NOTE re Brain Function and evolution-part 2

How does this ancient reward centre undermine the power of reason and urge us toward its priorities? Primarily with surges of a neurochemical called ‘dopamine’. The intensity of the surge is related to the evolutionary importance of the anticipated goal. When a new mate is in the offing, then, as Romeo and Juliet would attest, these surges can override sound judgment. Dopamine can be considered the “I’ve got to have it” neurochemical. How compelling is the drive to mate? A Dutch scientist recently reported that brain activity at the peak of the sexual crescendo looks a lot like the brain activity of someone shooting heroin.(i)

This mechanism of the brain has no power to analyse what causes a dopamine surge. It simply urges us toward whatever sends dopamine soaring. Half a century ago scientists discovered that when they planted an electrode in the reward centre of a rat so that it could hit a lever to reproduce the effects of dopamine, it kept hitting the lever until it dropped.(ii) Not even food would distract it from this “rewarding,” but self-destructive, activity. When dopamine is high, humans, too, may become unnaturally goal-oriented, and feel strangely impervious to probable repercussions.

Anyone who can create in another the anticipation of a reward that sends dopamine soaring, gains a powerful hold over him or her. For addicts the desired reward might be a substance or activity, but for a deeply religious person that highly coveted reward might be union with his Creator. Targets can be manipulated to put these desires before their wellbeing and the wellbeing of others.

According to a study published in the Journal of Neuroscience, ‘wanting’ and ‘liking’ are actually separate urges in the brain, controlled by different circuits. Unfortunately the drive to ‘want’ is stronger than the drive to ‘enjoy.’(iii) This means that people can be driven to crave activities or substances that are, in fact, no longer pleasurable to them, but do offer temporary relief from the cravings themselves.People often self medicate with a stimulant or compulsive behaviour, to stay a step ahead of uncomfortable withdrawal symptoms. The reward centre is thus implicated in all addictions. When people use cocaine or alcohol, or even become entranced with titillating two-dimensional computer images, they hijack the reward centre. That is, they exploit a survival mechanism that works to decrease their chances of survival.

Unfortunately, when dopamine has been extremely high, it does not just drop back to normal levels. It falls even lower (down-regulates), below base line levels as if the body needs to recover after over-stimulation. Until it returns to normal, the user suffers an uncomfortable withdrawal phase. At this point in the cycle, he is especially susceptible to any suggestion, substance or activity that will bring his dopamine back up so he feels better again. It is actually the recurring drops in dopamine, combined with the promise of relief (rather than true wellbeing), which keep people locked in addictive behaviour. Anyone who has ever fanaticised about a lover knows how compelling, yet empty, an exercise it can be. True contentment lies in equilibrium, not this neurochemical cycle of highs and lows.

NOTES
i. G. Holstege, J.R. Georgiadis, A.M.J. Paans, L.C. Meiners, F.H.C.E. van der Graaf, & A.A.T.S. Reinders, Brain Activation during Human Male Ejaculation, The Journal of Neuroscience, 23(27) (2003), 9185-9193. (parallel drawn between brain scans of ejaculation and heroin rush)

ii. J. Olds & P. Milner, Positive reinforcement produced by electrical stimulation of the septal area and other regions of rat brain, Journal of Comparative and Physiological Psychology, 47 (1954), 419-427.

iii. K.S. Smith & K.C. Berridge, (2007). Opioid Limbic Circuit for Reward: Interaction between Hedonic Hotspots of Nucleus Accumbens and Ventral Pallidum, The Journal of Neuroscience, 27(7) (2007), 1594-1605.