Maha Adamo

The Functional Neuroanatomy of Spatial Attention in Autism Spectrum Disorder

This study investigated the functional neuroanatomical correlates of spatial attention impairments in autism spectrum disorders (ASD) using an event-related functional magnetic resonance imaging (FMRI) design. Eight ASD participants and 8 normal comparison (NC) participants were tested with a task that required stimulus discrimination following a spatial cue that preceded target presentation by 100 msec (short interstimulus interval [ISI]) or 800 msec (long ISI). The ASD group showed significant behavioral spatial attention impairment in the short ISI condition. The FMRI results showed a reduction in activity within frontal, parietal, and occipital regions in ASD relative to the NC group, most notably within the inferior parietal lobule. ASD behavioral performance improved in the long ISI condition but was still impaired relative to the NC group. ASD FMRI activity in the long ISI condition suggested that the rudimentary framework of normal attention networks were engaged in ASD including bilateral activation within the frontal, parietal, and occipital lobes. Notable activation increases were observed in the superior parietal lobule and extrastriate cortex. No reliable activation was observed in the posterior cerebellar vermis in ASD participants during either long or short ISI conditions. In addition, no frontal activation during short ISI and severely reduced frontal activation during long ISI was observed in the ASD group. Taken together, these findings suggest a dysfunctional cerebello-frontal spatial attention system in ASD. The pattern of findings suggests that ASD is associated with a profound deficit in automatic spatial attention abilities and abnormal voluntary spatial attention abilities. This article also describes a method for reducing the contribution of physical eye movements to the blood-oxygenation level dependent activity in studies of ASD.

Your Divided Attention, Please! The Maintenance of Multiple Attentional Control Sets over Distinct Regions in Space.

When non-informative peripheral cues precede a target defined by a specific feature, cues that share the critical feature will capture attention while cues that do not will be effectively ignored. We tested whether different attentional control sets can be simultaneously maintained over distinct regions of space. Participants were instructed to respond only to specific colored targets at specific locations. Most trials included non-predictive cues whose location and/or color were either congruent or incongruent with the spatial and/or color properties of the impending target. We observed contingent capture only for cues that were consistent with the attentional control set applied to that region of space. This is the first demonstration that separate attentional control sets can be simultaneously maintained at distinct spatial locations, with implications for the flexibility of endogenous control over automatic attentional orienting.

Multiple attentional control settings influence late attentional selection but do not provide an early attentional filter.

When one is responding to targets containing a specific feature, non-predictive peripheral cues that share this feature lead to faster responses to the target, while cues that do not contain the target feature effectively are ignored, providing evidence for the role of attentional control settings (ACSs) in the contingent capture hypothesis. It is unclear, however, at what stage of processing multiple ACSs are implemented. We took advantage of the excellent temporal resolution of electroencephalography to demonstrate that the maintenance of multiple ACSs influences later stages of attentional selection rather than providing an early attentional filter. N2pc analyses for cues and targets revealed a similar degree of spatial capture for any peripheral cue, regardless of control settings, with target P3s reflecting the application of the ACS color contingencies.

The functional architecture for face-processing expertise: FMRI evidence of the developmental trajectory of the core and the extended face systems

Expertise in processing faces is a cornerstone of human social interaction. However, the developmental course of many key brain regions supporting face preferential processing in the human brain remains undefined. Here, we present findings from an FMRI study using a simple viewing paradigm of faces and objects in a continuous age sample covering the age range from 6 years through adulthood. These findings are the first to use such a sample paired with whole-brain FMRI analyses to investigate development within the core and extended face networks across the developmental spectrum from middle childhood to adulthood. We found evidence, albeit modest, for a developmental trend in the volume of the right fusiform face area (rFFA) but no developmental change in the intensity of activation. From a spatial perspective, the middle portion of the right fusiform gyrus most commonly found in adult studies of face processing was increasingly likely to be included in the FFA as age increased to adulthood. Outside of the FFA, the most striking finding was that children hyperactivated nearly every aspect of the extended face system relative to adults, including the amygdala, anterior temporal pole, insula, inferior frontal gyrus, anterior cingulate gyrus, and parietal cortex. Overall, the findings suggest that development is best characterized by increasing modulation of face-sensitive regions throughout the brain to engage only those systems necessary for task requirements.

