Glimpsed at last - the life of neuropsychology's most important patient

Leborgne's brain

Monsieur Leborgne, nicknamed Tan Tan, for that was the only syllable he could utter (save for a swear word or two), died in the care of the neurologist Paul Broca in Paris on April 17, 1861. Arguably the most important case in the history of neuropsychology, Leborgne's death coincided with a debate raging in scholarly circles about the location of language function in the brain. When Broca autopsied Leborgne's brain, he observed a malformation on the left frontal lobe - "Broca's area" - and concluded this was the site of speech production, a moment that the historian Stanley Finger has described as a "key turning point in the history of the brain sciences".

Broca was far from being the first person to propose that speech function is located in the frontal lobes, but crucially, the evidence from Leborgne helped him persuade the academic community. For centuries experts had believed mental functions were located in the brain's hollows; that the cortex ("husk" in Latin) was little more than a rind of tissue and blood vessels. Today, problems producing language are still termed Broca's aphasia in recognition of Broca's landmark contribution, although Broca in fact named Leborgne's problems aphémie (meaning “without speech”). The Greek term “aphasia” (also meaning “speechlessness”), adopted by medicine, was coined in Broca's day by the physician Armand Trousseau.

Far more is known about Gage's life

In terms of the historical record, Leborgne is like a mirror opposite of Phineas Gage - another of neuropsychology's legendary cases. The story of Gage's life and infamous accident, in which a tamping iron shot through his brain, has been researched in-depth, inspiring books, poems, YouTube skits and snowmen makers along the way. Yet relatively little is known about the brain damage Gage suffered because no autopsy was performed when he died and his brain was never preserved (that hasn't stopped scientists from attempting to simulate the likely damage).

In contrast, Broca was careful to save Leborgne's brain for posterity. He decided against a full dissection, performing a surface examination only. Today the preserved organ is housed at the Musée Dupuytren museum in Paris, where Broca placed it. The brain has been scanned numerous times using modern methods (e.g. PDF), allowing detailed analysis of the location and nature of any lesions. We now know that the frontal lobe damage to Leborgne's brain was more extensive and deeper than Broca had realised based on his superficial examinations. But, contra the situation with Gage, while we are well-informed about Leborgne's brain, before now his identity and life story have remained largely mysterious. Broca's medical notes revealed little.

Thankfully, in a new paper, Cezary Domanski at Maria Curie-Sklodowska University in Poland has used archive registers in France to uncover hitherto unknown detailed biographical information about Monsieur Leborgne. Born in Moret-sur-Loing - the picturesque town that inspired Monet and other impressionists - "Tan's" full name was Louis Victor Leborgne. He was the son of Pierre Christophe Leborgne, a school teacher, and Margueritte Savard. He had three older siblings, Lucille, Pierre and Anne, and two younger siblings, Arsene and Louise.

An epileptic since his youth, it was Leborgne's loss of speech that led to him being hospitalised at age 30. Unmarried, he ended up spending the remaining 21 years of his life in hospital. Before this incapacitation through illness, Domanski tells us Leborgne was a "formier" in Paris, a kind of skilled craftsman who made the wooden forms used by shoemakers in their work.  Together with the information on Leborgne's family, this news corrects at least one historical myth. The oft-told idea that Leborgne "was an uneducated illiterate from the lower social class should once and for all be deemed erroneous," writes Domanski.

Based on his inquiries, the Polish historian offers an intriguing speculation - given that Leborgne's birthplace of Moret was home to several tanneries, Domanski wonders if his repeated utterance of Tan was somehow connected to childhood memories of the pretty town.

"One thing remains certain," Domanski concludes, "The memory of the disease and cause of death of 'Monsieur Leborgne' proved far more enduring than the story of his life, which was deemed irrelevant even when the patient was still alive. It is time for Louis Victor Leborgne to regain his identity ...".

In 2009, out of the blue, a photograph was discovered of Phineas Gage. I wonder if we will ever look upon an image of Leborgne?

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Domanski CW (2013). Mysterious "Monsieur Leborgne": The Mystery of the Famous Patient in the History of Neuropsychology is Explained. Journal of the history of the neurosciences, 22 (1), 47-52 PMID: 23323531

--Further reading-- 
500 Francs Says Language Is Housed in the Frontal Lobes!
Speaking without Broca's area
Broca’s area: Nomenclature, anatomy, typology and asymmetry

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

What's it like to be face-blind?

Most of us take the ability to recognise each other for granted. What must it be like to go through life unable to identify and distinguish people based on their facial appearance?

