Educational fMRI: From the Lab to the Classroom.

Functional MRI (fMRI) findings hold many potential applications for education, and yet, the translation of fMRI findings to education has not flowed. Here, we address the types of fMRI that could better support applications of neuroscience to the classroom. This 'educational fMRI' comprises eight main challenges: (1) collecting artifact-free fMRI data in school-aged participants and in vulnerable young populations, (2) investigating heterogenous cohorts with wide variability in learning abilities and disabilities, (3) studying the brain under natural and ecological conditions, given that many practical topics of interest for education can be addressed only in ecological contexts, (4) depicting complex age-dependent associations of brain and behaviour with multi-modal imaging, (5) assessing changes in brain function related to developmental trajectories and instructional intervention with longitudinal designs, (6) providing system-level mechanistic explanations of brain function, so that useful individualized predictions about learning can be generated, (7) reporting negative findings, so that resources are not wasted on developing ineffective interventions, and (8) sharing data and creating large-scale longitudinal data repositories to ensure transparency and reproducibility of fMRI findings for education. These issues are of paramount importance to the development of optimal fMRI practices for educational applications.

Age Affects How Task Difficulty and Complexity Modulate Perceptual Decision-Making.

Decisions differ in difficulty and rely on perceptual information that varies in richness (complexity); aging affects cognitive function including decision-making, and yet, the interaction between difficulty and perceptual complexity have rarely been addressed in aging. Using a parametric fMRI modulation analysis and psychophysics, we address how task difficulty affects decision-making when controlling for the complexity of the perceptual context in which decisions are made. Perceptual complexity was varied in a factorial design while participants made perceptual judgments on the spatial frequency of two patches that either shared the same orientation (simple condition) or were orthogonal in orientation (complex condition). Psychophysical thresholds were measured for each participant in each condition and served to set individualized levels of difficulty during scanning. Findings indicate that discriminability interacts with complexity, to influence decisional difficulty. Modulation as a function of difficulty is maintained with age, as indicated by coupling between increased activation in fronto-parietal regions and suppression in the lateral hubs, however, age has a specific effect in the ventral anterior cingulate cortex (ACC), driven by performance at near-threshold (difficult) levels for the simpler stimulus combination condition, but not the more complex one. Taken together, our findings suggest that the context of difficulty, or what is perceived as important, changes with age, and that decisions that would seem neutral to younger participants, may carry more emphasis with age.

Face perception develops similarly across viewpoint in children and adolescents with and without autism spectrum disorder.

Atypical face perception has been associated with the socio-communicative difficulties that characterize autism spectrum disorder (ASD). Growing evidence, however, suggests that a widespread impairment in face perception is not as common as once thought. One important issue arising with the interpretation of this literature is the relationship between face processing and a more general perceptual tendency to focus on local rather than global information. Previous work has demonstrated that when discriminating faces presented from the same view, older adolescents and adults with ASD perform similarly to typically developing individuals. When faces are presented from different views, however, they perform more poorly-specifically, when access to local cues is minimized. In this study, we assessed the cross-sectional development of face identity discrimination across viewpoint using same- and different-view conditions in children and adolescents with and without ASD. Contrary to the findings in adults, our results revealed that all participants experienced greater difficulty identifying faces from different views than from same views, and demonstrated similar age-expected improvements in performance across tasks. These results suggest that differences in face discrimination across views may only emerge beyond the age of 15 years in ASD.

Behavioral evidence for a functional link between low- and mid-level visual perception in the autism spectrum.

BACKGROUND: Most investigations of visuo-perceptual abilities in the Autism Spectrum (AS) are level-specific, using tasks that selectively solicit either lower- (i.e., spatial frequency sensitivity), mid- (i.e., pattern discrimination) or higher-level processes (i.e., face identification) along the visual hierarchy. Less is known about how alterations at one level of processing (i.e., low-level) interact with that of another (i.e., mid-level). The aim of this study was to assess whether manipulating the physical properties (luminance vs texture) of local contour elements of a mid-level, visual pattern interferes with the discrimination of that pattern in a differential manner for individuals with AS. METHODS: Twenty-nine AS individuals and thirty control participants (range 14-27 years) were asked to discriminate between perfect circles and Radial Frequency Patterns (RFP) of two, three, five, and 10 radial frequencies (RF), or deformations along the pattern's contour. When RFP have few deformations (

Atypical Face Perception in Autism: A Point of View?

