© 2018 by Janelle E. Letzen, PhD

 
Famous Brains
Phineas Gage & the Frontal Lobe

Historians and psychologists alike often credit the initial understanding of this link to the unfortunate case of Phineas Gage, a quiet, hard-working railroad construction foreman.  In 1845, a then 25-year-old Gage suffered a devastating injury while on the job that would forever mark his place in history. In a fluke accident, a tamping iron (a small crowbar-like instrument) was blown completely through his head, entering his left cheek and exiting through his skull, thus destroying much of his left frontal lobe. Surprisingly, and to the shock of his coworkers, Gage remained conscious in the moments following the accident! In the months and years following the accident, Gage would go on to make a nearly full physical recovery.  While he lost vision in his eye and had obvious scars associated with the injury, Gage seemed to be in relatively good health.

However, and as quoted so famously by Dr. John Harlow (Gage’s doctor following the accident), he was “no longer Gage” (Harlow, 1868, p. 340). Further, and as the folklore goes, Gage’s friends described the once “happy go lucky” Gage now, post-accident, as a short-tempered, aggressive drunk who was no longer pleasant to be around. It was this apparent change in Gage’s personality that led doctors to suspect that the frontal lobe may play a significant role in personality and behavior. 

The marked and abrupt changes observed in Gage are often credited with leading to the development of localization theories of brain functioning, or that certain behaviors and functions are associated with specific areas of the brain. Importantly, Gage’s frontal lobe injury, was believed to be a significant factor in understanding the role of the frontal cortex in higher order cognitive functions, such as reasoning, inhibition, and personality. With little context or evidence to substantiate this understanding at the time, Gage’s story was seen

Sushi Science | Janelle Letzen | Phineas Gage
  • Link to post on Instagram

as an important early source of evidence to support the role of the frontal lobe in such aspects of functioning. Indeed, it is now evident that the orbitofrontal and ventromedial cortices are connected with limbic areas of the brain, and are important for emotional/social processing. Deficits in these areas (e.g., damage by a tamping iron through your skull) could lead to changes in social and behavioral regulation and decision making, as Gage reportedly experienced. 

Possibly. In a recent research study, it was estimated that the tamping iron that damaged Gage’s brain destroyed 11% of the white matter in his frontal lobe and 4% of his cerebral cortex (Van Horn et al., 2012). However, a further examination of the anecdotal evidence available at the time, suggests that Gage may not have endured as such a dramatic shift in his personality/functioning post-accident as an Intro to Psychology textbook may suggest (MacMillan & Lena, 2010). While there’s limited documentation of Gage post-accident, outside of Dr. Harlow’s accounts, the evidence that does exist (e.g., documentation of his move to and work history in Chile) would suggest that he was able to function relatively well with “no impairment,” as he did prior to the infamous tamping iron incident.  Seven years after his death, Gage's body was exhumed, with his skull and the tamping iron removed, now with a permanent resting place at the Harvard University School of Medicine in Cambridge, MA. 

A big thank you to Dr. Cameron Miller for writing this post! Dr. Miller is an Assistant Professor of Psychology at Mercer University, Psychology Urban Myths & History Enthusiast, and happily self-proclaimed Tamping Iron Novice. ​

H.M. & the Medial Temporal Lobe

Henry Molaison, or H.M., is one of the most famous patients in the psychology/neurology world. H.M. was a man who lived from 1926-2008. As a kid, he developed minor seizures that worsened over time. By his 20s, they strongly interfered with his regular activities despite an intensive medication regimen. 

H.M. underwent experimental surgery to control these seizures. In the 1950’s, we were still learning lots about brain function (to be honest, we still are…), so it was unclear whether this surgery would even work.

H.M.’s surgery involved removal of brain structures in the medial temporal lobe (MTL), including the hippocampus. While the surgery helped reduce his seizures, H.M. struggled to remember new information (called anterograde amnesia) as well as memories from before his surgery (called retrograde amnesia). His other thinking abilities seemed unaffected, including functions like how well he could make appropriate judgements, pay attention, and his general intelligence.

Over time, H.M. improved in 

hm.jpg
  • Link to post on Instagram

his ability to remember new information in two specific forms of learning. First, he regained some ability to remember general facts and concepts (like information about celebrities; “semantic memory”), but not life events or facts about himself (“episodic memory”). Second, H.M. retained the ability to learn a new skill and perform it another day (“procedural memory”), but he could not remember his own experience of learning the skill (because of his impaired episodic memory).

These studies helped researchers understand that there are different types of memory functions associated with somewhat unique brain systems. While the MTL/hippocampus are associated with individuals’ memories about themselves, other structures are important for learning motor skills and procedures.

