25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Bedtime Music for Sleep Problems in Older Adults With Dementia: A Feasibility Study

Sleep problems are highly prevalent in elderly persons with dementia. Poor sleep constitutes a major problem as it causes distress and may aggravate symptoms of dementia. Music has been proposed as a potential sleep aid, and in this study, we assessed the feasibility and effect of bedtime music listening for improving sleep problems in older adults with dementia. We used a within-subject design including 40 participants. Participants and caregivers evaluated the feasibility and sleep improvement after the intervention period. We measured sleep objectively with wrist actigraphy (total sleep time and sleep efficiency). In the intervention period, participants listened to music for 30 minutes every night at bedtime. We developed sleep playlists of different genres, and participants could choose the one they liked the best. We found that the music intervention was well-liked, and sleep improvement was observed in approximately half of the participants. Wrist actigraphy showed no significant changes in total sleep time or sleep efficiency. Music listening at bedtime could provide a safe, comfortable and low-cost intervention for sleep problems among elderly persons with dementia, the intervention is feasible, but more research is needed to determine the effect on sleep outcomes. (PsycInfo Database Record (c) 2021 APA, all rights reserved

Crystallization and preliminary structural analysis of the Listeria monocytogenes Ca2+-ATPase LMCA1

Ca(2+)-ATPases are ATP-driven membrane pumps that are responsible for the transport of Ca(2+) ions across the membrane. The Listeria monocytogenes Ca(2+)-ATPase LMCA1 has been crystallized in the Ca(2+)-free state stabilized by AlF(4) (−), representing an occluded E2–P(i)-like state. The crystals belonged to space group P2(1)2(1)2 and a complete data set extending to 4.3 Å resolution was collected. A molecular-replacement solution was obtained, revealing type I packing of the molecules in the crystal. Unbiased electron-density features were observed for AlF(4) (−) and for shifts of the helices, which were indicative of a reliable structure determination

Crystal Structure of the Vanadate-Inhibited Ca2+\mathrm{Ca^{2+}}-ATPase

Vanadate is the hallmark inhibitor of the P-type ATPase family; however, structural details of its inhibitory mechanism have remained unresolved. We have determined the crystal structure of sarcoplasmic reticulum Ca$^{2+}$-ATPase with bound vanadate in the absence of Ca$^{2+}$. Vanadate is bound at the catalytic site as a planar VO$_3$− in complex with water and Mg$^{2+}$ in a dephosphorylation transition-state-like conformation. Validating bound VO$_3$− by anomalous difference Fourier maps using long-wavelength data we also identify a hitherto undescribed Cl− site near the dephosphorylation site. Crystallization was facilitated by trinitrophenyl (TNP)-derivatized nucleotides that bind with the TNP moiety occupying the binding pocket that normally accommodates the adenine of ATP, rationalizing their remarkably high affinity for E2P-like conformations of the Ca$^{2+}$-ATPase. A comparison of the configurations of bound nucleotide analogs in the E2·VO$_3$− structure with that in E2·BeF$_3$− (E2P ground state analog) reveals multiple binding modes to the Ca$^{2+}$-ATPase