Fine motor challenges affect a substantial proportion of children on the autism spectrum, frequently impacting daily living activities, manual dexterity, handwriting, and social engagement. Although motor delays represent some of the earliest observable behavioral markers in early childhood, their underlying neurobiological architecture remains poorly understood. In particular, clinicians and developmental researchers have historically overlooked how biological sex modulates these neural substrates. Emerging neuroimaging evidence indicates that subcortical systems, specifically the dorsal striatum, play a pivotal role in motor control, motor learning, and habit formation. Investigating these subcortical circuits across early childhood provides crucial clarity on childhood milestones. A landmark longitudinal study has now demonstrated distinct neurostructural patterns governing fine motor development in autistic boys compared to autistic girls. By evaluating both structural volume and corticostriatal white matter microstructure across critical developmental windows, researchers have uncovered sex-divergent mechanisms that challenge one-size-fits-all neurodevelopmental models. Understanding these sex-specific neurodevelopmental trajectories allows pediatricians, child neurologists, and allied healthcare professionals to optimize early diagnostic protocols and personalize pediatric motor therapies.

The Neurobiology of Fine Motor Development in Autism

The dorsal striatum, which comprises the caudate nucleus and the putamen, serves as a primary input hub for the basal ganglia. Consequently, it integrates motor, cognitive, and sensory signals originating from expansive neocortical regions. In typical development, coordinated sensorimotor-striatal and prefrontal-striatal pathways facilitate the gradual automation of complex hand and finger movements. However, autistic individuals frequently display altered corticostriatal connectivity and anomalous morphological growth trajectories in these subcortical nuclei. These structural variations often correlate with difficulties in motor planning, grasp coordination, and praxis. Furthermore, structural brain differences between male and female presentations of autism have garnered increasing clinical attention. Autistic females frequently exhibit distinct phenotypic profiles, including camouflaging behaviors and different sensorimotor manifestations, compared to their male peers. Therefore, evaluating dorsal striatal volume alongside white matter tract microstructural integrity offers an exceptional biological window into how subcortical remodeling governs functional motor gains during preschool and early school-age years.

Longitudinal Neuroimaging and Motor Assessment Methodology

To investigate these developmental pathways, researchers conducted a comprehensive multimodal neuroimaging investigation with longitudinal behavioral follow-up. The investigators recruited a large, well-characterized pediatric cohort consisting of 356 children, including 234 autistic children and 122 nonautistic peers, assessed initially at approximately three years of age. A substantial subset of 195 children returned for longitudinal follow-up between two and three years later. At each developmental visit, clinicians administered standardized assessments to measure manual dexterity, visual-motor integration, and grasping proficiencies. Concurrently, participants underwent high-resolution structural magnetic resonance imaging and diffusion tensor imaging during natural, non-sedated sleep. The neuroimaging protocol specifically quantified volumetric measures of the caudate and putamen. Additionally, tractography techniques measured fractional anisotropy across sensorimotor-striatal and prefrontal-striatal white matter pathways. This robust longitudinal framework enabled researchers to delineate baseline neural structures and isolate their direct predictive value regarding subsequent motor progression.

Divergent Corticostriatal Profiles Between Autistic Boys and Girls

The baseline neuroimaging data revealed marked baseline differences in structure-function relationships that were entirely dependent on biological sex and clinical diagnosis. Specifically, at three years of age, significant associations emerged between putamen volume, sensorimotor-striatal fractional anisotropy, and fine motor abilities in autistic children. However, the exact directional nature of these structure-function relationships differed markedly between autistic boys and autistic girls. Autistic boys displayed a specific structural configuration where higher sensorimotor fractional anisotropy aligned with distinct motor scores. In contrast, autistic girls demonstrated an alternative subcortical profile linking putamen volume and motor performance. Interestingly, these anatomical associations were not statistically significant in nonautistic control children. This divergence indicates that motor control in young autistic children relies on unique subcortical neural mechanisms rather than merely reflecting accelerated or delayed typical maturation. Consequently, dorsal striatal circuitry exhibits atypical functional organization very early in autistic life.

