Life is full of choices. But how do individuals know what their preferences are and how do they act on them? And what leads mothers to make choices that benefit or lead to neglect of her offspring? Based on research performed using laboratory rats, a team of neuroscience researchers at Rutgers University-Newark suggest that an intricate system exists within the brain for establishing individual preferences, which ultimately impacts choices.
In the article, "Preference for cocaine-versus pup-associated cues differentially activates neurons expressing either Fos or CART in lactating, maternal rodents," which is in press for the September 2005 volume of the journal Neuroscience, Rutgers-Newark neuroscience professor Joan Morrell and her colleague Brandi Mattson reveal that individual preferences can be linked to the activation of specific sets of neurons within the brain. The researchers used postpartum rats in order to establish preferences and analyze how the mother rats' brains functioned when they selected an environment associated with their pups or another environment associated with the drug cocaine. In the experiment, rats learned over four days in which distinct environments they had access to their pups versus where they had access to cocaine. Following a 24-hour wait, the rats were given the opportunity to choose either the environment where they anticipated they would find either their pups or where they would find cocaine.
Using a computer program, the researchers recorded the rats' time and activity in each chamber as a means of determining their preferences for pups or cocaine. Then, the researchers analyzed and recorded the rats' brain activity at the time of their environmental choice.
According to Dr. Morrell, the analysis revealed clear patterns of neuronal activity when the rats made their choices and showed that specific brain regions were active when the animals were making one choice (pup-associated environment) in favor of another one (drug-associated environment). The researchers determined this by tracking the presence of proteins that demonstrate the activity of neurons within the brain.