For Kendra: On Memory

• Patterns of activity in the brain are remarkably similar when thinking about the past and the future. This is because we piece together fragments of memory from our past to get an idea of the future. (not a direct quote, but based on research by Donna Addis, Harvard)

• People with damaged hippocampi cannot think of the future or of the past. John Forbes’ hippocampi are half the size of a normal person’s. He cannot recall memories to form an idea of the future, or mental time travel. He is stuck in the present. (For more information on John, maybe look up Faraneh Vargha-Khadem, the neuroscientist studying John since he was born)

• Mental time travel is presumably a uniquely human trait. Most increments of time are fully understood by age 9.
  Memory only reaches its full power at the age of 25, when we can remember over 200 things/second.

• Every time you remember something, you change it slightly because the memory becomes fluid. Yadin Dudai proposed that “The safest memory, one that is uncontaminatable, can only exist within the mind of a patient with Amnesia. If you have a memory, the more you use it, the more you are likely to change it…The safest memories are in the brains of people who cannot remember.”

• Clive Wearing- One of the worst documented cases of Amnesia. He can remember his wife and how to conduct an orchestra, though he is not concious of it. http://en.wikipedia.org/wiki/Clive_Wearing

• Here are some fragmented notes I took on Karim Nader’s discovery of how anisomycin effects memory:

a rat hears a tone, after the tone it gets shocked. This happens over and over again. When they see a rat freeze after the tone, they know it is bracing itself for the shock. They know that the rat is remembering.
Injecting anisomycin, while the tone is playing, will prevent the memory of the tone and electrical shock from forming.
2000 Ladue‘s lab Karim Nader suggests injecting anisomycin into the rat while the rat is remembering the tone/electrical shock memory. A memory is static when it is not being used. A memory becomes fluid and malleable when it is being used. Nader played the tone and shocked a new rat repeatedly so that it would form a memory. He waited 60 days, played the tone, the rat froze up, expecting the tone, then Nader injected the anisomycin. The next day, the rat had no reaction to hearing the tone. It was suggested that maybe the rat’s memory wasn’t erased, but that it just had brain damage. To test this, Nader uses two different tones that both result in a shock. When he plays the tones, 45 days later, he only picks one tone where he will inject the chemical. Only the tone paired with the chemical was erased.

Lately:

• Stephen Jay Gould’s evolutionary theory that humans are born nine months prematurely. Proof? Our brains grow and develop so fast during infancy. If our brains fully developed during pregnancy, we would not fit through the birth canal. We’ve evolved to be born prematurely. Compare to bonobos.
• Peripersonal space is literally mapped in your parietal lobe.
• Mark Howe employed the mirror test developed by Gordon Gallup to see if toddlers were self-aware. Two of the eight children put their hands to their foreheads when they saw the paint. The same group of toddlers were then brought into a new room and were shown a drawer where a stuffed, toy lion was kept. Two weeks later, the same two children who saw themselves in the mirror, remembered where the lion was. A sense of self must exist before children can form memories relating to themselves. Our autobiographical memory, and therefore ourselves, can only begin once we can recognize ourselves.
• Selective memory erasing is possible ala Eternal Sunshine of the Spotless Mind. Injecting a patient with anisomycin while they are remembering or reliving a memory will erase a memory. Memories are made of proteins and anisomycin inhibits protein synthesis.

Natural Selection at Work to Prolong Human Cannibalism

Kuru is a terminal brain disease found in humans. It was first discovered in the 1950’s amongst the Fore tribe of Papua, New Guinea and named after the Fore word for “shaking”. The symptoms and origin are similar to Mad Cow Disease, or Bovine Spongiform Encephalopahthy. BSE effects cattle and is acquired by ingesting the remains of other cattle in the form of meat and bone meal. Members of the Fore tribe would eat the dead after cooking them in bamboo tubes with “spinach-like” greens as part of a funeral practice. They ate all of the body except for the gallbladder, which tasted bitter. 

“Why should the ground eat the dead? Better that we consume the dead and take that person into ourselves.” 

Kuru is the only example of a human prion disease epidemic. A prion is a particular form of malformed protein. The rogue prion protein persuades a normal protein to fold into an unusual shape. A prion disease is spread when an animal is fed contaminated meat from their own species. It is now thought that prion diseases may be able to spread to other species (ie. the mad cow disease epidemic).

Many members of the Fore tribe were resistant to the disease because of their genetic makeup. In humans, there are three variants of a marker  in the protein gene called Position 129 . They are: MM, MV, and VV. The Fore that survived the Kuru disease had the marker MV:  genetic protection against prion diseases. MV’s are much more resistant than people with identical genetic markers. 

Biological evidence of widespread human cannibalism:

More than half of the world’s population have the MV marker.  (Holy cow!)

Natural selection has been slowly filtering out the population of VV’s and MM’ because of ancient cannibalism-caused prion disease epidemics.