| Individuals with nonverbal learning disabilities (NLD) have an impaired ability to interpret facial expressions of emotion (FEE), the consequences of which can include progressively debilitating socioemotional disturbances. Thus, it is important to determine how the neuroanatomical structures underlying the perception of FEE in people with NLD differ from the normal population. To this end, functional magnetic resonance imaging was used to compare brain activation patterns in male and female adolescent subjects and male adult subjects with and without NLD. The subjects were presented with FEE at low and high intensities while they performed a gender decision task. Subjects with NLD displayed less activation in limbic areas responsible for processing emotion in the normal population. The NLD subjects exhibited more activity than controls in the orbital gyrus, inferior, middle and superior frontal gyri, fusiform and superior temporal gyri, insula, striatum and inferior and superior parietal lobules. Several of these structures participate in language function: as individuals with NLD have superior verbal abilities, it is probable that this population relies on their linguistic strengths to compensate for their nonverbal weaknesses whilst processing FEE. Additionally, because of an impaired capacity for attention to and discrimination of visual details, the NLD subjects showed more active responses for low intensity FEE in comparison to controls. This may have led to a failure of regions such as the middle and superior frontal and superior temporal gyri to habituate or sensitize appropriately to emotionally salient visual stimuli. In comparison with the normal population, people with NLD utilize different neural structures when processing FEE, in accordance with the strengths and deficits associated with the NLD syndrome. |
