Fluid intelligence, which is essential for human cognition and is linked to educational and professional success, social mobility, health, and longevity, as well as memory and other cognitive abilities, has been identified as a key feature of human cognition.
Fluid intelligence believed to be a key aspect of “active thinking,” including complex mental processes like abstraction, judgment, attention, strategy generation, and inhibition is used in everyday activities like planning a dinner party or completing a tax return.
There is ongoing debate about the exact nature of fluid intelligence, including whether it is a single ability or a group of abilities, and its relationship with the brain. Despite its importance in human behavior, the concept of fluid intelligence remains controversial.
Determining which parts of the brain are necessary for a particular ability requires studying patients who have damage or are missing those specific brain regions. However, these “lesion-deficit mapping” studies can be difficult to conduct due to the challenges of finding and testing patients with focal brain injuries.
As a result, past studies have largely relied on functional imaging (fMRI) techniques, which may not always be accurate.
Researchers from the UCL Queen Square Institute of Neurology and the National Hospital for Neurology and Neurosurgery at UCLH conducted the new study using the Raven Advanced Progressive Matrices (APM), the gold standard for measuring fluid intelligence, on 227 patients who had suffered damage to specific regions of the brain due to either a brain tumor or a stroke. The test has multiple-choice problems with visual patterns that get harder as you go. Each problem shows an unfinished geometric figure pattern and needs the selection of the missing component from a collection of numerous viable alternatives.
The researchers then devised a cutting-edge “lesion-deficit mapping” strategy to unravel the complex anatomical patterns of prevalent types of brain damage, such stroke.
The researchers approached the relationship between brain regions as a mathematical network, with connections representing the tendency of regions to be affected together due to the disease process or as a reflection of shared cognitive abilities.
This allowed researchers to map the various sections of the brain and identify which patients performed worse on the fluid intelligence test in relation to their injuries. This allowed them to decouple the brain map of cognitive skills from the patterns of damage.
Patients with right frontal lesions were shown to be more vulnerable to impairments in fluid intelligence, as opposed to a more generalized pattern of impairments in performance throughout the brain. Such damage is often seen in individuals with a variety of neurological diseases, such as traumatic brain injury and dementia, in addition to brain tumors and stroke.
The findings of their study show “for the first time that the right frontal regions of the brain are critical to the high-level functions involved in fluid intelligence, such as problem solving and reasoning,” adds lead author Professor Lisa Cipolotti.
“This supports the use of APM in a clinical setting, as a way of assessing fluid intelligence and identifying right frontal lobe dysfunction.
“Our approach of combining novel lesion-deficit mapping with detailed investigation of APM performance in a large sample of patients provides crucial information about the neural basis of fluid intelligence. More attention to lesion studies is essential to uncover the relationship between the brain and cognition, which often determines how neurological disorders are treated.”
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