Human brain and neuroscience

This is review of a set of lectures released by the Teaching Company and some teasers at the end of this article to entice you to learn more about how the brain works. I will highlight only three items from the lectures to give you an idea of what is discussed in them. If interested in the subject, you should watch the lectures.

On free will

It is possible to capture a sense of free will or the timing of when apparently free will takes place. The experiment works as following: you sit in a room and you have an apparatus attached to you to measure (1) muscle contraction when you tap your finger and (2) when you indicate that you have made the decision to tap the finger. Scientists found that brain regions responsible for triggering movements generate activity about half a second before any movement is made, called ‘readiness potential’, and a few tens of a second (tens of milliseconds) before the subject reports awareness of the decision.

The sequence looks as following: (1) there is preparatory activity in the form of readiness potential, (2) then self-awareness of the decision by the subject, and (3) finally the movement.

The fact that readiness potential precedes awareness or the subjective sense of making a decision seems to contradict our everyday idea of free will. It appears to be the case that there’s a neural commitment to decision before we become aware of making the decision.

According to one point of view, free will perhaps is ruled out by the idea that the output of our brains could somehow be predicted if we could know what was happening in every neuron, in every glial cell of our brain. But maybe a more useful interpretation is that when we think about something that’s 100 billion neurons, and we are trying to predict what a complex system with that many components is doing, we can’t do it. Nobody has done a complete computer simulation of even what a single neuron does biochemically and electrically, let alone the 100 billion neurons in an actual brain and 10,000 connections each neuron makes.

There is a more fundamental issue: when synapses communicate, when a presynaptic action potential arrives and gets to the presynaptic terminal, it often does not lead to neurotransmitter release. Even single synapses are unpredictable. There exists something quantum about single synapses, some quantum uncertainty about whether neurotransmitter is released or not. So it is not just that our knowledge of what a brain is going to do is limited by the state of all cells and synapses, in fact there are these unpredictable events that happen at a single synapse level.

If we could physically modify the brain to influence moral behavior, are we justified to do it?

In 2005 Dalai Lama made a speech to the Annual Society for Neuroscience meeting where such a question was presented to him: If neuroscience research could someday allow people to reach enlightenment by artificial means, such as drugs or surgery, would he be in favor of the treatment to alter people’s moral behavior? And what he said was that if such a treatment had been available, it would have saved him time spent in meditation, freeing him up to do more good works. He even pointed at his own head saying that if he could remove bad thoughts by just removing a brain region, he would do it.

Dalai Lama has taken the view that Buddhist doctrine is not unchanging, but in fact that when scientific discoveries come into conflict with Buddhist doctrine, the doctrine must give way. Dalai Lama has always been very interested in tinkering with engines, with motors, and he has a natural interest in science.

On meditation

When talking about meditation, Buddhists divide it into two major categories: one is focused with the goal of stilling the mind, a stabilizing meditation; and the other is an active cognitive process of understanding, for example meditating on an object or meditating on an idea.

Scientists measured electrical patterns of Buddhist monks during meditation in the Chechen monastery in Nepal by placing electrodes on the monks heads. When the monks were asked to generate a feeling of compassion, not directed at any particular being, but in general – a state known as ‘objectless meditation’ – it was observed that the activity in their brains started to vary in a coherent rhythmic manner suggesting that many neural structures were firing in synchrony with one another. Scans showed increased synchronized signal at 25 to 40 Hz rates, or at 24 to 40 oscillations per second, known as ‘gamma band oscillations’, the largest ever seen in people and comparable to people with pathological states such as seizures. Yet these monks were not epileptics.

Extra materials

Computers vs. brains

Scientific American published a fascinating diagram comparing brain computation and power consumption to that of the computers.

Computers-vs-Brains

3 pounds

Three pounds that lets us contemplate the universe! By comparison, an elephant’s brain weighs 11 pounds, while a cat’s brain an ounce. It seems that all functions of our bodies serve one purpose, and that to support the brain.

brain

Cerebral cortex

The human brain has three major structural components: the large dome-shaped cerebrum (top), the smaller somewhat spherical cerebellum (lower right), and the brainstem (center). Prominent in the brainstem are the medulla oblongata (the egg-shaped enlargement at center) and the thalamus (between the medulla and the cerebrum). The cerebrum is responsible for intelligence and reasoning. The cerebellum helps to maintain balance and posture. The medulla is involved in maintaining involuntary functions such as respiration, and the thalamus acts as a relay center for electrical impulses traveling to and from the cerebral cortex.

brain-cut

Motor and sensory functions

Many motor and sensory functions have been “mapped” to specific areas of the cerebral cortex, some of which are indicated here. In general, these areas exist in both hemispheres of the cerebrum, each serving the opposite side of the body. Less well defined are the areas of association, located mainly in the frontal cortex, operative in functions of thought and emotion and responsible for linking input from different senses. The areas of language are an exception: both Wernicke’s area, concerned with the comprehension of spoken language, and Broca’s area, governing the production of speech, have been pinpointed on the cortex.

motor-functions

Left and right brain functions

Although the cerebrum is symmetrical in structure, with two lobes emerging from the brain stem and matching motor and sensory areas in each, certain intellectual functions are restricted to one hemisphere. A person’s dominant hemisphere is usually occupied with language and logical operations, while the other hemisphere controls emotion and artistic and spatial skills. In nearly all right-handed and many left-handed people, the left hemisphere is dominant.

Left-right

Homunculus

And finally, no discussion about the brain would go without a reference to a sensory homunculus. The sensory areas of the cortex are divided into maps of organs and senses they are responsible for. Homunculus shows how much importance the brain gives to certain areas of the map, comparatively, by looking at how large they are.

homunculus

You can find the Neuroscience of Everyday Life lectures on the Teaching Company site.

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