Category: Inside the Brain

ABC Radio National’s All in the Mind recently had a two programme special (part 1, part 2) on the neuroscience of blindness, focusing on how blindness affects the development of the brain and how electronic neural implants and being developed to restore lost vision.

One of the most remarkable parts is the interview with psychologist Zoltan Torey, who became blind as a student in an industrial accident.

He has written The Crucible of Consciousness (ISBN 0195508726), a remarkable and highly regarded book on the conscious mind.

In the 1st part of the series, he describes how he constructs a a ‘visual’ representation of the world and how his blindness has informed his study of consciousness:

But what is new of course is just the way in which I am able to combine things in my brain without the interference of vision. Normally when people want to think they close their eyes because the flood of visual impressions that comes at you is a distraction. I have the privilege of not having to cope with that, of thinking without…I’m a sort of ‘thinkaholic’, if I might use this expression. This is the way I did my research work about psychology and the consciousness. Not being troubled with vision itself, it was possible for me to imagine complex internal systems, and so I have this marvellous opportunity to run an internal show like a movie director.

Researchers studying neuroplasticity (how the brain changes its structure and function) are now focusing on the brains of blind people, as it has become clear that, for example, the area of the brain normally functioning as the visual cortex in sighted people seems to be active during touch-based reading, which is something that doesn’t occur in sighted people.

The second programme looks at the latest research on ‘bionic’ retina implants, that aim to process light and, through implanted electrodes, stimulate the optic nerve to act as an artificial retina replacement.

Link to The Blind Brain: Part 1 of 2.
Link to The Blind Brain: Part 2 of 2 – The bionic eye.

Psychology Today has an interesting article on anthropologist Helen Fisher’s theory that SSRI drugs (commonly used as antidepressants) interfere with love and attraction.

SSRI stands for ‘Selective Serotonin Reuptake Inhibitor’ and the group includes drugs such as Prozac (fluoxetine), Seroxat (paroxetine) and Zoloft (sertraline) which all increase the availability of the neurotransmitter serotonin in the synapse – the chemical junction between neurons.

Despite the (somewhat misleading) use of the word ‘selective’ in the title, these drugs also affect many other types of neurotransmitters to varying degrees – of which dopamine is one.

Fisher maintains that as attraction, desire and sexual pleasure are known to involve dopamine circuits in the brain, these drugs interfere with relationship formation.

This dopamine deficit affects people in a variety of ways, according to Fisher and her research partner, Virginia-based psychiatrist J. Andrew Thomson, Jr. Singles using antidepressants may have a harder time meeting people, because their natural sexual response is dampened. Some researchers believe desire was designed to help people select mates who are genetically suited to them. The spark that ignites on meeting someone new is telling you something: This might be your match. When you miss those signals, your odds of finding an appropriate mate decrease.

Fisher outlines her theory in a paper published with psychiatrist J. Anderson Thomson in the recent book Evolutionary Cognitive Neuroscience.

Luckily, the paper is also available online as a pdf file if you want to see their argument in full.

As an aside, the Psychology Today article is by science writer Orli Van Mourik, who you may know from Neurontic blog.

Link to Psychology Today article ‘Sex, love and SSRIs’.
pdf of scientific paper (warning: big download!).

Neurophilosopher has a great review of a recent study on how short naps help improve memory, and how this is supported by the brain.

Participants were asked to learn an action task and were split into two groups. One group was allowed to have an afternoon nap, while the others remained awake.

Afterwards, those who had slept during the afternoon could perform the task better than those who hadn’t.

EEG recordings of the brain suggested how the learning boost occurred:

This study confirms that the consolidation of motor memories is associated with a particluar stage of sleep (NREM), and that this in turn is correlated with electrical activity in an anatomically discrete region of the brain (the motor cortex).

One interpretation of the findings is that power naps trigger accelerated memory consolidation. An alternative hypothesis is that a good night’s sleep consists of multiple stages which are devoted to the consolidation of memories encoded during waking hours; thus, a full night’s sleep may not be necessary for this consolidation to take place; as long as a sleep episode – be it a a short night’s sleep or an afternoon power nap – includes the corresponding stages (NREM), newly-encoded memories will be consolidated.

For more details and link to the full paper, check out the article over at the Neurophilosophy Blog.

Link to Neurophilosophy article ‘Power naps enhance memory consolidation’.

The Washington Post has just published an article on the worrying amount of brain damage suffered by US troops in Iraq because of shockwave injuries from roadside bombs known as improvised explosive devices or IEDs.

