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science philosophy scepticism

[neurosciencenews]

Nicotine Withdrawal Weakens Brain Connections Tied to Self Control Over Cigarette Cravings

High relapse rate in smokers may be explained by diminished connectivity among key brain networks.

People who try to quit smoking often say that kicking the habit makes the voice inside telling them to light up even louder, but why people succumb to those cravings so often has never been fully understood. Now, a new brain imaging study in this week’s JAMA Psychiatry from scientists in Penn Medicine and the National Institute on Drug Abuse (NIDA) Intramural Research Program shows how smokers suffering from nicotine withdrawal may have more trouble shifting from a key brain network—known as default mode, when people are in a so-called “introspective” or “self-referential” state— and into a control network, the so-called executive control network, that could help exert more conscious, self-control over cravings and to focus on quitting for good.

Read the full article Nicotine Withdrawal Weakens Brain Connections Tied to Self Control Over Cigarette Cravings at NeuroscienceNews.com.

The research is in JAMA Psychiatry. (full access paywall)

Research: “Large-Scale Brain Network Coupling Predicts Acute Nicotine Abstinence Effects on Craving and Cognitive Function” by Caryn Lerman, PhD; Hong Gu, PhD; James Loughead, PhD; Kosha Ruparel, MSE; Yihong Yang, PhD; and Elliot A. Stein, PhD in JAMA Psychiatry. doi:10.1001/jamapsychiatry.2013.4091

Image: Imaging showed a significantly weaker connectivity between the salience network and default mode network during abstinence, compared with their sated state. Also, weakened connectivity during abstinence was linked with increases in smoking urges, negative mood, and withdrawal symptoms, suggesting that this weaker internetwork connectivity may make it more difficult for people to quit. The image, which is not connected with the research and is for illustrative purposes only, shows an MRI scan of areas of the brain in the default mode network. Credit John Graner, Neuroimaging Department, National Intrepid Center of Excellence, Walter Reed National Military Medical Center.

[hyperfrontality]

Fascinating stuff!

I'm glad I'm not a smoker...

[hyperfrontality]

Chomsky and Quine on Analyticity

I found this cognitive science and philosophy themed blog a while ago, and I quite like it, so I'd say you should read it too!

This entry deals with WVO Quine's and Noam Chomsky's differing views on analyticity and the analytic/synthetic-distinction. Whereas Quine rejects the distinction based on several problems he sees with the notion of analyticity and the various difficulties we face when trying to define what analyticity is even supposed to be, Chomsky attempts to ground an idea of analyticity in linguistic concepts innate to the human mind - Chomsky argues that "since the experiments show that people intuitively distinguish between analytic and synthetic sentences, [..] we need to explain this fact".

Despite the fact that Chomsky and Quine are both methodological naturalists, they nonetheless disagree on a number of issues.  In this blog I will consider one such disagreement: their differing views on the status of the analytic/synthetic distinction. I will show that this dispute between them is an entirely naturalistic dispute. Traditionally, philosophers who used analyticity in their theorising did so in the service of a non-naturalistic philosophy. Such thinkers used analyticity as an explanation of non-naturalistic notions such as a-priori knowledge and our grasp of metaphysical necessity. One of my main reasons for discussing the dispute between Chomsky and Quine on analyticity is to illustrate a disagreement between both thinkers which, despite superficial appearances is entirely naturalistic. I will evaluate the evidence put forth by both thinkers and show that Chomsky has not offered sufficient evidence to justify his claim that analytic connections exist in natural language.

[hyperfrontality]

Coursera - Computational Neuroscience

Understanding how the brain works is one of the fundamental challenges in science today. This course will introduce you to basic computational techniques for analyzing, modeling, and understanding the behavior of cells and circuits in the brain. You do not need to have any prior background in neuroscience to take this course.

Just started this MOOC on computational neuroscience. Looks very interesting so far!

[neurosciencenews]

Ever So Slight Delay Improves Decision Making Accuracy

Read the full article Ever So Slight Delay Improves Decision Making Accuracy at NeuroscienceNews.com.

Findings could improve understanding of ADHD, schizophrenia, and other neuropsychiatric diseases.

