Related Experiment Videos
Hyperbaric effects on sensorimotor reactivity studied with acoustic startle in the rat
J M David1, J J Risso, M Weiss
1Laboratoire de Neurophysiologie Pharmacologique, Université de Provence, U.A. CNRS 372, Marseille St-Jérôme, France.
Physiology & Behavior
|January 1, 1988
Summary
High heliox pressure impairs auditory startle responses in rats, likely due to ear barotrauma. However, it enhances electrically evoked startle responses in the brainstem, suggesting increased synaptic excitability.
Area of Science:
- Neuroscience
- Physiology
- Barobiology
Background:
- The acoustic startle reflex is a fundamental sensorimotor response.
- Understanding the effects of hyperbaric environments on neural pathways is crucial for diving and space exploration.
Purpose of the Study:
- To investigate the impact of heliox high pressure on startle responses.
- To differentiate between peripheral and central nervous system effects on the acoustic startle reflex under hyperbaric conditions.
Main Methods:
- Rats were exposed to heliox pressures up to 50 bars.
- Startle responses were elicited by auditory stimuli and direct electrical stimulation of the cochlear nucleus and nucleus reticularis pontis caudalis.
- Nuchal electromyography and whole-body accelerometry were used to measure response amplitude and latency.
Main Results:
- Tone-evoked startle response amplitude decreased significantly (50% of control) under high pressure, suggesting peripheral auditory system impairment (barotrauma).
- Electrically-evoked startle response amplitude from brainstem nuclei increased significantly (250% of control) under hyperbaric conditions.
- Startle reflex latencies were not affected by heliox high pressures.
Conclusions:
- High heliox pressure affects sensorimotor reactivity by impairing peripheral auditory function and enhancing synaptic transmission in the lower brainstem and spinal cord.
- These findings highlight a dual effect of hyperbaric conditions on different components of the acoustic startle reflex arc.