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 15, 2011

The Brain Signature of Love

emotions,fMRI — alice @ 10:04 pm

From The Dana Foundation:

Study the literature of the world and you will find one theme that transcends both time and culture: that of love. Whether you are reading Shakespeare or Rumi, the manner in which love is described shows remarkable similarity. Those similarities go far beyond the page: Neuroscientists are now demonstrating that romantic love is also represented by a unique pattern of activation in the brain.

The neuroimaging of love

In the past six years, several groups of researchers have sought to localize romantic love in the brain using functional magnetic resonance imaging (fMRI) techniques. Though some have criticized the attempt as nothing more than modern day phrenology, those who seek the neural correlates of love believe it an essential avenue of study.

“The study of love is important so we might bring some rationality to a complex and emotional phenomenon,” says Stephanie Ortigue, a neuroscientist at Syracuse University. “These studies allow scientists to show that love is not a drug or a pathology but something that has a unique signature in the healthy brain.”

Read the entire article.

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February 17, 2009

The Default Mode Network and Self-Referential Processes in Depression

In a recent study, Sheline and colleagues examined whether patients with major depression were impaired in their ability to regulate the activity of the default mode network, which is characterized by self-referential functions.  To do so, they used fMRI to measure changes in brain activity occurring within this network in 20 individuals with major depression and 21 demographically similar control participants.  The depressed and healthy control participants were asked to examine negative pictures passively and also to reappraise them actively. 

In contrast to the depressed participants, the healthy control participants demonstrated reduced activity in widely distributed regions of the default mode network (ventromedial prefrontal cortex, prefrontal cortex, anterior cingulate, lateral parietal cortex, and lateral temporal cortex) while looking at the negative pictures and reappraising them.  Moreover, compared to the healthy control participants, the depressed participants demonstrated a larger increase in activity in other default mode network regions (amygdala, parahippocampus, and hippocampus) while they looked at negative pictures. 

Based on these data, Sheline and colleagues suggest that depression is characterized by both a stimulus-induced increase in brain activity and a failure to broadly decrease the activity of the default mode network.  Further, the authors suggest that these findings provide a brain network framework within which to consider the pathophysiology of depression.

Click here for full access to the study.

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February 16, 2009

When Your Gain is My Pain and Your Pain is My Gain: Neural Correlates of Envy and Schadenfreude

We often make social comparisons to evaluate others and ourselves.  In a recent study in Science, Takahashi and colleagues investigated the neurocognitive mechanisms of envy and schadenfreude (pleasure at another’s misfortune) using fMRI.  The researchers found that envy and schadenfreude are associated with different parts of the brain.  Whereas envy was associated with the dorsal anterior cingulate cortex, schadenfreude was associated with the ventral striatum. The dorsal anterior cingulate is involved in the processing of cognitive conflicts; envy-related activation in this region was greater when the envied person had superior and more self-relevant characteristics.  The ventral striatum is involved in processing reward and the schadenfreude-related activity in this region was stronger when misfortune befell an envied person more so than a neutral person.  Additionally, envy-related activity in the anterior cingulate predicted schadenfreude-related activity in the ventral striatum.  Takahashi and colleagues suggest that their findings document mechanisms of painful emotion, envy, and a rewarding reaction, schadenfreude.

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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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November 3, 2008

Human Brain is Capable of Subliminal Conditioning, Study Shows

From The Dana Foundation: Imagine you are playing a game of poker. Watching your opponent, you have a gut feeling that if you raise the bet, he will fold. You decide to go with your intuition and it works.

Were you just lucky?

According to neuroscientist Mathias Pessiglione, the gut feeling you experienced could be the result of your brain picking up subliminal cues from your opponent and associating them with a positive outcome. Pessiglione uses a poker game as a possible real-life example of the kind of subliminal instrumental conditioning that he and his colleagues at the Institut National de la santé et de la recherche médicale (INSERM), a public research institute in Paris, have demonstrated for the first time in the human brain.

They report the results of a carefully designed study using a system of masked cues matched to win or loss outcomes in the Aug. 28 issue of the journal Neuron.

Click here for complete article.

