The domestic cat is a very popular companion animal. However, there is very little work focusing on cat-specific physiology and behavior. In this review, we introduce our studies uncovering scent signals for species- and sex-recognition and the behavioral significance of the silver vine response in cats. Cat urine emits a specific catty smell. Our chemical analysis identified a sulfur-containing volatile organic compound, 3-mercapto-3-methyl-1-butanol, that is detectable in the urine of cats but not of dogs and humans. In addition, its level varies between sexes; its level is markedly higher in intact males than in castrated males or females. These indicate that the sulfur-containing compound is a urinary scent signal involved in species- and sex-recognition in cats. The other characteristic in cats is the behavioral response to silver vine, which comprises licking and chewing the plants, rubbing against the plants, and rolling over on the plants. Previous studies identified some bioactive compounds designated as matatabilactones from the plants, but little is known about why cats do the response to the plants. Our analyses found that nepetalactol which was missed in the plants is a potent bioactive compound for the response and stimulates the μ-opioid system which is responsible for the euphoria in humans. Nepetalactol has the repellent activity of pest insects such as mosquitoes. The rubbing and rolling responses to the plants transfer nepetalactol onto the feline fur that repels mosquitoes. The licking and chewing of the plants changes not only emission levels of nepetalactol and matatabilactones but also their contents which increase bioactivities toward cats and mosquitoes. These findings improve our understanding of the species-specific physiology and behavior in cats.

The present study examined long-term retention of learning of single alternate reward series in rats. Rats were given seven trials in a straight runway daily. During acquisition training of 16 days, Group SA (single alternate) received a series of seven trials of RNRNRNR (R: reward, N: non-reward) daily, whereas Group RD (random) was given presentation of either of RNRNNRR, RNNRRNR, RRNNRNR, or RRNRNNR in blocks of four days. After retention interval of 23 days, both groups were trained with a single alternate series of RNRNRNR as a test for 16 days. Anticipation of reward events in the series was indexed by slower running in non-rewarded trials than in rewarded trials. Although differentiation in running speed between rewarded and non-rewarded runs was not evident at the end of the acquisition training, Group SA developed reward-anticipation performance significantly faster than Group RD during the test. The results suggest that rats can retain learning of the single alternate series for a long period.