These sorts of injuries tend not to damage the skull, but can cause significant injury as the brain rapidly accelerates and decelerates inside the skull, and impacts on the inside of the bone casing.

These types of injury are known as ‘closed head injuries‘ as nothing penetrates the skull.

It’s a common misconception that a skull fracture always leads to a worse brain injury.

In fact, in some cases, if the skull breaks, it can allow some of the force of the impact to be dispersed (this is why bicycle and motorcycle helmets are designed to break).

If the skull doesn’t break, sometimes this can lead to the energy of the impact being more fully absorbed by the brain, often leading to shearing and tearing of the white matter pathways as the brain ‘bounces around’ inside.

The Washington Post article outlines why IEDs are likely to have this effect:

Here’s why IEDS carry such hidden danger. The detonation of any powerful explosive generates a blast wave of high pressure that spreads out at 1,600 feet per second from the point of explosion and travels hundreds of yards. The lethal blast wave is a two-part assault that rattles the brain against the skull. The initial shock wave of very high pressure is followed closely by the “secondary wind”: a huge volume of displaced air flooding back into the area, again under high pressure. No helmet or armor can defend against such a massive wave front.

It is these sudden and extreme differences in pressures — routinely 1,000 times greater than atmospheric pressure — that lead to significant neurological injury. Blast waves cause severe concussions, resulting in loss of consciousness and obvious neurological deficits such as blindness, deafness and mental retardation. Blast waves causing TBIs can leave a 19-year-old private who could easily run a six-minute mile unable to stand or even to think.

The article notes that the military have not had to deal with these sorts of injuries in such large numbers before, as IEDs have rarely been used on this scale.

Apparently, the military are currently poorly equipped to deal with these injuries, which is causing problems both for treatment in the field and for longer-term rehabilitation programmes.

The article also contains an interesting factual error: “Iraq has brought back one of the worst afflictions of World War I trench warfare: shell shock. The brain of a soldier exposed to a roadside bomb is shocked, truly.”

‘Shell shock‘ was given this name during World War I because it was originally thought to be due to the blasts of shells affecting the brain.

It was later discovered that the cause of the condition was combat trauma (i.e. emotional stress) rather than brain injury, so it doesn’t actually describe any type of closed head injury.

Link to Washington Post article ‘A Shock Wave of Brain Injuries’.

This week’s international edition of Newsweek has several articles on how researchers have found that physical exercise can sharpen the mind and boost brain function.

The first article looks at how scientists came to discover that exercise improves brain function, increases learning and can delay the onset of Alzheimer’s disease.

In terms of understanding why this occurs, it seems one factor is that exercise causes the release of brain-derived neurotrophic factor or BDNF, a key substance for promoting neural growth and development.

The second main article looks at the effect of exercise on mood.

It is now known that light exercise seems to be an effective treatment for mild to moderate depression, and, at least in the UK, is being recommended by mental health clinicians as a useful non-drug treatment.

The key, it seems, both for the beneficial effects on mood and mental sharpness, is not the intensity of the workout but whether it occurs regularly or not.

The pieces suggests that regular light exercise seems to be enough to keep the mind and brain trim, so you don’t have to wear yourself out to see the benefit.

The special issue has been put together with the help of Harvard Medical School, who roll out several experts to give advice in addition to a range of researchers interviewed for the main pieces.

Also look out for the embedded audio of an interview with two Harvard clinicians on the topic.

Link to article ‘Stronger, Faster, Smarter’.
Link to article ‘Exercise is a State of Mind’.

Nina and the Neurons is a BBC TV series aimed at children aged six and under that looks at the psychology and neuroscience of the senses.

It’s presented by the bubbly and attractive Nina who, with the help of a collection of animated neurons, explores and explains the senses and gives various sensory demonstrations.

The programme is shown on BBC Children’s channel CBeebies, but there’s some episodes kicking around internet bittorrent trackers and they’re well worth checking out either if you know children who might enjoy them, or if you’re interested in how neuroscience could be taught to young children.

Nina typically fields questions from children and then goes to meet their family and runs experiments with them to test out the ideas.

The programme is based at the Glasgow Science Centre which has earned a reputation for new and interesting ways of engaging the public in science education.

As well as the programme information page, there’s also a website of Nina’s Lab where children can match sensations to the senses.

Link to programme information.
Link to Nina’s Lab.