Some idea comes from a new, candid first-person account written for the journal Cognitive Neuropsychology by a doctor about his life-long face-blindness (known formally as prosopagnosia). It's a problem he didn't even realise he had for 30 years, and which he only discovered was a neuropsychological condition in 2006, when he was diagnosed for the first time. "It now seems remarkable that I lived at least half my life with a socially disabling condition of which not only myself, but also those around me, seemed unaware," writes Dr David Roger Fine, a gastroenterologist at the University of Southampton.

Looking back at his childhood, Fine realises that he can remember school buildings with detail, the clothes worn by his male friends, the hairstyles of the girls - but no faces. He got into difficulties in the playground confusing "high- and low- status boys", and was admonished for not raising his cap to his form teacher when he encountered her out of context and so failed to recognise her.

At senior school he made friends with a close-knit group, all of whom were physically distinctive and so easy to distinguish. In his professional life, Fine describes how there are some situations where his condition doesn't matter - such as committee meetings, where everyone keeps the same seat, and when he's giving a conference presentation. His job as a hospital doctor also involves distinct spatial areas of work and he uses these environmental contexts to help him judge who he is likely to encounter at any given time. Nonetheless, he often walks right past colleagues, earning him a reputation as capricious and aloof. More than once he's been accused of having Asperger's.

In his personal life, before marriage, romantic liaisons were especially problematic. Although women often dress in more distinctive ways than men, they also vary their appearance more often, for example changing their hair style and make-up after work. "It seemed to me that girls popped out of the Ether in one place then disappeared perhaps for months or even years before reappearing in another place, often disgruntled," he says.

Before his wife became his companion and minder, parties were particularly awkward and stressful. "I once met and had a long conversation with a man at a Christmas party," Fine recalls. "We circulated until we met again at the other side of the room and I introduced myself [again]. He looked puzzled until my wife came to my rescue." Making friends is nigh on impossible. "Recognising" strangers is a constant embarrassing risk.

Fine has had a successful career in spite of his prosopagnosia, but he feels his success was "blunted" by the condition. Now aged 60 he has highly developed strategies for coping - he has a better sense of people's age, which is one of the criteria he uses to distinguish people. The ethnic mix of modern Britain also helps. And he tries to focus on distinct items of jewellery, such as people's rings, that tend to be worn at all times. The increased popularity of tattoos is another help, although it can cause problems too - one female colleague with a tattoo low on her chest visible in summer clothes "caused consternation in the corridor [one winter] as she unbuttoned her blouse by way of identification."

Looking to the future, Fine is worried that his confusion about people's identity could lead to him being misdiagnosed with dementia. "During a recent hospital stay I asked the nurses to introduce themselves every time, as I was concerned that I might be misdiagnosed as confused if I muddled them up."

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Experts used to think that the inability to recognise faces was a problem that nearly always arose after brain injury. In recent years, however, it's become apparent that many people are born with face-blindness (or develop it early in life), with the prevalence estimated at two per cent of the population. Do you have the condition or know anyone who has? How do you/they cope?

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Fine, D. (2012). A life with prosopagnosia. Cognitive Neuropsychology, 1-6 DOI: 10.1080/02643294.2012.736377

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

The Alien awakened by a rubber hand

What happens if you administer a tactile illusion to a brain-damaged patient whose hand is out of their control? A team of researchers has done just that, figuring that illusions could offer new insights into complex neuropsychological disorders.

The patient in question was a 69-year-old lady whose left-sided stroke had left her with alien hand syndrome*. Most of the time her right hand was held in a clenched position that she couldn't open. Occasionally, accompanied by a mild electric sensation, it moved involuntarily, jerking, or even slapping her in the face.

Michael Schaefer and his colleagues at Otto-von-Guericke University Magdeburg tested the lady on two sensorimotor illusions - the traditional rubber hand illusion and the lesser-known somatic rubber hand illusion. The first involved the patient placing one of her arms on the table-top, with the other underneath. A rubber arm was placed alongside her real arm on the table. The researcher then stroked the patient's hidden arm and the rubber arm in synchrony. When the illusion works it creates the sensation of feeling in the rubber arm, as if it's a part of the person's body. In fact the patient experienced no feeling in the rubber arm at all, regardless of whether it was her healthy arm or alien arm that was being stroked under the table. The rubber hand illusion doesn't work for everyone so this null finding is not particularly surprising.

