and Results: Results show lucid dreaming to have REM-like power in frequency bands delta and theta, and higher-than-REM activity in the gamma band, the between-states-difference peaking around 40 Hz. Power in the 40 Hz band is strongest in the frontal and frontolateral region. Overall coherence levels are similar in waking and lucid dreaming and significantly higher than in REM sleep, throughout the entire frequency spectrum analyzed. Regarding specific frequency bands, waking is characterized by high coherence in alpha, and lucid dreaming by increased delta and theta band coherence. In lucid dreaming, coherence is largest in frontolateral and frontal areas.

Conclusions: Our data show that lucid dreaming constitutes a hybrid state of consciousness with definable and measurable differences from waking and from REM sleep, particularly in frontal areas.

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May 19, 2009

Learning, Arts, and the Brain: the Dana Consortium Report on Arts and Cognition

From the Dana Foundation: The Dana Foundation released at a news conference on March 4, Learning, Arts, and the Brain, a three-year study at seven universities, which finds strong links between arts education and cognitive development. Speakers included Michael Gazzaniga, Ph.D., UC, Santa Barbara; Michael Posner, Ph.D., University of Oregon;  Elizabeth Spelke, Ph.D., Harvard University  and Brian Wandell, Ph.D., Stanford University.  Guy Mckhann, M.D., Johns Hopkins University gave a summary and Dana Gioia, chairman of the National Endowment for the Arts spoke of the study’s importance to the field of education.

Click here for the webcast archive.

Click here for the event transcript.

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April 10, 2009

Investigating the Awareness of Remembering

Ken A. Paller, Joel L.Voss, Carmen E. Westerberg
Article in Perspectives on Psychological Science

Abstract
There is a marked lack of consensus concerning the best way to learn how conscious experiences arise. In this article, we advocate for scientific approaches that attempt to bring together four types of phenomena and their corresponding theoretical accounts: behavioral acts, cognitive events, neural events, and subjective experience. We propose that the key challenge is to comprehensively specify the relationships among these four facets of the problem of understanding consciousness without excluding any facet. Although other perspectives on consciousness can also be informative, combining these four perspectives could lead to significant progress in explaining a conscious experience such as remembering. We summarize some relevant findings from cognitive neuroscience investigations of the conscious experience of memory retrieval and of memory behaviors that transpire in the absence of the awareness of remembering. These examples illustrate suitable scientific strategies for making progress in understanding consciousness by developing and testing theories that connect the behavioral expression of recall and recognition, the requisite cognitive transactions, the neural events that make remembering possible, and the awareness of remembering.

Click here for the full paper.

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January 31, 2009

Hyperactivity and Hyperconnectivity of the Default Network in Schizophrenia and in First-degree Relatives of Persons with Schizophrenia

Susan Whitfield-Gabrieli, Heidi W. Thermenos, Snezana Milanovic, Ming T. Tsuang, Stephen V. Faraone, Robert W. McCarley, Martha E. Shenton, Alan I. Green, Alfonso Nieto-Castanon, Peter LaViolette, Joanne Wojcik, John D. E. Gabrieli and Larry J. Seidman
Article in PNAS

Abstract
We examined the status of the neural network mediating the default mode of brain function, which typically exhibits greater activation during rest than during task, in patients in the early phase of schizophrenia and in young first-degree relatives of persons with schizophrenia. During functional MRI, patients, relatives, and controls alternated between rest and performance of working memory (WM) tasks. As expected, controls exhibited task-related suppression of activation in the default network, including medial prefrontal cortex (MPFC) and posterior cingulate cortex/precuneus. Patients and relatives exhibited significantly reduced task-related suppression in MPFC, and these reductions remained after controlling for performance. Increased task-related MPFC suppression correlated with better WM performance in patients and relatives and with less psychopathology in all 3 groups. For WM task performance, patients and relatives had greater activation in right dorsolateral prefrontal cortex (DLPFC) than controls. During rest and task, patients and relatives exhibited abnormally high functional connectivity within the default network. The magnitudes of default network connectivity during rest and task correlated with psychopathology in the patients. Further, during both rest and task, patients exhibited reduced anticorrelations between MPFC and DLPFC, a region that was hyperactivated by patients and relatives during WM performance. Among patients, the magnitude of MPFC task suppression negatively correlated with default connectivity, suggesting an association between the hyperactivation and hyperconnectivity in schizophrenia. Hyperactivation (reduced task-related suppression) of default regions and hyperconnectivity of the default network may contribute to disturbances of thought in schizophrenia and risk for the illness.

