The caudate nucleus has been thought to be involved in the control of motor commands by the cerebrum, and recent studies suggest that it may play a role in the control of attachment behavior, cognition, emotion, and mental functions. Implied by the basal ganglia’s involvement in the execution, planning and control of movement, the caudate nucleus functions in a situation-dependent manner where processing of external stimuli is important on the basis of learning and memory. Sensory processing, which determines the response to external stimuli, has been shown to be related to various brain regions but it remains unknown how sensory processing is associated with the structure of the caudate nucleus and white matter microstructures of the caudate. Using four diffusion parameters derived from diffusion tensor imaging (DTI) (i.e., fractional anisotropy (FA), mean diffusivity (MD), axonal diffusivity (AD), and radial diffusivity (RD)) and the Adolescent/Adult Sensory Profile (AASP) questionnaire of 99 healthy subjects [42 males and 57 females; mean age:26.9 years, standard deviation 6.9], we investigated the relationship between white matter structure in the caudate nucleus and sensory processing. In consistent with what had been suggested by the results of previous studies, we found significant correlations between AD, MD and tactile sensation. Furthermore, we found a significant correlation between AD, MD and tactile sensory avoidance, the AASP sub-scores regarding the tactile senses. To the best of our knowledge, this is the first study to show that DTI diffusion parameters correlate with AASP scores in specific brain regions.

Despite the importance of child-caregiver interactions in child development, the association between parenting stress and the brain development of children remains unclear. We investigated how parenting stress relates to neural connectivity in the white matter structures and whether it has any associations with volume of thalamic subfields in 47 typically developing children (24 girls, mean age: 8.96 years old). While parents completed the Parenting Stress Index (PSI), children underwent diffusion tensor imaging (DTI) and structural magnetic resonance imaging (sMRI) scanning. The six PSI subscales reflecting child characteristics were negatively associated with the mean fractional anisotropy values of the bilateral anterior thalamic radiations (ATRs), bridging thalamus to the prefrontal cortex. Our exploratory analysis on thalamic subfields disclosed significant negative associations between the six PSI subscales and the volume of the right reuniens nuclei (MV-re) that is situated in the medial ventral thalamus and mediates interaction between the hippocampus and the prefrontal cortex. Considering a reduced white matter integrity in bilateral ATRs and smaller MV-re volume, parenting stress stemming from child-related features may reflect inefficient exchange of information via thalamocortical circuits in the developing brain. Our findings indicate the significance of interactions in child-caregiver dyads in brain development and particularly, thalamic structures.