Comparing brain activations associated with working memory and fluid intelligence

- Working memory and fluid intelligence tasks both activate fronto-parietal cortex.
- However, fronto-parietal activation is not limited to these cognitive domains.
- Fronto-parietal activation may represent goal-directed behaviour more generally.
- Caution in warranted in asserting a neural basis for improving fluid intelligence via training of working memory.

Working memory (WM) and fluid intelligence (Gf) are thought to be highly related, though psychometrically distinct cognitive constructs. Both are important in a wide range of cognitively demanding tasks, and predictive of success in educational, occupational, and social domains. From a cognitive perspective, WM and Gf may share a capacity constraint due to the shared demand for attentional resources. Neuroimaging investigations of these two cognitive constructs have suggested similar shared frontal and parietal areas of neural activation as well, though to our knowledge the two have not been investigated in the same population. Here, we examine group level functional activations for tasks of WM (dual n-back), Gf (Raven's Standard Progressive Matrices; RSPM), as well as a theoretically unrelated comparison task of visual word/pseudoword decoding (lexical decision task) in a large sample of healthy young adults (N = 63) aged 18-40. Consistent with previous research, results indicate large areas of fronto-parietal activation in response to increasing task demands for the n-back task (dorsolateral, ventrolateral, and rostral prefrontal cortex, premotor cortex, and posterior parietal cortex), which largely subsume similar but more circumscribed regions of activation for the RSPM and lexical decision tasks. These results are discussed in terms of a task-general central network which may underlie performance of WM, Gf, and word decoding tasks alike, and perhaps even goal-directed behaviour more generally.