Vocal communication is a conserved vertebrate social behavior that begins at birth with infant cries. These neonatal signals vary with context to elicit parental care matched to infant needs and vary across species to align with different ecologies and social systems. Such natural variation provides a route to identify proximate neural and genetic mechanisms that support flexible neonatal vocal behaviors and their evolution. The authors previously characterized neonatal vocalizations in North American deer mice and documented heritable interspecific differences in call features. In the present work they focused on the temporal structure of neonatal cries, a feature known in humans and rodents to carry information about infant distress.
The study reports that temporal aspects of deer mouse neonatal vocalizations have diverged more between species than spectral aspects. That is, measures related to timing and duration of calls showed greater interspecific variation than measures based on frequency content. This emphasis on temporal variation motivated further investigation into mechanisms that could govern timing of infant vocal output.
To evaluate the functional significance of temporal variation, the authors used a playback assay testing how cry features influence parental approach. They found that cry duration affected the ability of pup vocalizations to elicit parental approach in the assay, indicating that temporal properties can alter parental behavioral responses to infants.
Given the cerebellum’s conserved role in temporal control of motor rhythms, the investigators examined components of the olivocerebellar system in neonatal deer mice. They report interspecies differences in the gross anatomy of the neonatal cerebellum and the inferior olive. These anatomical differences across species motivated experiments to test whether olivocerebellar function contributes to shaping the temporal properties of neonatal cries.
The authors used pharmacological manipulation to perturb olivocerebellar function and measured consequences for neonatal vocal timing. They observed that disruption of olivocerebellar activity altered the temporal structure of neonatal cries in deer mice. These results provide causal evidence that olivocerebellar circuits contribute to timing features of infant vocalizations.
To investigate genetic contributions to variation in cry timing, the team employed an interspecies cross to map the genetic architecture of neonatal cry duration. Their mapping identified a single quantitative trait locus (QTL) that was significantly associated with cry duration. The presence of a locus with appreciable effect suggests that at least part of the interspecific difference in temporal structure has a segregating genetic basis amenable to further dissection.
Within the significant QTL the authors nominated candidate genes that could plausibly underlie species differences in cry duration. Among these candidates are genes that are differentially expressed between the deer mouse species studied, genes with known functions in cerebellar development, and genes previously linked to the duration of neonatal vocal signals in house mice. The source reports these classes of candidate genes but does not provide exhaustive lists or individual gene-level details in the text provided here.
Combining behavioral assays, neuroanatomical comparison, pharmacology, and quantitative genetics, the study implicates the cerebellar system in the temporal control of a neonatal social behavior—infant crying—in deer mice. Temporal features of calls diverged more across species than spectral features, and cry duration modulated parental approach in playback. Anatomical differences in the neonatal cerebellum and inferior olive, and perturbation of olivocerebellar function, altered vocal timing. A single significant QTL associated with cry duration was identified, and candidate genes within that locus include genes expressed differentially between species and genes with cerebellar roles and prior links to neonatal vocal duration in other mouse models. These results generate testable neural and genetic hypotheses about how infant crying can evolve and identify the cerebellar system as a proximate contributor to neonatal social vocal behavior.
Competing interests: The authors declared no competing interest. The reporting here reflects the content provided in the source preprint and does not add study-specific numbers, statistical values, or unreported experimental details.