Face perception is the most commonly used visual metric of social perception in autism. However, when found to be atypical, the origin of face perception differences in autism is contentious. One hypothesis proposes that a locally oriented visual analysis, characteristic of individuals with autism, ultimately affects performance on face tasks where a global analysis is optimal. The objective of this study was to evaluate this hypothesis by assessing face identity discrimination with synthetic faces presented with and without changes in viewpoint, with the former condition minimizing access to local face attributes used for identity discrimination. Twenty-eight individuals with autism and 30 neurotypical participants performed a face identity discrimination task. Stimuli were synthetic faces extracted from traditional face photographs in both front and 20° side viewpoints, digitized from 37 points to provide a continuous measure of facial geometry. Face identity discrimination thresholds were obtained using a two-alternative, temporal forced choice match-to-sample paradigm. Analyses revealed an interaction between group and condition, with group differences found only for the viewpoint change condition, where performance in the autism group was decreased compared to that of neurotypical participants. The selective decrease in performance for the viewpoint change condition suggests that face identity discrimination in autism is more difficult when access to local cues is minimized, and/or when dependence on integrative analysis is increased. These results lend support to a perceptual contribution of atypical face perception in autism.

Dopamine transporter SLC6A3 genotype affects cortico-striatal activity of set-shifts in Parkinson's disease.

Parkinson's disease is a neurodegenerative condition that affects motor function along with a wide range of cognitive domains, including executive function. The hallmark of the pathology is its significant loss of nigrostriatal dopamine, which is necessary for the cortico-striatal interactions that underlie executive control. Striatal dopamine reuptake is mediated by the SLC6A3 gene (formerly named DAT1) and its polymorphisms, which have been largely overlooked in Parkinson's disease. Thirty patients (ages 53-68 years; 19 males, 11 females) at early stages of Parkinson's disease, were genotyped according to a 9-repeat (9R) or 10-repeat (10R) allele on the SLC6A3/DAT1 gene. They underwent neuropsychological assessment and functional magnetic resonance imaging while performing a set-shifting task (a computerized Wisconsin Card Sorting Task) that relies on fronto-striatal interactions. Patients homozygous on the 10R allele performed significantly better on working memory tasks than 9R-carrier patients. Most importantly, patients carrying a 9R allele exhibited less activation than their 10R homozygous counterparts in the prefrontal cortex, premotor cortex and caudate nucleus, when planning and executing a set-shift. This pattern was exacerbated for conditions that usually recruit the striatum compared to those that do not. This is the first study indicating that the SLC6A3/DAT1 genotype has a significant effect on fronto-striatal activation and performance in Parkinson's disease. This effect is stronger for conditions that engage the striatum. Longitudinal studies are warranted to assess this polymorphism's effect on the clinical evolution of patients with Parkinson's disease, especially with cognitive decline.

Effect of mild cognitive impairment on the patterns of neural activity in early Parkinson's disease.

We have previously observed decreased activation of corticostriatal loops involved in planning (cognitive loop) and execution (motor loop) of a set shift in patients with early Parkinson's disease (PD) compared with control subjects. Here, we aimed to assess whether cognitive impairment in PD could drive these differences. Nondemented patients underwent a comprehensive neuropsychological evaluation and participated in our Wisconsin Card Sorting task functional magnetic resonance imaging protocol. Patients were separated into 2 groups according to the presence of mild cognitive impairment (MCI). Patients with MCI displayed reduced activity in the cognitive corticostriatal loop, which includes the caudate nucleus and prefrontal cortex while planning a set shift, whereas non-MCI patients exhibited activation patterns similar to those of healthy participants from our previous studies. Furthermore, reduced activation was observed in the premotor cortex of the MCI patients. Finally, hippocampal activity, correlated with individual memory scores, suggesting a compensatory mechanism in patients with preserved memory. These results suggest that the presence of MCI in PD affects activity in the prefrontal cortex and caudate nucleus as well as motor-related regions.

Investigating the interaction between low and intermediate levels of spatial vision at different periods of development.

Although much research has investigated the visual development of lower (local) and higher levels (global) of processing in isolation, less is known about the developmental interactions between mechanisms mediating early- and intermediate-level vision. The objective of this study was to evaluate the development of intermediate-level vision by assessing the ability to discriminate circular shapes (global) whose contour was defined by different local attributes: luminance and texture. School-aged children, adolescents, and adults were asked to discriminate a deformed circle (radial frequency patterns or RFP) from a circle. RFPs varied as a function of (a) number of bumps or curvatures (radial frequency of three, five, and 10) and (b) the physical attribute (luminance or texture) that defined the contour. Deformation thresholds were measured for each radial frequency and attribute condition. In general, results indicated that when compared to adolescents and adults children performed worse only when luminance-defined shapes had fewer curvatures (i.e., three and five), but for texture-defined shapes, children performed worse across all types of radial frequencies (three, five, and 10). This suggests that sensitivity to global shapes mediated by intermediate level vision is differentially affected by the type of local information defining the global shape at different periods of development.

