LONDON — Fluid intelligence is a defining factor of human cognition, according to scientists. It’s what helps us react to unexpected situations, formulate new ideas, and carefully plan strategies for success. Studies show that high fluid intelligence predicts professional prosperity, social mobility, health, and longevity, and also correlates with stronger additional cognitive capacities like memory. Now, new research has mapped the parts of the brain that support our ability to think quickly.
Scientists at University College London explain fluid intelligence is key to “active thinking,” which is an array of complex mental processes involved in abstraction, inhibition, judgment, attention, and strategy generation. We use fluid intelligence on a daily basis, while driving a car or organizing a dinner party, for example.
“Our findings indicate 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,” says lead study author Professor Lisa Cipolotti of the UCL Queen Square Institute of Neurology in a media release.
Despite modern science largely agreeing that fluid intelligence is a key aspect of what makes us human, it remains unclear whether it is a single or a cluster of cognitive abilities, and the exact nature of its relationship with the brain is still unknown. It’s also quite difficult for scientists to study these matters; in order to establish which parts of the brain are necessary for a certain ability, researchers must study patients in whom that part is either missing or damaged.
These so-called “lesion-deficit mapping” studies are not easy to conduct. So, earlier studies have mainly made use of functional imaging (fMRI) techniques, which are not entirely accurate and sometimes can be misleading.
A stroke could reveal the brain’s thinking centers
This latest project, led by UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery at UCLH researchers, included a total of 227 patients who had experienced either a brain tumor or stroke to specific parts of their brains. The team accomplished this using the Raven Advanced Progressive Matrices (APM): the best-established test of fluid intelligence.
The APM features various multiple choice visual pattern problems of increasing difficulty. Each of the problems show an incomplete pattern of geometric figures and asks participants to select the missing piece from a set of multiple possible choices.
Next, researchers introduced a novel “lesion-deficit mapping” approach that helped to disentangle the intricate anatomical patterns of common brain injuries, such as stroke. Study authors’ chosen approach treated the relations between brain regions like a mathematical network featuring networks describing the tendency of regions to be affected together, either due to the disease process itself or in reflection of common cognitive ability.
This strategy helped the research team disentangle the brain map of cognitive abilities from the damage patterns, facilitating mapping of the different parts of the brain and the determination of which patients did worse in the fluid intelligence task according to their injuries.
Brain damage confirms which regions handle thinking
Results show fluid intelligence-impaired performance was mostly limited to patients with right frontal lesions, as opposed to a wide set of regions distributed across the brain. Alongside brain tumors and stroke, researchers often saw similar damage in patients with a variety of other neurological conditions, such as traumatic brain injury and dementia.
“This supports the use of APM in a clinical setting, as a way of assessing fluid intelligence and identifying right frontal lobe dysfunction,” Prof. Cipolotti concludes.
“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.”
The study is published in the journal Brain.