Brain scanning the deceased

I’ve got an article in The Observer about how, a little surprisingly, the dead are becoming an increasing focus for brain scanning studies.

I first discussed this curious corner of neuroscience back in 2007 but a recent Neuroskeptic post reminded me of the area and I decided to check in on how it’s progressing.

It turns out that brain scanning the dead is becoming increasingly common in research and medicine and the article looks at how the science is progressing. Crucially, it’s helping us better understand ourselves in both life and death.

For thousands of years, direct studies of the human brain required the dead. The main method of study was dissection, which needed, rather inconveniently for the owner, physical access to their brain. Despite occasional unfortunate cases where the living brain was exposed on the battlefield or the surgeon’s table, corpses and preserved brains were the source of most of our knowledge.

When brain scanning technologies were invented in the 20th century they allowed the structure and function of the brain to be shown in living humans for the first time. This was as important for neuroscientists as the invention of the telescope and the cadaver slowly faded into the background of brain research. But recently, scrutiny of the post-mortem brain has seen something of a revival, a resurrection you might say, as modern researchers have become increasingly interested in applying their new scanning technologies to the brains of the deceased.

It’s a fascinating area and you can read the full article at the link below.

UPDATE: I’ve just noticed two of the links to studies have gone AWOL from the online article. The study that looked for the source of a mysterious signal by scanning people, cadavers and dummies and found it was a scanner problem was this one and the study that used corpses to test in-scanner motion correction was this one.

 

Link to Observer article on brain scanning the dead.

Seeing ourselves through the eyes of the machine

I’ve got an article in The Observer about how our inventions have profoundly shaped how we view ourselves because we’ve traditionally looked to technology for metaphors of human nature.

We tend to think that we understand ourselves and then create technologies to take advantage of that new knowledge but it usually happens the other way round – we invent something new and then use that as a metaphor to explain the mind and brain.

As history has moved on, the mind has been variously explained in terms of a wax tablets, a house with many rooms, pressures and fluids, phonograph recordings, telegraph signalling, and computing.

The idea that these are metaphors sometimes gets lost which, in some ways, is quite worrying.

It could be that we’ve reached “the end of history” as far as neuroscience goes and that everything we’ll ever say about the brain will be based on our current “brain as calculation” metaphors. But if this is not the case, there is a danger that we’ll sideline aspects of human nature that don’t easily fit the concept. Our subjective experience, emotions and the constantly varying awareness of our own minds have traditionally been much harder to understand as forms of “information processing”. Importantly, these aspects of mental life are exactly where things tend to go awry in mental illness, and it may be that our main approach for understanding the mind and brain is insufficient for tackling problems such as depression and psychosis. It could be we simply need more time with our current concepts, but history might show us that our destiny lies in another metaphor, perhaps from a future technology.

I mention Douwe Draaisma’s book Metaphors of Memory in the article but I also really recommend Alison Winter’s book Memory: Fragments of a Modern History which also covers the fascinating interaction between technological developments and how we understand ourselves.

You can read my full article at the link below.
 

Link to article in The Observer.

Awaiting a theory of neural weather

In a recent New York Times editorial, psychologist Gary Marcus noted that neuroscience is still awaiting a ‘bridging’ theory that elegantly connects neuroscience with psychology.

This reflects a common belief in cognitive science that there is a ‘missing law’ to be discovered that will tell us how mind and brain are linked – but it is quite possible there just isn’t one to be discovered.

Marcus, not arguing for the theory himself, describes it when he writes:

What we are really looking for is a bridge, some way of connecting two separate scientific languages — those of neuroscience and psychology.

Such bridges don’t come easily or often, maybe once in a generation, but when they do arrive, they can change everything. An example is the discovery of DNA, which allowed us to understand how genetic information could be represented and replicated in a physical structure. In one stroke, this bridge transformed biology from a mystery — in which the physical basis of life was almost entirely unknown — into a tractable if challenging set of problems, such as sequencing genes, working out the proteins that they encode and discerning the circumstances that govern their distribution in the body.

Neuroscience awaits a similar breakthrough. We know that there must be some lawful relation between assemblies of neurons and the elements of thought, but we are currently at a loss to describe those laws.

The idea of a DNA-like missing component that will allow us to connect theories of psychology and neuroscience is an attractive one, but it is equally as likely that the connection between mind and brain is more like the relationship between molecular interactions and the weather.

In this case, there is no ‘special theory’ that connects weather to molecules because different atmospheric phenomena are understood in multiple ways and across multiple models, each of which has a differing relationship to the scale at which the physical data is understood – fluid flows, as statistical models, atomic interactions and so on.

In explanatory terms, ‘psychology’ is probably a lot like the weather. The idea of their being a ‘psychological level’ is a human concept and its conceptual components won’t neatly relate to neural function in a uniform way.

Some functions will have much more direct relationships – like basic sensory information and its representation in the brain’s ‘sensotopic maps’. A good example might be how visual information in space is represented in an equivalent retinotopic map in the brain.

Other functions will have more more indirect relationships but in great part because of how we define ‘functions’. Some have very empirical definitions – take iconic memory – whereas others will be cultural or folk concepts – think vicarious embarrassment or nostalgia.

