During the past decade, neurobiology has provided increasing insight into how the brain processes emotion. The normal and pathological development of anxiety, an affect of long-standing interest to psychoanalysts, has been one focus of this research.
Many analysts would agree that our psychoanalytic theory of anxiety is incomplete and evolving. While neurobiological findings in this arena are mere fragments of the pieces of the puzzle, they provide promising points of integration with psychoanalysis's almost ten decades of clinical observation and theory construction.
Two areas of neurobiological research are seminal and relevant to the interests of child and adult analysts. One area of inquiry concerns genetic and non-genetic modes of inheriting a predisposition to anxiety. These studies provide a more refined appreciation of the integration of nature and nurture, rather than reinforcing the view that one or the other developmental influence has exclusive importance. A second fruitful area is the physiology of the amygdala, a specialized collection of neurons in the temporal lobe which appears to be the center for processing the emotion of fear. Current understanding of the amygdala supports the proposition of an unconscious emotional life and increases our empathic appreciation of the sensitivities of our phobic, panic-prone patients, as well as many depressed patients.
The work of Jerome Kagan of Harvard supports the concept of an inborn, biologically based temperamental predisposition to severe anxiety. Using behavioral and physiological markers, Kagan conducted a longitudinal study of behaviorally inhibited children.
Behavioral inhibition is an observable marker used to identify trait anxiety in young children. Kagan reports that 20 percent of Caucasian American children are born predisposed to be irritable infants, shy and fearful toddlers, and cautious and introverted schoolchildren. They demonstrate an essential temperamental trait of withdrawal from novelty.
Physiological probes of behaviorally inhibited children disclose significantly higher measures of activity in the sympathetic nervous system and hypothalamic-pituitary axis than in non-inhibited children. Kagan postulates that anxiety-prone children are bom with a lower firing threshold in amygdala and hypothalamic neurons. His work provides a robust model for predicting temperamental forerunners of anxiety disorders.
While Kagan's findings may lend themselves to reductive biological interpretation, related studies by Steven Suomi at NIMH correct that possibility by showing how plastic the neurocircuitry of anxiety is in childhood, even among the temperamentally anxious. Suomi finds that 20 percent of young rhesus monkeys are extremely behaviorally inhibited. This anxious behavior continues throughout major periods of development. Like Kagan, Suomi finds elevated hypothalamic-pituitary axis reactivity in his behaviorally inhibited subjects.
An increasing body of longitudinal data from Suomi's lab indicates that certain early experiences can alter both behavioral and physiological developmental trajectories. Thus genetic endowment and early experience both influence the experience of reality and affect brain development. For example, behaviorally inhibited and physiologically reactive infants reared by unusually nurturing foster mothers develop “secure” early attachments and appear to have optimal long-term development. These infants become adept at recruiting social support and tend to rise to the top of the dominance hierarchy despite their temperament as infants.
Some very recently reported research lends support to a model of early development that emphasizes the two-way influence between genes and experience. D. Liu, M.J. Meaney, et al. recently reported that variations in maternal care affect the development of individual differences in neuroendocrine response to stress in rats. The adult offspring of rat mothers who spent more time licking and grooming their pups during the first 10 days of life showed lower stress hormone secretion during a stressor, more environmental exploration (an indicator of low anxiety), more cell receptors throughout the brain for anxiety-relieving neurotransmitters, and more stress hormone receptors in the hippocampus (which helps mediate negative feedback inhibition of the stress response).
The licking and grooming triggers the release of thyroid hormones, which in turn increases the amounts of serotonin sent to the hippocampus. Serotonin causes a long-lasting increase in stress hormone receptors in the hippocampus.
To what extent genomic material remains open to the influence of beneficial experience is an obvious area of interest for psychoanalysis. Neurobiological studies contribute information relevant to this question.
For example, nerve growth factors appear to be inhibited in certain regions of the brain by stress hormones. These nerve growth factors are responsible for growth and repair of cells in the hippocampus, which again modulates the stress response. Serotonergic agents increase levels of brain serotonin, which initiates a series of intracellular adaptations leading to the transcription of genetic material coded for nerve growth factors. Studies suggest the possibility that other stress-relieving interventions can also activate the brain's encoded reparative mechanisms.
Studies of the amygdala demonstrate that emotional learning and the processing of fear are mediated by subcortical pathways. Emotional learning — which includes the association of an object with fear — occurs without involving the higher processing systems of the brain, responsible for consciousness, thinking, and reasoning. In response to danger stimuli, the amygdala constructs “fast and dirty” perceptual representations which it imposes upon higher processing areas, including the cortex. Under normal conditions, the cortex binds together a representation of an object that contains more accurate information about its degree of dangerousness. The cortex also exerts a modulating influence over the amygdala. In anxiety disorders, this cortical modulatory role may be lost, and the individual may have a predominantly amygdala-driven mode of perception and response: alarmist perceptions and full-blast, somatizing responses.
Individuals with anxiety disorders appear to have lower firing thresholds in their amygdala circuits. Because the subcortical neurocircuitry of anxiety is easily invaded by signs and features of danger, this physiology results in a persistent unconscious vigilance. This heightened reactivity to nuances of danger is passed along by the amygdala's extensive neuronal connections to heart, stomach, hypothalamus, and emotional memory systems. Fear conditioning in the temperamentally anxious can quickly produce long-lasting phobias.
From such studies clinicians gain a heightened empathy for the subjective life of the anxious child and adult. A continuous flow of separation anxiety is prompted by the persistent tracking of the unfamiliar and dangerous. Reactivity to details and symbols of the strange cause so much background noise that the quieter signals of safety are not perceived.
Lester Isenstadt, M.D., is an adult and child psychoanalyst and a supervising child analyst with the San Francisco Psychoanalytic Institute. He practices in Berkeley, Calif., and teaches at conferences on the integration of neurobiology and psychoanalysis.
Specific psychoanalytic interventions, incorporating knowledge gained from neurobiology, remain to be studied. Such interventions may fortify the cortex's ability to modulate the amygdala and its outflow circuits. The anatomical studies of Francine Benes of McLean Hospital provide evidence for the enhancement of cortical modulatory power over the limbic brain. She observed continued myelination of connections between the human cortex and limbic system extending into the sixth decade, suggesting a progressive integration of cognition with emotion. (The formation of a myelin sheath around a nerve axon allows that nerve cell to communicate with other nerve cells.) Such myelination may be the anatomical equivalent of the wisdom gained from life's experience and knowledge — and one of the results of the psychoanalytic process.