Things got more interesting when the researchers tested their patient with the somatic rubber hand illusion (see picture, above). This procedure involved the rubber arm being placed between the patient's two real arms on a table-top. This time, the patient was blindfolded and the researcher (wearing plastic surgical gloves) picked up one of the patient's hands and used it to tap the rubber hand. At the same time, and in synchrony, the researcher tapped the patient's other hand. This procedure creates the strong illusion for the participant that they are touching their own hand rather than the rubber hand - a feeling that the patient said she experienced.

But something surprising also happened when the researchers tried out this illusion. Within moments, the patient's alien hand leapt up off the table and was grabbed by her healthy hand. She said she felt an electric sensation in her alien hand prior to it rousing. The illusory experience seemed to have awakened her alien hand. This effect occurred every time the procedure was repeated. But crucially it only happened when it was the patient's healthy hand that was used to tap the rubber hand, whilst the patient's alien hand was simultaneously tapped by the researcher (and not when the illusion was done the other way around). The awakening effect also disappeared when the procedure was repeated with the patient's blindfold removed, which is known to destroy the illusion.

All this suggests that it wasn't touching the alien hand per se that roused it, but rather it was the experience of the body illusion. Schaefer and his colleagues think that their patient has a disconnect between the anterior supplementary motor area (SMA) at the front of her brain (involved in inhibitory control) and other brain regions involved in movement. They reckon this impaired motor integration somehow interacted with the illusory feelings of body ownership triggered by the rubber hand trick. Perhaps, they said, the illusion further weakened the SMA's already compromised control of the alien hand.

"Although our results should be confirmed by further studies, we believe that the examination of experimental-induced illusions in patients with disorders of self-embodiment is promising and might help us to develop treatments for these diseases in the future."

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Michael Schaefer, Hans-Jochen Heinze, and Imke Galazky (2012). Waking up the alien hand: rubber hand illusion interacts with alien hand syndrome. Neurocase: The Neural Basis of Cognition DOI: 10.1080/13554794.2012.667132

Further reading: Sergio Della Sala on the bizarre ‘Dr Strangelove syndrome’ and what it tells us about free will (Psychologist magazine article).
Simulating anarchic hand syndrome in the lab (earlier Digest report).

*Some experts prefer the term anarchic hand syndrome for this patient's condition, reserving the term alien hand syndrome for a distinct but related condition in which the patient no longer believes the hand is theirs. For consistency I decided to use the terminology adopted by the authors of this paper.

Post written by Christian Jarrett for the BPS Research Digest.

Neuroscience still haunted by Phineas Gage

From Van Horn et al 2012

Seven years after his death, Phineas Gage's body was dug out of the ground and his skull passed to a doctor, John Harlow, who'd treated him in life. Although Gage's brain had long-since decayed, his skull remained intact and was of particular medical interest because in 1848, in an explosives accident, Gage had survived a three and a half foot long iron rod shooting straight into his face, through his brain, and out the top of his head. Although he died in 1860, Gage has lived on as one of psychology's foundation myths - a classic example of frontal brain damage affecting personality.

Traditional accounts have it that Gage was permanently changed by his injury, becoming a drunken, aggressive waster. But in recent years a reappraisal of Gage's activities during the remainder of his life suggests he underwent an impressive social recovery. For example, he worked as a stagecoach driver along a 100-mile route in Chile, a job that would have required significant psychosocial competence.

If we could ever find out exactly the brain damage that Gage suffered it would help inform the debates surrounding how much he did or didn't recover and provide intriguing insights about neurorehabilitation. That's what Harlow hoped to do back in the nineteenth century. From inspecting Gage's skull he concluded that the left frontal and middle lobes must have been destroyed and that the partial recovery made by Gage was likely due to compensation by the right hemisphere.

Housed in a museum together with the rod that made him famous, Gage's skull was then left untouched for nearly a hundred years. However, beginning in the 1980s, each new generation of scientists has used the technology of the day to make another attempt to recreate Gage's injury.

In 1982, using CT scans of the skull, Rick and Ken Tyler concluded that although the left side of the brain suffered the most damage, the right hemisphere was probably damaged too. In the nineties, Hanna Damasio and her colleagues performed a 3D reconstruction of Gage's injury and they too concluded the damage was bilateral (pdf). Another ten years went by and then another simulation. In the most sophisticated analysis to date, Peter Ratiu and his colleagues overlaid a 3D representation of a brain within a 3D reconstruction of Gage's skull and simulated the path of the iron rod (pdf). They concluded that the damage was only to the left, just as Harlow had said, which would make the new claims about Gage's recovery more explicable.

