October 22, 2007

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

brain imaging, memory — thomasr

The 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

EEG, brain imaging, pain, social neuroscience, social psychology, theory of mind — thomasr

Although 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, brain imaging, comparative studies — thomasr

Attention 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.


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May 24, 2007

Does the brain show a lie?

brain imaging, fMRI, personality, self-awareness — thomasr

Amanda 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

brain imaging, decision making, fMRI, neuroimaging — thomasr

In 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

abnormal psych, brain imaging, cognitive development, cognitive science, genetics, journal, personality, social neuroscience, social psychology, theory of mind — thomasr

The 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

Pain 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

brain imaging, cognitive neuroscience, executive functions, fMRI — thomasr

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 14, 2007

Cerebellum on emotions

brain imaging, brain injury, emotions — thomasr

When the neuro-talk falls on emotions, most start thinking about the amygdala. Little do we associate with that hind-brain structure we call the cerebellum. Although it is known that this structure is involved in more than movements, little is really known about it’s cognitive functions, let alone in emotions.

In an article by Turner et al. in Neuropsychologia, the function of the cerebellum in emotions is explored by comparing six patients with cerebellar injury and healthy subjects. By applying both behavioural and PET methods, the results demonstrate that cerebellum plays a role in both positive and negative emotions.

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January 3, 2007

Which brain regions enable us to remember our past and anticipate our future?

SCR Feature, brain imaging, future thinking, memory, self-awareness — thomasr
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December 31, 2006

Conscious and nonconscious memory related brain activity

brain imaging, fMRI, memory, neuroimaging, unconscious processes — alice

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 30, 2006

Visuo-spatial consciousness and parieto-occipital EEGs

EEG, attention, brain imaging, neuroscience, perception — alice
Which brain areas are involved in visuospatial consciousness? In a recent study by Babiloni and colleagues, subjects performed a visual perception task. Interestingly, these scientists found that visual-evoked potentials at parieto-occipital areas had the same peak latencies for cases of conscious, as well as unconscious, perception. These visual-evoked potentials were located to the occipital (BA 19) and parietal (BA 7) cortices.

Source strength was significantly stronger in consciously, compared to unconsciously, perceived cases at about +300 ms poststimulus. Babiloni and colleagues concluded that these features of the observed parieto-occipital activation might be connected to visuospatial consciousness.

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December 22, 2006

Inducing a dreamy state

altered states, brain imaging, memory, perception, phenomenology, psychiatry — thomasr

Brain stimulation provides an interesting tool to study the functions of a given area of the brain. In a study by Vignal et al. published in Brain, artificial stimulation or seizures in specific mesial temporal lobe structures were assessed both in terms of location and phenomenology.

Among the findings, the researchers found that “Forty-five per cent of dreamy states were evoked by stimulation of the amygdala, 37.5% by the hippocampus and 17.5% by the para-hippocampal gyrus.”

Furthermore, they found that their study “demonstrates the existence of large neural networks that produce recall of memories via activation of the hippocampus, amygdala and rhinal cortex.”

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December 21, 2006

Functional neuroimaging in unconscious states

abnormal states, brain imaging, brain injury, fMRI, unconscious states — thomasr

Steven 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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December 17, 2006

The impact of invisible stimuli

attention, brain imaging, fMRI, perception, unconscious processes — thomasr

The more clear a stimulus is, the more distracting it can be. Or so you might think. In a recent Science publiation Tsushima et al. report that weak stimuli that are irrelevant to the task being performed—have
a greater impact than strong, easily noticeable distractors.

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