Posts Tagged ‘Two_System_View’

Review of The Washington Post’s The Aging Brain

December 7, 2011

This piece1 is informative and offers some good advice, but is woefully deficient in some areas that should have been included. The article is basically an annotated diagram that begins with the first step of the eye seeing something. The second step is the information arriving at the visual cortex that identifies what the eyes see. The third step is the information flowing through the associative cortex to develop further understanding. The fourth step is the information arriving at the hippocampus (actually it should be hippocampi as there is one hippocampus in each hemisphere of the brain. Information must be processed by these hippocampi if it is to be recalled later. People who have lost their hippocampi via surgery, accidents, or dementia, are unable to learn/remember new information. But it is the prefrontal cortext decides whether this new information warrants processing by the hippocampi for later use. The prefrontal cortex is an important part of the brain as it not only decides what is worth remembering, but it is involved in all the decisions we make and is responsible for regulating our behavior. Unfortunately, it is late maturing (not until our twenties) and early to decline (sometime after age 50). So far this description is accurate and it is understood that there would be similar, but not identical stages of processing for other modalities of information.

There is another section of the article on how to slow the effects of aging that provides the following advice:

Calm Down – this is good advice as the piece correctly states that stress can destroy synapses , it fouls up the hippocampus and the prefrontal cortex. It does not mention that the various types of meditation are beneficial in helping us to calm down.

Exercise – this is good advice as the increased blood flow and oxygen uptake it engenders is beneficial to the brain.

Make friends – more good advice. There have been a number of Healthymemory Blog Post extolling the benefits of socialization.

Sleep well – more good advice. Getting adequate sleep is important not only to general health, but is also critical to important brain and memory processes.

Ask about estrogen – Ladies, you can judge this one for yourselves. This recommendation is based on one study. Given the somewhat uneven results from estrogen therapies, some skepticism might be in order.

Do what you do best – Although it is true that expertise is maintained well into old age and that you are less likely to lose what you know well, it is a somewhat misleading strategy for slowing the effects of aging. Although it is fine to continuing growing in your area of expertise, it would be a mistake not to expand into some new areas. Research has indicated that maintaining brain and cognitive health should not be a reactive, defensive matter, but rather a proactive effort to continue growing cognitive competence.

An interesting question to ask, is why does the prefrontal cortex start to decline after age 50? Is it solely a matter of aging? There is the Dumbledore Hypothesis regarding the effects of aging on the brain (See the Healthymemory Blog posts, “More on Attention and Cognitive Control,”, “Passing 65,” and “Memory and Aging.). This hypothesis fits well with the Two System View of Cognition (see the Healthymemory Blog post “The Two System View of Cognition.”). According to this view, there are two primary means of processing information. System One is fast and automatic. It is the result of prior learning. This is the system that is doing the majority of the processing when we converse, drive a car, etc. System Two is slow, effortful, and demands attention. This is what is at work when we are trying to learning something new, to solve a math problem, or recognize something that is illogical or contradictory in what the person we are conversing with has said (or in our own conversation if we recognize something illogical or contradictory in what we have said. According to the Dumbledore Hypothesis as we age we increasingly rely on System One processing because we have learned much and don’t need to do as much processing as a younger person who does not have such a wealth of experience to draw upon. The problem is that since we do less System Two processing we use our prefrontal cortex less. The use it or lose it advice that we know from physical exercise also applies to cognitive exercise. When we use our prefrontal cortex more glucose is sent there. So the loss in the functioning in the prefrontal cortex might not be solely do to aging. It might be in part, perhaps in large part, to a loss in the frequency of its use.

So the new idea is to challenge our minds and to continue to learn new things as we age. (See the Healthymemory Blog post, “A Quote Worth Pondering.”) It is not too late to learn a new language, or new subject matter. These activities will engage the prefrontal cortex. Mnemonic techniques have the benefit of not only being a technique that enhances memory, but are also means of providing cognitive exercise that exercises the prefrontal cortex and activates both cortices of the brain. So aging should not cause us to be reactive and defensive, but we should go on offense, be proactive, and continue to grow cognitively.

1Berkowitz, B. & Cuadra, C. (2011). The Aging Brain in The Washington Post Health & Science Section, E1, 6 December.

© Douglas Griffith and, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

What is Consciousness?

April 24, 2010

On one level this might seem like a stupid question1. Of course, you might say, we experience consciousness most of the time when we are awake and even some of the time when we are asleep. Although this is true, the nature and role of consciousness are matters of intense debate within psychology and philosophy with little prospect of being resolved soon. That is why it is so refreshing that recent theory and data in neuroscience are offering some insight into how consciousness is manifest in the brain.

It is called the global workspace theory and was first presented by Bernard Baars of the Neuroscience Institute in San Diego, California. According to this theory, non-conscious experiences are processed locally within separate regions of the brain. We only become conscious of this information if these signals are broadcast to assembly of neurons distributed across many different regions of the brain—the global workspace, which then reverberates in a flash of coordinated activity. This coordinated activity produces a mental interpretation of the world that has integrated all the senses into a single picture. This is obviously related to the previous blog post “The Two System View of Cognition.” The two systems are System 1, Intuition, and System 2, Reasoning. System 1 processes information every quickly below the level of consciousness. When a visual event occurs it would be processed locally in the visual cortex. For the even to become conscious it would need to be broadcast to an assembly of neurons distributed across many regions of the brain. This produces consciousness and is a limited System 2 Process. We are extremely limited in the amount of information to which we can attend. Apparently this is due to this activation of large areas of the brain. When we driving most of the activation is local and occurs below the level of awareness. A slowing or stopping vehicle ahead of us can lead to this wider broadcast to many regions of the brain. We then become conscious of the need to slow down or stop and act accordingly.

This neural activity has been documented in brain imaging studies (See the blog post, “How Can the Brain Be Imaged?”).

Conflicting pieces of information are filtered out. This is an important feature as our attentional resources are quite limited. We cannot perceive two perceptions at once. This is evident in such ambiguous visual illusions as the Necker Cube, which changes in depth, the profile/vase illusions, in which you see either two human profiles or a vase, and the My Wife and My Mother-in-Law illusion, in which the two perceptions are of a beautiful young lady with her head turned away, or the profile of a very old woman. Although we can rapidly alternate between the two percepts, they cannot be perceived simultaneously. They also do experiments in which different images are projected to each eye. Rather than merge the two percepts, only one percept can be perceived at a time.

1This post is based largely on an article by Anil Ananthaswamy. (2010). Brain Chat. New Scientist, 20 March, 38-41.

© Douglas Griffith and, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.