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January 12, 2008

Neuronal correlates of “free will” are associated with regional specialization in the human intrinsic/default network

Ilan Goldberg, Shimon Ullman and Rafael Malach
In press article in Consciousness & Cognition

Abstract: 
Recently, we proposed a fundamental subdivision of the human cortex into two complementary networks-an ‘‘extrinsic” one which deals with the external environment, and an ‘‘intrinsic” one which largely overlaps with the ‘‘default mode” system, and deals with internally oriented and endogenous mental processes. Here we tested this hypothesis by contrasting decision making under external and internally-derived conditions. Subjects were presented with an external cue, and were required to either follow an external instruction (‘‘determined” condition) or to ignore it and follow a voluntary decision process (‘‘free-will” condition). Our results show that a well defined component of the intrinsic system-the right inferior parietal cortex-was preferentially activated during the ‘‘free-will” condition. Importantly, this activity was significantly higher than the base-line resting state. The results support a self-related role for the intrinsic system and provide clear evidence for both hemispheric and regional specialization in the human intrinsic system.

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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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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 2, 2007

Language and self-awareness

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May 24, 2007

Does the brain show a lie?

noliemri.pngAmanda lies flat on her back, clad in a steel blue hospital gown and an air of anticipation, as she is rolled headfirst into a beeping, 10-ton functional magnetic resonance imaging (fMRI) unit. Once inside, the 20-something blonde uses a handheld device to respond to questions about the playing cards appearing on the screen at the foot of the machine. With each click of the button, she is either lying or telling the truth about whether a card presented to her matches the one in her pocket, and the white-coated technician who watches her brain image morph into patterns on his computer screen seems to know the difference.

It’s unlikely anyone would shell out $10,000 to exonerate herself in a dispute over gin rummy. But Amanda, the model in a demo video for Tarzana, Calif.-based No Lie MRI, is helping to make a point: lie-detection is going high-tech. No Lie MRI claims it can identify lies with 90% accuracy. The service is meant for “anybody who wants to demonstrate that they are telling truth to others,” says founder and CEO Joel Huizenga. “Everyone should be allowed to use whatever method they can to defend themselves.

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May 22, 2007

The units of thought

moshebar_rs.jpgWhat is the nature of thought? And what is the resting state? Moshe Bar and colleagues argues in a new paper (PDF) in the journal Hippocampus that besides the long-held idea that associative processing provides the vehicle of thought, that “one primary outcome of associative processing is the generation of predictions, which approximate the immediately relevant future and thus facilitate perception, action, and the progression of thought”.

From the article:

Associations are proposed to provide the units of thought,b ut they should not be perceived as the actual content of thought; they merely provide the vehicle for linking related representations. In fact, our proposal is that the primary role of associations and associative activation is to generate predictions, which guide our actions, expectations, plans, and thoughts. To elaborate on this it will be useful to consider our broader theoretical framework: We propose that rather than passively ‘‘waiting’’ to be activated by sensations, the human brain is constantly busy generating predictions that approximate the immediate, directly relevant, future. Building on previous work, this proposal posits that rudimentary information is first extracted rapidly from a perceptual input, and then used to derive analogies linking the input with the most similar representations in memory. The linked stored representations in turn selectively activate the associations that are relevant in the specific context, which provides focused, testable predictions. These predictions facilitate perception and cognition by presensitizing representations all the way downstream to primary cortices. For example, we see a fork, the image of which will

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Resting states in unconscious monkeys

Nature has an interesting report from Marc Raichle‘s laboratory that studies the resting states in monkeys. This study not only demonstrates that resting states occur in non-human primates, but that it is possible to find such activity during unconscious states.

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April 23, 2007

What is happening in the brain when our minds wander?