The BPS Research Digest has picked up on a curious case study of a brain injured man whose identity appears dependent on the environment he is in, owing to severe memory problems.

The case was published in the neurological journal Neurocase by psychologist Giovannina Conchiglia and colleagues.

The patient was investigated by the team after he suffered left-focused damage to the frontal and temporal lobes after the oxygen supply to the brain was cut off during a heart attack.

Unfortunately, the full paper isn’t available online, but it’s well worth reading if you do have access to the journal.

The researchers put the patient, named AD, in various environments, such as a bar or kitchen, where he assumed the identity of a barmen and chef.

Interestingly, this didn’t happen in all cases:

During the first two experiments A.D was attracted by social and environmental stimuli, and did not in fact hesitate after a short while to interpret the role expected of him, and to “take on” the personality of the barman and chef, respectively. It is to be emphasised that in none of the experiments proposed did A.D. imitate the characters interpreted by the actors/experimenters, but rather assumed his own role in keeping with the context. In the last experiment, however, the patient manifested a different form of behaviour, in that he did not assume any role, as he considered that specific context inadequate…

His refusal to take on the role of laundryman in Experiment 3 is relevant since it is unlikely to be suited to him. The roles he adopts, therefore, must in some way correspond to certain traits of his personality structure or his social prerogatives, however versatile these may be.

There is now a growing recognition that symptoms caused by brain injury might be influenced not only by physical damage, but also by the wishes and desires of the patient.

Recent research has looked at this effect in both confabulations and delusions and found a strong interaction between unusual neurological conditions and the motivations of the patient.

This suggests that symptoms are influenced as much by the remaining intact brain areas, as the damaged ones.

Link to BPSRD article ‘Brain damage turns man into human chameleon’.
Link to abstract of Neurocase paper.

The New York Times has a fantastic article and video documentary on people who have decided to find out whether they carry the gene for the degenerative brain disorder Huntingdon’s disease, even before it’s started to causes any symptoms.

The disorder is caused by a single gene which, if inherited, causes a progressive deterioration in areas of the basal ganglia and frontal lobe which are eventually lethal.

The symptoms usually only appear in middle age and include, most visibly, uncontrolled movements of the body.

However, cognitive problems (such as impairments in memory, concentration, perception and strategic thinking), and the development of mood disorders and psychosis are also possible.

Because the disorder only takes hold in later years, many people with parents or grandparents with the disorder have to decide whether to get tested, and discover whether they have the gene and are fated to develop Huntingdon’s later in life.

The NYT article reports on how one young woman, who has taken the test and found out that she will develop the disorder, deals with the knowledge of her neurological fate.

Ms. Moser is still part of a distinct minority. But some researchers say her attitude is increasingly common among young people who know they may develop Huntington’s.

More informed about the genetics of the disease than any previous generation, they are convinced that they would rather know how many healthy years they have left than wake up one day to find the illness upon them. They are confident that new reproductive technologies can allow them to have children without transmitting the disease and are eager to be first in line should a treatment become available.

“We’re seeing a shift,” said Dr. Michael Hayden, a professor of human genetics at the University of British Columbia in Vancouver who has been providing various tests for Huntington’s for 20 years. “Younger people are coming for testing now, people in their 20s and early 30s; before, that was very rare. I’ve counseled some of them. They feel it is part of their heritage and that it is possible to lead a life that’s not defined by this gene.”

As well as showing some of the striking and distinctive movements associated with the disorder, the videos also relate some insightful reflections from Katie Moser, the subject of the article.

It’s common for there to be no cure for neurological illness, but usually there are some treatments which can slow down the symptoms.

Unlike some other disorders, there are remarkably few of these treatments for Huntingdon’s disease, although research is currently being undertaken to try and improve the situation.

Link to NYT article ‘Facing Life With a Lethal Gene’.
Link to Wikipedia page on Huntingdon’s.

Nobel prize-winning neuroscientist Eric Kandel has been asked to describe four advances in neuroscience from the past year that inspire optimism in an article for Edge.

His choices demonstrate an eclectic interest in modern mind and brain science.

The first is the discovery that MicroRNA is involved in synaptic connections and the second is advances in the understanding of how the hippocampus might store spatial information.

Kandel’s third choice is the discovery that single genes might lead to quite profound changes in social behaviour.

Perhaps his fourth choice is the most interesting, however. He cites neuroscientific evidence for the effectiveness of psychotherapy in treating mental illness, particularly for a type of therapy called cognitive behavioural therapy or CBT.

