Serotonin is a neurotransmitter system that is essential for driving behavior related to movement, attention and foraging. In humans, an increase or decrease in

healthy levels of serotonin result in neuropsychological issues, including anxiety and depression. Despite these health concerns, our understanding of serotonin regulation and homeostasis is still poorly understood and needs more research from a variety of model and non-model animal systems. This study was designed to study serotonin homeostasis in the blind Mexican cavefish, a non-model system for understanding complex biological

traits. The blind Mexican cavefish provides a multi-population species that includes river dwelling fish with eyes, that are considered ancestral, and cave derived populations that lack eyes and pigment. Previous research found that cavefish exhibit increased levels of

serotonin that is hypothesized to drive decreased sleep and increased activity in cavefish. We wanted to test the hypothesis that increased levels of serotonin are sequestered or degraded in the brain via genetic compensation. To test this hypothesis, we compared

mRNA gene expression of the serotonin promoting enzymes tryptophan hydroxylase 1 and 2 (tph1 and tph2) between surface and cave larvae. However, we did not find significant differences in gene expression between the two populations. To further explore serotonin regulation, we quantified the number of cells in the locus coeruleus expressing the serotonin transporter solute carrier family 6 member 4 (slc6a4a). We did find a significant increase in neurons expressing slc6a4a in the dorsal raphe of cavefish. This research provides insight into the regulation of serotonin in a non-model species, the blind Mexican cavefish. Future work will functionally test whether free serotonin is sequestered more rapidly before being implemented in circuits.

Kinematic analysis pipelines now provide temporal and geometric resolution for

determining a variety of body movements. These machine-learning trained programs allow behavioral neuroscientists to dissect complex behaviors and relate changes in those movements to conserved neural assemblages. These analyses are common in model organisms, but a lack of ethologically driven kinematic work in non-models has hampered our understanding of how evolution shapes behavior through changes in sensorimotor circuits. Astyanax Mexicanus is a unique model organism for investigating how the brain adapts to changes in environmental conditions and how evolutionary divergence at the genotypic and phenotypic level impacts behavior. In this study, we analyzed the kinematic movements in open-arena assays of 1- to 2-week-old larvae of wildtype and hybrid genotypes of surface fish and cavefish populations (Molino, Tinaja, Pachon). 10-15 second videos of open arena conditions were recorded at 200 fps, specifically aimed to identify behavioral differences in light (white light) and dark (infrared light) conditions. Bout transition probabilities were analyzed using spectral gap and spectral entropy metrics. Analysis of bout transition probabilities in cave and surface populations reveals that all populations exhibit a conserved dominant exploratory scaffold, but differ in how they allocate probability mass across subsidiary motor programs. Baseline flexibility across all conditions for

surface fish is generally higher while cavefish depict more stereotypy in behaviors. In general, transitions from IR to white light resulted in increased mixing of behavioral states. These results suggest that central sensorimotor architectures are preserved, with the process of evolution exerting change upon bout dynamics through genetic variation and environmental variability.

Sleep plays a crucial role in human development, particularly in early childhood. While its influence on brain function is well documented, the relationship between sleep and auditory processing in the developing brain remains underexplored. The present study aimed to investigate how sleep duration impacts cortical responses to music, focusing on children aged 5 to 10.

The development of lexical tone processing in children is shaped by both  language experience and acoustic salience. While mismatch responses (MMRs) and late  negativity (LN) components of event-related potentials (ERPs) have revealed early  sensitivity to lexical tone in monolingual children, the timeline for achieving adult-like  neural responses—particularly for acoustically distinct versus subtle tone contrasts— remains unclear. Moreover, little is known about how bilingual language experience,  especially with tonal versus non-tonal home languages, modulates this neural processing.