Biology subjects

Laber, D.

Publications and source records attributed to Laber, D..

3 recordsLinked to original sources

bioRxiv2021

Postsynaptic plasticity of cholinergic synapses underlies the induction and expression of appetitive memories in Drosophila

In vertebrates, several forms of memory-relevant synaptic plasticity involve postsynaptic rearrangements of glutamate receptors. In contrast, previous work indicates that Drosophila and other invertebrates store memories using presynaptic plasticity of cholinergic synapses. Here, we provide evidence for postsynaptic plasticity at cholinergic output synapses from the Drosophila mushroom bodies (MBs). We find that the nicotinic acetylcholine receptor (nAChR) subunit 5 is required within specific MB output neurons (MBONs) for appetitive memory induction, but is dispensable for aversive memories. In addition, nAChR 2 subunits mediate memory expression and likely functions downstream of 5 and the postsynaptic scaffold protein Dlg. We show that postsynaptic plasticity traces can be induced independently of the presynapse, and that in vivo dynamics of 2 nAChR subunits are changed both in the context of associative and non-associative memory formation, underlying different plasticity rules. Therefore, regardless of neurotransmitter identity, key principles of postsynaptic plasticity support memory storage across phyla.

neuroscience↗

bioRxiv2019

Network-specific synchronization of electrical slow-wave oscillations regulates sleep in Drosophila

Slow-wave rhythms characteristic of deep sleep oscillate in the delta band (0.5-4 Hz) and can be found across various brain regions in vertebrates. Across systems it is however unclear how oscillations arise and whether they are the causal functional unit steering behavior. Here, for the first time in any invertebrate, we discover sleep-relevant delta oscillations in Drosophila. We find that slow-wave oscillations in the sleep-regulating R2 network increase with sleep need. Optical multi-unit voltage recordings reveal that single R2 neurons get synchronized by sensory and circadian input pathways. We show that this synchronization depends on NMDA receptor (NMDARs) coincidence detector function and on an interplay of cholinergic and glutamatergic inputs setting a resonance frequency. Genetically targeting the coincidence detector function of NMDARs in R2, and thus the uncovered mechanism underlying synchronization, abolished network-specific slow-wave oscillations. It also disrupted sleep and facilitated light-induced wakening, directly establishing a causal role for slow-wave oscillations in regulating sleep and sensory gating. We therefore propose that the synchronization-based increase in oscillatory power likely represents an evolutionarily conserved, potentially optimal, strategy for constructing sleep-regulating sensory gates.

neuroscience↗

bioRxiv2018

Rapid active zone remodeling consolidates presynaptic potentiation

Synaptic transmission is mediated by neurotransmitter release at presynaptic active zones (AZs) followed by postsynaptic neurotransmitter detection. Plastic changes in transmission maintain functionality during perturbations and enable memory formation. Postsynaptic plasticity targets neurotransmitter receptors, but presynaptic plasticity mechanisms directly regulating the neurotransmitter release apparatus remain largely enigmatic. Here we describe that AZs consist of nano-modular release site units and identify a molecular sequence adding more modules within minutes of plasticity induction. This requires cognate transport machinery and a discrete subset of AZ scaffold proteins. Structural remodeling is not required for the immediate potentiation of neurotransmitter release, but rather necessary to sustain this potentiation over longer timescales. Finally, mutations in Unc13 that disrupt homeostatic plasticity at the neuromuscular junction also impair shot-term memory when central neurons are targeted, suggesting that both forms of plasticity operate via Unc13. Together, while immediate synaptic potentiation capitalizes on available material, it triggers the coincident incorporation of modular release sites to consolidate stable synapse function.

neuroscience↗