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January 17, 2009

Learning, Arts, and the Brain: The Dana Consortium Report

From the Dana Foundation: Learning, Arts, and the Brain, a study three years in the making, is the result of research by cognitive neuroscientists from seven leading universities across the United States. In the Dana Consortium study, released in March 2008, researchers grappled with a fundamental question: Are smart people drawn to the arts or does arts training make people smarter?

For the first time, coordinated, multi-university scientific research brings us closer to answering that question.  Learning, Arts, and the Brain advances our understanding of the effects of music, dance, and drama education on other types of learning. Children motivated in the arts develop attention skills and strategies for memory retrieval that also apply to other subject areas.

The research was led by Dr. Michael S. Gazzaniga of the University of California at Santa Barbara. “A life-affirming dimension is opening up in neuroscience,” said Dr. Gazzaniga, “to discover how the performance and appreciation of the arts enlarge cognitive capacities will be a long step forward in learning how better to learn and more enjoyably and productively to live.  The consortium’s new findings and conceptual advances have clarified what now needs to be done.”

Click here for complete article

Click here to download a a PDF version of the full report (2MB)

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November 24, 2008

Gamma oscillations mediate stimulus competition and attentional selection in a cortical network model

Christoph Börgers, Steven Epstein, and Nancy J. Kopell
Article in Proceedings of the National Academy of Science, USA

Abstract
Simultaneous presentation of multiple stimuli can reduce the firing rates of neurons in extrastriate visual cortex below the rate elicited by a single preferred stimulus. We describe computational results suggesting how this remarkable effect may arise from strong excitatory drive to a substantial local population of fast-spiking inhibitory interneurons, which can lead to a loss of coherence in that population and thereby raise the effectiveness of inhibition. We propose that in attentional states fast-spiking interneurons may be subject to a bath of inhibition resulting from cholinergic activation of a second class of inhibitory interneurons, restoring conditions needed for gamma rhythmicity. Oscillations and coherence are emergent features, not assumptions, in our model. The gamma oscillations in turn support stimulus competition. The mechanism is a form of “oscillatory selection,” in which neural interactions change phase relationships that regulate firing rates, and attention shapes those neural interactions.

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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 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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December 11, 2007

Belief, disbelief and uncertainty activate distinct brain regions

The capacity of the human mind to believe or disbelieve a statement is a powerful force for controlling both behavior and emotion, but the basis of these states in the brain is not yet understood. A new study found that belief, disbelief and uncertainty activate distinct regions of the brain, with belief/disbelief affecting areas associated with the pleasantness/unpleasantness of tastes and odors. The study will publish online in the Annals of Neurology, the official journal of the American Neurological Association.

Led by Sam Harris of the University of California, Los Angeles, the study involved 14 adults who underwent functional MRI scans during which they were presented with short statements that they had to evaluate as true, false or undecided. Each participant underwent three scans while they evaluated statements from a broad variety of categories such as mathematical, geographical, autobiographical, religious and factual. The statements were designed to be clearly true, false or undecidable.