A picture says more than a thousand words: Behavioural and ERP evidence for attentional enhancements due to action affordances

Previous research has demonstrated that, in addition to ventral stream processing of object form, manipulable objects are represented functionally in the dorsal stream. Here, we demonstrate how the two streams interact via attentional selection and consolidation such that objects whose form fits the function of a previously seen object, such as a tool, benefit from attentional enhancements due to the action affordance of the tool. Using the attentional blink (AB) paradigm and event-related potentials (ERPs), we tested whether providing an action relationship between two objects appearing closely together in time counteracts the typical decrement observed for processing of the second item. We used images (experiments 1a and 2) and names (experiment 1b) of common tools, objects that can be acted upon by those tools, and unrelated objects. We found that pictorial presentation of a tool and its action counterpart results in a diminished attentional blink as well as enhanced attentional selection seen as a larger P3, relative to tools and unrelated objects, and that this attentional enhancement is not driven by semantic associations. This means that the action affordance instantiated by the perception of a tool will reduce the functional blindness normally observed when two targets are presented too closely in time, specifically when the physical properties of the tool that elicit an action affordance are perceived.

Parallel, independent attentional control settings for colors and shapes.

Attentional capture can be contingent on attentional control settings (ACSs), such that peripheral cues influence processing for a subsequent target only when they share a critical feature with the target. Our previous demonstration that two ACSs from within the same feature category can be maintained simultaneously allows us to investigate the processing stage at which such ACSs are implemented. We compared the relative efficacy of ACSs from two different feature categories (shape and color) that are associated with different levels within the visual processing hierarchy. Participants were instructed to respond to one of two colors at one location and one of two shapes at another location, while ignoring the nontarget color and shape. We observed that spatial capture was modulated by whether the cues fit an ACS, with slightly greater contingent capture effects for ACSs defined by color than by shape. Thus, two ACSs from different feature sets (color and shape) can be maintained in parallel, although effectiveness of the control set varied with the type of feature.

Development of brain systems for nonsymbolic numerosity and the relationship to formal math academic achievement

A central question in cognitive and educational neuroscience is whether brain operations supporting nonlinguistic intuitive number sense (numerosity) predict individual acquisition and academic achievement for symbolic or “formal” math knowledge. Here, we conducted a developmental functional magnetic resonance imaging (MRI) study of nonsymbolic numerosity task performance in 44 participants including 14 school age children (6–12 years old), 14 adolescents (13–17 years old), and 16 adults and compared a brain activity measure of numerosity precision to scores from the Woodcock–Johnson III Broad Math index of math academic achievement. Accuracy and reaction time from the numerosity task did not reliably predict formal math achievement. We found a significant positive developmental trend for improved numerosity precision in the parietal cortex and intraparietal sulcus specifically. Controlling for age and overall cognitive ability, we found a reliable positive relationship between individual math achievement scores and parietal lobe activity only in children. In addition, children showed robust positive relationships between math achievement and numerosity precision within ventral stream processing areas bilaterally. The pattern of results suggests a dynamic developmental trajectory for visual discrimination strategies that predict the acquisition of formal math knowledge. In adults, the efficiency of visual discrimination marked by numerosity acuity in ventral occipital–temporal cortex and hippocampus differentiated individuals with better or worse formal math achievement, respectively. Overall, these results suggest that two different brain systems for nonsymbolic numerosity acuity may contribute to individual differences in math achievement and that the contribution of these systems differs across development. Hum Brain Mapp 36:804–826, 2015.

The right time and the left time: Spatial associations of temporal cues affect target detection in right brain-damaged patients

Humans map timewords such as “yesterday” or “future” onto a mental timeline that holds temporally earlier events on the left side of space and temporally later events on the right side. The perception of time and spatial mapping both are partially subserved by right temporo-parietal brain regions. We tested stroke patients with right-hemisphere lesions on a spatio-temporal cueing task to see whether spatial associations of noninformative temporal cues would elicit the same cognitive deficits as do typical stimulus-driven exogenous cues. While our right brain-damaged patients were able to maintain a mental timeline with words referring to the past sitting to the left and words referring to the future sitting to the right, we also observed that the typical deficit in disengaging from incongruently cued locations persists for noninformative cues that are mapped onto a mental spatial continuum.