Columbia University Medical Center (CUMC) researchers have found that decision-making accuracy can be improved by postponing the onset of a decision by a mere fraction of a second. The results could further our understanding of neuropsychiatric conditions characterized by abnormalities in cognitive function and lead to new training strategies to improve decision-making in high-stake environments. The study was published in the March 5 online issue of the journal PLoS One.

The research is in PLOS ONE. (full open access)

Research: “Humans Optimize Decision-Making by Delaying Decision Onset” by Tobias Teichert, Vincent P. Ferrera, and Jack Grinband in PLOS ONE. doi:10.1371/journal.pone.0089638

Image: Cyclic Deadline Task. (A) A cue instructed subjects to attend to one of two streams of coherently moving random dots and report its direction of motion by pressing a button with their left or right index finger. The relevant stream of target dots was either lighter than the background, in which case the distractor was black, or darker than the background, in which case the distractor was white. The distractor dots could move either in the same or opposite direction as the target (congruent and incongruent condition). In addition, the distractor could move upwards, i.e. orthogonal to the axis of motion of the target dots (neutral condition). (B/C) The task was performed in a cyclic manner requiring a response from the subject once every 2 seconds. The time of the intended response was indicated by an auditory click. Clicks were presented once every second to convey a stronger sense of rhythm, but responses were only required on every other click, following the cue and stimulus presentation. Stimulus duration was randomized between blocks of trials. Credit Teichert et al/PLOS ONE

[themedicalstate]

Why does the brain remember dreams?

Some people recall a dream every morning, whereas others rarely recall one. A team led by Perrine Ruby, an Inserm Research Fellow at the Lyon Neuroscience Research Center (Inserm/CNRS/Université Claude Bernard Lyon 1), has studied the brain activity of these two types of dreamers in order to understand the differences between them. In a study published in the journal Neuropsychopharmacology, the researchers show that the temporo-parietal junction, an information-processing hub in the brain, is more active in high dream recallers. Increased activity in this brain region might facilitate attention orienting toward external stimuli and promote intrasleep wakefulness, thereby facilitating the encoding of dreams in memory.

The reason for dreaming is still a mystery for the researchers who study the difference between “high dream recallers,” who recall dreams regularly, and “low dream recallers,” who recall dreams rarely. In January 2013 (work published in the journal Cerebral Cortex), the team led by Perrine Ruby, Inserm researcher at the Lyon Neuroscience Research Center, made the following two observations: “high dream recallers” have twice as many time of wakefulness during sleep as “low dream recallers” and their brains are more reactive to auditory stimuli during sleep and wakefulness. This increased brain reactivity may promote awakenings during the night, and may thus facilitate memorisation of dreams during brief periods of wakefulness.

In this new study, the research team sought to identify which areas of the brain differentiate high and low dream recallers. They used Positron Emission Tomography (PET) to measure the spontaneous brain activity of 41 volunteers during wakefulness and sleep. The volunteers were classified into 2 groups: 21 “high dream recallers” who recalled dreams 5.2 mornings  per week in average, and 20 “low dream recallers,” who reported 2 dreams per month in average. High dream recallers, both while awake and while asleep, showed stronger spontaneous brain activity in the medial prefrontal cortex (mPFC) and in the temporo-parietal junction (TPJ), an area of the brain involved in attention orienting toward external stimuli.

The South African neuropsychologist Mark Solms had observed in earlier studies that lesions in these two brain areas led to a cessation of dream recall.  The originality of the French team’s results is to show brain activity differences between high and low dream recallers during sleep and also during wakefulness.

“Our results suggest that high and low dream recallers differ in dream  memorization, but do not exclude that they  also differ in dream production. Indeed, it is possible that high dream recallers produce a larger amount of dreaming than low dream recallers” concludes the research team.

[neurosciencenews]

Surface Characteristics Influence Cellular Growth on Semiconductor Material

Read the full article Surface Characteristics Influence Cellular Growth on Semiconductor Material at NeuroscienceNews.com.

Changing the texture and surface characteristics of a semiconductor material at the nanoscale can influence the way that neural cells grow on the material.

The finding stems from a study performed by researchers at North Carolina State University, the University of North Carolina at Chapel Hill and Purdue University, and may have utility for developing future neural implants.

