fMRI Investigation of Working Memory for Faces in Autism: Visual Coding and Underconnectivity with Frontal Areas

Abstract

Brain activation and functional connectivity were investigated in high functioning autism using functional magnetic resonance imaging in an n-back working memory task involving photographic face stimuli. The autism group showed reliably lower activation compared with controls in the inferior left prefrontal area (involved in verbal processing and working memory maintenance) and the right posterior temporal area (associated with theory of mind processing). The participants with autism also showed activation in a somewhat different location in the fusiform area than the control participants. These results suggest that the neural circuitry of the brain for face processing in autism may be analyzing the features of the face more as objects and less in terms of their human significance. The functional connectivity results revealed that the abnormal fusiform activation was embedded in a larger context of smaller and less synchronized networks, particularly indicating lower functional connectivity with frontal areas. In contrast to the underconnectivity with frontal areas, the autism group showed no underconnectivity among posterior cortical regions. These results extend previous findings of abnormal face perception in autism by demonstrating that the abnormalities are embedded in an abnormal cortical network that manages to perform the working memory task proficiently, using a visually oriented, asocial processing style that minimizes reliance on prefrontal areas.

Sensory Sensitivities and Performance on Sensory Perceptual Tasks in High-functioning Individuals with Autism

“…The elementary sensory-higher cortical sensory dichotomy is also consistent with the pattern of dichotomous deficits reported in the motor, memory, language, and abstraction domains in studies of the profile of neuropsychologic functioning in high functioning individuals with autism (Minshew, Goldstein, & Siegel, 1997;Williams, Goldstein & Minshew, 2006) and of the impairments in integration of information causing postural instability (Minshew, Sung, Jones, & Furman, 2004). Functional imaging studies using social, language, and reasoning tasks have provided evidence of a generalized pattern of underdevelopment of the higher-order circuitry necessary for these tasks Just et al, 2004;Just et al, 2007;Kana et al, 2006Kana et al, , 2007Koshino et al, 2007;Minshew, Sweeney, & Luna, 2002). The presence of the same pattern of elementary ability-higher ability dissociation in the sensory and motor domains as in the memory, language and abstraction domains suggests that the sensory and motor impairments are involved by the same neurobiological process as the triad of signs and symptoms on which the diagnosis is based.…”

“…With regard to the current study of sensory perception, the neuropsychologic tests employed are coarse measures, and more refined tests might well reveal abnormalities in a greater proportion of subjects. Alternatively, the intact performance in some individuals with autism might also be related to compensatory mechanisms in the brain that function under relatively undemanding test circumstances but break down under more demanding circumstances; examination of brain activation with fMRI during test performance might reveal abnormal connectivity patterns, as has been documented in the case of verbal working memory (Koshino et al, 2005;Koshino et al, 2007). Yet another alternative is that a large number of verbal individuals with autism have sparing of the sensory system because this system develops very early in the brain and the onset of the developmental neurobiologic disturbance responsible for autism occurs later in most individuals.…”

A cross-syndrome study of the development of holistic face recognition in children with autism, Down syndrome, and Williams syndrome

“…Third, we omitted the memory component from the task in which participants had to learn the target faces in a training faces; in our task, the target face was presented simultaneously with the two response stimuli. We believe the last of these differences is most likely to explain the opposite direction of the part-whole effect (see Koshino et al, 2008, for a discussion on using face working memory tasks). In the Tanaka and Farah paradigm, participants first memorise faces.…”

“…The other option is that the improvement in task performance with age is related to other cognitive factors (attention, speed of processing, working memory capacity, and so forth). These options are not mutually exclusive (e.g., Koshino et al, 2008;Mervis et al, 1997).…”

“…Regions of the 'social brain network', including the superior temporal sulcus and the amygdala have also been found to exhibit atypical activation patterns in individuals with autism (Baron- Cohen & Belmonte, 2005;Hadjikani, et al, 2004;Pelphrey et al, 2005). Recently, in an adult sample with autism, Koshino et al (2008) found activation in a different location in the fusiform area in response to faces compared to control participants. They also reported lower functional connectivity of fusiform areas with frontal areas, implying that the face recognition system sits in an abnormal cortical network (see also, Hadjikani, Joseph, Snyder, & Tager-Flusberg, 2007).…”