The Answer to Life, the Universe, and Everything: Dopamine

Read Montague, the director of the Human Neuroimaging Lab at Baylor College of Medicine in Houston, TX, is trying to crack the code of how the brain makes decisions — the neurochemical foundation of free will.

The neurotransmitter dopamine‘s effect on creating the sensation of reward in the brain was discovered in the 50′s. Montague’s research is showing that the activity of dopamine neurons influences decision making in a more complex manner than previously thought. Dopamine isn’t just produced when something favorable happens. It’s also produced as soon as there’s an expectation that something favorable will happen.

What’s interesting about this system is that it’s all about expectation. Dopamine neurons constantly generate patterns based upon experience: If this, then that. The cacophony of reality is distilled into models of correlation. And if these predictions ever prove incorrect, then the neurons immediately readjust their expectations. The discrepancy is internalized; the anomaly is remembered. “The accuracy comes from the mismatch,” Montague says. “You learn how the world works by focusing on the prediction errors, on the events that you didn’t expect.” Our knowledge, in other words, emerges from our cellular mistakes. The brain learns how to be right by focusing on what it got wrong.

So the brain learns by avoiding prior mistakes and trying to supply itself with “fixes” of dopamine — kind of a brute force trial-and-error. Is that the meaning of life? Too much dopamine causes an organism to ignore its basic survival instincts even to its own death:

They inserted the needle right next to the nucleus accumbens (NAcc), a part of the brain dense with dopamine neurons and involved with the processing of pleasurable rewards, like food and sex.

Olds and Milner quickly discovered that too much pleasure can be fatal. After they ran a small current into the wire, so that the NAcc was continually excited, the scientists noticed that the rodents lost interest in everything else. They stopped eating and drinking. All courtship behavior ceased. The rats would just cower in the corner of their cage, transfixed by their bliss. Within days all of the animals had perished. They had died of thirst.

Maybe the ultimate goal is to do whatever it takes to keep as much dopamine flowing as possible while still keeping yourself fed, sheltered, and breeding for as long as possible. It’s elegantly simple. Working out the details of pursuing that goal is the interesting part.

[Seed Magazine]

Brains Can Hack Themselves

A woman who had absolutely no balance and could not stand without falling due to a loss of vestibular function fully regained it with the use of accelerometers that sent signals through the brain via electrodes attached to her tongue.

A man who had been blind since birth was able to distinguish people and objects and even perceive three-dimensional space by feeling a matrix of vibrating stimulators against his back.

Both of these feats were accomplished by Paul Bach-y-Rita, a researcher at the University of Wisconsin-Madison. They are demonstrations of neuroplasticity — the brain’s ability to reprogram itself — in this case substituting one sense for another.

Bach-y-Rita determined that skin and its touch receptors could substitute for a retina, because both the skin and the retina are two-dimensional sheets, covered with sensory receptors that allow a ‘picture’ to form on them.

It is one thing to find a new data port, or way of getting sensations to the brain, but another for the brain to decode these skin sensations and turn them into pictures. To do that, the brain has to learn something new. This adaptability implies that the brain is plastic, in the sense that it can reorganise its sensory perceptual system.

The entire article is really worth a read.

[The Telegraph via RichardDawkins.net]