Physiological Correlates of Anxiety a Preliminary Investigation of the Orienting Reflex

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Abstract
The orienting reflex (OR) was investigated in 16 anxiety patients (anxiety-group) and 16 normal subjects (control-group), with the aim of measuring internal inhibition by determining the habituation rate and observing the incidence of signs of sleep in the EEG. Recordings were made of the EEG, heart rate, respiration, skin-resistance level and GSR, and the response to 50 sound stimuli was studied. The results of this preliminary investigation have led to the following tentative conclusions: 1. Anxiety has no influence on the OR. No significant difference was found between the two groups as regards the elicitation and habituation of the OR. Cortical function, as measured by the OR, is not impaired in anxiety. 2. A significant difference in mean skin-resistance level at the end of the stimulus period, mean heart rate/min., muscle tension and incidence of signs of sleep in the EEG was found between the two groups. In anxiety, deficiency of inhibitory i.e. negative feedback and synchronizing mechanisms, results in over-activity of the reticular activating system, which is further enhanced by the operation of positive feedback or self-regenerative mechanisms. This over-activity of the reticular activating system is shown by the absence of a “sleep-response” and, in general, by an increase of tonus, i.e. muscle tonus, sympathetic tonus and Bremer's “cortical tonus”. A desynchronized EEG and a low skin-resistance level are not necessary correlates of anxiety. The independence of habituating and synchronizing mechanisms with regard to internal inhibition is mentioned. Support is given for the view of weakened inhibition and also for the concept of “autonomy” in anxiety.