As we learn more things to recognize, some brain regions get bigger; others shrink.

Face recognition and place recognition are both critical for everyday interactions, and they both depend on specialized regions of the brain. Neuroscientists generally suspect that as these regions develop, facial and place recognition improve. If so, there may be a lot of room for improvement. A recent study published in Science found that the parts of the brain that are associated with face and place recognition continue to develop well into adulthood, long after most of the brain’s architecture is in place.

The study looked at 26 children ages five through 12 and 26 adults aged 22 to 28. These subjects all participated in MRI and quantitative MRI imaging. These techniques allowed the researchers to assess the amount of brain matter in different regions, as well as the lipid composition of different parts of the brain. The brain is primarily made up of lipids—also known as fats—so differences in lipid distribution within the brain could be related to differences in functionality for different brain regions.

The researchers also looked at the activity of different brain regions. Participants’ responses to images of places and faces were tracked using fMRI, which allowed the scientists to see changes in blood flow to the brain that occur in response to stimulation. This helped them to identify which brain regions were primarily associated with recognizing these items.

By combining these measurements, the researchers could see if the relevant brain tissues were being pruned or being elaborated during childhood. They could also see which brain regions may be developing in response to the increased need for facial recognition that comes as we mature and which brain regions are getting more elaborate as we get exposed to an increasing number of places.

The brain region activated by faces in these participants was the posterior fusiform gyrus. This region appeared to have been pruned, meaning it was relatively smaller in adults as compared to children. This may be due to more efficient face processing due to increased age, which could require fewer neurons.

However, the opposite was seen in the brain region associated with place recognition, known as the collateral sulcus. This result suggests that efficiency-related pruning does not occur for place recognition in the same way that it occurs for face-recognition tasks.

The researchers saw that the composition of the brain tissues associated with these two tasks was the same in children but was significantly different in adults. So, even though these two brain regions are both associated with recognition tasks, their fat composition becomes different during the aging process, which suggests that their specialization also differs with aging.

To explain their findings, the researchers hypothesize that, during the aging process, there may be changes to the number of cells and their connections within the brain region associated with facial recognition. However, it is hard to see these specific cell-level morphological changes in live tissue, since collecting live samples of these brain tissues to analyze is generally not considered ethical. Future directions for this research could provide more insight into aging-related differences in other brain structures associated with discrete tasks as they become increasingly specialized, such as the language center of the brain.

Via: Ars Technica