Attention is the ability of the brain to selectively concentrate on one aspect of the environment while ignoring other things. There are two types of attention in two separate regions of the brain. The prefrontal cortex directly behind the forehead is in charge of willful concentration; if you are studying for a test or writing a novel, the impetus and the orders come from there. But if there is a sudden, riveting event — the attack of a tiger or the scream of a child — it is the parietal cortex behind the ear that is activated.
Scientists have learned that these two brain regions sustain concentration when the neurons emit pulses of electricity at specific rates — faster frequencies for the automatic processing of the parietal region, slower frequencies for the deliberate, intentional work of the prefrontal region.
A credit line must be used when reproducing images; if one is not provided below, credit the images to "MIT. Previous image Next image. A new study by MIT neuroscientists reveals how the brain achieves this type of focused attention on faces or other objects: A part of the prefrontal cortex known as the inferior frontal junction IFJ controls visual processing areas that are tuned to recognize a specific category of objects, the researchers report in the April 10 online edition of Science.
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 IFJ has previously been implicated in a cognitive ability known as working memory, which is what allows us to gather and coordinate information while performing a task — such as remembering and dialing a phone number, or doing a math problem.
For this study, the researchers used magnetoencephalography MEG to scan human subjects as they viewed a series of overlapping images of faces and houses. Unlike functional magnetic resonance imaging fMRI , which is commonly used to measure brain activity, MEG can reveal the precise timing of neural activity, down to the millisecond.
The researchers presented the overlapping streams at two different rhythms — two images per second and 1. Each subject was told to pay attention to either faces or houses; because the houses and faces were in the same spot, the brain could not use spatial information to distinguish them. When the subjects were told to look for faces, activity in the FFA and the IFJ became synchronized, suggesting that they were communicating with each other.
The researchers also found that the communication was initiated by the IFJ and the activity was staggered by 20 milliseconds — about the amount of time it would take for neurons to electrically convey information from the IFJ to either the FFA or PPA.
The researchers believe that the IFJ holds onto the idea of the object that the brain is looking for and directs the correct part of the brain to look for it. The scientists next used similar techniques in the thalamus, which previous studies suggested plays a role in attention.
Manipulating the activity of neurons in an area called the visual thalamic reticular nucleus visTRN either before or during cue presentation increased errors, suggesting that the PFC interacts with the sensory thalamus to shift attentional focus. The team found that when the mice needed to focus on the light, activity dropped in the visTRN and rose in another part of the thalamus that processes visual information, the lateral geniculate nucleus LGN.
Finally, the researchers developed a technique to directly measure nerve cell inhibition. They found that LGN neurons were inhibited more when the mice had to concentrate on the sound. References: Thalamic control of sensory selection in divided attention. Epub Oct PMID: Site Menu Home. Search Health Topics. Search the NIH Guide.
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