https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:6928 41%). In older animals (P11–P25) this changed, with AP discharge consisting of brief bursts at current onset (~46% of neurons). Investigation of major subthreshold whole cell currents showed the rapid A-type potassium current (IAr) dominated at all ages examined (90% of neurons at E15–E17, decreasing to >50% after P10). IAr expression levels, based on peak current amplitude, increased during development. Steady-state inactivation and activation for IAr were slightly less potent in E15–E17 versus P21–P25 neurons at potentials near RMP (-55 mV). Together, our data indicate that intrinsic properties and IAr expression change dramatically in SDH neurons during development, with the greatest alterations occurring on either side of a critical period, P6–P10.]]> Sat 24 Mar 2018 08:40:23 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1951 Sat 24 Mar 2018 08:33:18 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1879 Sat 24 Mar 2018 08:31:19 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:11329 Sat 24 Mar 2018 08:12:34 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:11513 Sat 24 Mar 2018 08:11:08 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5793 Sat 24 Mar 2018 07:44:56 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5804 Sat 24 Mar 2018 07:44:54 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5796 Sat 24 Mar 2018 07:44:53 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:4459 Sat 24 Mar 2018 07:18:30 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:22273 IN), resting membrane potential, AP amplitude, half-width and AHP amplitude were similar across spinal cord regions in both neonates and adults (~100 neurons for each region and age). In contrast, these intrinsic membrane properties differed dramatically between neonates and adults. Five types of AP discharge were observed during depolarizing current injection. In neonates, single spiking dominated (~40%) and the proportions of each discharge category did not differ across spinal regions. In adults, initial bursting dominated in each spinal region, but was significantly more prevalent in rostral segments (49% of neurons in C2-4 vs. 29% in L3-5). During development the dominant AP discharge pattern changed from single spiking to initial bursting. The rapid A-type potassium current (I_Ar) dominated in neonates and adults, but its prevalence decreased (~80% vs. ~50% of neurons) in all regions during development. I_Ar steady state inactivation and activation also changed in upper cervical and lumbar regions during development. Together, our data show the intrinsic properties of SDH neurons are generally conserved in the three spinal cord regions examined in both neonate and adult mice. We propose the conserved intrinsic membrane properties of SDH neurons along the length of the spinal cord cannot explain the marked differences in pain experienced in the limbs, viscera, and head and neck.]]> Sat 24 Mar 2018 07:17:39 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24319 in vivo preparation to make patch-clamp recordings from superficial dorsal horn (SDH) neurons receiving colonic inputs in naïve male mice. Recordings were made in the lumbosacral spinal cord (L6-S1) under isoflurane anesthesia. Noxious colorectal distension (CRD) was used to determine whether SDH neurons received inputs from mechanical stimulation/distension of the colon. Responses to hind paw/tail cutaneous stimulation and intrinsic and synaptic properties were also assessed, as well as action potential discharge properties. Approximately 11% of lumbosacral SDH neurons in the cohort of neurons sampled responded to CRD and a majority of these responses were subthreshold. Most CRD-responsive neurons (80%) also responded to cutaneous stimuli, compared with <50% of CRD-non-responsive neurons. Furthermore, CRD-responsive neurons had more hyperpolarized resting membrane potentials, larger rheobase currents, and reduced levels of excitatory drive, compared to CRD-non-responsive neurons. Our results demonstrate that CRD-responsive neurons can be distinguished from CRD-non-responsive neurons by several differences in their membrane properties and excitatory synaptic inputs. We also demonstrate that SDH neurons with colonic inputs show predominately subthreshold responses to CRD and exhibit a high degree of viscerosomatic convergence.]]> Sat 24 Mar 2018 07:14:41 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:16907 A miniature inhibitory postsynaptic current (mIPSC) amplitude was increased in spa and ot but not spd, suggesting diminished glycinergic drive leads to compensatory adjustments in the other major fast inhibitory synaptic transmitter system in these mutants. Overall, our data suggest long-term reduction in glycinergic drive to HMs results in changes in intrinsic and synaptic properties that are consistent with homeostatic plasticity in spa and ot but not in spd. We propose such plasticity is an attempt to stabilize HM output, which succeeds in spa but fails in ot.]]> Mon 30 Sep 2019 12:26:58 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:22855 Mon 30 Sep 2019 12:19:51 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:25370 Mon 30 Sep 2019 12:12:52 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:52855 92%). Short-term plasticity was studied by examining discharge rate modulation following release from hyperpolarization [postinhibitory rebound firing (PRF)] and depolarization [firing rate adaptation (FRA)]. PRF and FRA gain were similar in Deiters’ and non-Deiters’ neurons (PRF 24.9 vs. 20.2 Hz and FRA gain 231.5 vs. 287.8 spikes/s/nA, respectively). Inhibitory synaptic input to both populations showed that GABAergic rather than glycinergic inhibition dominated. However, GABAA miniature inhibitory postsynaptic current (mIPSC) frequency was much higher in Deiters’ neurons compared with non-Deiters’ neurons (∼15.9 vs. 1.4 Hz, respectively). Our data suggest that Deiters’ neurons can be reliably identified by their intrinsic membrane and synaptic properties. They are tonically active and glutamatergic, have low sensitivity or “gain,” exhibit little adaptation, and receive strong GABAergic input. Deiters’ neurons also have minimal short-term plasticity, and together these features suggest they are well suited to a role in encoding tonic signals for the vestibulospinal reflex. New & Noteworthy: Deiters’ neurons within the lateral vestibular nucleus project the length of the spinal cord and activate antigravity extensor muscles. Deiters’ neurons were characterized anatomically and physiologically in mice. Deiters’ neurons are tonically active, have homogeneous intrinsic membrane properties, including low input resistance, and receive significant GABAAergic synaptic inputs. Deiters’ neurons show little modulation in response to current injection. These features are consistent with Deiters’ neurons responding to perturbations to maintain posture and balance.]]> Mon 30 Oct 2023 09:54:00 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:38353 Mon 30 Aug 2021 16:06:38 AEST ]]>