Attracting Abundance

The Law

Two Doors to Success

Happiness - VII

"Where there is hope, 
there is faith.
Where there is faith,
miracles happen."

I have mentioned two forms of positive emotions - hedonia (momentary highs) and eudaimonia (life satisfaction). A lot of work has been done in the field of neural circuits involved in hedonia in animals by studying the response of brain to rewards. (Berridge et al, 2011, Psychology of Well Being, 1(1), 1 - 3). These mechanisms are very similar across species. Further hedonic and eudaimonic well being in human are highly correlated as many of the brain circuits involved in hedonic emotions are also active in eudaimonic experiences.

The Reward Circuit

Using advanced scientific techniques (Smith et al, 2011, Proceedings of National Academy of Sciences, 108(27), 255-264) it has been possible to isolate separate neural connections within the ventral striatal circuit - specifically within nucleus accumbens (Note: nucleus accumbens plays a central role in the reward circuit. Its operation is based mainly on two neurotransmitters - dopamine and serotonin. Dopamine promotes desire. the effects of serotonin includes satiety and inhibition. Please read the detailed note below for further explanations on nucleus accumbens) and ventral pallidum for wanting, liking and prediction components of the same reward. The ventral striatum is a region deep in the center of the brain that is associated with wanting, liking and reward for a large number of species. It is sub-cortical part of the brain which means that the structure is located below the cortex which covers the surface of the brain. In humans, the region most activated by the hedonic pleasure is the ventral pre-frontal cortex which is a region in front of the brain directly above the eyeballs, but there is some activity in ventral striatum as well.

(Note: The role of nucleus accumbens in the so called "reard circuit" is most widely accepted. When we indulge in an activity that gives pleasure such as eating, having sex, taking drugs etc. dopamine neurons along with other neurons are activated in ventral tegmental area. See figure above. These neurons travel to the nucleus accumbens increasing the dopamine levels in the nucleus accumbens.

The association between rewarding experience and dopamine levels in the nucleus accumbens led to a belief that the chief role of nucleus accumbens if in mediaing rewards. Thus it is often held responsible for addictions. however subsequent research work has shown that dopamine levels in nucleus accumbens rise in response to both pleasant and unpleasant stimuli.

The most widely accepted perspective now is that dopamine levels rise on positive and negative experiences. Dopamine signaling may be involved with strong information about environmental stimuli associated with these different types of experiences. These memory stores can be called upon in future to help us remember how to realize the pleasurable experiences again or avoid the unpleasant experiences. In addictive process, it may be that the connection between an initial pleasurable drug experience and the stimuli associated with it becomes too strong. This can foster compulsive drug seeking after exposure to a related environmental cue (e.g. cigarette smoking upon smelling cigarette smoke).

Although the function of nucleus accumbens is still to be fully understood, suffice it is to know that nucleus accumbens is an important area in forming memories involving salient environmental stimuli, both pleasant and unpleasant)

In a typical experiment designed to investigate brain circuit activated during hedonic pleasure (Costa et al, 2010, Human Brain Mapping, 31(9), 1446 - 57). Participants were presented with text that had been rated as highly positive and then asked to generate imagery related to this text for 12 seconds during which brain function was monitored by fMRI (Functional Magnetic Resonance Imaging). This was then contrasted with a similar exercise with a negative text. The former produced greater activity in nucleus accumbens (within the ventral striatum) and a region of the ventromedial prefrontal cortex. Functional connectivity between the nucleus accumbens and the amygdala (a brain region commonly activated by positive an negative emotional signals) and between the ventral pre-frontal cortex and amygdala was significantly increased during the positive compared to the negative imagery conditions. A similar pattern of pre-forntal activity was seen in a study conducted on mothers (Nitschke et al, 2004, NeuroImage, 21(2), 583 - 92) soon after the birth of their first child. The magnitude of pre-frontal activation predicted the intensity of positive mood ratings.

The studies reviewed above examine the regions of brain activity by short-lived motional signals. It is not clear as to what kind of brain circuitry actually happens on enduring forms of well being. Moreover the studies reviewed above focus on positive effect . There are suggestions that the enduring form of well being is also associated with resilience in the face of adversity which promotes quicker recovery - getting up after falling down so to say.

Namaste

Prabir