Fluctuating existence

The Neurologist has a fascinating case report of a women with Parkinson’s disease who experienced a fluctuating belief that she didn’t exist.

Cotard’s delusion is usually described as the ‘belief that you’re dead’ although Jules Cotard, for whom the delusion is named, defined it as a délire des négations – the delusion of negation, or nihilism, as it’s usually translated.

In fact, in his original case report, Cotard’s patient didn’t believe they were dead but that they had “no brain, nerves, chest, or entrails, and was just skin and bone”.

This new case report in The Neurologist describes a patient with Parkinson’s disease who experiences something similar with the delusion appearing as their Parkinson’s medication began to wear off.

In December 2010, she went to follow-up visit accompanied by her caregivers and they reported that, in the last 2 months, the patient has developed a sudden onset of nihilistic delusion, mainly during the “wearing-off” condition and associated with end of dose dyskinesias and akathisia. The patient repeatedly complained of having lost both of her eyes, mouth, nose, and ears. Often during these events, she insisted to have a mirror to see herself. She expressed the false belief that she did not have the whole body and that nothing existed, including herself, without any insight. This nihilistic delusion, compatible with the diagnosis of Cotard syndrome, clearly improved with the administration of the following dose of levodopa and the associated amelioration of motor symptoms.

This is interesting because the Parkinson’s medication – levodopa – is a precursor to dopamine and is used to increase dopamine levels in the brain.

Increased dopamine levels in mid-brain areas are considered to be a key causal factor in generating the delusions and hallucinations of psychosis, but in this case delusions reliably appeared as dopamine levels were likely to have been dropping due to the medication wearing off.

Although this is a single case study, the effect was reliable when repeated, but it doesn’t mean that this would happen with everybody in the same situation.

But what it really shows is that the neurobiology of psychosis is not a simple ‘chemical imbalance’ but, in part, a complex dysregulation that can effect individuals differently due to the inherent interconnectedness of neural systems.

Link to PubMed entry for case report.

Bringing us closer to the blueprints of the brain

I’ve got a piece in today’s Observer about the amazing science of doing functional brain imaging and behavioural studies with babies while they are still in the womb to see the earliest stages of neurocognitive development.

Brain development during pregnancy is key for future health, which is why it gets checked so thoroughly during prenatal examinations. But neuroscientists have become increasingly interested in how the activity of the brain becomes progressively integrated and synchronised during development to support human experience, something developmental neuroscientist Moriah Thomason calls “bringing us closer to the blueprints of the brain”.

It’s difficult to state how remarkable this is, both technically and scientifically, as researchers have managed to measure the unborn brain in action as it responds to the outside world through the womb.

The article looks at how this science is developing and what it’s telling us about the earliest stages of the developing brain.

Exciting stuff.

Link to ‘Prenatal blueprints give an early glimpse of a baby’s developing brain’

Why you can live a normal life with half a brain

A few extreme cases show that people can be missing large chunks of their brains with no significant ill-effect – why? Tom Stafford explains what it tells us about the true nature of our grey matter.

How much of our brain do we actually need? A number of stories have appeared in the news in recent months about people with chunks of their brains missing or damaged. These cases tell a story about the mind that goes deeper than their initial shock factor. It isn’t just that we don’t understand how the brain works, but that we may be thinking about it in the entirely wrong way.

Earlier this year, a case was reported of a woman who is missing her cerebellum, a distinct structure found at the back of the brain. By some estimates the human cerebellum contains half the brain cells you have. This isn’t just brain damage – the whole structure is absent. Yet this woman lives a normal life; she graduated from school, got married and had a kid following an uneventful pregnancy and birth. A pretty standard biography for a 24-year-old.

The woman wasn’t completely unaffected – she had suffered from uncertain, clumsy, movements her whole life. But the surprise is how she moves at all, missing a part of the brain that is so fundamental it evolved with the first vertebrates. The sharks that swam when dinosaurs walked the Earth had cerebellums.