Now Gage's skull has been analysed yet again. A team of experts, led by John Van Horn, based at the University of California and Harvard Medical School, has used diffusion imaging data, together with anatomical MRI, to try to find out how Gage's injury affected the connective tissues of his brain. As they explain: "while many authors have focused on the gross damage done by the iron to Gage's frontal cortical grey matter, little consideration has been given to the degree of damage to and destruction of major connections between discretely affected regions and the rest of his brain."

Van Horn's team scanned the brains of 110 right-handed men (Gage was right-handed) of a similar age to Gage at the time of his injury (the range was 25 to 36; Gage was aged 25 when the rod entered his head). The scans used diffusion tensor imaging to map the connective white-matter tracts of the men's brains in intricate detail. Next, these scans were averaged and integrated with the 3D reconstruction of Gage's skull that was created by Ratiu's team back in 2004. The trajectory of the rod was simulated and an estimate was made of the damage the rod would have done to the connective tissues of Gage's brain, based on it resembling the average of the 110 healthy men's brains.

Is it reasonable to suppose that the connective networks of Gage's brain were akin to the averaged networks of 110 healthy men scanned in the twenty-first century? "Such a supposition may have its limitations and could be open to debate," the researchers conceded. "Nevertheless, ours represents the best current estimation as to the extent of brain damage likely to have occurred at the level of both cortex and white matter fiber pathways."

So what damage do they think Gage incurred? Van Horn's team think that 4 per cent of Gage's cortical grey matter was damaged in the left hemisphere and 11 per cent of his cortical white matter. Among the important connective bundles that were damaged, they said, are the uncinate fasciculus (which connects the frontal lobes with the limbic system), the cingulum bundle (connecting parts of the limbic system with each other), and the superior longitudinal fasciculus (long-distance fibres linking the front and back of the brain). Abnormalities in the uncinate fasciculus, they explained, have previously been associated with mental illness and related to cognitive deficits in traumatic brain injury. This spread of damage to Gage's white matter tracts would have affected not only the left frontal lobe, the researchers explained, but indirectly would have affected the functioning of the right hemisphere too.

The pattern of damage Gage suffered would be expected to have a profound effect, the researchers said, having "a considerable impact on executive as well as emotional functions," and "likely combined to give rise to the behavioural and cognitive symptomatology originally reported by Harlow." However, they stressed that it could have been a lot worse. A simulation of 500 random similarly-sized lesions showed the damage caused by the iron rod was below the average you'd expect by chance. Gage was lucky not to have been left blinded or dead.

The researchers concluded that "consideration of white matter damage and connectivity loss is ... an essential consideration when interpreting and discussing this famous case study and its role in the history of neuroscience." But how useful is this new analysis really? In particular, does it shed any light on the re-appraisal of the Gage myth that's emerged over the last decade or so, in which Gage is considered to have made an impressive psychosocial recovery?

This photo of Gage was discovered in 2009

The man responsible for much of this reassessment is the historian Malcolm Macmillan, the author of An Odd Kind of Fame: Stories of Phineas Gage, and several subsequent articles. He told the Digest that the results were "very interesting" and that it was "particularly gratifying" that the new analysis had confirmed the earlier conclusions of Ratiu's team that Gage's damage was left frontal. However, Macmillan has some reservations - for example he pointed out the limitations in the method of averaging from multiple brains to estimate the structure of Gage's brain.

Moreover, whilst the inferred damaged to Gage's connective pathways might explain the changes to his behaviour in the first two to three years post-accident, Macmillan and his colleague Matthew Lena, "are most interested in what happened in the last five or six years of Phineas' life. If Lena and I are right about the post-accident Phineas gradually changing from the commonly portrayed impulsive and uninhibited person into one who made a reasonable 'social recovery,'" Macmillan said, "we need to know if and how changes in the tracts contributed. As I see it, and unfortunately, it seems unlikely that we will ever be able to reconstruct those long-term changes."

But there's always room for hope. Macmillan added: "From people who use tractography to map the changes in the connections following traumatic brain injury, I understand there is evidence that damaged tracts may re-establish their original connections or build alternative pathways as the brain recovers from oedema. In the short-term, some of the original functions may thus recover. It would be truly wonderful if were we able to confirm that possibility in Phineas' case."
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Van Horn, J., Irimia, A., Torgerson, C., Chambers, M., Kikinis, R., and Toga, A. (2012). Mapping Connectivity Damage in the Case of Phineas Gage. PLoS ONE, 7 (5) DOI: 10.1371/journal.pone.0037454

Post written by Christian Jarrett for the BPS Research Digest.

