Tremor, affecting a dystonic body part, is a frequent feature of adult-onset dystonia. However, our understanding of dystonic tremor pathophysiology remains ambiguous, as its interplay with the main co-occurring disorder, dystonia, is largely unknown. We used a combination of functional MRI, voxel-based morphometry and diffusion-weighted imaging to investigate similar and distinct patterns of brain functional and structural alterations in patients with dystonic tremor of voice (DTv) and isolated spasmodic dysphonia (SD). We found that, compared to controls, SD patients with and without DTv showed similarly increased activation in the sensorimotor cortex, inferior frontal (IFG) and superior temporal gyri, putamen and ventral thalamus, as well as deficient activation in the inferior parietal cortex and middle frontal gyrus (MFG). Common structural alterations were observed in the IFG and putamen, which were further coupled with functional abnormalities in both patient groups. Abnormal activation in left putamen was correlated with SD onset; SD/DTv onset was associated with right putaminal volumetric changes. DTv severity established a significant relationship with abnormal volume of the left IFG. Direct patient group comparisons showed that SD/DTv patients had additional abnormalities in MFG and cerebellar function and white matter integrity in the posterior limb of the internal capsule. Our findings suggest that dystonia and dystonic tremor, at least in the case of SD and SD/DTv, are heterogeneous disorders at different ends of the same pathophysiological spectrum, with each disorder carrying a characteristic neural signature, which may potentially help development of differential markers for these two conditions.

Faces are often used in psychological and neuroimaging research to assess perceptual and emotional processes. Most available stimulus sets, however, represent minimal diversity in both race and ethnicity, which may confound understanding of these processes in diverse/racially heterogeneous samples. Having a diverse stimulus set of faces and emotional expressions could mitigate these biases and may also be useful in research that specifically examines the effects of race and ethnicity on perceptual, emotional and social processes. The racially diverse affective expression (RADIATE) face stimulus set is designed to provide an open-access set of 1,721 facial expressions of Black, White, Hispanic and Asian adult models. Moreover, the diversity of this stimulus set reflects census data showing a change in demographics in the United States from a white majority to a nonwhite majority by 2020. Psychometric results are provided describing the initial validity and reliability of the stimuli based on judgments of the emotional expressions.

Focal dystonias are the most common type of isolated dystonia. Although their causative pathophysiology remains unclear, it is thought to involve abnormal functioning of the basal ganglia-thalamo-cortical circuitry. We used high-resolution research tomography with the radioligand 11 C-NNC-112 to examine striatal dopamine D 1 receptor function in two independent groups of patients, writer's cramp and laryngeal dystonia, compared to healthy controls. We found that availability of dopamine D 1 receptors was significantly increased in bilateral putamen by 19.6-22.5% in writer's cramp and in right putamen and caudate nucleus by 24.6-26.8% in laryngeal dystonia (all P 4 0.009). This suggests hyperactivity of the direct basal ganglia pathway in focal dystonia. Our findings paralleled abnormally decreased dopaminergic function via the indirect basal ganglia pathway and decreased symptom-induced phasic striatal dopamine release in writer's cramp and laryngeal dystonia. When examining topological distribution of dopamine D 1 and D 2 receptor abnormalities in these forms of dystonia, we found abnormal separation of direct and indirect pathways within the striatum, with negligible, if any, overlap between the two pathways and with the regions of phasic dopamine release. However, despite topological disorganization of dopaminergic function, alterations of dopamine D 1 and D 2 receptors were somatotopically localized within the striatal hand and larynx representations in writer's cramp and laryngeal dystonia, respectively. This finding points to their direct relevance to disorder-characteristic clinical features. Increased D 1 receptor availability showed significant negative correlations with dystonia duration but not its severity, likely representing a developmental endophenotype of this disorder. In conclusion, a comprehensive pathophysiological mechanism of abnormal basal ganglia function in focal dystonia is built upon upregulated dopamine D 1 receptors that abnormally increase excitation of the direct pathway, downregulated dopamine D 2 receptors that abnormally decrease inhibition within the indirect pathway, and weakened nigrostriatal phasic dopamine release during symptomatic task performance. Collectively, these aberrations of striatal dopaminergic function underlie imbalance between direct and indirect basal ganglia pathways and lead to abnormal thalamo-motor-cortical hyperexcitability in dystonia.

