May 28, 2011

A Conversation on the Neuroethics of Deep Brain Stimulation

In this webcast provided by the Dana Foundation, Drs. Philip Campbell, Joseph Fins, Jonathan Moreno and Helen Mayberg discussed the ethical considerations of using deep brain stimulation. The topics covered in this interesting discussion included surgical experimentation, consciousness, depression, technology and public policy. Dr. Judy Illes served as the moderator.

Click here for the webcast.

Click here for an edited transcript of the discussion.

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April 19, 2011

Scientists find way to map brain’s complexity

From Reuters:

Scientists say they have moved a step closer to developing a computer model of the brain after finding a way to map both the connections and functions of nerve cells in the brain together for the first time.

In a study in the journal Nature on Sunday, researchers from Britain’s University College London (UCL) described a technique developed in mice which enabled them to combine information about the function of neurons with details of their connections.

The study is part of an emerging area of neuroscience research known as ‘connectomics‘. A little like genomics, which maps our genetic make-up, connectomics aims to map the brain’s connections, known as synapses.

By untangling and being able to map these connections — and deciphering how information flows through the brain’s circuits — scientists hope to understand how thoughts and perceptions are generated in the brain and how these functions go wrong in diseases such as Alzheimer’s, schizophrenia and stroke.

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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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October 25, 2009

Theta Rhythm and Memory Performance

In a recent study, Sebastian Guderian and colleagues examined the relation between theta oscillations and memory performance. During the study phase of this memory experiment, participants were presented with words and either performed a semantic or phonemic encoding task (there were two levels of processing used in this experiment). During the study phase, the researchers obtained whole-head MEG recordings. Later on during the test phase, the participants were given a free-recall test on the words that were presented to them during the study phase.

Interestingly, Guderian and colleagues found that amplitudes of theta oscillations that shortly preceded the presentation of the words were higher for those words that were later recalled during the free-recall test, compared to those words that were later forgotten.

Although past studies have shown that specific patterns of brain activity are associated with the encoding of items, this study by Guderian and colleagues is one of a handful of more recent studies that demonstrate pre-stimulus brain activity that is associated with later memory performance (another example is a study by Otten and colleagues).

Moreover, although semantic study tasks typically lead to better memory performance compared to phonemic tasks, the results of the study by Guederian and colleagues suggest that this study task benefit is not only statistically independent from the theta-related recall benefit, but that these benefits are additive.

Click here for the full paper.

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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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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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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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November 2, 2008

Theta phase synchrony and conscious target perception: Impact of intensive mental training

Heleen A. Slagter, Antoine Lutz, Lawrence L. Greischar, Sander Nieuwenhuis, and Richard J. Davidson.
Article in Journal of Cognitive Neuroscience

Abstract
The information processing capacity of the human mind is limited, as is evidenced by the attentional blink-a deficit in identifying the second of two targets (T1 and T2) presented in close succession. This deficit is thought to result from an overinvestment of limited resources in T1 processing. We previously reported that intensive mental training in a style of meditation aimed at reducing elaborate object processing, reduced brain resource allocation to T1, and improved T2 accuracy [Slagter, H. A., Lutz, A., Greisschar, L. L., Frances, A. D., Nieuwenhuis, S., Davis, J., et al. Mental training affects distribution of limited brain resources. PloS Biology, 5, e138, 2007]. Here we report EEG spectral analyses to examine the possibility that this reduction in elaborate T1 processing rendered the system more available to process new target information, as indexed by T2-locked phase variability. Intensive mental training was associated with decreased cross-trial variability in the phase of oscillatory theta activity after successfully detected T2s, in particular, for those individuals who showed the greatest reduction in brain resource allocation to T1. These data implicate theta phase locking in conscious target perception, and suggest that after mental training the cognitive system is more rapidly available to process new target information. Mental training was not associated with changes in the amplitude of T2-induced responses or oscillatory activity before task onset. In combination, these findings illustrate the usefulness of systematic mental training in the study of the human mind by revealing the neural mechanisms that enable the brain to successfully represent target information.

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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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November 18, 2007

Measuring pain

brain imaging,pain — thomasr @ 8:33 am

Nature News features an article about a recent study relating pain intensity and EEG signals.

Recordings from electrodes in the human brain may offer the first objective way to measure the intensity of pain. Researchers say that they have found a neural signal that correlates with the amount of pain that an individual feels. The signal could be used to refine pain-relief techniques that involve stimulating the brain with electricity, they say.

Single cells have previously been identified in the human brain that are active in pain, but their response is binary, signalling either pain or no pain. Now, Morten Kringelbach of the psychiatry department at the University of Oxford, UK, and his colleagues have identified low-frequency brain waves that emanate from two regions buried deep within the brain when a patient is in pain. The more pain that is experienced, the longer the waves last.

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October 22, 2007

The Feeling of Familiarity of Music and Odors: The Same Neural Signature?

brain imaging,memory — thomasr @ 6:45 am

familiarityhpc.jpegThe feeling of familiarity can be triggered by stimuli from all sensory modalities, suggesting a multimodal nature of its neural bases.

In the present experiment, we investigated this hypothesis by studying the neural bases of familiarity processing of odors and music. In particular, we focused on familiarity referring to the participants’ life experience. Items were classified as familiar or unfamiliar based on participants’ individual responses, and activation patterns evoked by familiar items were compared with those evoked by unfamiliar items. For the feeling of familiarity, a bimodal activation pattern was observed in the left hemisphere, specifically the superior and inferior frontal gyri, the precuneus, the angular gyrus, the parahippocampal gyrus, and the hippocampus.

Together with previously reported data on verbal items, visual items, and auditory items other than music, this outcome suggests a multimodal neural system of the feeling of familiarity. The feeling of unfamiliarity was related to a smaller bimodal activation pattern mainly located in the right insula and likely related to the detection of novelty.

Plailly et al. in Cerebral Cortex

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Empathy for Pain and Touch in the Human Somatosensory Cortex

empathicpain.jpegAlthough feeling pain and touch has long been considered inherently private, recent neuroimaging and neurophysiological studies hint at the social implications of this experience. Here we used somatosensory-evoked potentials (SEPs) to investigate whether mere observation of painful and tactile stimuli delivered to a model would modulate neural activity in the somatic system of an onlooker.

Viewing video clips showing pain and tactile stimuli delivered to others, respectively, increased and decreased the amplitude of the P45 SEP component that reflects the activity of the primary somatosensory cortex (S1). These modulations correlated with the intensity but not with the unpleasantness of the pain and touch ascribed to the model or the aversion induced in the onlooker by the video clips. Thus, modulation of S1 activity contingent upon observation of others’ pain and touch may reflect the mapping of sensory qualities of observed painful and tactile stimuli.

Results indicate that the S1 is not only involved in the actual perception of pain and touch but also plays an important role in extracting somatic features from social interactions.

Bufalari et al. in Cerebral Cortex

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June 15, 2007

Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations

attention.jpgAttention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention.

Science

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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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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 20, 2007

Biological Psychiatry — Special issue on autism

autist.gifThe journal Biological Psychiatry has a special issue on the autism spectrum, its diagnosis and treatment.

It is a comprehensive yet diverse collection of multidisciplinary treatment of the issue, containing articles onautism and phenotypic homogeneity; cortical layering and thickness; cortical dysfunction; executive function and gaze fixation.

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February 8, 2007

Pain in the brain

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

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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