Total recall: The man who can remember every day of his life in detail

For most of us, it's tricky enough to remember what we were doing this time last week, let alone on some random day years ago. But for a blind 20-year-old man referred to by researchers as HK, every day of his life since the age of about eleven is recorded in his memory in detail. HK has a rare condition known as hyperthymesia and his is only the second case ever documented in the scientific literature (the first, a woman known as AJ, was reported in 2006; pdf).

Brandon Ally and his team have completed comprehensive tests with HK and they've scanned his brain and compared its structure with 30 age-matched controls. They found that HK has normal intelligence, that he performs normally on standard desktop tests of short and long-term recall, and that he has normal verbal learning skills. It's specifically his autobiographical memory that's phenomenal.

The researchers assessed HK's autobiographical memory by choosing four dates from each year of his life since his first memory (that was from 1993 when he was aged three and half), making 80 dates in total. For each of these dates, they gathered at least three facts from HK's family, medical records and the historical records for his neighbourhood in Nashville. HK was then interviewed about each of these 80 dates - for example, he was asked "Can you tell me what happened during your day on January 2nd, 2001". His answers, often detailed, were transcribed and fact-checked.

HK's recollection of days from his life between the ages of 9 and 12 grew dramatically more accurate and detailed, reaching nearly 90 per cent accuracy for memories at age 11, rising to near perfect accuracy thereafter. For some dates, HK was quizzed again at a second session - the consistency of his answers was 100 per cent.

What's it like to have hyperthymesia? HK told the researchers that his autobiographical memories are rich in sensory and emotional details and feel just as vivid regardless of whether they're from years ago or from yesterday. Ninety per cent of the time he experiences these memories in the first-person, compared with rates of approximately 66 per cent in the general population. HK said autobiographical memories frequently enter his consciousness, triggered by news, smells, sounds and emotions. Most days he wakes up thinking about what he's done on that day in previous years. Bad memories come to mind just as often as positive ones, but he is able to choose to focus more on the positive.

In terms of brain structure, overall HK's brain was smaller than average (likely related to his having been born prematurely at 27 weeks). By contrast, his right amygdala was larger, by about 20 per cent, than in the controls. He also has enhanced functional connectivity between his right amygdala and hippocampus and in other regions. The amygdala is a small subcortical structure and part of the limbic system, which is involved in emotional processing. The researchers think that HK's enlarged amygdala and its enhanced connectivity lends a deeper personal salience to his experiences than is normal, thus making them more memorable.

Ally and his team acknowledged that "unique case studies such as HK are not easily translated or generalisable to the normal population", and so should be interpreted with caution. That said, they argued their results provide further evidence for the role of the amygdala in autobiographical memory. "Further, perhaps the present findings can help guide future regions of brain stimulation in memory-disordered populations, with the goal of improving memory function," they speculated. "Indeed, brain stimulation to deep, subcortical memory-related structures has shown very early promise in patients with Alzheimer's Disease."
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Ally, B., Hussey, E., and Donahue, M. (2012). A case of hyperthymesia: rethinking the role of the amygdala in autobiographical memory. Neurocase, 1-16 DOI: 10.1080/13554794.2011.654225

Post written by Christian Jarrett for the BPS Research Digest.

The woman who grew phantom fingers that she'd never physically had

Inside the human brain there is a map of the body drawn in neural tissue. When a person loses a limb, the neural representation of that body part still exists in the map, and more often than not, it continues to give rise to "phantom" sensations. Sometimes neurons in adjacent areas of the body map invade the tissue that represents the missing limb. This can lead to the curious situation where stimulation of a person's face (or other areas) provokes feelings in their phantom limb, as documented by the great neuroscientist V.S. Ramachandran. Cases like this are often cited as evidence for the brain's plasticity.

Now Ramachandran and his colleague Paul McGeoch have reported a phantom limb case that illustrates how aspects of the body map are apparently hard-wired. The case is a 57-year-old woman (known as R.N.) who was born with a deformed right hand consisting of only three fingers and a rudimentary thumb. After a car crash at age 18, R.N.'s deformed hand was amputated, which gave rise to feelings of a phantom hand. Curiously, R.N. experienced her phantom hand as having a full complement of five fingers, albeit that some of the digits were foreshortened. In other words, she was experiencing the sensation of having fingers that she'd never physically possessed.

