Two interesting reports published have shed new light on the neurophysiology of the brain and, in one case, contributed to a better understanding of how the brain functions in addiction.
The first report, 1 which appeared in the journal Science, involved a 28 year old man who had been a long-term (14 year) cigarette user until suffering a stroke that damaged a small part of his brain known as the insula. This structure, which is roughly located just behind each ear and toward the center of the brain, has long been known to play a role in regulating the body’s conscious decisions regarding internal signals such as hunger.
Surprisingly, after his stroke the patient stopped smoking without withdrawal symptoms. “I simply ‘forgot’ to smoke” he stated to his physicians. As of the date of the report, the urge to smoke has not returned.
Following discovery of the patient’s surprising outcome, investigators conducted a medical records review and identified a further 32 brain injury patients that had smoked prior to their injury. Of these, 16 patients reported that they had ceased smoking without experiencing significant withdrawal symptoms. MRI scans revealed damage to the insula in each of these 16 patients.
The second report 2 is no less fascination than the first and is made even more remarkable in that it is a first-person account related by Ian McDonald, a British neurologist and amateur classical pianist, who suffered a “mild” stroke in 2004.
Initially, Dr. McDonald was unaware that he has suffered a stroke. It was only after he began to experience difficulty performing tasks that had been routine that he sought attention from a fellow neurologist. An MRI scan of the brain revealed that he had suffered a discreet (not widespread) stroke involving the right supramarginal and angular gyri which are, in turn, part of the brain’s parietal lobe.
Quite interestingly, the “routine” tasks that Dr. McDonald had experienced difficulty with were reading sheet music, playing even simple melodies, and being able to appreciate the subtleties of tone or timing of music being performed by others.
Fortunately, Dr. McDonald has made an almost complete recovery although he no longer plays piano in concert with other musicians..
These reports emphasize both the wide variety of consequences that may be present in brain injury as well as reminding us of the difficulties involved in research of human neurophysiology. Since no physician or researcher can intentionally damage part of the human brain in order to study the consequences, it has been necessary to observe the changes in function that result from “natural” or “accidental” brain injury. The above cases are illustrative of this strategy.
Another form of brain disease that has contributed volumes to neuro-medicine and neurophysiology is substance abuse and addiction, particularly in understanding the roles of various neurotransmitters in both health and disease.
Further developments along these lines of clinical research are eagerly awaited.
Additional Information
The National Institutes of Health and the National Institute of Drug Addiction publication The Brain: Using Neurobiology Through the Study of Addiction is written at the high school level and is probably the best online summary regarding the field of neurobiology that you will find.
The Dana Foundation publishes the online journal Cerebrum, a well-written and easily understandable summary of recent research and publications of interest.
Notes
1. Naqvi, Nasir; Rudrauf, David; Damasio, Hanna, and Bechara, Antoine (2007)
Damage to the Insula Disrupts Addiction to Cigarette Smoking. Science 26 January 2007:
Vol. 315 (5811) pp. 531 – 534
2. McDonald, I. (2006) Musical Alexia with Recovery: A Personal Account. Brain 129: 2554–2561.
