Theta oscillations in the rat MS/DB complex in vitro: a locally generated, inhibition-based brain rhythm

The medial septum/diagonal band (MS/DB) complex, which forms part of the septohippocampal feedback loop, is thought to be critical for the generation and/or maintenance of the hippocampal theta rhythm (4-15 Hz) in vivo. Previously we demonstrated the presence of theta frequency rhythmic activity, within an in vitro slice preparation of the MS/DB, following application of the AMPA/kainate receptor agonist kainate (25–100 nM). Here we further investigate this rhythmic activity, in particular the effects of GABAA receptor mediated inhibition, on kainate induced theta activity in the MS/DB, using bath application of bicuculline. Longitudinal slices of the MS/DB (450 μm), from 21 day old rats, were maintained at 32°C in an interface recording chamber perfused with oxygenated ACSF. Following the bath application of kainate at 100 nM to the MS/DB, extracellular recordings of neuronal population activity, using ACSF-filled micropipettes, revealed rhythmic theta frequency activity. Bicuculline was then applied to the recording chamber and subsequent changes to the kainate induced activity were recorded at 30 and 60 minutes there after. Application of 10 µM bicuculline produced a significant reduction (P< 0.05, Student's T test) in the activity recorded at theta frequency (spectral integral in 4-15 Hz range) and in peak amplitude within 60 minutes of application (n=6). These results indicate a pivotal role for inhibitory transmission in pacing and maintaining the rhythmic activity that is observed in the MS/DB slice preparation following kainate induced theta frequency oscillations. SPONSOR: British Neuroscience Association

Involvement of electrical signalling in theta frequency oscillations generated in the medial septum/diagonal band of Broca in vitro

Theta frequency (4 – 15 Hz) extracellular field activity can be reliably and repeatedly evoked in the medial septum/diagonal band of Broca (MS/DB) in vitro by the application of kainate. We have previously demonstrated a critical role for inhibitory neurotransmission in the maintenance of this activity and presented data that indicates parvalbumin GABAergic neurons are responsible for pacing rhythmic theta activity in the MS/DB. Evidence of functional electrical coupling between GABAergic interneurons has been reported in the hippocampus and neocortex and it has recently become clear that gap junctions may have a significant function in the generation of neuronal population activity. Here we demonstrate that application of the gap-junction uncoupling agent carbenoxolone causes a significant reduction (P< 0.05, Paired T test) in the kainate induced activity recorded at theta frequency (spectral integral in 4-15 Hz range) in the MS/DB slice in vitro. MS/DB slices were prepared from male Wistar rats (21 days), which were terminally anaesthetised with pentobarbitone sodium (120 mg.kg-1, i.p.). The animals were transcardially perfused with ~ 25ml of modified ACSF and rapidly decapitated. Longitudinal slices (450 µm) were placed in an interface recording chamber and maintained at 32°C. Persistent theta oscillations were induced by bath application of 100 nM kainate. Carbenoxolone was bath applied to stabilized kainate induced activity at a concentration of 100 μM for 60 minutes. At 60 minutes there was a significant reduction in the theta frequency activity recorded (56.6% ± 2.3) and in peak amplitude (n = 6). These results indicate a pivotal role for electrical signalling in the theta frequency rhythmic activity induced in the MS/DB upon application of kainate

Involvement of electrical signalling in theta frequency oscillations generated in the medial septum/diagonal band of Broca in vitro

Theta frequency (4 – 15 Hz) extracellular field activity can be reliably and repeatedly evoked in the medial septum/diagonal band of Broca (MS/DB) in vitro by the application of kainate. We have previously demonstrated a critical role for inhibitory neurotransmission in the maintenance of this activity and presented data that indicates parvalbumin GABAergic neurons are responsible for pacing rhythmic theta activity in the MS/DB. Evidence of functional electrical coupling between GABAergic interneurons has been reported in the hippocampus and neocortex and it has recently become clear that gap junctions may have a significant function in the generation of neuronal population activity. Here we demonstrate that application of the gap-junction uncoupling agent carbenoxolone causes a significant reduction (P< 0.05, Paired T test) in the kainate induced activity recorded at theta frequency (spectral integral in 4-15 Hz range) in the MS/DB slice in vitro. MS/DB slices were prepared from male Wistar rats (21 days), which were terminally anaesthetised with pentobarbitone sodium (120 mg.kg-1, i.p.). The animals were transcardially perfused with ~ 25ml of modified ACSF and rapidly decapitated. Longitudinal slices (450 µm) were placed in an interface recording chamber and maintained at 32°C. Persistent theta oscillations were induced by bath application of 100 nM kainate. Carbenoxolone was bath applied to stabilized kainate induced activity at a concentration of 100 μM for 60 minutes. At 60 minutes there was a significant reduction in the theta frequency activity recorded (56.6% ± 2.3) and in peak amplitude (n = 6). These results indicate a pivotal role for electrical signalling in the theta frequency rhythmic activity induced in the MS/DB upon application of kainate

