From the excerpt:
It is now becoming clear that addiction is associated with long-lasting changes in the electrical, morphological, and biochemical functions of neurons and synaptic connections within the medial forebrain pleasure circuit. There are strong suggestions that these changes underlie many of the terrifying aspects of addiction, including tolerance (needing successively larger doses to get high), craving, withdrawal, and relapse. Provocatively, such persistent changes appear to be nearly identical to experience- and learning-driven changes in neural circuitry that are used to store memories in other brain regions. In this way, memory, pleasure, and addiction are closely intertwined.
I am absolutely fascinated by this line of research. The physical changes at the synaptic level is a truly compelling find, yet it flows logically from what is known about what happens to the brain from ordinary experience without the assistance of a chemical agent. When memories are formed the synapses increase the amount of neurotransmitter released and the rate of firing. It only makes sense that addiction would produce the same results.
ReplyDelete@SG It's definitely interesting stuff, especially - for me - the idea that the physiological changes associated with learning and memory appear to be common across multiple brain regions. It would appear then that the resulting alteration of synaptic behavior is not so much related to whether the chemicals are exogenous or endogenous, but rather the degree to which the pattern of activity sets off a feedback loop that alters the expression of various membrane proteins.
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