A brain-scan study conducted by a French research team suggests that language performance and differences in brain activity may be affected by a person's sex.
Researchers at Montpellier 1 University (UM1) say that they have found differences among male and female groups on activation strength linked to verbal fluency, i.e. word generation, in a new fMRI study.
The findings from previous fMRI studies identifying the neural basis of sex differences in language production are still in debate, according to background information in a research article published in the journal Cortex.
Particularly, the question of group differences in verbal abilities, which might account for neurocognitive differences elicited between men and women, still remain unresolved.
Despite the cerebral regions involved in both men and women being identical, men show greater activation than women, irrespective of performance levels in classical language regions - namely, frontal, temporal and occipital lobes, and cerebellum.
The researchers revealed that from a representative sample of 331 French speakers, students showing a sex difference for a verbal fluency task, with women scoring higher than men as reported in the literature, four groups of 11 healthy right handed subjects were selected a priori.
According to them, the selection was based on sex and contrasted scores in a fluency task, that is, high versus low verbal fluency scores.
The 44 subjects were submitted to a covert verbal fluency fMRI protocol, they revealed.
Besides a sex effect, the research team also noticed a performance effect irrespective of sex.
Low fluency subjects elicit greater activation in the anterior cingulate than high fluency subjects, with the later activating the cerebellum more than those with low performances.
The researchers say that the combined sex and performance effects play a role on activation strength.
High fluency men differ both from low fluency men and high and low fluency women, as they show more activation in the right precuneus and left dorsolateral prefrontal cortex and less activation in right inferior frontal gyrus.
The researchers also noticed that in low fluency women, the left anterior cingulate was activated more than in those with high fluency scores.
By dissociating sex and performance effects on brain regional activation strength, the study clearly shows either an effect exclusively related to sex in several regions, or another effect exclusively related to performance or indeed to the both in certain other regions.
Based on their observations, the researchers suggest that investigating the neural correlates of verbal fluency focusing on sex differences should take into account behavioural variations in order not to alter the conclusion, and better grasp the complexity of the phenomenon being studied.