New research shows how brain prepares to start searching

November 13, 2013 by Ian Richards, University of Lincoln
New research shows how brain prepares to start searching
A packed car park.

Many of us have steeled ourselves for those 'needle in a haystack' tasks of finding our vehicle in an airport car park, or scouring the supermarket shelves for a favourite brand.

A new scientific study has revealed that our understanding of how the prepares to perform visual search tasks of varying difficulty may now need to be revised.

When people search for a specific object, they tend to hold in mind a of it, based on key attributes like shape, size or colour. Scientists call this 'advanced specification'. For example, we might search for a friend at a busy railway station by scanning the platform for someone who is very tall or who is wearing a green coat, or a combination of these characteristics.

Researchers from the School of Psychology at the University of Lincoln, UK, set out to better explain how these abstract visual representations are formed. They used fMRI scanners to record neural activity when volunteers prepared to search for a target object: a coloured letter amid a screen of other coloured letters.

Their findings, published in the journal Brain Research, are the first to fully isolate the different areas of the human brain involved in this "prepare to search" function. Surprisingly, they show that the advanced frontal areas of the brain, usually key to advanced cognitive tasks, appear to take a backseat. Instead it is the basic back areas of the brain and the sub-cortical areas that do the work.

Dr Patrick Bourke from the University of Lincoln's School of Psychology, who led the study, said: "Up until now, when researchers have studied visual search tasks they have also found that frontal areas of the brain were active. This has been assumed to indicate a control system: an 'executive' that largely resides in the advanced front of the brain which sends signals to the simpler back of the brain, activating visual memories. Here, when we isolated the 'prepare' part of the task from the actual search and response phase we found that this activation in the front was no longer present."

This finding has important implications for understanding the fundamental brain processes involved. It was previously thought that the Intra-parietal region of the brain, which is linked to visual attention, was the central component of the supposed "front-back" control network, relaying useful information (such as a shape or colour bias) from frontal areas of the brain to the back, where simple visual representations of the object are held. If the frontal areas are not activated in the preparation phase, this cannot be the case.

The study also showed that the pattern of brain activation varied depending on the anticipated difficulty of the task, even when the target object was the same. This indicates that rather than holding in mind a single representation of an object, a new target is constructed each time, depending on the nature of the task.

Dr Bourke added: "While consistent with previous brain imaging work on , these results change the interpretations and assumptions that have been applied previously. Notably, they highlight a difference between studies of animals' brains and those of humans.  Studies with monkeys convincingly show the front-back control system and we thought we understood how this worked. At the same time our findings are consistent with a growing body of brain imaging work in humans that also shows no frontal activation when short term memories are held."

Explore further: How visual representations are improved by reducing noise in the brain

More information: "Functional brain organization of preparatory attentional control in visual search" was published in the journal Brain Research (September 2013).

Related Stories

How visual representations are improved by reducing noise in the brain

November 6, 2013
Neuroscientist Suresh Krishna from the German Primate Center (DPZ) in cooperation with Annegret Falkner and Michael Goldberg at Columbia University, New York has revealed how the activity of neurons in an important area of ...

Lost your keys? Your cat? The brain can rapidly mobilize a search party

April 21, 2013
A contact lens on the bathroom floor, an escaped hamster in the backyard, a car key in a bed of gravel: How are we able to focus so sharply to find that proverbial needle in a haystack? Scientists at the University of California, ...

Blind brain receives 'visual' cues to identify shape

February 18, 2013
A significant number of blind humans, not unlike bats and dolphins, can localize silent objects in their environment simply by making clicking sounds with their mouth and listening to the returning echoes. Some of these individuals ...

New study decodes brain's process for decision making

November 8, 2013
(Medical Xpress)—When faced with a choice, the brain retrieves specific traces of memories, rather than a generalized overview of past experiences, from its mental Rolodex, according to new brain-imaging research from The ...

Learning to control brain activity improves visual sensitivity

December 4, 2012
Training human volunteers to control their own brain activity in precise areas of the brain can enhance fundamental aspects of their visual sensitivity, according to a new study. This non-invasive 'neurofeedback' approach ...

Visual working memory not as specialized in the brain as visual encoding, study finds

February 6, 2012
Researchers have long known that specific parts of the brain activate when people view particular images. For example, a region called the fusiform face area turns on when the eyes glance at faces, and another region called ...

Recommended for you

Research reveals atomic-level changes in ALS-linked protein

January 18, 2018
For the first time, researchers have described atom-by-atom changes in a family of proteins linked to amyotrophic lateral sclerosis (ALS), a group of brain disorders known as frontotemporal dementia and degenerative diseases ...

Fragile X finding shows normal neurons that interact poorly

January 18, 2018
Neurons in mice afflicted with the genetic defect that causes Fragile X syndrome (FXS) appear similar to those in healthy mice, but these neurons fail to interact normally, resulting in the long-known cognitive impairments, ...

How your brain remembers what you had for dinner last night

January 17, 2018
Confirming earlier computational models, researchers at University of California San Diego and UC San Diego School of Medicine, with colleagues in Arizona and Louisiana, report that episodic memories are encoded in the hippocampus ...

Recording a thought's fleeting trip through the brain

January 17, 2018
University of California, Berkeley neuroscientists have tracked the progress of a thought through the brain, showing clearly how the prefrontal cortex at the front of the brain coordinates activity to help us act in response ...

Midbrain 'start neurons' control whether we walk or run

January 17, 2018
Locomotion comprises the most fundamental movements we perform. It is a complex sequence from initiating the first step, to stopping when we reach our goal. At the same time, locomotion is executed at different speeds to ...

Neuroscientists suggest a model for how we gain volitional control of what we hold in our minds

January 16, 2018
Working memory is a sort of "mental sketchpad" that allows you to accomplish everyday tasks such as calling in your hungry family's takeout order and finding the bathroom you were just told "will be the third door on the ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.