Face processing changes in normal aging revealed by fMRI adaptation.

We investigated the neural correlates of facial processing changes in healthy aging using fMRI and an adaptation paradigm. In the scanner, participants were successively presented with faces that varied in identity, viewpoint, both, or neither and performed a head size detection task independent of identity or viewpoint. In right fusiform face area (FFA), older adults failed to show adaptation to the same face repeatedly presented in the same view, which elicited the most adaptation in young adults. We also performed a multivariate analysis to examine correlations between whole-brain activation patterns and behavioral performance in a face-matching task tested outside the scanner. Despite poor neural adaptation in right FFA, high-performing older adults engaged the same face-processing network as high-performing young adults across conditions, except the one presenting a same facial identity across different viewpoints. Low-performing older adults used this network to a lesser extent. Additionally, high-performing older adults uniquely recruited a set of areas related to better performance across all conditions, indicating age-specific involvement of this added network. This network did not include the core ventral face-processing areas but involved the left inferior occipital gyrus, frontal, and parietal regions. Although our adaptation results show that the neuronal representations of the core face-preferring areas become less selective with age, our multivariate analysis indicates that older adults utilize a distinct network of regions associated with better face matching performance, suggesting that engaging this network may compensate for deficiencies in ventral face processing regions.

Visual bandwidths for face orientation increase during healthy aging.

Perception of visual motion declines during healthy aging, and evidence suggests that this reflects decreases in cortical GABA inhibition that increase neural noise and motion bandwidths. This is supported by neurophysiological data on motion perception in senescent monkeys. Much less is known about deficits in higher level form vision. For example, face perception of frontal views remains relatively constant from adolescence through age 70 with a modest decline thereafter. However, we have shown recently that the elderly have a specific deficit in face matching when a transformation must be made between frontal and left or right side views. Here we use face view adaptation to demonstrate that this deficit results from significant broadening of cortical bandwidths for face orientation along with increased internal noise. A neural model shows that these bandwidths increase by a factor of 1.74 between age 26 and age 67 years. This is similar to the increase reported for motion bandwidths in senescent monkeys. Furthermore, the neural model demonstrates that head orientation bandwidth increases can arise from decreased cortical inhibition. Thus, high levels of form vision degrade in parallel with higher levels of motion perception and likely result from similar causes.

Seeing an unfamiliar face in rotational motion does not aid identity discrimination across viewpoints.

Discriminating the identity of static face views is viewpoint-dependent (Lee, Matsumiya, & Wilson, 2006), yet the benefit of facial motion on improving cross-view discrimination remains unclear. We investigate here, whether seeing a face rotating in a single direction reduces the viewpoint dependence of neighboring views, in particular, along the trajectory of that motion direction. Results indicate that seeing an unfamiliar face rotating in a given direction does not aid identity discrimination of neighboring views regardless of the direction of rotation. These findings suggest that unfamiliar faces are represented in a view-specific manner.

Preservation of shape discrimination in aging.

The representation of objects becomes increasingly complex at higher levels of the human visual cortex. Shapes of intermediate complexity serve as a step in the representation of such intricate constructs. Healthy aging has adverse effects on cortical function, and we sought to determine the effects of age on the efficacy and speed of neuronal mechanisms underlying shape processing. Using deformed circular shapes, we probe object representation by varying the characteristics that define the shape and by assessing lateral interactions among shapes. Results indicate that performance declines with age for shapes defined by texture but not by luminance. However, there is no age-related slowing for the processing of shape, and probes of lateral interactions reveal spared function for complex shape combinations. Findings suggest that the effect of age on shapes defined by texture arises from lower stages of visual processing, and that the representation of shape combinations is spared because of its robust nature.

Aging disrupts the neural transformations that link facial identity across views.

