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Figure C.9. Nanotechnology application: helmet incorporating P50 midlatency auditory evoked potential recording and near-infrared detection of frontal lobe blood flow to measure sensory gating and hypofrontality, respectively. A. Evoked potential module including audio stimulator (earphones), surface electrodes (vertex, mastoids, forehead), amplifiers, averager with wave recognition software, and data storage device for downloading. B. Near-infrared detection module for frontal lobe blood flow measurement. C. Flip-down screen for tracking eye movements and display of results from sensory gating and frontal blood flow measurements.

Implementation of this methodology would be limited to the ability to record midlatency auditory evoked responses in varied environments. The foreseen method of implementation would involve the use of an electronically shielded helmet (Figure C.9) containing the following: (1) P50 potential recording electrodes at the vertex, mastoids, and ground; (2) eye movement recording using a flip-down transparent screen to monitor the movements of one eye within acceptable limits that do not interfere with P50 potential acquisition; and (3) electrodes on the forehead to monitor muscle contractions that could interfere with P50 potential acquisition. The helmet would incorporate an audio stimulator for delivering click stimuli, operational amplifiers for the three measures, averaging software, wave detection software (not currently available), and simple computation and display on the flip-down screen of sensory gating as a percent. A high percentage compared to control conditions would be indicative of a lack of sensory gating (indicating increased distractibility, uncontrolled anxiety, etc.). An individual could don the helmet and obtain a measure of sensory gating within 5-7 minutes.

The applications for this nanotechnology would be considerable, including military uses for self-monitoring human performance in advance of and during critical maneuvers; for self-monitoring by astronauts on long-duration space missions; for pilots, drivers and operators of sensitive and complex equipment, etc. It should be noted that this physiological measure can not be "faked" and is applicable across languages and cultures.

Hypofrontality

In general, the role of the frontal cortex is to control, through inhibition, those old parts of the brain we inherited from our early ancestors, the emotional brainstem (Damasio 1999). If the frontal cortex loses some of its inhibitory power, "primordial" behaviors are released. This can occur when the cortex suffers from decreased blood flow, known as "hypofrontality." Instinctive behaviors then can be released, including, in the extreme, exaggerated fight versus flight responses to misperceived threats, i.e., violent behavior in an attempt to attack or flee. "Hypofrontality" is evident in such disorders as schizophrenia, PTSD, and depression, as well as in neurodegenerative disorders like Alzheimer's and Huntington's diseases. Decreased frontal lobe blood flow can be induced by alcohol. Damage, decreased uptake of glucose, reduced blood flow, and reduced function have all been observed in the frontal cortex of violent individuals and murderers.

The proposed method described below could be used to detect preclinical dysfunction (i.e., could be used to screen and select crews for military or space travel operations); to determine individual performance under stress (i.e., could be used to prospectively evaluate individual performance in flight simulation/virtual emergency conditions); and to monitor the effects of chronic stressors (i.e., monitor sensory gating during long-duration missions). This nanomethodology would be virtually realtime; would not require invasive measures (such as sampling blood levels of cortisol, which are difficult to carry out accurately, are variable and delayed rather than predictive); and would be more reliable than, for example, urine cortisol levels (which would be delayed, or could be compensated for during chronic stress). Training in individual and communal coping strategies is crucial for alleviating some of the sequelae of chronic stress, and the degree of effectiveness of these strategies could be quantitatively assessed using sensory gating of the P50 potential as well as frontal lobe blood flow. That is, these measures could be used to determine the efficacy of any therapeutic strategy, i.e., to measure outcome.

A detecting module located over frontal areas with a display on the flip-down screen could be incorporated in the helmet to provide a noninvasive measure of frontal lobe blood flow for self-monitoring in advance of critical maneuvers. The potential nanotechnology involved in such measures has already been addressed (Chance and Kang n.d.). Briefly, since hemoglobin is a strong absorber, changes in this molecule could be monitored using near-infrared detection. This promising field has the potential for monitoring changes in blood flow as well as hemoglobin saturation, a measure of energy usage.

Peripheral nanotechnology applications such as P50 potential recordings and frontal blood flow measures are likely to provide proximal, efficient, and useful improvements in human performance. Nanotechnology, by being transparently integrated into our executive functions, will become part of the enculturation process, modulating brain structure and driving our evolution.

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