This case points to a sad fact about brain science. We don’t often shout about it, but there are large gaps in even our basic understanding of the brain. We can’t agree on the function of even some of the most important brain regions, such as the cerebellum. Rare cases such as this show up that ignorance. Every so often someone walks into a hospital and their brain scan reveals the startling differences we can have inside our heads. Startling differences which may have only small observable effects on our behaviour.

Part of the problem may be our way of thinking. It is natural to see the brain as a piece of naturally selected technology, and in human technology there is often a one-to-one mapping between structure and function. If I have a toaster, the heat is provided by the heating element, the time is controlled by the timer and the popping up is driven by a spring. The case of the missing cerebellum reveals there is no such simple scheme for the brain. Although we love to talk about the brain region for vision, for hunger or for love, there are no such brain regions, because the brain isn’t technology where any function is governed by just one part.

Take another recent case, that of a man who was found to have a tapeworm in his brain. Over four years it burrowed “from one side to the other“, causing a variety of problems such as seizures, memory problems and weird smell sensations. Sounds to me like he got off lightly for having a living thing move through his brain. If the brain worked like most designed technology this wouldn’t be possible. If a worm burrowed from one side of your phone to the other, the gadget would die. Indeed, when an early electromechanical computer malfunctioned in the 1940s, an investigation revealed the problem: a moth trapped in a relay – the first actual case of a computer bug being found.

Part of the explanation for the brain’s apparent resilience is its ‘plasticity’ – an ability to adapt its structure based on experience. But another clue comes from a concept advocated by Nobel Prize-winning neuroscientist Gerald Edelman. He noticed that biological functions are often supported by multiple structures – single physical features are coded for by multiple genes, for example, so that knocking out any single gene can’t prevent that feature from developing apparently normally. He called the ability of multiple different structures to support a single function ‘degeneracy’.

And so it is with the brain. The important functions our brain carries out are not farmed out to single distinct brain regions, but instead supported by multiple regions, often in similar but slightly different ways. If one structure breaks down, the others can pick up the slack.

This helps explain why cognitive neuroscientists have such problems working out what different brain regions do. If you try and understand brain areas using a simple one-function-per-region and one-region-per-function rule you’ll never be able to design the experiments needed to unpick the degenerate tangle of structure and function.

The cerebellum is most famous for controlling precise movements, but other areas of the brain such as the basal ganglia and the motor cortex are also intimately involved in moving our bodies. Asking what unique thing each area does may be the wrong question, when they are all contributing to the same thing. Memory is another example of an essential biological function which seems to be supported by multiple brain systems. If you bump into someone you’ve met once before, you might remember that they have a reputation for being nice, remember a specific incident of them being nice, or just retrieve a vague positive feeling about them – all forms of memory which tell you to trust this person, and all supported by different brain areas doing the same job in a slightly different way.

Edelman and his colleague, Joseph Gally, called degeneracy a “ubiquitous biological property … a feature of complexity”, claiming it was an inevitable outcome of natural selection. It explains both why unusual brain conditions are not as catastrophic as they might be, and also why scientists find the brain so confounding to try and understand.

My BBC Future column from before Christmas. The original is here. Thanks to everyone on twitter who chipped in on the plural of cerebellum

Cushing’s abandoned brains

I’ve just found a great short documentary about the abandoned brain collection of pioneering neurosurgeon Harvey Cushing.

The video describes how Cushing’s archives, which genuinely involved hundreds of brains in jars, as well as rare slides and photos of the early days of brain surgery, were rediscovered in the basement of Yale University and restored to public view.

Cushing is often called the ‘father of modern neurosurgery’ and spent a lot of time studying brain pathology by archiving and classifying tumours, bleeds and post-mortem brains in jars for others to learn from, as well as creating amazing medical illustrations – including the one below.

