Generalized Theory Of Personality

Dr. C. Robert Cloninger, M.D. in the early to mid-1980s worked on a general theory of personality while at the Washington University School Of Medicine, St. Louis, Missouri in the fields of Genetics and Psychiatry. His work culminated in an article which described a classification of personality variants. See the bibliography for the particulars of the article. I will paraphrase that article.

As a result of his work in the fields of genetics and psychiatry, Dr. Cloninger cites considerable evidence for a generalized theory of personality. He hypothesizes that there are three dimensions of personality that are genetically independent and that have predictable patterns of interaction in their adaptive responses to specific classes of environmental stimuli.

The three underlying genetic dimensions of personality he calls Novelty Seeking (NS), Harm Avoidance (HA) and Reward Dependence (RD). Their attributes are as follows:

DIMENSIONS OF PERSONALITY

Each of these three dimensions are variously blended together as a genetic distribution in a Gaussian manner to yield an overall personality. Please do read his article in order to gain a more comprehensive understanding of his theory.

Dr. Cloninger goes on to state that each brain system, i.e., NS, HA & RD, is associated with a related personality dimension and a principal monoamine neuromodulator. The basis of his theory lies in the studies of many scientists work concerning pathways of nerve tracts in the brain and the function of these areas which are being connected. Please refer to the following table for correspondences:

Generalized Personality Theory Correspondences

Thus we have a theory put forth based upon much scientific work which correlates brain systems with behavior and neurotransmitters. How then does the theory of Dr. Cloninger fit with the information on brain hierarchy? All of the proposed neuromodulatory systems are autoactive, none have activity which is correlated with movement per se and all are independent of each other. These elements all fit with the proposed theory of Dr. Cloninger. NE & 5-HT neurons are highly state dependent, while DA neurons are state independent. Stimuli or conditions known to be related to changes in 5-HT activity are inversely associated with similar changes in NE neurons. Sensory evoked loci responses of NE neurons habituate while those of 5-HT do not. The activity of DA neurons is not at all related to those of 5-HT or NE neurons. The similarity in 5-HT & NE activity is paralleled in the general anatomical areas to which each project. However, each terminates in different layers of the neocortex in the same areas. DA fibers terminate in more discrete loci and are more topographically organized than 5-HT or NE neurons. The function of 5-HT & NE activity appears to be related to the smooth coordination of diverse central nervous functions to act in concert with the level of motor outflow. DA loci appear to be related to the purposive, rapid response initiation of major muscle groups and to fixation and focusing of attention.

Since Dr. Cloninger states that DA is related to behavioral activation and novelty seeking, this fits with the above information. He also states that 5-HT is related to behavioral inhibition or harm avoidance and that NE is related to behavioral maintenance or reward dependence. As NE & 5-HT are opposite in action, this also makes sense in light of the above information.

Let us pursue his thoughts further. DA has as relevant stimuli: novelty, potential reward and potential relief from monotony or punishment. 5-HT has as relevant stimuli: conditioned signals for punishment, novelty or frustrative non-reward. NE has as relevant stimuli: conditioned signals for reward or relief of punishment. The roles for 5-HT & NE appear to be consistent with the above information as NE neurons habituate and 5-HT neurons do not.

Dr. Cloninger also gives information concerning behavioral responses, DA has a response of exploratory pursuit, appetitive approach and active avoidance or escape. This does fit with the above information. 5-HT is listed as a behavioral response of passive avoidance and extinction. NE is listed as a behavioral response of resistance to extinction. Again NE & 5-HT roles appear to be consistent. The major locus of origin of NE neurons is the Locus Ceruleus of the Pons. This center is the origin of the behavioral response of "fight or flight" and other fear related activity which may be perceived as a threat to the individual. Since both DA & NE are catecholamines and are involved in behavioral activation while 5-HT is a tryptophane (amino acid) derivative and involved in behavioral quieting, it appears that extinction of behavior is generally conserved while that of being frightened is dependent upon learned circumstances.

Thus we have an emerging picture whereby the conscious entity of the left hemisphere receives activation from below by the neuromodulators 5-HT, NE or DA and responds with the excitatory amino acids Glu/Asp as modulated by GABA interneurons to descending nervous loci to yield an appropriate conscious action from the brain.

It has been found that many parts of the nervous system produce patterns independent of their sensory input. Neural circuits that produce self-sustaining patterns of behavior are called central pattern generators (CPGs).

Neuromodulators also act to modify the Central Pattern Generators (CPGs) of the CNS.

• 1. The dopaminergic system encodes the increase or decrease in the cumulative future rewards and controls action selection by the CPGs.
• 2. The serotonergic system regulates the time scale of evaluation by CPGs, i.e., how far into the future rewards are taken into account.
• 3. The noradrenergic system controls the scope of action of CPGs, the balance between local optimization and global exploration.
• 4. The acetylcholinergic system controls the rate of learning and forgetting in the entire brain and plays a crucial role in the movement of short term memory in the Limbic System to long term memory in the Cerebellum.

Thus a consistent and observable pattern is emerging from studies that shows the basis of human behavior is both a function of neuroarchitecture and learning.

Now, let us go to the next Chapter to discuss brain dominance and hemispherical thinking in light of what we have just learned!