Biology subjects

Beatty, J. A.

Publications and source records attributed to Beatty, J. A..

3 recordsLinked to original sources

bioRxiv2022

Heterogeneity of burst firing in mouse thalamic reticular nucleus neurons

The thalamic reticular nucleus (TRN) sits at the interface of the thalamus and neocortex and provides the majority of inhibition to thalamic relay nuclei. Functionally, the activity of TRN neurons can impact sensory processing and may influence arousal states. TRN neurons discharge action potentials in two distinct output modes: tonic or burst firing. Burst output, a transient high frequency discharge of action potentials, is dependent on the activation of transient low-threshold voltage-dependent T-type calcium current (IT). In our current study, we identify a broad range of burst firing frequencies in TRN neurons, which depend on the activation of IT. The amplitude of the low-threshold calcium spike (LTS) underlying the burst positively correlated with burst frequency and number of action potentials per burst. Activation of small conductance calcium-activated potassium (SK) channels on TRN neurons can impact burst discharge. Attenuation of SK channels increased TRN neuron burst frequency through an increase in LTS duration, but not magnitude. The broad range of burst firing frequencies could provide distinct downstream inhibition within thalamic nuclei.

neuroscience↗

bioRxiv2022

Structural and functional changes of pyramidal neurons at the site of an implanted microelectrode array in rat primary motor cortex

Devices capable of recording or stimulating neuronal signals have created new opportunities to understand normal physiology and treat sources of pathology in the brain. However, it is possible that the initial surgical insertion and subsequent tissue response to implanted electrodes may influence the nature of the signals detected or stimulated. In this study, we characterized structural and functional changes in pyramidal neurons surrounding silicon or polyimide-based electrodes implanted in the motor cortex of rats. Devices were captured in 300 m-thick tissue slices collected at the 1 or 6 week time point post-implantation, and individual neurons were assessed using a combination of whole-cell electrophysiology and 2-photon imaging. We observed disruption of the dendritic arbor of neurons near (<100 m) the device surface at both time points, as well as a significant reduction in spine densities. These effects were accompanied by a decrease in the frequency of spontaneous excitatory post-synaptic currents (sEPSCs), a loss in sag amplitude, and an increase in spike frequency adaptation at the 6 week time point. Interestingly, we also noted a significant increase in filopodial density in neurons surrounding devices. Results were similar for polyimide and silicon-based electrodes. We hypothesize that the effects observed in this study may contribute to the signal loss and instability that often accompany chronically implanted electrodes.

bioengineering↗

bioRxiv2022

Faecal virome of the Australian grey-headed flying fox from urban/suburban environments contains novel coronaviruses, retroviruses and sapoviruses

Bats are important reservoirs for viruses of public health and veterinary concern. Virus studies in Australian bats usually target the families Paramyxoviridae, Coronaviridae and Rhabdoviridae, with little known about their overall virome composition. We used metatranscriptomic sequencing to characterise the faecal virome of grey-headed flying foxes from three colonies in urban/suburban locations from two Australian states. We identified viruses from three mammalian-infecting (Coronaviridae, Caliciviridae, Retroviridae) and one possible mammalian-infecting (Birnaviridae) family. Of particular interest were a novel bat betacoronavirus (subgenus Nobecovirus) and a novel bat sapovirus (Caliciviridae), the first identified in Australian bats, as well as a potentially exogenous retrovirus. The novel betacoronavirus was detected in two sampling locations 1,375 km apart and falls in a viral lineage likely with a long association with bats. This study highlights the utility of unbiased sequencing of faecal samples for identifying novel viruses and revealing broad-scale patterns of virus ecology and evolution.

microbiology↗