Phantoms in the Brain

When I was reading one of my favourite books to date, “Phantoms in the Brain” by V.S. Ramachandran, I kept note of some facts that I found useful or particularly interesting. 

Fun Facts:

• In multiple personality disorders, eye structures and blood chemistry can change with different personas
• You can identify certain diseases by a person’s smell, for instance: diabetic ketosis – sweetish nail polish breath, typhoid fever – freshly baked bread odor, scrofula – stale-beer stench, rubella – newly plucked chicken feathers, lung abscess – foul smell, liver failure – ammonia-like windex odor, pseudomonas infection – grape juice, isovaleric acidemia – sweaty feet smell (yum yum)
• Poetry is processed in the right temporal lobe
• A distressed person who experiences a stroke in the corpus collosum might experience her left hand trying to strangle her – this is because the suicidal tendencies of the right hemisphere are no longer inhibited by the rational left hemisphere
• A stroke in the left brain might result in a patient who is anxious, depressed, and worried about prospect for recovery; a stroke in the right brain, however, might result in a patient who is blissfully indifferent
• There are two different smile circuits: (1) spontaneous smile – basal ganglia (no thought), (2) conscious smile (brain giving direction) – auditory to motor cortex. Therefore, a stroke in the right motor cortex means the instruction to smile results in right-side only, while a spontaneous smile is normal. A stroke in the basal ganglia results in a patient being incapable of a normal spontaneous smile, but an actual attempt at smiling works out alright
• A paralyzed person may still lift their arms when yawning, because a different brain pathway is used than a conscious attempt to lift the arms (unconscious lifting linked to respiratory centers in the brain stem)
• The Penfield homunculus is the name for the “little man in the brain,” whereby the body is mapped on the cerebral cortex. Brain circuitry can be remapped because the brain is flexible to change even in adulthood, which is why phantom limbs appear. These phantoms limbs can often experience sensation when the area mapped closest on the brain is stimulated on the body (see map below):

• There are two visual pathways: (1) old – goes to superior colliculus in brain stem, then to parietal lobes, used for orienting behaviour and nicknamed ‘the zombie in the brain’, (2) new – travels to lateral geniculate nucleus (a relay station for primary visual cortex), used for identifying objects. Damage to the new pathway is what we know as blindness in the conventional sense. Damage to the old pathway is known as “blindsight,” whereby patients can be somewhat oriented toward an object or target without consciously knowing how or what it is. 
• Charles Bonnet syndrome affects people whose vision has become compromised by glaucoma, cataracts, macular degeneration, or diabetic retinopathy. Many people develop hallucinations though they are either completely or partially blind (as if to replace reality) – it goes unreported for fear of being labeled senile or insane
• Everyone has a natural blind spot, called ‘scotoma’, but the region is automatically filled in by other visual areas of other brain

His distortions are due to the fact that the homunculus is proportioned according to the amount of cortex devoted to each body part (more devotion = more sensation)