CBT is the most comprehensively researched of all the psychotherapies.

It has been shown to be as effective, if not more effective, than medication for anxiety and depressive disorders in randomised controlled trials, although best results are usually reported when both medication and CBT are combined, particularly in moderate or severe cases.

Recently, researchers have started to use brain scanning techniques to see how the function of the brain changes after CBT treatment.

Link to Kandel’s article ‘A Neuroscience Sampling’ from Edge.

Neurologist Prof Kevin Nelson and colleagues have just published a study in the journal Neurology showing that out-of-body experiences and near death experiences are more likely to occur in people who have unusual experiences when falling asleep or waking.

Science Daily reports that:

They found that an out-of-body experience is statistically as likely to occur during a near death experience as it is to occur during the transition between wakefulness and sleep. Nelson suggests that phenomena in the brain’s arousal system, which regulates different states of consciousness including REM sleep and wakefulness, may be the cause for these types of out-of-body displays.

Hallucinations and free-form ideas are very common in the period of entering sleep (called the hypnagogic state) and the period of waking (called the hypnopompic state).

Artists and visionaries throughout history have found inspiration from these unusual sleep-related experiences, as recounted in a recent Fortean Times article.

Link to coverage from Science Daily.
Link to coverage from the Daily Telegraph.
Link to PubMed entry for scientific paper.

Wired magazine has a fascinating feature article about an operation to implant deep brain stimulation electrodes in a patient with Parkinson’s disease. Crucially, the article is written the patient himself.

Deep brain stimulation involves inserting permanent electrodes into the brain to pump tiny pulses of electricity into key areas.

It’s most commonly used as a treatment for Parkinson’s disease which causes problems with the ‘motor loop’ – a network of brain areas that control movement (actually there are two main ones, the direct and indirect).

This is why patients with Parkinson’s disease have trouble moving and have a visible tremor.

The loops consist of a series of areas that might boost activity or reduce activity in subsequent parts of the loop.

Damage to any of these areas might mean that the following area might not get enough activation (like with a faulty accelerator), or might be too active because it is not being damped down correctly (like with a faulty brake).

Neurosurgeons can try and restore balance in this loop by either damping down an area by surgery (e.g. a pallidotomy) or by increasing activation at an area by deep brain stimulation.

This is exactly the treatment that Steven Guile, the author of the Wired article, describes.

I’ll be kept awake for the entire procedure. During the surgery I will talk and move my limbs on command, which helps Team Hubris know which part of my brain is being poked.

Unfortunately, this also means I’m conscious when [neurosurgeon] Henderson produces what looks like a hand drill and uses it to burr two dime-sized holes into the top of my skull. It doesn’t hurt, but it’s loud.

Team Hubris is installing a deep brain stimulator, essentially a neurological pacemaker, in my head. This involves threading two sets of stiff wires in through my scalp, through my cerebrum ‚Äî most of my brain ‚Äî and into my subthalamic nucleus, a target the size of a lima bean, located near the brain stem. Each wire is a little thinner than a small, unfolded paper clip, with four electrodes at one end. The electrodes will eventually deliver small shocks to my STN. How did I get into this mess? Well, I have Parkinson’s disease. If the surgery works, these wires will continually stimulate my brain in an attempt to relieve my symptoms.

The article is a wonderful tale of neurosurgery from the inside and a great guide to some of the science and medicine of the condition.

There’s also a fantastic a video segment where Gulie narrates and explains the operation.

Link to Wired article ‘A Shock to the System’ (via Neurophilosopher).

BBC Radio 4 recently broadcast a documentary on the long-term effects of ecstasy (MDMA) now that the ‘E Generation’ are in their 40s.

The documentary looks at the evidence for long-term effects of ecstasy and dispels some of the myths that were promoted in anti-ecstasy campaigns of the early 90s (for example, the famously flawed brain scans presented to suggest that ecstasy leaves functional ‘holes’ in the brain).

It is clear that such scare stories about the drug’s damaging effects were greatly exaggerated.

The evidence does suggest, however, that heavy and / or long-term ecstasy use does lead to mild to moderate cognitive impairment in some people (memory seems particularly sensitive to change).

There is still a need for much more systematic research in this area, particularly as the evidence on whether these long-term impairments get better is quite mixed.

The programme is presented by Dr John Marsden who has researched the impact and neuroscience of ecstasy and talks to a number of people who were heavy ecstasy users in the past.

Link to ‘The E Generation at 40’ with audio.

