What Research Challenges Do We Face in Studying Communication?

Scientists face three major challenges in understanding linguistic deficits and the brain. The greatest challenge is that there are no animal models to study. Scientists have good animal models for studying auditory communication, such as animals like frogs and birds that use sound in their courtship displays, or animals like insect-eating bats that use complex sounds to locate their food. There are no animal models, however, for studying the neural processing of language because language — that infinite capacity to combine words into unique phrases and sentences —  occurs only in humans.

The second challenge is overcoming resolution problems in space and time. Prior to functional brain imaging, language areas were determined post-mortem. Two specialized brain areas in humans, Broca’s and Wernicke’s regions, were first identified from deceased patients with severe language disorders. Functional brain imaging has greatly advanced our understanding of the relevant regions and connections. Functional magnetic resonance imaging (FMRI) helped identify additional brain regions associated with the processing of language, while diffusion tensor imaging (DTI) helped identify the connections between regions. Unfortunately, these techniques have poor resolution in time.

The timing, or sequencing of language processing has been studied with electrical activity (evoked potentials, or EPs, and electroencephalograms, or EEGs, as well as magnetic activity (magnetoencephalograms, or MEGs).  Unfortunately, these techniques have poor resolution in space.

For us to better understand higher-order language processing, therefore, we will need new techniques or a combination of techniques that provide good resolution in both space and time.

Finally, conflicting neuroimaging results must be reconciled. It is possible that the heterogeneous nature of language deficits in children with ASD leads to conflicting results. The inconsistency in results may be simply a consequence of studying different subgroups. Better genetic and/or behavioral categorization of children with ASD into subgroups for study will help resolve and reconcile divergent studies of language impairment and the brain.