Improving Human Performance

Sensory Gating

Human performance, being under direct control from the brain, is dependent on a pyramid of processes. Accurate human performance depends on practice gained from learning and memory, which in turn depends on selective attention to the performance of the task at hand, which in turn depends on "preattentional" arousal mechanisms that determine a level of attention (e.g., I need to be awake in order to pay attention). Human performance can be improved with training, which involves higher-level processes such as learning and memory. However, the most common factor leading to poor human performance is a lower-level process, lack of attention, or distractibility. Distractibility can result from fatigue, stress, and disease, to name a few. Is it possible to decrease the degree of distractibility, or at least to monitor the level of distractibility? Can nanotechnology provide a critical service in the crucial area of distractibility?

The National Research Council's Committee on Space Biology and Medicine (1998) has concluded,

Cumulative stress has certain reliable effects, including psychophysiological changes related to alterations in the sympathetic-adrenal-medullary system and the hypothalamic-pituitary-adrenal axis (hormonal secretions, muscle tension, heart and respiration rate, gastrointestinal symptoms), subjective discomfort (anxiety; depression; changes in sleeping, eating and hygiene), interpersonal friction, and impairment of sustained cognitive functioning. The person's appraisal of a feature of the environment as stressful and the extent to which he or she can cope with it are often more important than the objective characteristics of the threat.

It is therefore critical to develop a method for measuring our susceptibility under stress to respond inappropriately to features of the environment. "Sensory gating" has been conceptualized as a critical function of the central nervous system to filter out extraneous background information and to focus attention on newer, more salient stimuli. By monitoring our sensory gating capability, our ability to appraise and filter out unwanted stimuli can be assessed, and the chances of successful subsequent task performance can be determined.

One proposed measure of sensory gating capability is the P50 potential. The P50 potential is a midlatency auditory evoked potential that is (a) rapidly habituating, (b) sleep state-dependent, and (c) generated in part by cholinergic elements of the Reticular Activating System (the RAS modulates sleep-wake states, arousal, and fight versus flight responses). Using a paired stimulus paradigm, sensory gating of the P50 potential has been found to be reduced in such disorders as anxiety disorder (especially post-traumatic stress disorder, PTSD), depression, and schizophrenia (Garcia-Rill 1997). Another "preattentional" measure, the startle response, could be used, however, due to its marked habituation, measurement time is too prolonged (>20 min), and because compliance using startling, loud stimuli could also be a problem, the use of the P50 potential is preferable.

Sensory gating deficits can be induced by stress and thus represent a serious impediment to proper performance under complex operational demands. We propose the development of a nanoscale module designed for the use of the P50 potential as a measure of sensory gating (Figure C.9).

A method to assess performance readiness could be used as a predictor of performance success, especially if it were noninvasive, reliable, and not time-consuming. If stress or other factors have produced decreased sensory gating, then remedial actions could be instituted to restore sensory gating to acceptable levels, e.g., coping strategies, relaxation techniques, pharmacotherapy. It should be noted that this technique also may be useful in detecting slowly developing (as a result of cumulative stress) chronic sensory gating deficits that could arise from clinical depression or anxiety disorder, in which case remedial actions may require psychopharmacological intervention with, for example, anxiolytics or antidepressants.

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