Biology subjects

O'Brien, C.

Publications and source records attributed to O'Brien, C..

22 records · Page 2Linked to original sources

bioRxiv2020

Unilateral vocal nerve resection alters neurogenesis in the avian song system in a region-specific manner

New neurons undergo a critical period soon after migration during which the behavior of the animal may result in the survival or culling of these cells. In the songbird song system, new neurons may be maintained in the song motor pathway with respect to motor progression toward a target song--during juvenile song learning, seasonal song restructuring, and experimentally manipulated song variability. However, it is not known whether the quality of song per se, without progressive improvement, may also influence new neuron survival. To test this idea, we experimentally altered song acoustic structure by unilateral denervation of the syrinx. We found no effect of aberrant song on numbers of new neurons in the HVC of the song motor pathway, a loss of left-side dominance in new neurons in the auditory region caudomedial nidopallium (NCM), and a bilateral decrease in new neurons in the basal ganglia nucleus Area X. We propose new neuron survival may be determined in response to behavioral feedback in accordance with the function of new neurons within a given brain region. Studying the effects of singing behaviors on new neurons across multiple brain regions that subserve singing may give rise to general rules underlying the regulation of new neuron survival across taxa and brain regions more broadly.

neuroscience↗

bioRxiv2019

Tbx2a modulates switching of opsin gene expression

Differences in sensory tuning are reported to maintain species boundaries and may even lead to speciation. Variation in the tuning of color vision is likely due to differences in the expression of opsin genes. Over 1,000 species of African cichlid fishes provide an excellent model system for studying the genetic basis of opsin gene expression because of the presence of seven distinct genes, yet individual species typically express only a divergent set of three opsins. The evolution of such shifts is expected to arise through either (a) two simultaneous regulatory changes (one for each opsin), or (b) one regulatory change that simultaneously promotes expression of one opsin while repressing another. Here, we used QTL analyses, genome sequencing, and gene expression studies to identify the transcription factor Tbx2a as likely driving a switch between LWS and RH2 opsin expression. Binding sites for Tbx2a in the LWS promoter and the highly conserved Locus Control Region of RH2 act to concurrently promote LWS expression while repressing RH2 expression. Our data support the hypothesis that instant changes in visual tuning can be achieved by switching the expression of multiple genes by a single mutation and do not require independent changes in the regulatory regions of each opsin.

evolutionary biology↗

bioRxiv2019

Evaluating sepsis definitions for clinical decision support against a definition for epidemiological disease surveillance

Epidemiological definitions for sepsis have been used to improve disease surveillance and assist in national assessment of sepsis detection and treatment. However, epidemiological definitions are often optimized for retrospective review and alignment of epidemiological and real-time clinical decision support definitions is unknown. This 15-month retrospective observational study involving 43,046 adult patient encounters and 30,973 unique patients compared cohorts captured by the EHR-based Sepsis-1, Sepsis-3, and Duke Adult Sepsis definitions. We assessed hospital length of stay, in-hospital mortality, admission to the intensive care unit, and sensitivity and specificity of these definitions compared to the Centers for Disease Control and Prevention epidemiological gold-standard definition. Both Duke Adult Sepsis and Sepsis-3 maintained a high specificity, but the former had higher sensitivity. By directly comparing definitions designed for clinical decision support with an epidemiological disease surveillance tool, this work provides guidance to health systems seeking to implement clinical decision support to improve sepsis management.

epidemiology↗

bioRxiv2019

Dissociating proprioceptive deficits in Autism Spectrum Disorders: Intact acuity but impaired sensory integration in postural control.

We investigated the presence of proprioceptive deficits in adults with Autism Spectrum Disorder (ASD), by assessing peripheral proprioceptive information (or proprioceptive acuity) as well as integration of proprioceptive information in the context of postural control. We hypothesized that proprioceptive acuity would be intact but that integration during a postural control task would be impaired. Sixteen adults with ASD and sixteen Neurotypical (NT) adults were screened using an IQ test and the adolescent-adult sensory profile. Proprioceptive acuity was assessed using an ankle Joint Position Sense (JPS) task and integration of proprioceptive information was assessed using a postural adaptation task. This task comprised standing upright, without vision in three phases: standing on a fixed surface for 2 minutes (baseline), followed by standing on a surface tilting in proportion to participants body sway, or support-surface sway reference for 3 minutes (adaptation) and finally standing on the restored fixed surface for 3 minutes (reintegration). Results showed no group differences in proprioceptive acuity and in the baseline phase, but greater postural sway during adaptation in individuals with ASD compared with NT controls. Specifically, group differences were not present in the first 30s of adaptation, but emerged after the second window suggesting a deficit in sensory integration of proprioception in adults with ASD. Our results suggest that peripheral proprioceptive information is intact in ASD but neural sensory integration of proprioception is impaired in this group.

neuroscience↗