Our complex environment and the limited processing capacity of our brain require us to focus our attention on one thing at a time. This allows us to process a specific stream of information selectively in the presence of other information. For example at a party you can focus your attention on the voice of the person you are talking to, without actively processing all the other voices around you. Sometimes we fail to focus our attention, and get distracted. This is not always a bad thing; certain situations actually require us to redirect our attention, for example when someone calls your name. Research on attention has focused primarily on our ability to maintain our attention. In the current study we look how the brain switches our attention to novel important information.
Now let’s take a step back and have a look at what happens in the brain when we focus our attention. Our brain can be divided into several specialized regions, for example regions processing sound, regions processing vision and regions executing movements. Within these regions there is an ever finer specialization. For example part of the visual cortex is specialized in processing visual information of faces, while another part of the visual cortex is specialized in processing visual information of scenes. When we are talking to someone and focus our attention on the person’s face, the brain will increase processing in the ‘face area’ and decrease processing in other parts of the visual cortex. This allows us to process the visual information of the face in more detail and prevents you from getting distracted easily. One brain regions that plays an important role in focusing attention is the prefrontal cortex. It increases communication with the brain region involved in processing the attended information and increases activity in that region.
When we switch our attention the prefrontal cortex is activated as well. But another region seems to play an important role here; the basal ganglia. In this study we investigated how these two brain regions interact to switch attention using functional magnetic resonance imaging. This technique allowed us to measure brain activity while participants were switching their attention. In addition we applied advanced analyses (dynamic causal modeling) to assess connectivity between brain regions.
In our study we asked participants to switch their attention between images of faces and scenes. A switch from a face to a scene requires, first, releasing attention from the face, and second, focusing attention on the scene. We showed that the basal ganglia play an important role in these two processes. The communication between the prefrontal cortex and specific regions of the visual cortex that is necessary to focus attention is controlled by the basal ganglia. Specifically, we found that when we switch our attention from a face to a scene, the basal ganglia will decrease communication between the prefrontal cortex and the ‘face area’ and enhance communication between the prefrontal cortex and the ‘scene area’.
Our findings advance our knowledge of human attention which is compromised in a number of diseases such as ADHD. They also highlight the importance of looking at the brain on a system-level, taking into account not only the activity in separate regions, but also the interaction between regions.
This post was written by Martine van Schouwenburg, former post doc of the lab and accompanies this paper:
MR van Schouwenburg, HEM den Ouden, R Cools (in press). Selective attentional enhancement and inhibition of fronto-posterior connectivity by the basal ganglia during attention switching. Cerebral Cortex.