An analysis of the effects of the developmental environment on the prepulse-inhibition of the auditory startle response.

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17530542
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Experimental psychology
• Research Institution: RIKEN
• Principal Investigator: YAMADA Kazuyuki RIKEN, Support Unit for Animal Experiments, Research Specialist, 動物実験支援ユニット, 専門職研究員 (50212288)
• Project Period (FY): 2005 – 2006
• Keywords: auditory startle response / prepulse inhibition / environmental enrichment / toy(s) / bedding materials / behavioral test battery / developmental environment / housing environment

Research Abstract

The effect of the environmental factors during development in the prepulse-inhibition (PPI) of the auditory startle response in the mouse was examined from the viewpoint of environmental enrichment. The outline of experimental results is as follows.
1) The effect of the housing material: We began to house them with various bedding materials for four weeks after their weaning period. Then the behavior analysis was conducted from the age of eight weeks using the basic test battery, which consists of an open field, the light and dark box, the elevated plus maze, the auditory startle response, and the classical fear conditioning test. As a result, the behavior of mice variably changed according to the kind of bedding materials. We could not find bedding materials that prompted PPI, but found a material that reduced PPI. These results suggest that the environmental stimulation with the bedding materials plays a key role for the behavioral development of the individual mouse.
2) The effect of the rotation disk (toy): After their weaning period, a rotation disk was introduced in each home cage and a mouse was allowed to play with it freely for four weeks. Then the behavior analysis was conducted from the age of eight weeks using the basic test battery as described above. As a result, the introduction of the toy affected various behaviors of mice after four weeks housing with them. Especially, the introduction of the toy tended to prompt PPI, although it did not reach statistical significance. It is necessary to clarify the condition that could clearly prompt PPI.
In this research, results suggest that both bedding materials and the rotation disk can affect the housing environment and significantly effects on the behavioral development. However, these results are not necessarily parallel to each other. Therefore, further behavioral and biological experiments are required.