Healthy human aging can have adverse effects on cortical function and on the brain's ability to integrate visual information to form complex representations. Facial identification is crucial to successful social discourse, and yet, it remains unclear whether the neuronal mechanisms underlying face perception per se, and the speed with which they process information, change with age. We present face images whose discrimination relies strictly on the shape and geometry of a face at various stimulus durations. Interestingly, we demonstrate that facial identity matching is maintained with age when faces are shown in the same view (e.g., front-front or side-side), regardless of exposure duration, but degrades when faces are shown in different views (e.g., front and turned 20 degrees to the side) and does not improve at longer durations. Our results indicate that perceptual processing speed for complex representations and the mechanisms underlying same-view facial identity discrimination are maintained with age. In contrast, information is degraded in the neural transformations that represent facial identity across views. We suggest that the accumulation of useful information over time to refine a representation within a population of neurons saturates earlier in the aging visual system than it does in the younger system and contributes to the age-related deterioration of face discrimination across views.

Evaluating shape after-effects with radial frequency patterns.

Mechanisms selective for complex shape are vulnerable to adaptation techniques historically used to probe those underlying performance in lower-level visual tasks. We explored the nature of these shape after-effects using radial frequency patterns. Adapting to a radial frequency pattern resulted in a strong and systematic after-effect of a pattern that was 180 degrees out of phase with the adapting pattern. This after-effect was characterized as both a shift in the point of subjective equality and an increase in response uncertainty. The after-effect transferred across adapting pattern contrast and adaptor amplitude, suggesting an involvement from shape-specific mechanisms located at higher processing stages along the visual pathway. Moreover, our results suggested that the shift in the point of subjective equality was guided by global processing mechanisms, whereas the increase in uncertainty reflected activity from local processing mechanisms. Together, these results suggest that shape-specific after-effects reflect gain control processes at various stages of processing along the ventral pathway.

Dynamics of shape interaction in human vision.

Spatial context can alter perceived shape, and temporal context can influence the perception of a stimulus. We sought to determine the time course of shape interactions by using a paradigm in which closed shape contours are laterally displaced over space and time. Target and masks are separated by various stimulus onset asynchrony (SOA) values, yielding forward, backward, and simultaneous masking conditions. Results indicate that spatial lateral interactions of shape are amplified by temporal asynchrony, reaching a peak at SOAs of 80-110 ms. Mask amplitude scales all effects and masking is shape specific. When a single mask follows the target, both spatial configuration and mask onset transient are critical in determining depth of masking. When the target is followed by two sequential masks, the possibility of apparent motion determines whether one or both masks drive masking. These findings suggest that temporal interactions of shape are dependent on an interactive combination of shape specificity and transients, that apparent motion plays a modulatory role, and that target shape is determined after a temporal window, not at its onset.

Curvature population coding for complex shapes in human vision.

In the primate visual system relatively complex patterns such as curved shapes are first represented at intermediate levels of the ventral pathway. Furthermore, there is now evidence for the existence of curvature population coding in primate V4. We sought to determine whether similar encoding occurs in the human visual system by using a context-dependent lateral masking paradigm. In this paradigm a central closed contour comprising the test pattern is masked by surrounding larger or smaller patterns with various configurations. Results indicate that test thresholds are not affected by a circular control mask, and that elevations are greatest when curvature extrema of the mask are aligned with those of the target. These lateral interactions extend over greater than 1 degrees and are tuned for target shape. Masking increases with the number of local curvature extrema aligned with the target. Finally, masking persists when target and mask have orthogonal local orientations and increases with mask amplitude. These findings are incompatible with local orientation-selective interactions (V1-mediated) but are consistent with the existence of population codes based on curvature maxima at intermediate levels of processing (presumably V4) in human vision. The paradigm we introduce provides a new tool for evaluating the representation of complex percepts.

Central and peripheral interactions in the perception of optic flow.

The purpose of this work was to evaluate the effects of central and peripheral stimulation on the perception of optic flow over large spatial extents. Coherence thresholds were measured for RDKs simulating observer translation and radial motion. Experiments 1 and 3a measured sensitivity to a range of speeds for a circular central region, for several annular regions of increasing eccentricity, and for a full-field stimulus (80 degrees diameter). Results suggest that the spatial extent over which signals are integrated may vary in order to maximize the information available for perceptual representations. Experiments 2 and 3b evaluated central and peripheral interactions in a direction discrimination task, by comparing the effects of different signal strengths and directions in one of the two regions. The presence of noise dots (0% coherence) in either center or periphery led to a performance decrease from baseline measures. A similar decrease was observed when dots in the two regions moved in opposite directions. When dots in both regions moved in the same direction, a stronger peripheral signal led to facilitation of direction discrimination, whereas a stronger central signal did not. These findings suggest that central and peripheral inputs are not separable in the integration of optic flow, that they contribute equally to the percept under normal conditions (equal signal strength), and that peripheral stimulation seems important under ecologically relevant conditions such as poor visibility.