Aberrant sensory processing plays a fundamental role in the pathophysiology of dystonia; however, its underpinning neural mechanisms in relation to dystonia phenotype and genotype remain unclear. We examined temporal and spatial discrimination thresholds in patients with isolated laryngeal form of dystonia (LD), who exhibited different clinical phenotypes (adductor vs. abductor forms) and potentially different genotypes (sporadic vs. familial forms). We correlated our behavioral findings with the brain gray matter volume and functional activity during resting and symptomatic speech production. We found that temporal but not spatial discrimination was significantly altered across all forms of LD, with higher frequency of abnormalities seen in familial than sporadic patients. Common neural correlates of abnormal temporal discrimination across all forms were found with structural and functional changes in the middle frontal and primary somatosensory cortices. In addition, patients with familial LD had greater cerebellar involvement in processing of altered temporal discrimination, whereas sporadic LD patients had greater recruitment of the putamen and sensorimotor cortex. Based on the clinical phenotype, adductor form-specific correlations between abnormal discrimination and brain changes were found in the frontal cortex, whereas abductor form-specific correlations were observed in the cerebellum and putamen. Our behavioral and neuroimaging findings outline the relationship of abnormal sensory discrimination with the phenotype and genotype of isolated LD, suggesting the presence of potentially divergent pathophysiological pathways underlying different manifestations of this disorder.

Background Up to 12% of patients with laryngeal dystonia report familial history of dystonia, pointing to involvement of genetic factors; however, its genetic causes remain unknown. Methods Using Sanger sequencing, we screened 57 patients with isolated laryngeal dystonia for mutations in known dystonia genes TOR1A (DYT1), THAP1 (DYT6), TUBB4A (DYT4) and GNAL (DYT25). Using functional MRI, we explored the influence of the identified mutation on brain activation during symptomatic task production. Results We identified one patient with laryngeal dystonia who was a GNAL mutation career. Compared to 26 patients without known mutations, the GNAL carrier had increased activity in the fronto-parietal cortex and decreased activity in the cerebellum. Conclusions Our data show that GNAL mutation may represent one of the rare causative genetic factors of isolated laryngeal dystonia. Exploratory evidence of distinct neural abnormalities in the GNAL carrier may suggest the presence of divergent pathophysiological cascades underlying this disorder.

The race of an individual is a salient physical feature that is rapidly processed by the brain and can bias our perceptions of others. How the race of others explicitly impacts our actions toward them during intergroup contexts is not well understood. In the current study, we examined how task-irrelevant race information influences cognitive control in a go/no-go task in a community sample of Black (n = 54) and White (n = 51) participants. We examined the neural correlates of behavioral effects using functional magnetic resonance imaging and explored the influence of implicit racial attitudes on brain-behavior associations. Both Black and White participants showed more cognitive control failures, as indexed by dprime, to Black versus White faces, despite the irrelevance of race to the task demands. This behavioral pattern was paralleled by greater activity to Black faces in the fusiform face area, implicated in processing face and in-group information, and lateral orbitofrontal cortex, associated with resolving stimulus-response conflict. Exploratory brain-behavior associations suggest different patterns in Black and White individuals. Black participants exhibited a negative association between fusiform activity and response time during impulsive errors to Black faces, whereas White participants showed a positive association between lateral OFC activity and cognitive control performance to Black faces when accounting for implicit racial associations. Together our findings propose that attention to race information is associated with diminished cognitive control that may be driven by different mechanisms for Black and White individuals.

Healthy development is a fundamental right of the individual, regardless of race, ethnicity, or social class. Youth require special protections of their rights, in part owing to vulnerabilities related to psychological and brain immaturity. These rights include not only protection against harm but opportunities for building the cognitive, emotional, and social skills necessary for becoming a contributing member of society. They apply to all youth, including those within the adult criminal justice system, which raises the legal question of when adult capacity and responsibility begin and special protections are no longer warranted. This article highlights ( a) empirical findings from developmental science on when psychological and neurobiological development reaches maturity; ( b) the extent to which this scientific knowledge guides current policies and practices in the treatment of youth in the United States; and ( c) emerging policies in the treatment of young people in the justice system based on developmental science. Expected final online publication date for the Annual Review of Law and Social Science, Volume 16 is October 13, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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