Tan & Broca's Area

Take a moment to be meta and think about the last thing you thought about. What if you tried to say that thought aloud, but the only sound to leave your mouth was “tan”? This phenomenon happened to a 51-year-old man named Louis Leborgne whose neurological condition was instrumental in our initial understanding of language systems.

Over 150 years ago, Leborgne was a patient of Dr. Paul Broca. It was clear that Leborgne had neurological damage, but physicians didn’t know the exact nature. Leborgne was nicknamed “Tan” because he could only say “tan” when trying to speak. Interestingly, he could change the pitch and volume of his voice, suggesting the damage was not associated with these language functions. He also retained understanding of what others said to him, further ruling out an association between the damage and comprehension. 

tan.jpg
  • Link to post on Instagram

After Tan died in 1861, Dr. Broca did a brain autopsy. He noticed tissue deformities in the frontal lobe of Tan’s left hemisphere, specifically in a region anatomically referred to as the inferior frontal gyrus (IFG). Dr. Broca decided that this area was the “center of articulated speech” and called Tan’s condition “aphémie” – aka “aphasia.

Years later, we now know that the language system and production are more complex than one region. In fact, studies have found that most patients with Broca’s aphasia have damage to a wider set of brain regions. Some have suggested that Broca stopped the autopsy after seeing IFG damage, which is why this is the main region noted in his reports. However, this IFG segment – commonly called “Broca’s area” – is still generally thought to play a key role in language production.

There is more than one type of aphasia, with symptoms depending on brain damage location. Experts consider that Tan had expressive, or Broca’s, aphasia. In this aphasia, a person can understand what others say but has difficulty communicating their own thoughts. However, this does not mean that the person will only say “tan” like Leborgne did - the sounds, words, and extent of language production in a person with Broca’s aphasia widely varies.

References

[1] Harlow, J.M. (1868). Recovery from the passage of an iron bar through the head. Publications of the Massachusetts Medical Society, 2, 327-347.

[2] Macmillan, M. & Lena, M.L. (2010). Rehabilitating Phineas Gage. Neuropsychological Rehabilitation, 20, 641-658.
[3] Van Horn, J. D., et al. (2012). Mapping Connectivity Damage in the Case of Phineas Gage. PLoS ONE, 7(5), e37454. DOI: 10.1371/journal.pone.0037454

[4] Corkin, Suzanne (1984). "Lasting consequences of bilateral medial temporal lobectomy: Clinical course and experimental findings in H.M.". Seminars in Neurology. New York, NY: Thieme-Stratton Inc. 4 (4): 249-259.
[5] Squire, L.R. (2009). The legacy of patient H.M. for neuroscience. Neuron. 61(1):6-9.
[6] Squire, L. R., & Wixted, J. T. (2011). The cognitive neuroscience of human memory since H.M. Annual review of neuroscience, 34, 259-88.
[7] Scoville, W. B., & Milner, B. (1957). Loss of recent memory after bilateral hippocampal lesions. Journal of neurology, neurosurgery, and psychiatry, 20(1), 11.
[8] O’Kane G., Kensinger E. A. & Corkin S. Evidence for semantic learning in profound amnesia: an investigation with patient H.M. Hippocampus 14, 417–425 (2004).
[9] Annese, J., Schenker-Ahmed, N. M., Bartsch, H., Maechler, P., Sheh, C., Thomas, N., Kayano, J., Ghatan, A., Bresler, N., Frosch, M. P., Klaming, R., … Corkin, S. (2014). Postmortem examination of patient H.M.'s brain based on histological sectioning and digital 3D reconstruction. Nature communications, 5, 3122.
[10] Cohen N. J. & Squire L. R. Preserved learning and retention of pattern analyzing skill in amnesia: dissociation of knowing how and knowing that. Science 210, 207–209 (1980).

[11] Mohammed, N., Narayan, V., Patra, D. P., & Nanda, A. (2018). Louis Victor Leborgne (“Tan”). World neurosurgery, 114, 121-125.
[12] Dronkers, N. F., Plaisant, O., Iba-Zizen, M. T., & Cabanis, E. A. (2007). Paul Broca's historic cases: high resolution MR imaging of the brains of Leborgne and Lelong. Brain, 130(5), 1432-1441.
[13] Domanski, C. W. (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.
[14] Horwitz, B., Amunts, K., Bhattacharyya, R., Patkin, D., Jeffries, K., Zilles, K., & Braun, A. R. (2003). Activation of Broca’s area during the production of spoken and signed language: A combined cytoarchitectonic mapping and PET analysis. Neuropsychologia, 41(14), 1868-1876.