Behind our foreheads lies the most evolutionarily advanced piece of the brain. This is the part of the cortex that makes us different from so many other animals. It is involved in decision-making, problem-solving and many other complex cognitive functions. However, this area, which is known as the frontal cortex, is not fully formed by the time of birth.
From birth until early adulthood, the frontal lobe undergoes massive pruning and organization that leads to a mature brain. All of the turmoil of adolescence is a part of the frontal lobe trying to sort itself out.
Researchers at the Hopkins School of Medicine, led by Stacey Perry, explored the functions of the frontal lobe in macaque monkeys. Many primates also undergo cortex development similar to humans. Because of this, macaques can be used to study mechanisms of cognitive development that can then be compared to human studies.
In particular, the team wanted to explore whether or not attention only appears in adult primates. Do juveniles and adults actually have different capabilities based on their age?
The animals were tested in a series of trials in which they were presented with stimuli on a computer screen. The stimuli consisted of different shapes which were superimposed by various line structures. In some cases, the macaques received a food pellet if they were able to attend to the shape of the object. This means that they were reinforced to recognize a specific shape and to choose that shape from two stimuli on successive trials.
In other cases, the macaques were trained to attend to the line structures and to disregard the shape that was simultaneously presented. This means that the macaques needed to forget their previous training in favor of the new one.
These two tasks test two different types of attention. In the first case, the monkeys were found to exhibit attention set formation, which means that they could pay attention to one feature over any others. In the second task, the macaques showed attention set-shifting which means that they shifted their attention from the shape in the image to the lines. The group used these two skills as determinants of higher cognitive function.
Juvenile macaques could not perform nearly as well on these tasks as the adult macaques. They experienced many more errors in completing these attention tests. When similar tests were done in humans, children who were five or six years old also made many more errors than adults. Children at this age have similar brain development to the juvenile macaques.
While it has been known that, anatomically, some structures are formed before others, this study showed that the functions of the frontal cortex are also based on age. Specifically, attention seems to mature later in development. If adults and children have different capabilities for attention, this could lead to questions about the best type of education for children.
This research suggests that macaques may be a useful model to study children with attentional and other developmental disorders.
