Impairment of spatial performance by continuous intensive noise: A behavioral view.

Abstract

A wide range of animal and human investigations have tested the neurobiological and immunological aspects of noise. Few studies, however, have explored the behavioral characteristics of noise on neuromotor movements. To examine this correlation, we tested the effects of continuous intensive noise on retention and contextual transfer in a spatial memory task in adult male rats. The natural noise was recorded in a football stadium and set at high (HI), moderate (MI), and low (LI) intensities, levels corresponding to 86-90, 64-68, and 52-54 A-weighted decibels (dbA), respectively. Rats were trained in a Morris water maze for 3 consecutive days. On day 4, visible and probe tests were conducted under the same intensities. Retention was evaluated on day 7 with high-intensity noise exposure. The contextual transfer test was held on day 8 after exposure to 30-min highintensity noise. The escape latency and distance traveled were recorded and used for subsequent analyses. Our results showed significant increases in latency and distance traveled, attributable to increasing the noise intensity during the acquisition period. Additionally, performance in the LI group was significantly impaired in the retention test at the high intensity. In the contextual transfer test, results showed no significant increase except in the LI group, whereas a higher latency and distance traveled were found in the HI group. High-intensity noise appeared to damage the learning process. However, because the most robust results were found in the MI group, training with moderate-intensity noise can promote better performance under continuous highintensity noise.