DISCUSSION PAPER: DEMONSTRATION OF EXPERIMENTAL TECHNIQUES

USING NONHUMAN PRIMATES

H. H. Reynolds, C. H. Kratochvil, G. L. Wilson, A. G. Koestler 0. L. Lewis, J. A Chisum, N. D. Catone, J. A. Tremblay, J. T. Murray

€3. G. Steinhauser, and K. H. Schultz 657lst Aerorriedical Research Laboratory, Holloiiian Air Force Base, N . M .

The increasing dignity attributed to man and the value placed on his life, particularly in Western society, has resulted in the use of infrahumans as man’s precursor or surrogate in the study of those environments that may pose a high risk to man under some planned or unplanned circumstance. Since exploration of the space environment and its assumed concomitant hazards have constituted a great unknown for man, there has evolved a requirement to ascertain first the degree of risk and then establish safety criteria for man. To this end, the Aero- medical Research Laboratory at Holloman Air Force Base, N. M. was estab- lished in the early fifties, beginning with the now famous sled rides of CoI. John Paul Stapp; then the Man High Balloon Project; later, the ballistic and orbital flights of Ham and Enos, the Project Mercury chimponauts; and more recently, accomplishing the extensive laboratory studies df rapid decompression, toxic hazards, ionizing radiation, visual incapacitation, deceleration from high speeds, and the expanding of experimental medicine and neurosciences programs.

As a part of the conference resulting in this monograph, the Holloman Aero- medical Laboratory brought to The New York Academy of Sciences an exhibit that is representative of four of its ongoing research projects. Two chimpanzees and two monkeys are the experimental subjects and are trained to perform both simple and complex operant tasks.

In all tasks developed by Aeromedical Laboratory scientists, the most basic question involves the integrity of the motor system of these nonhuman primates, since man is required to act effectively on his environment, generally using his limbs in the acts of locomotion or object manipulation. This is, of course, one of the prime reasons for using nonhuman primates as precursors for man; that is, they have a central nervous system quite like man’s and have hands that permit them to make fine tactual discriminations and that afford the means to grasp, hold, manipulate, and move objects within the environment. In addition, the sensory systems of the nonhuman primates are most similar to man’s, and allow the study of auditory and visual functioning under extreme conditions, which then provides some knowledge of what man may encounter under like circumstances.

An experimental drug-study chamber (FIGURE 1 ) houses a single rhesus mon- key that is required to press levers continually with right and left hands in response to red cue lights-inferential evidence of the integrity of the motor tracts. Addi- tionally, periodic visual and auditory signals are presented, and measures of response time are made to gather data concerning control and experimental latencies. At the Aeromedical Laboratory, ten chambers such as this one (FIGURE 2) permit the simultaneous exposure of several subjects to drugs or toxic agents with which man may come in contact, and ensures that effects on primary sense modalities are understood prior to any exposure of man.

A Plexiglas@’ restraint chair (FIGURE 3 ) is used to seat a rhesus monkey before a display-response panel, which requires continual monitoring and responding and permits an assessment of “vigilance” behavior. This task-arrangement may

381

382

be used in the study of any number of environments that may affect attention, motor integrity, and ability to persevere over extended periods of time.

One of the two chimpanzees is seated in a restraint chair before a display panel with response push-bottons (FIGURE 4) . This experimental paradigm requires that the chimp respond to rapidly changing visual signals that are randomly presented from one to two seconds apart. During exposure to increasing altitudes, the time of useful consciousness may be ascertained by the number of signals to which the subject can respond and by the recorded reaction times.

The last exhibit item is a reclining couch and display panel in which a chimpan- zee is the experimental subject (FIGURE 5) . In addition to visual, auditory, and choice-discrimination measures, there are physiological sensors for heart rate, respiration, temperature, and cortical EEG. This total configuration is employed in the study of altered atmospheric pressures, particularly that of the near-vacuum condition (150,000 feet), and helps to ensure that an astronaut on orbit or

Annals New York Academy of Sciences

FIGURE 1. Behavioral toxicology. Experimental drug-study chamber housing single rhesus monkey, required to press levers in response to red cue lights.

FIG

UR

E

2.

Ten

exp

erim

enta

l dru

g-st

udy

cham

bers

per

mit

the

sim

ulta

neou

s exp

osur

e of s

ever

al su

bjec

ts to

dru

gs o

r to

xic

agen

ts w

ith w

hich

man

may

co

me

in c

onta

ct.

w

00

w

384 Annals New York Academy of Sciences

FIGURE 3. A performance task for maintaining behavior (multiple experimental uses). A Plexiglas restrain chair seats a rhesus monkey before display-response panel that requires continual monitoring and responding.

Reynolds et al. : Discussion Paper 385

FIGURE 4. Useful consciousness and altered atmospheric pressure. Chimpanzee in restraint chair before a display panel with response push buttons, requiring response to rapidly changing visual signals.

386 Annals New York Academy of Sciences

FIGURE 5. Psychophysiology of rapid decompression. Reclining couch and display panel in which a chimpanzee is the experimental subject.

engaged in extravehicular activity (EVA) is afforded optimal safety devices and recovery techniques. This experiment has literally rewritten altitude physiology textbooks that previously claimed incapacitation and almost certain death when sudden and even short-duration exposure above 63,000 feet occurred.

All in all, the Aeromedical Laboratory at Holloman is devoted to man’s safety and survival through carefully designed laboratory investigations of high-risk situations. There is no other way that this is possible than with the use of man’s closest living relatives, in keeping with Western philosophy regarding man’s special place in this universe.