Low serotonin levels and steady-state dopamine levels characterize the dream state. A low serotonin level "also promotes heightened emotionality, both positive and negative," writes Panksepp in Affective Neuroscience. "It is a neurochemical state that leads to impulsive behavior in humans, even ones as extreme as suicide. Probably the most striking and highly replicable neurochemical finding in the whole psychiatric literature is that individuals who have killed themselves typically have abnormally low brain serotonin activity."
With the introduction and success of drugs like Prozac, a serotonin reuptake inhibitor, we have come to better understand that low serotonin levels are associated with depressed mood. As mentioned previously, Allman explains in Evolving Brains that "serotonergic neurons play a fundamental role in the integration of behavior." Below in the blocked quotation, he cites the work of Steven Soumi and Dee Higley in explaining that low serotonin levels in individuals are also associated with increased vigilance, allowing certain individuals to serve a sort of sentinel role in their group. Perhaps continuing stressful circumstances kindle hypervigilance and somehow also decreases serotonin levels. This seems to make sense because, under the constant pressure of threat and the resulting hypervigilance required to address that threat, a person or animal would understandably become depressed and exhausted. So genetics, in providing for sentinels within groups, along with a stressful environment, may together contribute to a more sever form of depression perhaps sometimes taking shape as obsessive-compulsive disorder (OCD).
Steven Soumi and Dee Higley have suggested that animals with high serotonin levels, while more stable, are less sensitive to hazards and opportunities in the environment, which may explain why there is a diversity of serotonin levels in natural monkey populations. The low-serotonin monkeys may be the first of their group to find new food sources and may serve as sentinels that detect predators. The evolution of this increased sensitivity to environmental risks and opportunities is analogous to the evolution of specific alarm and food calls that serve to alert other group members, probably close kin sharing many genes in common, to the presence of predators or resources. Such behaviors may endanger an individual but enhance the survival of close relatives and the propagation of genes shared with the individual. The potential adaptive significance of genes for low serotonergic function may explain why mood disorders, which are associated with low serotonin levels and are typically treated by drugs that enhance the concentration of synaptic serotonin, are so prevalent in the human population.
In The Trouble With Testosterone and Other Essays on the Biology of the Human Predicament (1997), Robert M. Sapolsky writes: "People with anxiety disorders can be thought of as persistently mobilizing coping responses that are disproportionately large. For them, life is filled with threats around every corner, threats that demand a constant hypervigilance, an endless skittering search for safety, a sense that the rules are constantly changing."
Many people with disorders involving obsessions and compulsions would describe themselves as being hypervigilant, meaning they feel oversensitive to stimuli in their environment. Allman writes: "The mechanisms for vigilance that conferred a survival advantage in the evolutionary past may in some cases turn pathological in contemporary life, in which we are flooded with artificial stimuli demanding our attention."
Perhaps modern relationships, especially troubled family relationships, also contribute to hypervigilance that sometimes turns into obsessions and compulsions, especially when no acceptable outlet is available for one's emotional energy, particularly rage that must be repressed.
Working on the premise that the VIGILANCE system is inextricably linked with the SEEKING system, hypervigilance prompts SEEKING action directed towards resolving whatever danger is detected. Such coordinated action requires that the corpus striata complex coordinate dopamine neurosignaling. Over time, perhaps it is possible that hypervigilance kindles dopamine transmission—raw motivation to solve problems and quell anxiety—that subsequently co-opts symptoms from whatever influences or bioprograms that are available. When current circumstances are generally safe and secure, resulting OCD symptoms might be mild, perhaps involving cleaning or organizing. When actual circumstances are threatening and chronic, and when no acceptable outlet for hypervigilance is available, such kindled dopamine transmission might manifest in more severe symptoms such as self-directed grooming routines like trichotillomania and skin picking. We will discuss these symptoms further in Part 3 of CorticalBrain.com.
In the following subsection, Amy F.T. Arnsten suggests that the prefrontal cortex can go "off-line" due to increased catecholamines including dopamine in the brain. This dysfunction is crucial to understanding why people with compulsions continue in behaviors that, from an objective perspective, are senseless and damaging. For lack of a better term, these are called "off-line" episodes fugues, which we briefly discussed above.
Next-> Stress, attention, learning, memory, and ADHD:
To continue exploring CorticalBrain.com in an orderly fashion, link to Subcortical Brain Structures, Stress, Emotions, and Mental Illness. Or, you may Explore the Site Outline.
If you would like be informed about new features and improvements as they are added to CorticalBrain.com, please send an e-mail to info(at)corticalbrain.com