Dr. John L. Turner Blog

Lobar divisions were simple enough, so now we can go a bit more in depth. As you view the brain, there are several key landmarks that will interest you:

Looking at the brain, take note of the precentral and postcentral gyri. The convolutions are know as gyri and the dips between (the deep narrow furrows) adjacent gyri are the sulci. The precentral gyrus is the motor strip, the postcentral gyrus is the sensotry strip. Cells and connections for the muscles of the body are found along each gyrus and laid out according to body area.
There are important gyri in the temporal, frontal and occipital lobes. Looking at the left side, there is now great difference on how the brain appears but there is a significant difference in functional areas. In approximately 95% of the right-handed population, the centers for speech are in the left hemisphere as shown below:

I'm not trying to make a surgeon of you, but there is an interesting point to make here. In a person who is not a native speaker of the English language, say a Japanese speaker, reader and writer, these areas vary somewhat in location from the English-language brain, something important when considering a surgical approach to the regions involving and near the speech centers.
So here we have it, different cortical areas based upon function.

The numbers areas described by Brodmann. More details are in MMM's appendix and describe cortical areas in more detail. This is enough for our purposes as we approach the subject of how much brain is put to use.

Next will be a consideration of the deep brain structures and their special functions.

Any questions at this point?

Have a nice day!

The Neuron: 

This is a simplified artist's concept of the nerve cell or neuron of the human brain. The cell body extrudes dendrites which make contact with other neuronal cell bodies.

The axon extends as a process from the cell body and exhibits segmental insulation with sheaths of myelin produced by specialized cells known as Schwann cells. The electrochemical signal is transmitted from cell body to axon terminal by means of salutatory conduction from node (between the segments is a space called the Node of Ranvier) to node.

The dendritic connections with other nerve cells may be very complex, forming an intertwining network. The cell body is able to adapt its receptor shape which further adds to the enormous complexity of the circuit. As new memories are formed, or new abilities are learned, neuronal connections multiply as necessary to establish the necessary patterns in the brain.

A neuron communicates with other neurons via dendritic connections (the synapse) with up to 10,000 or more connections to other neurons
The aforementioned cortex is the thin layer of the brain commonly called the grey matter. Of the 100 billion cortical neurons, half are found in the cortex of the cerebellum. Neurons are sustained by astrocytes and other glial cells which make up 90% of the brain's substance and are now known to form interconnections of their own.

These are the basics you will need to understand the next section.

 For the next blog entry, neural anatomy and physiology will be discussed.

Remember, the number of possible neural connections is a figure that is greater than all the known particles in the universe! Although the actual connections made grow at a rapid rate as an infant and slow down somewhat as we age, everything that happens, all that takes place, makes new connections and/or strengthens old connections. How could such tremendous processing power be guided and directed?

I'll begin next time with basic neural anatomy and how signals flow from dendrite to neuron, from axon to neuron and so forth.

What do you think of when you think of a nerve cell or neuron?

Have a nice day!

How much brain?

As promised, I want to begin a discussion of the often asked question, "How much of our brains do we really use?"

Before reading further, I ask you to zip to the end and leave a comment for your answer to this question:

                              "How much of your brain do you use?"

Then, read what follows and see if it changes your opinion.

 Ok, if you did that, left your answer, then please continue.

Here we go:

Part 1  

I mentioned earlier that when my first daughter Ku'ulei was three years old, I was an every-other weekend dad and in the midst of divorce number two (ouch!). One Saturday morning, I had a 35mm camera on the table when I asked her, out of the blue, "Ku'ulei, how much of your brain do you use?" She was about to take a mouthful of cereal when I posed the question and she stopped, looked at me quizzically and then with a bit of contempt in her voice, she replied, "All of it, of course!" and resumed her breakfast without a second thought.

It is not until we are told by someone of authority that we use 10% of our brains that we yield to superior knowledge and begin to repeat this oft-quoted figure.

The cortex of the human brain (the thin layer that covers the convolutions) contains at least 100 billion neurons. Half of this number is found in the cerebellar cortex, which is a surprising finding. The cerebellum (literally "little brain") is the fist-sized structure at the base of the brain, tucked in just behind the brainstem and has many connections regarding motor coordination.

The figure of 100 billion is also of interest because it roughly correlates to the number of grains of sand on all of the world's beaches, and to the estimated number of stars in our galaxy, The Milky Way. It is difficult to imagine that only 10% of the cortical neurons are put to use and only 10% of the remaining brain substance (the supporting cells, the deep grey-matter cell collections, etc.) are left unused. It is far more likely that the 10% figure has been passed down by word and may have been correct in the early days of neuroanatomy and neurophysiology during the times of Galen, but things have changed. Functional MRI, magnetoencephalography and other highly-sophisticated instrumentation have allowed brain function to be explored in great depth and are a far cry when the days of brain stimulation during surgery was the only technique available

In the coming sections, I will expound upon this topic, first starting with basic brain anatomy (also found in the appendix of MMM) and we will try to answer the question of how much brain is put to use, how it is put to use and when it is used. Could it be that abilities such as precognition, telepathy and clairvoyance, are parts of the brain that lie dormant, ready for activation? And that we must learn to use these brain functions again? This seems likely as remote viewing may be a good example of activating long-unused brain areas.