cognition,cognitive neuroscience,fMRI — alice @ 1:34 am

/category/perception/feed/blindsight2.jpgIt seems like science still has a ways to go before this question can be answered, but scientists have already started the investigation. In a recent study, Mason and colleagues used fMRI and thought sampling to study which areas of the brain show increased activations in one kind of situation where our minds are likely to wander: when we perform tasks that become banal with continual practice. They compared brain activity that was associated with performing blocks of well-practiced tasks with that of non-practiced, but otherwise identical, tasks and observed greater activation for the practiced tasks in following brain areas: bilateral medial prefrontal cortex (BAs 6, 8, 9, and 10); bilateral superior frontal gyri (BAs 8 and 9); anterior cingulate (BA10); bilateral aspects of the posterior cingulate (BAs 29 and 30); precuneus (BAs 7 and 31); left angular gyrus (BA 39); bilateral aspects of the insula (BA 13); left superior temporal (BA 22), the right superior temporal (BA 41) and the left middle temporal gyri (BA 19). They also found a significant positive relation between changes in brain activity in many of the aforementioned regions for blocks in which subjects performed practiced, relative to non-practiced, tasks and the subjects’ frequency of mind-wandering, which was assessed using the daydream frequency scale of the Imaginal Processes Inventory. Following-up with this intriguing study, it would be interesting to examine the brain activity that arises during specific instances, as opposed to blocks, when participants report mind-wandering.

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March 7, 2007

Scientists Try to Predict Intentions

mecklinger_tool.jpgIn case you didn’t hear about it there are recent claims that brain scanners can predict people’s action before they act. Here is a report from Associated Press.

At a laboratory in Germany, volunteers slide into a donut-shaped MRI machine and perform simple tasks, such as deciding whether to add or subtract two numbers, or choosing which of two buttons to press. They have no inkling that scientists in the next room are trying to read their minds – using a brain scan to figure out their intention before it is turned into action.

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February 8, 2007

Pain in the brain

EEG,brain imaging,fMRI,pain,perception — thomasr @ 5:21 am

/category/perception/feed/index_pain.gifPain is one of the most prominent examples of the problem of consciousness: from a subjective point of view we know the experience of pain all too well. Seen from the objective side of pain, the neural processes related to pain are becoming unravelled. But the essential relationship between neural processes going on from the sensation to the experience are much less known.

In a study by Christmann and colleagues, a combination of EEG and fMRI demonstrates how regional brain areas make different contributions — and at different times — to the experience of pain.

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How the brain becomes aware of errors

For a long time psychologists have devised methods to make people erroneous on a task. A well-known example is the Stroop effect, a demonstration of interference in the reaction time of a task. When a word such as blue, green, red, etc. is printed in a colour differing from the colour expressed by the word’s semantic meaning (e.g. the word “red” printed in blue ink), a delay occurs in the processing of the word’s colour, leading to slower test reaction times and an increase in mistakes.

The study of the neural correlates of the Stroop effect have revealed, among other correlates, an increased activation in the prefrontal cortex. But what happens if you discover that you have made a mistake and try to correct it? This kind of “error awareness” has now been documented in a recent study published in NeuroImage. We here bring the abstract and a poster.

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January 17, 2007

The Multi-Source Interference Task

attention,brain networks,fMRI — alice @ 11:35 pm

Abstract of The Multi-Source Interference Task: an fMRI task that reliably activates the cingulo-frontal-parietal cognitive/attention network, in Nature.

In this protocol we describe how to perform the Multi-Source Interference Task (MSIT), a validated functional magnetic resonance imaging (fMRI) task that reliably and robustly activates the cingulo-frontal-parietal cognitive/attention network (CFP network) within individual subjects. The MSIT can be used to (i) identify the cognitive/attention network in normal volunteers and (ii) test its integrity in people with neuropsychiatric disorders. It is simple to perform, can be completed in less than 15 min and is not language specific, making it appropriate for children, adults and the elderly. Since its validation, over 100 adults have performed the task. The MSIT produces a robust and temporally stable reaction time interference effect (range 200–350 ms), and single runs of the MSIT have produced CFP network activation in approximately 95% of tested subjects. The robust, reliable and temporally stable neuroimaging and performance data make the MSIT a useful task with which to study normal human cognition and psychiatric pathophysiology.

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December 31, 2006

Conscious and nonconscious memory related brain activity

Are conscious and nonconscious processes supported by overlapping brain regions? In a recent study, Slotnick and Schacter investigated whether activity, related to visual memory, in early visual regions (BA17 and BA18) is reflective of nonconscious processing. The results of their study suggest that early visual regions (BA17, BA18) are associated with nonconcsious memory, while late visual regions (BA19, BA37) are associated with conscious memory. Click through for abstract. Hubmed.

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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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