TED Talk: RAMACHANDRAN on your mind
TED Talk VS Ramachandran on your mind
It is a 3 pound mass of jelly. It can contemplate the universe, the meaning of infinity, and contemplate itself contemplating the meaning of infinity.
The holy grail of neuroscience is understanding consciousness.
How to study the brain? Look at patients with sustained damage in the brain.
This gives you a highly selective non-function in one region while other functions are intact. This way you can find out what the circuitry is doing.
Example1: Capgras syndrome
Fussiform gyrus (tucked away in the temporal lobe) is the face area of the brain.
If this area is damaged, the individual cannot process facial information. They cannot recognize friends or themselves in front of a mirror, however, they can recognize people through their voices.
Very rare syndrome.
Patient looks at his mother and recognizes her as an imposter pretending to be his mother. Most common interpretation is the Oedipus complex of Freud – as a baby you have a strong sexual attraction to your mother, and as you grow the cortex develops and inhibits these latent sexual urges towards you mother and then a blow to the head damages the cortex allowing these latent sexual urges to resurface (argument never made sense to ramachandran since patients usually exhibit the same delusional behavior towards their dogs).
So what is really going on?
Look at the structure/function of the normal visual pathways of the brain. Visual information comes in from the eyeballs to the visual areas at the back of the brain (around 30 areas). After processing the messege is passed to the Fusiform Gyrus where faces are perceived. When this area] is damaged you lost the ability to recognize faces. From this area the message cascades to the amygdala (the limbic system, the emotional core of the brain) which gauges the emotional significance of what you are looking at (prey, predator, mate, object). If the amygdala is excited the message cascades into the autonomic nervous system (increase HR, sweating).
So in the case of the capgrass delusion, the wire from the visual centers to the emotional centers is probably cut. Vision is normal. Emotion is normal. But the wire between them is cut which accounts for his delusions of mother as imposter. When the patient speaks to his mother, he recognizes her immediately. Auditory processing probably goes through another pathway in the brain which is normal and not cut.
How is all this circuitry set up in the brain? Nature (Genes) or Nurture
Phantom Limb (Feeling presence of missing limb or internal viscera- arm, leg, uterus).
Patients claim they can move the phantom and have a compelling sensory experience. In half of the patients they feel that their limb is paralyzed. In these patients, the arm was paralyzed since the peripheral nerve was severed during injury; the arm was placed in a sling for a period of time before surgeons decided to amputate the arm. This is what gives a phantom arm with the same pains (very painful, drives patients to depression and suicide).
Why does this happen?
When the arm was intact – though paralyzed- the brain sends a MOVE command to the arm. However, the brain is getting visual feedback that says NO.
This gets wired into the circuitry of the brain => Learned Paralysis.
The mere command of a paralyzed arm creates a sensation of paralyzed arm. When the arm is amputated, this learned paralysis is carried over into your body image, into your phantom limb.
How do your unlearn Learned Paralysis to relieve the patient from the excruciating clenching spasm of the phantom arm?
Maybe you can relieve pain by sending the brain visual feedback that is obeying his command.
Virtual reality – Millions of dollars – infeasible
Mirror Box – 3 dollars’ worth. IDEA: Patient puts his phantom left arm on the left side of the mirror, and the normal hand on the right side of the mirror. Patient then makes the same gestures in both hands, and looks though the mirror. Looking at the reflection of the right arm through the mirror, the patient feels the phantom left arm being resurrected. With any movement, the patient feels that phantom arm a gain and his pain is relieved.
“This proves my theory about learned paralysis and the critical role of visual input. But I will not get a
Nobel prize for making somebody move his phantom limb”.
How does this happen?
The brain is faced with tremendous sensory conflict. Its getting messages from vision saying that the phantom is back, while there is no proprioception, muscle signals say there is no arm, while motor command from the brain says there is an arm. As a result of this conflict, the brain goes into denial, it gauges the signal. The arm disappears and therefore the pain disappears, since you cannot have disembodied pain floating out there in space.
Other form of paralysis like Stroke or focal dystonia could be overcome using the mirror box.
Stroke is damage of fibers, but has some component of Learned Paralysis, Mirror Box Could be used here.
Example 3: Synesthesia: Seeing colored numbers. Tones might also evoke color.
Discovered by Francis Galton (Darwin’s Cousin).
Synethesia: Mingling of the senses. Genetic. Eight times more common among artists, poets, novelists and other creative people.
What causes it?
Cross wiring between color map (or tone map) and number map in the brain (both areas are close to each other in the fusiform gyrus).
This is accidental and probably due to an abnormal gene. When we are born, in the brain everything is wired to everything else. Over time these links are trimmed down to create the characteristic modular architecture of the adult brain. Mutated genes causes deficient trimming.
What if this genes is expressed in every area of the brain? What if everything is crosswired?
Artists Poets, etc. (creative people) have the ability to engage in metaphorical thinking, linking seemingly unrelated ideas.
Example: It is the east —- Juliet is the sun.
Normal People think Juliet is radiant like the sun, radiant like the sun.
Schizcos: Juliet is a glowing ball of fire.
In Synesthetes, If you assume that this greater cross wiring and concepts are in different parts of the brain then, it’s going to create a greater propensity towards metaphoric thinking and creativity.
You are all Synesthetes, but you are in denial about it.
You are all doing a cross-model synesthetic abstraction. The sharp inflection in the right image (Which you read as K K as processed by you auditory cortex) mimics the visual inflection of the jagged shape.
Your brain in this case is engaging in a primitive form of abstraction.
Photons in the eye are creating the shape, and hair cells in the ear are exciting the auditory pattern, and the brain is able to extract the common denominator.
THIS HAPPENS IN THE FUSIFORM GYRUS. When the FG is damaged, people cannot process the difference between KIKI and BUBA, and they also lose the ability to engage in metaphorical thinking.
Fusiform Gurus is about eight times the size in humans compared to lower primates.
Ie. Something very interesting is happening in the angular gyrus since it is the crossroads between hearing, vision and touch.
“ I think it’s a basis of many uniquely human abilities, like abstraction, metaphor, creativity; Questions philosophers have been studying for millennia, we scientist can now explore with brain imaging and by studying patients and asking the right questions.