[15] From these results, they concluded that an increase in mesolimbic dopamine efflux is associated with the appetitive and consummatory stages of sexual behaviour in male rats.
[15] Additional studies have also provided further evidence for the role of the nucleus accumbens on sexual behaviour in rats.
[16] In this experiment, the role of the nucleus accumbens was characterized through recording neuronal activity of single cells in this area of the brain.
[16] It has been observed that in certain species, males allocate sperm differently due to the Coolidge effect.
[17] An experiment performed on an external fertilizing fish called Rhodeus amarus, also known as the European bitterling, was used to show that sperm can be allocated differently if a novel partner is around, but that it also happens if there is male-male competition.
[17] It is important to know that the European bitterling mating system works by females depositing their eggs into the gill filaments of freshwater mussels by her long ovipositor and then males proceed by ejecting their sperm into the gills of the mussel hosting the eggs.
[17] When the Coolidge effect was applied to this system, the experiment showed that it is the mussels, or the site of fertilization, that the males prefer to be novel.
[25][26][27][28] A study in decorated crickets, Gryllodes sigillatus, showed that even though females do display the Coolidge effect, the males in this species have no preference for novel mates.
[25] To measure the Coolidge effect, the variables examined were the amount of courtship for the preferred mate and the size of the spermatophore transferred to the female.
[25] The outcome of the experiment showed that there was no difference in the latency to re-mating of males confined with novel females and those paired with previous mates.
[25] This experiment would suggest that the Coolidge effect is not applicable since the males of the Gryllodes sigillatus do not prefer novel females.
[29] Caps at the end of these cylinders prevented access to the females but had a hole in them to allow their odors to pass through to the male's cage.
[31] In this study, male hamsters were given lesions to either the hippocampus or the perirhinal-entorhinal cortex or received a sham treatment.
[31] The results from this study revealed that the perirhinal-entorhinal cortex region of the brain in golden hamsters is crucial for the recognition of familiar conspecifics and certain social behaviors.
[31] The conclusion from this experiment was also consistent in rats and monkeys, since damage to this region of the brain impaired standard recognition memory, which would suggest that the hippocampal region of the brain is not crucial in social behavior memory, but rather, the perirhinal-entorhinal cortex.
[33] Although males typically will prefer novel mates every time the opportunity is present, there is a physical limit to the sex drive.
[6] An experiment performed on rats showed that when left to reproduce to sexual satiety, the motor ejaculatory behavior, intromission, and dislodging seminal plugs were all possible after multiple mates, but little to no sperm would be produced during ejaculation.
[6] Another study performed on rats showed the same results, but found data that concluded that reaching optimal chances of impregnating their mates happened after resting for 15 days.
[34] These experiments would suggest that one of the major limitations on the Coolidge effect is the physical boundaries of gamete production.
[36] Repeated mating with the same male also resulted in a decrease in proceptivity, which is thought to suggest sexual satiety.
[3] Their experiment, which used hamsters instead of rats, concluded that it does occur to a lesser degree in females, where the evolutionary advantage of mating with multiple partners is less straightforward.