Thursday, November 16, 2006

Is there a biology of intelligence?

Because I once had an article in Behavioral and Brain Science, I receive email on final drafts of forthcoming articles for review. The purpose of this post is to point you to an interesting review and synthesis by R.E. Jung and R.J. Haier that will appear in a future issue. Its title is "The Parieto-Frontal Integration Theory (P-FIT) of Intelligence: Converging Neuroimaging Evidence." (Note added in Sept, 2007: the reference is Behavioral and Brain Sciences (2007) 30, 135-187)

The article reviews 37 modern neuroimaging studies, including functional (i.e. functional Magnetic Resonance Imaging, Positron Emission Tomography) and structural (i.e. Magnetic Resonance Spectroscopy, Diffusion Tensor Imaging,Voxel Based Morphometry)paradigms. They converge on a striking consensus suggesting that variations in a distributed network predict individual differences found on intelligence and reasoning tasks. They describe this network as the Parieto-Frontal Integration Theory: P-FIT. (How is a network a theory? Oh well, not to worry).

The P-FIT includes, by Brodmann Areas (BAs): dorsolateral prefrontal cortex (BAs 6, 9, 10, 45, 46, 47), the inferior (BAs 39/40) and superior parietal (BA 7) lobe, the anterior cingulate (BA 32), and regions within the temporal (BAs 21, 37) and occipital lobes (BAs 18 & 19). White matter regions (i.e., arcuate fasciculus) are also implicated.

The P-FIT is examined in light of findings from both human lesion studies, including missile wounds, frontal lobotomy/leukotomy, temporal lobectomy, and lesions resulting in damage to the language network (e.g., aphasia), as well as from imaging research identifying brain regions under significant genetic control. Overall, they conclude that modern neuroimaging techniques are beginning to articulate a biology of intelligence. They propose that the P-FIT provides a parsimonious account for many of the empirical observations to-date relating individual differences in intelligence test scores to variations in brain structure and function. They hope the model provides a framework for testing new hypotheses in future experimental designs.

Here is a graphic of the brain areas (copyright Cambridge University Press).

Legend: Brain regions by Brodmann Area (BA) associated with better performance on measures of intelligence and reasoning. Numbers represent BAs; solid blue circles = predominant left hemisphere associations; shadow blue circle = predominant left medial associations; shadow red circles = predominant bilateral associations; yellow arrow = arcuate fasciculus.

No comments:

Post a Comment