The article by Cook, Hammett and Larsson (2016) offers a significant contribution to the understanding of the relationship between neurochemical processes and cognitive performance, with a specific focus on the association between cortical GABA (gamma-aminobutyric acid) concentration, visuospatial intelligence and perceptual suppression in visual tasks. This investigation combines spectroscopic neuroimaging methods, psychometric tests and psychophysical paradigms to explore a long-standing hypothesis: that cognitive efficiency is related to the ability to suppress irrelevant information in sensory processing.
The central hypothesis of the study is based on the assumption that GABA-mediated inhibitory mechanisms play a key role in filtering out unnecessary visual stimuli, thus contributing to more efficient cognitive performance. To test this hypothesis, the authors measured GABA levels in the primary visual cortex of healthy individuals using magnetic resonance spectroscopy (MRS), and compared them with scores on a matrix reasoning subtest (WASI) and with visual suppression indices in first- and second-order stimuli.
The results revealed robust correlations between GABA levels and the three domains investigated: visuospatial intelligence (r = 0.83; p = 0.0054), magnitude of first- and second-order visual suppression (r = 0.88; p = 0.0017), and between visual suppression and intelligence (r = 0.87; p = 0.0021). These findings indicate that higher GABA concentrations in the visual cortex are associated with better performance in cognitive tasks requiring spatial reasoning, as well as with a greater ability to suppress redundant visual stimuli.
Interestingly, although first- and second-order suppression indices were not significantly correlated with each other, both showed a strong association with GABA and intelligence, suggesting that inhibitory mediation does not depend exclusively on a single type of stimulus, but reflects a more general control mechanism in visual processing. This finding is consistent with models of inhibition-stabilized networks (ISNs), such as the one proposed by Ozeki et al., in which inhibition acts not directly by suppressing the stimulus, but by stabilizing the excitatory responses of the system, allowing a more precise filtering of relevant information.
From a methodological point of view, the study adopts strategies consistent with the neuroimaging literature, using a standardized protocol for acquisition and analysis of the GABA signal, which includes the subtraction of edited spectra and control of variables such as the presence of cerebrospinal fluid. In addition, the intelligence test chosen — the matrix reasoning subscale of the WASI — is particularly sensitive to visuospatial abilities, which makes the results even more specific to the investigated domain.
In terms of implications, the findings support the idea that GABA may serve as a neurochemical marker of cognitive efficiency by modulating the perceptual signal and facilitating the suppression of sensory noise. This effect may be relevant both for understanding individual variations in intelligence and for understanding perceptual-cognitive deficits in disorders such as schizophrenia, in which reduced GABA levels have been documented. Although the study was limited to a small group of highly educated young adults, its conclusions pave the way for broader investigations that consider different cortical regions, cognitive domains, and clinical populations.
In summary, the paper by Cook et al. provides robust empirical evidence for a functional link between GABA levels in the visual cortex, perceptual suppression, and visuospatial intelligence. Such a connection not only reinforces theories that postulate intelligence as an integrative function of inhibitory control, but also suggests a specific neurobiological pathway—the GABAergic system—that could be targeted for future interventions and translational studies.
Reference:
COOK, Emily; HAMMETT, Stephen T.; LARSSON, Jonas. GABA predicts visual intelligence. Neuroscience Letters, v. 632, p. 50–54, 2016. Available at: https://doi.org/10.1016/j.neulet.2016.07.053. Accessed on: June 17, 2025.