Predictive Biomarkers for Motor Skill Trajectories Over Time

Beyond baseline observations, the longitudinal findings identified powerful sex-specific predictive markers for motor skill progression over time. Baseline microstructural integrity within sensorimotor-striatal and prefrontal-striatal white matter tracts significantly predicted longitudinal fine motor improvement in autistic girls. Autistic girls exhibiting higher baseline fractional anisotropy in these pathways demonstrated superior developmental gains at the longitudinal follow-up. Remarkably, this predictive corticostriatal relationship was absent in autistic boys, whose longitudinal motor progress did not correlate with baseline tract microstructure. These findings suggest that young autistic girls recruit prefrontal and sensorimotor striatal loops as a critical compensatory or foundational scaffold for motor skill acquisition. Meanwhile, autistic boys may depend on alternate neural circuits, such as cerebellar or primary motor cortical pathways, to achieve functional gains. Therefore, the neurobiological substrates driving motor recovery and growth diverge substantially between sexes during early childhood.

Clinical Implications for Pediatric Practice and Early Interventions

These neuroimaging insights provide profound clinical takeaways for pediatricians, pediatric neurologists, child psychiatrists, and developmental therapists. First, motor impairments in autism are biological in origin and stem from distinct subcortical organization rather than secondary behavioral disengagement. Clinicians should systematically screen for fine motor delays during standard autism evaluations, recognizing that motor deficits impact adaptive functioning and quality of life. Second, therapeutic strategies must acknowledge that autistic boys and girls process sensorimotor tasks through distinct neural architecture. Occupational therapy and motor rehabilitation protocols might require tailored approaches to optimize neuroplasticity in each sex. For example, therapies that engage cognitive-prefrontal planning loops may uniquely benefit autistic girls during early development. Ultimately, identifying objective subcortical biomarkers paves the way for precise, individualized intervention plans that support lifelong motor autonomy and developmental success.

What is the clinical significance of fine motor delays in autistic children?

Fine motor challenges frequently undermine functional independence in young autistic children by impairing self-care activities, writing capabilities, and tool manipulation. Moreover, early motor difficulties often correlate with downstream communication and social challenges, making targeted motor evaluation a critical priority during routine pediatric neurodevelopmental surveillance and clinical management.

How does the dorsal striatum influence fine motor development in autism?

The dorsal striatum coordinates motor planning, automated motor responses, and sensorimotor integration by connecting with neocortical areas. In autistic children, structural variations in putamen volume and sensorimotor-striatal white matter tracts directly influence manual dexterity, exhibiting distinct morphological and functional relationships between boys and girls.

Why do autistic boys and girls show different neurodevelopmental motor pathways?

Autistic girls and boys demonstrate distinct patterns of subcortical structural organization and white matter maturation. Specifically, autistic girls rely more heavily on prefrontal and sensorimotor corticostriatal pathways to scaffold developmental fine motor gains, whereas autistic boys utilize alternative neural networks during early childhood maturation.

Disclaimer: This content is for informational and educational purposes only and does not constitute formal medical advice. Healthcare professionals should evaluate clinical scenarios individually and refer to the latest local and national guidelines for clinical practice.

References

• Surgent O et al. Sex Differences in the Striatal Contributions to Longitudinal Fine Motor Development in Autistic Children. Biol Psychiatry. 2025 Jun 15. doi: 10.1016/j.biopsych.2025.01.005. PMID: 39818327.
• Andrews DS et al. Cortical Thickness Differences in Autistic Children With and Without Intellectual Disability. Autism Res. 2025 Mar;18(3):486-497. doi: 10.1002/aur.3313.
• Surgent OJ et al. Gray matter microstructure differences in autistic males: A gray matter based spatial statistics study. NeuroImage Clin. 2023;37:103306. doi: 10.1016/j.nicl.2023.103306.
• Supekar K, Menon V. Sex differences in structural organization of motor systems and their relation to clinical symptoms in autism. Mol Autism. 2015;6:50. doi: 10.1186/s13229-015-0042-7.