The Brain

brain01

At the annual meetings of the American Academy of Neurology one of the most popular educational events is the ‘Neuro Bowl’, a team competition in which neurologists have the opportunity to pit their wits against a demonic quizmaster. ‘Neurology at the Cinema’ features prominently in the questions asked and has been a popular theme for film producers long before the current rash of memory films like Total Recall and The Unknown.

 

Neurology is a discipline where acute powers of observation are essential. Many neurological disorders can be recognized by the trained eye in the street and the father of our speciality, Jean Martin Charcot, became famous in nineteenth century literary Paris for his public Tuesday afternoon demonstrations at L’Hopital Salpetriere. Cinematographic filming was used from the beginning of the twentieth century as an educational tool in neurology and video films of neurological disorders are part and parcel of modern neurological teaching.

 

The story of Patient 39 has much to interest and perhaps teach a neurologist. A great deal of what we now know about the localistaion of brain function stems from the horrific injuries sustained by soldiers in the two World Wars.  For example in 1941, Doctor Russell Brain, a neurologist working at the Royal London Hospital in Whitechapel, described abnormalities in visual perceptual processing in three patients with severe damage to areas of the right side of their brain, in regions called the parietal and occipital lobes, similar to that sustained by Patient 39. Although these individuals could describe routes accurately and had preserved topographical memory they persistently turned right instead of left, a result of neglect of the left half of external space that led to severe disorientation. Limbs on their left side were ignored or considered to be alien to the rest of their body. Patients with such injuries were also known to have difficulties with dressing, reading, drawing, writing and recognizing commonplace objects.

 

As well as the injuries to the right side of the brain, Dr Moran, who treats Patient 39 in William Boyd’s ‘A Ghost of a Bird’, also notes that Patient 39 had sustained additional insult to the left side of the brain and to his lower brain stem and was suffering from severe amnesia.

                                               

Amnesia is a common occurrence after both open and closed head injury and is usually due to damage to areas of the brain known as the temporal and frontal lobes.  The memory disturbance takes two main forms; Retrograde amnesia, which leads to loss of memories that were formed shortly before the traumatic event, and a period of irreversible anterograde amnesia, which leads to problems creating new memories after the insult. The combination of these two is referred to as post-traumatic amnesia and its duration is used as an index of the severity of head trauma.  

 

Some recent work in animals has also raised the possibility that brain damage may not only erase memory but can create convincing false memories due to faulty processing in a small region of the temporal lobe known as the perirhinal region. Damage to this region appears to lead to the convincing experience of false memories. This has implications for our understanding of how the human brain controls memory, and how most of us are able to easily tell apart true memories from things we have imagined, dreamed or invented. Although it would be highly unusual, it is conceivable that a severely agnostic and amnesic patient could confuse figments of his imagination for real events.

 

AJL69_V2

Neurologist Professor Andrew Lees writes about amnesia and brain damage