Monday, March 12, 2012

Depth and Breadth for an Efficient Brain: No Short Cuts

Maturation of a neural network. Over time, new nodes are formed 
with their respective connections, and existing connections are 
strengthened. The overall system, still maintains a small world 
structure, and its original base structure.
What are the sorts of activity over the lifespan that shape the efficiency of our brains? Short of taking a pill or undergoing microneurosurgery, how do we engage in cognitive processes that encourage favorable levels of neurotransmitter activity and optimal configurations of neural connectivity? For that matter, is it possible to bypass all the "hard work" of thinking and doing and just pop a pill to make our minds more intelligent? To preempt the latter question, perhaps there is no short cut. But that does not mean we give up. Rather, it means it is all the more critical to lay the right foundations, and it also means, it is never too late to start.

A recent development in our understanding of neural structure might be mapped onto this set of physical properties. Based on graph theory, we now know that the way in which the human brain is wired resembles a small-world network. That is, neurons are connected to each other in the brain such that there is an optimal balance between short-distance, local, connections with close neighboring neurons, as well as long-distance connections via hub neurons. This balance of having both types of connections results in the most efficient structure with which information can be transmitted from one neuron to another, on average. Too many local connections, and information must shuttle through an adverse number of short-range synapses before reaching a distant neuron, increasing time of transfer. Too many long-distance connections, and also information must ridiculously pass through distant neurons before arriving at the neuron which is just beside. Other properties emerge that also are used to characterize the degree to which a network is a small-world network - level of clustering and randomness of connections. Using such indices, we now know that the evident connectivity of the brain seems to represent a high-level of efficiency with regards to the processing of information pertaining to stimuli, memory, thought, and action. Because of such neural organization, we are able to read or hear, comprehend, remember, reason, and respond, all literally within the blink of an eye.

With this background, we come back to the opening questions. If our brains are generally already efficient, how does this efficiency change with age, and if it goes down (as we are apt to assume), how do we keep it at optimum efficiency for as long as possible apart from the use of chemical and physical interventions? How do we optimize our small-world networks via mental interventions?

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