A small satellite version of a soft x-ray polarimeter

We describe a new implementation of a broad-band soft X-ray polarimeter, substantially based on a previous design. This implementation, the Pioneer Soft X-ray Polarimeter (PiSoX) is a SmallSat, designed for NASA’s call for Astrophysics Pioneers, small missions that could be CubeSats, balloon experiments, or SmallSats. As in REDSoX, the grating arrangement is designed optimally for the purpose of polarimetry with broad-band focussing optics by matching the dispersion of the spectrometer channels to laterally graded multilayers (LGMLs). The system can achieve polarization modulation factors over 90%. For PiSoX, the optics are lightweight Si mirrors in a one-bounce parabolic configuration. High efficiency, blazed gratings from opposite sectors are oriented to disperse to a LGML forming a channel covering the wavelength range from 35 Å to 75 Å (165 - 350 eV). Upon satellite rotation, the intensities of the dispersed spectra, after reflection and polarizing by the LGMLs, give the three Stokes parameters needed to determine a source’s linear polarization fraction and orientation. The design can be extended to higher energies as LGMLs are developed further. We describe examples of the potential scientific return from instruments based on this design.Accepted manuscrip

Domestic dog health worsens with socio-economic deprivation of their home communities

Dogs play an important role in infectious disease transmission as reservoir hosts of many zoonotic and wildlife pathogens. Nevertheless, unlike wildlife species involved in the life cycle of pathogens, whose health status might be a direct reflection of their fitness and competitive abilities, dog health condition could be sensitive to socio-economic factors impacting the well-being of their owners. Here, we compare several dog health indicators in three rural communities of Panama with different degrees of socio-economic deprivation. From a total of 78 individuals, we collected blood and fecal samples, and assessed their body condition. With the blood samples, we performed routine hematologic evaluation (complete blood counts) and measured cytokine levels (Interferon-γ and Interleukin-10) through enzyme-linked immunosorbent assays. With the fecal samples we diagnosed helminthiases. Dogs were also serologically tested for exposure to Trypanosoma cruzi and canine distemper virus, and molecular tests were done to assess T. cruzi infection status. We found significant differences between dog health measurements, pathogen prevalence, parasite richness, and economic status of the human communities where the dogs lived. We found dogs that were less healthy, more likely to be infected with zoonotic pathogens, and more likely to be seropositive to canine distemper virus in the communities with lower economic status. This study concludes that isolated communities of lower economic status in Panama may have less healthy dogs that could become major reservoirs in the transmission of diseases to humans and sympatric wildlife

Search for the Zγ decay mode of new high-mass resonances in pp collisions at √s = 13 TeV with the ATLAS detector

This letter presents a search for narrow, high-mass resonances in the Zγ final state with the Z boson decaying into a pair of electrons or muons. The √s = 13 TeV pp collision data were recorded by the ATLAS detector at the CERN Large Hadron Collider and have an integrated luminosity of 140 fb−1. The data are found to be in agreement with the Standard Model background expectation. Upper limits are set on the resonance production cross section times the decay branching ratio into Zγ. For spin-0 resonances produced via gluon–gluon fusion, the observed limits at 95% confidence level vary between 65.5 fb and 0.6 fb, while for spin-2 resonances produced via gluon–gluon fusion (or quark–antiquark initial states) limits vary between 77.4 (76.1) fb and 0.6 (0.5) fb, for the mass range from 220 GeV to 3400 GeV