Phantoms in the Brain

Phantoms in the Brain: Probing the Mysteries of the Human Mind by V.S. Ramachandran and Sandra Blakeslee, HarperCollins, 1999. 

Phantom Limb Syndrome

V.S. Ramachandran has done important work on phantom limbs. People who have had limbs amputated often retain the amputated limb in their body image. They also often experience pain in their phantom limbs. Ramachandran’s explanation is that the part of the brain devoted to the limb that was amputated now receives input from other parts of the body. So when these other parts are touched, the person experiences the touch in the part of the body image devoted to the missing limb. 

Tinnitus

Neurologist A. T. Caccace has compared phantom limb pain to gaze tinnitus (ringing in the ears). Some people experience their tinnitus only when looking to the left or right. The explanation is that the auditory nerve passes nearby to the oculomotor nerve.

Scotomas

Ramachandran discusses the scotomas or blank areas that occur with migraines. They are not black, but are filled in by interpolating from the part of the image surrounding the scotoma. Some people with neurological damage have permanent scotomas. Sometimes they see not the usual fill-in, but hallucinations, in their scotomas. This is called Charles Bonnet syndrome. It is common in old people suffering from macular degeneration, diabetic retinopathy and cataracts.

Pain Asymbolia

Pain asymbolia is a rare situation where the patient is aware of the physical sensation of pain, but the pain does not bother her emotionally. This is another example of disorders that result not from damage to a brain module, but rather from damage to the connection between two modules. Another interesting syndrome Ramachandran discusses is Capgras’ delusion, where the patient regards a family member as an impostor, due to a lack of emotion when the person is recognized. The author explains this as a failure in the neurons connecting recognition to emotion.

Musical Genius

Alfred Russel Wallace believed that natural selection was insufficient to explain the existence of musical genius. Wallace thought that the potential for musical genius developed in advance of its expression or survival value, and that it must have a divine cause.