Neuroscience
It's 50 years since the American neurologist Norman Geschwind published his hugely influential Disconnexion Syndromes in Animals and Man, in which he argued that many brain disorders and injuries could best be understood in terms of the damage incurred to the white-matter pathways connecting different areas of the brain.
To mark this anniversary, an international team of researchers has used modern brain imaging techniques to reveal, in an open-access article for Cerebral Cortex, the likely damage to brain connectivity suffered by three of psychology's most famous cases: the 19th century rail worker Phineas Gage, who survived an iron rod passing through his brain; Louis Victor Leborgne, the 19th century aphasic patient studied by Paul Broca who played a key role in our understanding of language function in the brain; and the most studied amnesiac in history, Henry Molaison (known as H.M. in the literature), who died in 2008.
Michel Thiebaut de Schotten and his colleagues first obtained existing information about the brains of these three cases. For Gage they used a CT scan taken of his skull by researchers in 2004 and mapped the signs of injury onto a simulation of his brain. Leborgne's brain is in preservation at the Dupuytren Museum in Paris and they used an MRI scan of it taken in 2007. For Molaison's brain they used an MRI scan taken while he was still alive in 1993.
Next, the researchers created an intricately detailed map of the human brain's connective pathways. They used an advanced version of a technique known as diffusion tensor imaging to plot the connective tissues in the brains of 129 healthy volunteers (aged 18-79; 59 men). They combined the data from all these healthy people's brains to create an average road-map of the human brain's connective tracts.
The final step involved applying the information on the brain damage incurred by the three famous cases onto this road map of the human brain's connective pathways, to see which important tracts had probably been affected.
In the case of Gage, the researchers estimate that he suffered widespread damage to several connective pathways in his frontal lobes, beyond the specific damage thought to have been inflicted by the passage of the iron bar. These pathways include the uncinate fasciculus, the frontal intralobar networks, and the fronto-striatal-thalamal-frontal network, with likely implications for his decision-making and emotional functioning.
Mapping Leborgne's brain lesions onto the connectivity roadmap, the researchers estimate that he suffered extensive damage to many tracts, including almost all the dorsolateral tracts of the left hemisphere which would have had profound implications for his language function (on top of the effects caused by localised damage to what is now known as Broca's area in the left frontal lobe). The researchers think Leborgne also likely suffered damage to pathways not involved in language, such as the left cortico-spinal tract (which could explain the documented paralysis of his right arm and leg).
Finally, turning to Molaison, the researchers again estimate wide-spread damage to connective tissues beyond the main brain regions, including the hippocampus, that were directly removed by surgery (Molaison became amnesic after radical neurosurgery to treat his epilepsy). This includes the fornix, the ventral cingulum, uncinate fasciculus and anterior commissure. Damage to that last tract, which is involved in processing smell, might explain lab reports that Molaison had problems with his odour discrimination.
What to make of these new insights? The researchers said they have "demonstrated the validity of applying an atlas based approach to reappraise the effects of disconnection in 3 historic patients". Their research is certainly a fitting tribute to the legacy of Geshwind, showing how "social behaviour, language, and memory depend on the coordinated activity of different regions rather than single areas in the frontal or temporal lobes." However, the researchers also admitted that much caution is needed: their research involved many ambitious leaps and generalisations. What is for sure is that these new insights will further fuel the mythical status of these three patients. Gage, Leborgne and Molaison are the psychological case studies that just keep giving.
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Thiebaut de Schotten M, Dell'Acqua F, Ratiu P, Leslie A, Howells H, Cabanis E, Iba-Zizen MT, Plaisant O, Simmons A, Dronkers NF, Corkin S, & Catani M (2015). From Phineas Gage and Monsieur Leborgne to H.M.: Revisiting Disconnection Syndromes. Cerebral cortex (New York, N.Y. : 1991) PMID: 26271113
--further reading--
Neuroscience still haunted by Phineas Gage
What the textbooks don't tell you about psychology's most famous case study
Glimpsed at last - the life of neuropsychology's most important patient
Looking Back: Understanding amnesia – Is it time to forget HM?
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
Our free fortnightly email will keep you up-to-date with all the psychology research we digest: Sign up!
- What The Textbooks Don't Tell You About Psychology's Most Famous Case Study
Image: Photograph by Jack Wilgus of a daguerreotype of Phineas Gage in the collection of Jack and Beverly Wilgus.It's a remarkable, mythical tale with lashings of gore – no wonder it's a favourite of psychology students the world over. I'm...
- Glimpsed At Last - The Life Of Neuropsychology's Most Important Patient
Leborgne's brainMonsieur 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...
- Doubts Cast On The Influential Dual-stream Theory Of Visual Processing
Psychologists in Germany have challenged one of the most influential theories in neuropsychology - the dual stream model of visual processing proposed by Mel Goodale and David Milner. This model proposes that visual information entering the...
- Hoarding Behavior In Brain Damage
From a University of Iowa press release:Brain Region Identified That Controls Collecting Behavior [snip] By studying patients who developed abnormal hoarding behavior following brain injury, neurology researchers in the University of Iowa Roy J....
- A New Slant On Frontal Connectivity: The Frontal Aslant Tract
The frontal aslant tract is shown in yellow (Fig 5, Catani et al., 2012). It's not every day that you hear about a newly described white matter pathway in the human brain. An interesting new study by a group of researchers in London and Chicago found...