So it’s unlikely we’re going to find an all-purpose theoretical bridge to connect psychology and neuroscience. Instead, we’ll probably end up with what Kenneth Kendler calls ‘patchy reductionism’ – making pragmatic links between mind and brain where possible using a variety of theories and descriptions.

A search for a general ‘bridging theory’ may be a fruitless one.
 

Link to NYT piece ‘The Trouble With Brain Science’.

Out on a limb too many

Two neuropsychologists have written a fascinating review article about the desire to amputate a perfectly healthy limb known variously as apotemnophilia, xenomelia or body integrity identity disorder

The article is published in the Journal of Neuropsychiatric Disease and Treatment although some who have these desires would probably disagree that it is a disease or disorder and are more likely to compare it to something akin to being transgender.

The article also discusses the two main themes in the research literature: an association with sexual fetish for limb aputation (most associated with the use of the name apotemnophilia) and an alteration in body image linked to differences in the function of the parietal lobe in the brain (most associated with the use of the name xenomelia).

It’s a fascinating review of what we know about this under-recognised form of human experience but it also has an interesting snippet about how this desire first came to light not in the scientific literature, but in the letters page of Penthouse magazine:

A first description of this condition traces back to a series of letters published in 1972 in the magazine Penthouse. These letters were from erotically-obsessed persons who wanted to become amputees themselves. However, the first scientific report of this desire only appeared in 1977: Money et al described two cases who had intense desire toward amputation of a healthy limb. Another milestone was a 2005 study by Michael First, an American psychiatrist, who published the first systematic attempt to describe individuals who desire amputation of a healthy limb. Thanks to this survey, which included 52 volunteers, a number of key features of the condition are identified: gender prevalence (most individuals are men), side preference (left-sided amputations are most frequently desired), and finally, a preference toward amputation of the leg versus the arm.

The review also discusses a potentially related experience which has recently been reported – the desire to be paralysed.

If you want a more journalistic account, Matter published an extensive piece on the condition last year.
 

Link to scientific review article on apotemnophilia / xenomelia.
Link to Matter article.

A reality rabbit-hole from the dream world

I’ve got an article in The Observer about how the science of lucid dreaming is being pushed forward by the development of ‘in-dream’ experiments.

A lucid dream is where you become aware you are dreaming and where you can potentially change elements of the dream as it happens.

The piece discusses how eye movements allow communication from within dreams to researchers in the sleep lab and how this has led to studies involving people doing experimental tasks in the dream world.

One of our most mysterious and intriguing states of consciousness is the dream. We lose consciousness when we enter the deep waters of sleep, only to regain it as we emerge into a series of uncanny private realities. These air pockets of inner experience have been difficult for psychologists to study scientifically and, as a result, researchers have mostly resorted to measuring brain activity as the sleeper lies passive. But interest has recently returned to a technique that allows real-time communication from within the dream world.

The article also touches on the ‘dream hacking’ community who borrow from the scientific literature to try an increase their chances of having a lucid dream, sometimes using psychiatric medication for which vivid dreams are considered a side-effect.

The full piece is at the link below.
 

Link to article in The Observer.

Research Digest post #2

My time in the BPS Research Digest hotseat continues. Today’s post is about a lovely study by Stuart Ritchie and colleagues which uses a unique dataset to look at the effect of alcohol on cognitive function across the lifespan. Here’s the intro:

The cognitive cost or benefit of booze depends on your genes, suggests a new study which uses a unique longitudinal data set.

Inside the laboratory psychologists use a control group to isolate the effects of specific variables. But many important real world problems can’t be captured in the lab. Ageing is a good example: if we want to know what predicts a healthy old age, running experiments is difficult, even if only for the reason that they take a lifetime to get the results. Questions about potentially harmful substances are another good example: if we suspect something may be harmful we can hardly give it to half of a group of volunteer participants. The question of the long-term effects of alcohol consumption on cognitive ability combines both of these difficulties.

You can read the rest here: Alcohol could have cognitive benefits – depending on your genes.

See also, Tuesday’s post: A self-fulfilling fallacy?

Detecting inner consciousness

CC Licensed photo by Flickr user hernán. Click for source.Mosaic has an excellent in-depth article on researchers who are trying to detect signs of consciousness in patients who have fallen into coma-like states.

The piece meshes the work of neuroscientists Adrian Owen, Nicholas Schiff and Steven Laureys who are independently looking at how to detect signs of consciousness in unresponsive brain-injured patients.

It’s an excellent piece and communicates the key difference between various states of poor response after brain injury that are crucial for making sense of the ‘consciousness in coma’ headlines.

One of the key concepts is the minimally conscious state which is where patients show signs of fleeting and impaired consciousness but which is nonetheless verifiably present.

However, MCS is still a very impaired state to be in and this is sometimes missed by news reports.

For example, lots of coverage of a recent Lancet study suggested that ‘one third of patients in persistent vegetative state (a state with no reliable signs of consciousness) may be conscious’ as if this meant they were fully conscious but trapped in their bodies, when actually they just reached criteria for minimally conscious state.

My only point of contention with the Mosaic article is that it’s a little too enthusiastic about sleeping pill zolpidem, which has been reported to lead to a ‘miraculous’ recovery in some case reports but where results from early systematic studies still look bleak.

Nevertheless, an excellent piece that’s probably one of the best accounts of this important and innovative area of research you’re likely to read for a long-time.
 

Link to Mosaic article ‘The Mind Readers’.