The research is in Acta Biomaterialia. (full access paywall)

Research: “Surface topography and chemistry shape cellular behavior on wide band-gap semiconductors” by Lauren E. Bain, Ramon Collazo, Shu-han Hsu, Nicole Pfiester Latham, Michael J. Manfra, and Albena Ivanisevic in Acta Biomaterialia. doi:10.1016/j.actbio.2014.02.038

Image: This image shows a PC12 cell growing onto a randomly textures surface. Note how the cell is spreading out in all directions. Credit North Carolina State University.

[bpod-bpod]

06 February 2014

Tuning In

Imagine you’re at a party. All around you guests are chatting and music is playing. But you’re only interested in hearing the person next to you. Fortunately, the brain is equipped with mechanisms that help to tune out this background noise and allow us to focus on specific sounds. Yet very little is known about how this actually works. These traces show how a ferret’s hearing system – surprisingly similar to our own – responds to speech in an increasingly noisy environment (top to bottom). The coloured traces on the left represent the sound itself, while the other peaks are patterns of nerve activity in different parts of the brain that process sound. They reveal that the background noise gets ‘tuned out’ gradually as the signals get closer to the main part of the brain (furthest right), revealing more about how we cope with noisy situations.

Written by Kat Arney

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Image courtesy of Neil Rabinowitz, Jan Schnupp and colleagues Department of Physiology, Anatomy and Genetics, University of Oxford Originally published under a Creative Commons licence Research published in PLOS Biology, November 2013

[hyperfrontality]

Amputee feels in real-time with bionic hand wired to nerves (w/ video)

Nine years after an accident caused the loss of his left hand, Dennis Aabo Sørensen from Denmark became the first amputee in the world to feel – in real-time – with a sensory-enhanced prosthetic hand that was surgically wired to nerves in his upper arm. Silvestro Micera and his team at EPFL (Switzerland) ...

This is some pretty awesome stuff!

[hyperfrontality]

In this week’s eSkeptic, we present an excerpt from 50 Great Myths of Popular Psychology: Shattering Widespread Misconceptions About Human Nature, by Scott O. Lilienfeld, Steven Jay Lynn, John Ruscio, and Barry L. Beyerstein (Wiley-Blackwell, 2009). This excerpt appears in the sold out issue of Skeptic magazine volume 15, number 3 and has been published by permission of the publisher and authors.

Top Ten Myths of Popular Psychology is taken from '50 Great Myths of Popular Psychology' by Lilienfeld, Lynn, Ruscio, and Beyerstein, which is a great book that you should read if you've ever wondered whether some of these surprising pop psychology 'facts' such as 'we only use 10% of our brains' are actually facts at all.

[neurosciencestuff]

Making your brain social

In many people with autism and other neurodevelopmental disorders, different parts of the brain don’t talk to each other very well. Scientists have now identified, for the first time, a way in which this decreased functional connectivity can come about. In a study published online today in Nature Neuroscience, scientists at the European Molecular Biology Laboratory (EMBL) in Monterotondo, Italy, and collaborators at the Istituto Italiano di Tecnologia (IIT), in Rovereto, and La Sapienza University in Rome, demonstrate that it can be caused by cells called microglia failing to trim connections between neurons.

“We show that a deficit in microglia during development can have widespread and long-lasting effects on brain wiring and behaviour,” says Cornelius Gross, who led the study. “It leads to weak brain connectivity, decreased social behaviour, and increased repetitive behaviour, all hallmarks of autism.”

The findings indicate that, by trimming surplus connections in the developing brain, microglia allow the remaining links to grow stronger, like high-speed fibre-optic cables carrying strong signals between brain regions. But if these cells fail to do their job at that crucial stage of development, those brain regions are left with a weaker communication network, which in turn has lifelong effects on behaviour.

