Researchers at McGill University have been able to identify the specific areas of the brain which are involved in delayed gratification. The study, which was published recently in the European Journal of Neuroscience, was able to demonstrate that the area of the brain associated with memory, the hippocampus, and the area associated with pleasure, the nucleus accumbens, work collectively when we make critical decisions where time is a factor. Conversely, when these two areas are ‘disconnected’ decisions which are related to delayed gratification are disrupted. These findings have implications for a range of neuropsychiatric disorders, including ADHD together with anxiety and eating disorders, although it’s thought that it also has implications for common issues such as drug and alcohol abuse, gambling and overspending on credit cards.
The researchers used rats which had been trained to choose between different stimuli by pressing their nose against two identical shapes on a touchscreen. Of course there was an ulterior motive for pressing the shape, as each one was linked to a sugar pellet reward. After a while, the rats learned to negotiate between having a small reward of one pellet immediately, or waiting for a larger reward of four pellets. From the results it appeared as though the average rat, just like us, was happy to wait for a short while for a larger reward, but only if the reward was large enough and the time lapse wasn’t too great.
However, when the researchers disrupted the connection between the hippocampus and the nucleus accumbens, the rats’ behaviour changed. They became more impatient and less likely to wait, selecting the immediate reward despite the fact that it was smaller. The scientists were interested to see that lesions to other parts of the brain didn’t elicit the same response, even if they were to the prefrontal cortex, a part of the brain known to affect decision making.
The lead researcher, Professor Chudasama, explained that this type of decision making is something that we all have to deal with on a daily basis. She further explained that the hippocampus is believed to have a role in future planning, while the nucleus accumbens is the so-called ‘reward centre’ of the brain where dopamine, the chemical responsible for pleasure and reward, is received. It’s likely that further research will be carried out to gain a more full understanding of these connections.