Tool Module: A Neuroanatomical and Psychological Model of Anxiety

The increasingly detailed data now available on the fear centres and the other areas associated with them in the brain have enabled scientists to develop various neuroanatomical and psychological models of anxiety.

One of the most interesting was proposed by Jeffrey A. Gray in 1990. Gray hypothesized that the various aspects of anxiety involve three brain systems that had already been well described: the behavioural inhibition system (BIS), the behavioural approach system (BAS), and the fight/flight system (F/FLS).

Thus, says Gray, the anxiety of anticipation is analogous to the state of inhibited action observed in animals that are faced with a a direct threat. When the behavioural inhibition system is activated, the animal immediately stops what it is doing, freezes, and becomes hypervigilant, alert to the slightest sign of danger. This state emerges in animals when they are placed in the presence of a potential source of punishment, or even just a new stimulus.

In humans, anxiety might also arise when the predictions that we have made on the basis of our memories of past experiences are not confirmed by our present experience. Gray says this state is also adaptive, because it focuses our attention and makes us look for new information to help us resolve the impasse.

In this same model, the behavioural approach system, which encourages goal-oriented behaviour, is activated by environmental stimuli associated with a reward, or with the absence or cessation of punishment. In humans, according to Gray, the behavioural approach system constitutes the neurophysiological basis of impulsiveness.

Lastly, the fight/flight system is triggered by the confirmed presence of an actual aversive or dangerous stimulus. This system then triggers a response either of flight or of defensive fighting behaviours specific to each species, such as biting, squealing, or punching. In humans, according to Grey, the fight-or-flight system is activated in a panic attack, for example. According to animal studies, this system seems to include the septohippocampal areas, the locus coeruleus, and the medial Raphe nuclei.

The concepts of the behavioural inhibition and behavioural approach systems have also contributed to psychological theories of personality. Psychologists hypothesize that an individual’s personality may be influenced by the sensitivity of his or her particular behavioural inhibition and behavioural approach systems. The fight/flight system, on the other hand, would appear to be influenced more by actual threatening situations and would not contribute to any description of personality.