R.N. was referred to the researchers more than 35 years after her accident, after her phantom hand had become unbearably painful and uncomfortable, including two of the fingers feeling as if they'd become twisted and bent until their tips touched. McGeoch and Ramachandran trained R.N. in using "mirror visual feedback", in which the reflection of her healthy left-hand was seen as superimposed onto where she felt her phantom right hand to be. After two weeks of 30-minutes daily feedback, R.N. was able to move her phantom fingers and was relieved of pain. Crucially, she also experienced that all five of her phantom fingers were now normal length.

McGeoch and Ramachandran said this case provides evidence that the brain has an innate template of a fully-formed hand. Freed from the visual, proprioceptive and tactile sensations of her deformed hand, and aided by the mirror training, R.N.s brain re-instated its innate map of a normal hand. "There appears to be a 'hard-wired' innately specified scaffold for body image," the researchers said. This account also helps explain the occurrence of phantom limbs in people born with missing limbs.

The researchers conceded that they were taking R.N.s account of her feelings on trust. It's possible she was confabulating - although they think this unlikely. If she were, McGeoch and Ramachandran think it more likely that R.N. would have claimed to have had normal length fingers prior to the mirror training.

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McGeoch, P., and Ramachandran, V. (2012). The appearance of new phantom fingers post-amputation in a phocomelus. Neurocase, 18 (2), 95-97 DOI: 10.1080/13554794.2011.556128



Post written by Christian Jarrett for the BPS Research Digest.

The stroke patient for whom strangers look normal whilst family look strange

Neuropsychologists in The Netherlands and the UK have documented the curious case of a 62-year-old stroke patient whose brain damage affected her perception of familiar faces whilst leaving her perception of unfamiliar faces intact

The woman, referred to as J.S., struggled to recognise family, fared slightly better with celebrities, whilst having no problems correctly categorising as unfamiliar the faces of complete strangers. When the woman's daughters came to visit her in hospital, she had no trouble recognising the daughter she hadn't seen for eight years, but struggled to identify her other daughter who visited daily.

Joost Heutink and his team confirmed this pattern of deficits by comparing J.S.'s performance against three age-matched women in a series of face recognition tasks. As well as having impaired recognition of her family (and to a lesser extent celebrities), J.S. also reported that the appearance of her family members was distorted. For example, she said her grandchildren looked grossly overweight and that they were a deep tanned colour. J.S. also had a general problem recognising emotional facial expressions.

Further details came from recordings of J.S.'s skin conductance (a measure of physiological arousal) when she looked at various faces. This showed that she experienced more arousal after looking at family members' faces as opposed to strangers and celebrities. This is normal, although the peak and latency of this arousal was delayed relative to the control participants.

So what explains J.S.'s pattern of deficits? Those familiar with neuropsychology may be reminded of Capgras Syndrome, in which the patient claims that one or more close relations have been replaced by an imposter. But J.S. does not have this syndrome. People with Capgras say that the imposter is a perfect likeness to the real relation. By contrast, J.S. does not think her relations are imposters, she just struggles to identify them and thinks their appearance has been distorted.

J.S.'s condition also bears some resemblance to prosopagnosia - a specific deficit affecting face recognition. Again, this doesn't really match J.S.'s neuropsychological profile. After all, her recognition of strangers' faces as unfamiliar was near perfect. Moreover, the brain region that's normally damaged in proposopagnosia - the fusiform face area - was unaffected in J.S.'s brain.

Joost Heutink and his colleagues think part of the answer may lie with a rare condition known as prosopometamorphopsia - in which other people's faces are perceived as being warped or distorted. The researchers suggest J.S. may have a form of this condition that interacts in some way with the emotional meaning of faces. So, if a face affects her emotionally (as happens with family), she perceives their face as distorted, which also has the side-effect of affecting her conscious recognition. This account fits with the distribution of brain damage in J.S.'s brain. In particular she suffered damage to the posterior superior temporal sulcus, which it's been suggested is involved in merging information about face identity with emotional context and meaning.

This account also helps explain two exceptions to J.S.'s relatively superior performance in recognising celebrity faces vs. family members. When it came to images of Hitler and Bin Laden (characters likely to trigger an emotional response), she believed they actually depicted imposters, and poor ones at that.

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Heutink, J., Brouwer, W., Kums, E., Young, A., and Bouma, A. (2012). When family looks strange and strangers look normal: A case of impaired face perception and recognition after stroke. Neurocase, 18 (1), 39-49 DOI: 10.1080/13554794.2010.547510

Post written by Christian Jarrett for the BPS Research Digest.