This archive became less necessary as technology moved on and the brain collection was moved into the basement below the medical school dormitories at Yale University and forgotten about.

The archives were eventually found again and restored as the Cushing Center which is now open to the public.

While the video focuses on the brains, Morbid Anatomy put some of the photos of patients from the archive online which are quite striking in themselves.

Link to Cushing’s Brains documentary on YouTube.
Link to Morbid Anatomy gallery of Cushing’s photos.

Beautiful online neuroscience learning

The Fundamentals of Neuroscience is a free online course from Harvard and it looks wonderful – thanks to them employing animators, digital artists and scientists to lift the course above the usual read and repeat learning.

The course is already underway but you can register and start learning until mid-December and you can watch any of the previews to get a feel for what’s being taught.

As you can see from the syllabus it focuses on the fairly low-level operation of the biology of brain but it’s all essential knowledge that will undoubtedly be a joy to encounter or re-acquaint yourself with.

You need to register to access the full content but there’s plenty of trailers online. Great stuff.

Link to ‘Fundamentals of Neuroscience’ course.

A Rush of Blood to the Brain

An article from Culture, Medicine, and Psychiatry that discusses the concept of ‘moral disability’ and brain trauma in Victorian times includes a fascinating section on what was presumably thought to be the science of ‘knocking some sense into the brain’.

The piece is by medical historian Brandy Shillace who researches Victorian scientific ideas and how they affected society.

Sadly, the article is locked (quite rightly, humanities can kill if not used correctly) but this is the key section:

While eighteenth-century French philosopher François Bichat had suggested that a blow suffered to one side of the head might restore the good senses of the disordered side, Wigan’s work suggested that “where such mental derangement depends on inflammation, fever, impoverished or diseased blood, or other manifestly bodily disease,” it could be cured by actively seeking and rooting out the source, by trephining the brain or otherwise subduing the offending hemisphere… The Lancet was replete with unusual cases of brain trauma and its curious results, many that seemed to support Wigan in his assumptions about physical trauma, variously applied.

I performed a survey from 1839 to 1858 and discovered a case of brain trauma in numerous issues, eight of which were particularly revelatory of the unusual nature of the brain and its hemispheres. The 1843 account of Dr. Peter S. Evans, “Derangement of the Brain by a Sudden Shock and Its Recovery,” claims that a boy was beaten into idiocy, and then beaten out of it again (regaining his full senses after being whipped by a cart driver). One of Wigan’s cases describes a young gentleman in a “paroxysm of maniacal delirium” who shot himself sane.

Not recommended.

Link to locked article in Culture, Medicine, and Psychiatry

Agents, social encounters and hallucinated voices

I’ve written a piece for the new PLOS Neuro Community about how the social aspects of hallucinated voices tend to be ignored and how we might go about making it more central in psychology and neuroscience.

It came about because the PLOS Neuro Community have asked authors of popular papers to write a more gentle introduction to the topic, so the piece is based on a PLOS Biology paper I wrote last year.

I’ve met a lot of people who hear hallucinated voices and I have always been struck by the number of people who feel accompanied by them, as if they were distinct and distinguishable personalities. Some experience their hallucinated entourage as hecklers or domineering bullies, some as curious and opaque narrators, others as helpful guardians, but most of the time, the voice hearer feels they share a relationship with a series of internal vocal individuals.

The piece discusses psychology and neuroscience but in the post, I also mention some work I’ve been doing with philosopher of mind Sam Wilkinson. As luck would have it, Sam just published a post about what we’re working on, on the excellent Imperfect Cognitions blog.

It looks at hallucinated voices and the representation of agency and agents. If you’re not used to these terms they can be slightly opaque but they refer to how the mind and brain represents autonomous individuals – be they human, animal, presumed or imaginary – and how that might relate to the experience of having hallucinated voices.

Link to A Social Visit with Hallucinated Voices.
Link to The Representation of Agents in Auditory Verbal Hallucinations.