06 August 2008

Dopaminergics

This is the second update to the programming section on the iPlant website and on Knol. 'Dopaminergics' is a play on words like neuroinformatics, but the general idea is something I take very seriously. I think a quantitative understanding of dopamine signalling in the brain will allow us to bridge the gap between sensory input and motor output.
In recent years it has become possible to assign exact numerical values to the dopamine release that accompanies specific rewards and states of attention. Microdialysis probes and other biosensors associate rewards, particularly unexpected rewards and rewarding brain stimulation, with sharp increases in dopamine concentration in the prefrontal cortex and basal ganglia in many animals. States of high or low attention have similarly been associated with high or low concentrations of dopamine in the prefrontal cortex. These numerical relations are referred to as dopaminergics.

Dopaminergics describe the relation between dopaminergic events (e.g. a salient object in the environment, the activation of a deep brain stimulation electrode, the discovery of a solution to a problem), dopamine release (e.g. 20nM increase in prefrontal cortex as evidenced by a microdialysis probe) and brain/mental states (e.g. attention, motivation, learning, memory, motor output). It may be helpful to think of dopaminergics as assembly code for the learning brain.


Early references to the dopaminergics of rewarding brain stimulation:

Garris et al (1997) Real-time measurement of electrically evoked extracellular dopamine in the striatum of freely moving rats. Journal of Neurochemistry;

Fiorino et al (1993) Electrical stimulation of reward sites in the ventral tegmental area increases dopamine transmission in the nucleus accumbens of the rat. Behavioral brain research;

Bean & Roth (1991) Extracellular dopamine and neurotensin in rat prefrontal cortex in vivo: effects of median forebrain bundle stimulation frequency, stimulation pattern, and dopamine autoreceptors. Journal of Neuroscience.
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