How brain pays attention decoded

MIT neuroscientists have identified a brain circuit which is key to shifting our focus from one object to another.

Massachusetts Institute of Technology neuroscientists found how the brain achieves focused attention on faces or other objects.

They found that a part of the prefrontal cortex known as the inferior frontal junction (IFJ) controls visual processing areas that are tuned to recognise a specific category of objects.

Scientists know less about this type of attention, known as object-based attention, than spatial attention, which involves focusing on what's happening in a particular location.

"However, the new findings suggest that these two types of attention have similar mechanisms involving related brain regions," said Robert Desimone, the Doris and Don Berkey Professor of Neuroscience, director of MIT's McGovern Institute for Brain Research, and senior author of the paper

"The interactions are surprisingly similar to those seen in spatial attention. It seems like it's a parallel process involving different areas," Desimone said.

In both cases, the prefrontal cortex - the control center for most cognitive functions - appears to take charge of the brain's attention and control relevant parts of the visual cortex, which receives sensory input.

For spatial attention, that involves regions of the visual cortex that map to a particular area within the visual field.

In the new study, the researchers found that IFJ coordinates with a brain region that processes faces, known as the fusiform face area (FFA), and a region that interprets information about places, known as the parahippocampal place area (PPA).

The FFA and PPA were first identified in the human cortex by Nancy Kanwisher, the Walter A Rosenblith Professor of Cognitive Neuroscience at MIT.

For this study, the researchers used magnetoencephalography (MEG) to scan human subjects as they viewed a series of overlapping images of faces and houses.

The researchers presented the overlapping streams at two different rhythms - two images per second and 1.5 images per second - allowing them to identify brain regions responding to those stimuli.

Each subject was told to pay attention to either faces or houses; because the houses and faces were in the same spot, the brain couldn't use spatial information to distinguish them.

When the subjects were told to look for faces, activity in the FFA and the IFJ became synchronised, suggesting that they were communicating with each other.

When the subjects paid attention to houses, the IFJ synchronised instead with the PPA, researchers found.