Yang Zhan, a postdoctoral fellow in Gross’ lab at EMBL, analysed the strength of connections between different areas of brain in mice that were genetically engineered to have fewer microglia during development. Working with Alessandro Gozzi’s lab at IIT and Davide Ragozzino at La Sapienza University, the EMBL scientists combined this approach with high-resolution fMRI (functional Magnetic Resonance Imaging) scans of the mice’s brains, taking full advantage of a novel technique developed at IIT, which enables scientists to obtain detailed, three-dimensional maps of the brain’s functional connections. The team found that mice with fewer microglia had weaker connections between neurons, and less cross-talk between different brain regions. When Rosa Paolicelli, a PhD student in Gross’ lab, studied the mice’s behaviour, she discovered that mice with fewer microglia and decreased connectivity displayed behaviours commonly associated with autism spectrum disorders. These mice spent more time repeatedly grooming themselves, and avoided social interactions.

“This is an exciting time to be studying microglia,” Gross concludes:  “they’re turning out to be major players in how our brain gets wired up.”

[neurosciencestuff]

Your Brain Is Fine-Tuning Its Wiring Throughout Your Life

The white matter microstructure, the communication pathways of the brain, continues to develop/mature as one ages. Studies link age-related differences in white matter microstructure to specific cognitive abilities in childhood and adulthood.

Most prior studies, however, did not include individuals from the entire life span or evaluated a limited section of white matter tracts. This knowledge gap prompted a new study published this week in Biological Psychiatry.

Dr. Bart Peters, of the Zucker Hillside Hospital, and his colleagues investigated the relationship of age and neurocognitive performance to nine white matter tracts from childhood to late adulthood.

To accomplish this, they recruited 296 healthy volunteers who ranged from 8 to 68 years of age. The participants completed a comprehensive battery of tests designed to measure their cognitive functioning, including speed, attention, memory, and learning. They also underwent a non-invasive diffusion tensor imaging scan, a technology that allowed the researchers to create maps of the 9 major white matter tracts under investigation.

The combination of this data allowed them to identify the neurocognitive correlates of each white matter tract in relation to its unique aging pattern.

They found that, from childhood into early adulthood, differences in fractional anisotropy – a measure of connectivity – of the cingulum were associated with executive functioning, whereas fractional anisotropy of the inferior fronto-occipital fasciculus was associated with visual learning and global cognitive performance via speed of processing.

"Our study identified key brain circuits that develop during adolescence and young adulthood that are associated with the growth of learning, memory and planning abilities. These findings suggest that young people may not have full capacity of these functions until these connections have completed their normal trajectory of maturation beyond adolescence," explained Peters.

"Our brain is changing throughout our lives. These changes underlie the capacities that emerge and are refined through adulthood," commented Dr. John Krystal, Editor of Biological Psychiatry. “There are clues that the steps that we take to preserve our medical health and stimulate our minds also serve to further refine and maintain these connections. For good reasons, attending to brain health is increasingly a focus of healthy aging.”

In addition, many individuals diagnosed with psychiatric disorders suffer with neurocognitive dysfunction as part of their illness, which is particularly difficult to alleviate with currently available treatments. Studies such as this may help to identify specific brain circuits/pathways that could serve as potential targets for treatment interventions.

[ausjake]

Variously stained neurons. Some are Purkinje cells, which are some of the largest neurons in the human brain.

[hyperfrontality]

[hyperfrontality]

How can different areas of the brain perform and coordinate complex actions?

Neural circuits must perform computations and then selectively output the results to other circuits. Yet synapses do not change radically at millisecond timescales. A key question then is: how is communication between neural circuits controlled? In motor control, brain areas directly involved in driving movement are active well before movement begins. Muscle activity is some readout of neural activity, yet it remains largely unchanged during preparation. Here we find that during preparation, while the monkey holds still, changes in motor cortical activity cancel out at the level of these population readouts. Motor cortex can thereby prepare the movement without prematurely causing it. Further, we found evidence that this mechanism also operates in dorsal premotor cortex, largely accounting for how preparatory activity is attenuated in primary motor cortex. Selective use of 'output-null' vs. 'output-potent' patterns of activity may thus help control communication to the muscles and between these brain areas.

[hyperfrontality]

Patricia Churchland on evolution and morality

[neurosciencestuff]

Image: Fotolia

Deprivation of vision during critical periods of childhood development has long been thought to result in irreversible vision loss. Now, researchers from the Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard Medical School (HMS) and Massachusetts Institute...

[himynameispau]

[hyperfrontality]

It's strange to know that this now defunct, strange looking collection of cells was once a working biological computer so complex and powerful it could create a conscious person.