Neuroscience
Using brain imaging to reevaluate psychology's three most famous cases
To mark this anniversary, an international team of researchers has used modern brain imaging techniques to reveal, in an open-access article for Cerebral Cortex, the likely damage to brain connectivity suffered by three of psychology's most famous cases: the 19th century rail worker Phineas Gage, who survived an iron rod passing through his brain; Louis Victor Leborgne, the 19th century aphasic patient studied by Paul Broca who played a key role in our understanding of language function in the brain; and the most studied amnesiac in history, Henry Molaison (known as H.M. in the literature), who died in 2008.
Michel Thiebaut de Schotten and his colleagues first obtained existing information about the brains of these three cases. For Gage they used a CT scan taken of his skull by researchers in 2004 and mapped the signs of injury onto a simulation of his brain. Leborgne's brain is in preservation at the Dupuytren Museum in Paris and they used an MRI scan of it taken in 2007. For Molaison's brain they used an MRI scan taken while he was still alive in 1993.
Next, the researchers created an intricately detailed map of the human brain's connective pathways. They used an advanced version of a technique known as diffusion tensor imaging to plot the connective tissues in the brains of 129 healthy volunteers (aged 18-79; 59 men). They combined the data from all these healthy people's brains to create an average road-map of the human brain's connective tracts.
The final step involved applying the information on the brain damage incurred by the three famous cases onto this road map of the human brain's connective pathways, to see which important tracts had probably been affected.
In the case of Gage, the researchers estimate that he suffered widespread damage to several connective pathways in his frontal lobes, beyond the specific damage thought to have been inflicted by the passage of the iron bar. These pathways include the uncinate fasciculus, the frontal intralobar networks, and the fronto-striatal-thalamal-frontal network, with likely implications for his decision-making and emotional functioning.
Mapping Leborgne's brain lesions onto the connectivity roadmap, the researchers estimate that he suffered extensive damage to many tracts, including almost all the dorsolateral tracts of the left hemisphere which would have had profound implications for his language function (on top of the effects caused by localised damage to what is now known as Broca's area in the left frontal lobe). The researchers think Leborgne also likely suffered damage to pathways not involved in language, such as the left cortico-spinal tract (which could explain the documented paralysis of his right arm and leg).
Finally, turning to Molaison, the researchers again estimate wide-spread damage to connective tissues beyond the main brain regions, including the hippocampus, that were directly removed by surgery (Molaison became amnesic after radical neurosurgery to treat his epilepsy). This includes the fornix, the ventral cingulum, uncinate fasciculus and anterior commissure. Damage to that last tract, which is involved in processing smell, might explain lab reports that Molaison had problems with his odour discrimination.
What to make of these new insights? The researchers said they have "demonstrated the validity of applying an atlas based approach to reappraise the effects of disconnection in 3 historic patients". Their research is certainly a fitting tribute to the legacy of Geshwind, showing how "social behaviour, language, and memory depend on the coordinated activity of different regions rather than single areas in the frontal or temporal lobes." However, the researchers also admitted that much caution is needed: their research involved many ambitious leaps and generalisations. What is for sure is that these new insights will further fuel the mythical status of these three patients. Gage, Leborgne and Molaison are the psychological case studies that just keep giving.
_________________________________
Thiebaut de Schotten M, Dell'Acqua F, Ratiu P, Leslie A, Howells H, Cabanis E, Iba-Zizen MT, Plaisant O, Simmons A, Dronkers NF, Corkin S, & Catani M (2015). From Phineas Gage and Monsieur Leborgne to H.M.: Revisiting Disconnection Syndromes. Cerebral cortex (New York, N.Y. : 1991) PMID: 26271113
--further reading--
Neuroscience still haunted by Phineas Gage
What the textbooks don't tell you about psychology's most famous case study
Glimpsed at last - the life of neuropsychology's most important patient
Looking Back: Understanding amnesia – Is it time to forget HM?
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
Our free fortnightly email will keep you up-to-date with all the psychology research we digest: Sign up!
- What The Textbooks Don't Tell You About Psychology's Most Famous Case Study
Image: Photograph by Jack Wilgus of a daguerreotype of Phineas Gage in the collection of Jack and Beverly Wilgus.It's a remarkable, mythical tale with lashings of gore – no wonder it's a favourite of psychology students the world over. I'm...
- Glimpsed At Last - The Life Of Neuropsychology's Most Important Patient
Leborgne's brainMonsieur 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...
- Doubts Cast On The Influential Dual-stream Theory Of Visual Processing
Psychologists in Germany have challenged one of the most influential theories in neuropsychology - the dual stream model of visual processing proposed by Mel Goodale and David Milner. This model proposes that visual information entering the...
- Hoarding Behavior In Brain Damage
From a University of Iowa press release:Brain Region Identified That Controls Collecting Behavior [snip] By studying patients who developed abnormal hoarding behavior following brain injury, neurology researchers in the University of Iowa Roy J....
- A New Slant On Frontal Connectivity: The Frontal Aslant Tract
The frontal aslant tract is shown in yellow (Fig 5, Catani et al., 2012). It's not every day that you hear about a newly described white matter pathway in the human brain. An interesting new study by a group of researchers in London and Chicago found...