[Cite as http://purl.org/au-research/grants/nhmrc/403994]
Prof Mathew Martin-Iverson
Brief description People and other animals startle when they here a sudden loud sound. How much one startles depends in part on how loud the sound is. The relationship between the loudness of the sound and the size of the startle resembles a ski slope. Each individual has a ski slope that differs from others; the beginning of the ski slope (threshold) occurs at a different loudness, the slope is a different steepness, and the height of the ski slope where the plateau occurs is different. There are genetic differences in ski slopes as well. The size of the startle reflex can also be reduced by preceding the startling sound with a quiet stimulus a few tens of milliseconds before the startling stimulus. This is known as prepulse inhibition of the startle reflex or PPI for short. There is much interest in PPI, because it differs in people with certain mental illnesses, such as schizophrenia or post-traumatic stress disorder, and certain neurological illnesses, such as Huntington's chorea. It is also affected by drugs, including stimulants, stress hormones, and cannabis. In almost all the hundreds of experiments on PPI the effect of the prepulse on the response to a startling stimulus is measured at only one startling stimulus loudness. This loudness can be at very different parts of the ski slope for different people or other animals: it may be in the steep slope for one person, well into the plateau for another, or even at the bottom of the ski slope below the threshold in others. The effect of PPI is very different depending on what part of the ski slope the loudness represents. A lack of consistent effects in the literature on PPI by drugs and genetics is explained by this difference. Experiments are planned that will investigate the effect of drugs that are similar to those that treat schizophrenia, stress hormones and cannabis on the effect of prepulses on the whole ski slope. This procedure will provide the consistency in results so far absent.
Funding Amount $AUD 252,761.74
Funding Scheme NHMRC Project Grants
Standard Project Grant