Contrasting belief and disbelief trials yielded increased signal in the (VMPFC), which is involved in linking factual knowledge with emotion. “The involvement of the VMPFC in belief processing suggests an anatomical link between the purely cognitive aspects of belief and human emotion and reward,” the authors state. The fact that ethical belief showed a similar pattern of activation to mathematical belief suggests that the physiological difference between belief and disbelief is not related to content or emotional associations, they note.

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December 10, 2007

Researchers can read thoughts to decipher what a person is actually seeing

From physorg.com — Following ground-breaking research showing that neurons in the human brain respond in an abstract manner to particular individuals or objects, University of Leicester researchers have now discovered that, from the firing of this type of neuron, they can tell what a person is actually seeing.

The original research by Dr R Quian Quiroga, of the University’s Department of Engineering, showed that one neuron fired to, for instance, Jennifer Aniston, another one to Halle Berry, another one to the Sydney Opera House, etc. The responses were abstract. For example, the neuron firing to Halle Berry responded to several different pictures of her and even to the letters of her name, but not to other people or names.

This result, published in Nature in 2005 and selected as one of the top 100 scientific stories of the year by Discover Magazine, came from data from patients suffering from epilepsy. As candidates for epilepsy surgery, they are implanted with intracranial electrodes to determine as accurately as possible the area where the seizures originate. From that, clinicians can evaluate the potential outcome of curative surgery.

Dr Quian Quiroga’s latest research, which has appeared in the Journal of Neurophysiology, follows on from this. Dr Quian Quiroga explained:

“For example, if the ‘Jennifer Aniston neuron’ increases its firing then we can predict that the subject is seeing Jennifer Aniston. If the ‘Halle Berry neuron’ fires, then we can predict that the subject is seeing Halle Berry, and so on. “To do this, we used and optimised a ‘decoding algorithms’, which is a mathematical method to infer the stimulus from the neuronal firing. We also needed to optimise our recording and data processing tools to record simultaneously from as many neurons as possible. Currently we are able to record simultaneously from up to 100 neurons in the human brain.

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December 2, 2007

Subjective values

Neuroimaging studies of decision-making have generally related neural activity to objective measures (such as reward magnitude, probability or delay), despite choice preferences being subjective. However, economic theories posit that decision-makers behave as though different options have different subjective values.

Here we use functional magnetic resonance imaging to show that neural activity in several brain regions—particularly the ventral striatum, medial prefrontal cortex and posterior cingulate cortex—tracks the revealed subjective value of delayed monetary rewards.

This similarity provides unambiguous evidence that the subjective value of potential rewards is explicitly represented in the human brain.

Joseph W Kable & Paul W Glimcher, The neural correlates of subjective value during intertemporal choice. Nature Neuroscience 10, 1625 – 1633 (2007)

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October 31, 2007

Dynamic neural correlates of consciousness

EEG,fMRI,neuroimaging,perception — thomasr @ 3:27 am

PLOS Biology has a most interesting article from Stanislas Dehaene‘s group on the neurodynamics of conscious experience. The researchers studied brain activation using EEG, while subjects rated visually presented stimuli on a scale from unseen to clearly seen. It was found that conscious experience of a stimulus was related to the engagement of a widespread network involving the frontal, parietal and temporal cortices.

SCR note: It is mentioning a recent study using fMRI (Christensen et al. 2006) provided comparable results, and adding two factors; (1) the conscious experience of a visual stimulus involved activation of both thalami, and (2) subjects consistently rated some experiences as vague, i.e., as “detected but not identified”. This experience was associated with both lower activation in those regions involved in conscious experience, and unique activation of additional regions, including some prefrontal regions.

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August 31, 2007

Final proof of role of neural coherence in consciousness?

neuralsynchrony.jpgMelloni et al. have recently demonstrated, in the Journal of Neuroscience, that neural synchrony in the gamma range between distal rain regions is important for conscious perception. The authors say about their work that “the access to conscious perception is the early transient global increase of phase synchrony of oscillatory activity in the gamma frequency range”

Here we link to the article and some related works.

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