ABC Radio’s Science Show just had a special edition on the evolution of the brain and the development of social intelligence.

The programme talks to some of the leading researchers in social intelligence whose research interests range from comparing the behaviours of animals across species, to neuroimaging humans, to building robots to mimic social interaction.

In particular, the programme tackles the ‘social intelligence hypothesis’ that suggests that our increase in brain size during evolution has been driven by the need to work in groups and make sense of complex relationships.

Prof Steven Mithen explains:

There seems to be two key figures of brain expansion, and I think this is where the social intelligence hypothesis becomes very interesting. The first was around two million years ago, and at that time brains expanded perhaps about 50%. So we went from brain size of around 450cc to a brain size of around 1,000cc by 1.8 million years ago. What’s interesting during that time is that we don’t see dramatic changes in human behaviour as represented by the archaeological remains….

So archaeologists asked; why are brains getting larger and what is it providing? Brains wouldn’t get larger just for any reasons because brain tissue is metabolically very expensive, so it’s got to be serving a really important purpose. I think the social intelligence hypothesis suggests to us that that expansion of brain size around two million years ago was because people were living in larger groups, more complex groups, having to keep track of different people, a larger number of social relationships which we simply required a larger brain to do.

Link to Science Show special on ‘The social intelligence hypothesis’.

An excerpt from the entry for the psychedelic drug 4-TASB from the book Phenethylamines I Have Known And Loved (otherwise known as PiHKAL).

The drug was one of many developed by chemist and psychedelics researcher Alexander Shulgin. As with hundreds of other compounds, the chemical structure and effects of this new drug are described in the book.

From the experiences of testing this compound, it seems 4-TASB was not a success:

Music was lovely during the experiment, but pictures were not particularly exciting. I had feelings that my nerve-endings were raw and active. There was water retention. There was heartbeat wrongness, and respiration wrongness. During my attempts to sleep, my eyes-closed fantasies became extremely negative. I could actually feel the continuous electrical impulses travelling between my nerve endings. Disturbing. There was continuous erotic arousability, and this seemed to be part of the same over-sensitivity of the nervous system; orgasm didn’t soothe or smooth out the feeling of vulnerability. This is a very threatening material. DO NOT REPEAT.

Link to 4-TASB entry from online PiHKAL.

Below is an excerpt from a review, published in this week’s Nature, of the book The Science of Orgasm (ISBN 9780801884900).

The review is by Prof Tim Spector whose work we’ve featured previously on Mind Hacks.

Spector published the results of a study in 2005 on the genetics of female orgasm which generated a range of critical commentaries.

His review tackles a new book which aims to cover the latest research on orgasm from a number of perspectives, but also gives a glimpse into the neuroscience of orgasm itself.

In my view, the best part of the book is the neurochemistry of the orgasm. Studies of paraplegic women clearly show the importance in female orgasm of multiple complex neural pathways such as the vagus nerve.

Functional brain imaging is an exciting area for study and (despite poor-quality pictures) the authors present the latest findings of multiple areas of brain activity during orgasm — which make any simplistic dopamine (stimulatory) – serotonin (inhibitory) mode of action unlikely.

They postulate a central role for areas such as the cingulate cortex, which is also where pain is perceived — linking pain and orgasm as related sensory processes. Orgasms apparently alter pain perception and increase pain thresholds, and this link may explain bizarre reports of women having orgasms during childbirth.

However, just when I was ready for the truth — a clear definition of orgasm and where it arises in the brain — I was told it was not a reflex, only a perception of neural activity and, even worse, probably a form of diffuse consciousness in an as yet undiscovered fifth dimension.

After such a careful, slow build-up of teasing and tantalizing data, I was definitely left frustrated — and wanting more.

Link to Spectors’ review (not freely available unfortunately).
Link to info on the book from the publishers.

The fruit pictured on the right is called a soursop – a reportedly delicious fruit from the French West Indies that contains very small amounts of a substance that kills dopamine neurons.

Two research studies have looked at the substance – annonacin – and found it to kill off dopamine neurons in test tube trials.

Annonacin is only present in small quantities so occasionally eating soursop should be safe.

However, it is thought that the high rates of treatment resistant Parkinson’s disease in the French West Indies may be linked to high levels of soursop consumption.

Parkinson’s disease is caused by the death of dopamine neurons in the nigrostriatal pathway of the brain.

Link to neurotoxicity study on soursop.
Link to study on link with Parkinson’s disease.