Biology subjects

Csillag, V.

Publications and source records attributed to Csillag, V..

7 recordsLinked to original sources

bioRxiv2025

Collateral connectomes of Esr1-positive hypothalamic neurons modulate defensive behavior plasticity

The ventromedial hypothalamus (VMH) projects to the periaqueductal gray (PAG) and anterior hypothalamic nucleus (AHN), mediating freezing and escape behaviors, respectively. We investigated VMH collateral (VMH-coll) neurons, which innervate both PAG and AHN, to elucidate their role in postsynaptic processing and defensive behavior plasticity. Using all-optical voltage imaging of 22,151 postsynaptic neurons ex vivo, we found that VMH-coll neurons engage inhibitory mechanisms at both synaptic ends and can induce synaptic circuit plasticity. In vivo optogenetic activation of the VMH-coll somas induced escape behaviors. We identified an Esr1-expressing VMH-coll subpopulation with postsynaptic connectome resembling that of wild-type collaterals on the PAG side. Activation of Esr1+VMH-coll neurons evoked freezing and unexpected flattening behavior, previously not linked to the VMH. Neuropeptides such as PACAP and dynorphin modulated both Esr1+VMH-coll connectomes. In vivo {kappa}-opioid receptor antagonism impaired Esr1+VMH-coll-mediated defensive behaviors. These findings unveiled the central role of VMH-coll pathways in innate defensive behavior plasticity.

neuroscience↗

bioRxiv2023

All-optical voltage imaging-guided postsynaptic single-cell transcriptome profiling with Voltage-Seq

Neuronal pathways recruit large postsynaptic populations and maintain connections via distinct postsynaptic response types (PRTs). Until recently, PRTs were only accessible as a selection criterion for single-cell RNA-sequencing (scRNA-seq) through probing by low-throughput whole-cell electrophysiology. To overcome these limitations and target neurons based on specific PRTs for soma collection and subsequent scRNA-seq, we developed Voltage-Seq. An on-site analysis tool, VoltView, was created to guide soma harvesting of specific PRTs using a classifier based on a previously acquired connectome database from multiple animals. Here, we present a detailed step-by-step protocol, including setting up the optical path, the imaging setup, detailing the imaging procedure, and analysis, the reagents and protocols, complete procedure for sequencing library preparation, and provide other tips and pitfalls to assist researchers in conducting high-throughput all-optical voltage imaging, and to obtain the single-cell transcriptomic data from selected postsynaptic neurons. Voltage-seq workflow can be completed in [~]6 weeks including 4-5 weeks of viral expression of the Voltron sensor. The approach allows researchers to resolve the connectivity ratio of a specific pathway and explore the diversity of PRTs within that connectome. Furthermore, the high throughput in conjunction with quick analysis gives unique access to find specific connections within a large postsynaptic connectome. Voltage-seq also allows the investigation of correlations between connectivity and gene expression changes in a postsynaptic cell-type-specific manner in both excitatory and inhibitory connections.

neuroscience↗

bioRxiv2023

Central cholinergic regulation of the GnRH system: involvement of ACh/GABA co-transmission

Gonadotropin-releasing hormone (GnRH)-synthesizing neurons orchestrate reproduction centrally. Early studies have proposed the contribution of acetylcholine (ACh) to hypothalamic control of reproduction, although the causal mechanisms have not been clarified. Here, we report that in vivo pharmacogenetic activation of the cholinergic system increased the secretion of luteinizing hormone (LH) in orchidectomized mice. 3DISCO immunocytochemistry and electron microscopy revealed the innervation of GnRH neurons by cholinergic axons. Retrograde viral labeling initiated from GnRH-Cre neurons identified the medial septum and the diagonal band of Broca as exclusive sites of origin for cholinergic afferents of GnRH neurons. In acute brain slices, ACh and the ACh receptor (AChR) agonist carbachol evoked a biphasic effect on the firing rate in GnRH neurons, first increasing and then diminishing it. In the presence of tetrodotoxin, carbachol induced an inward current, followed by a decline in the frequency of mPSCs, indicating a direct influence on GnRH cells. RT-PCR and whole-cell patch-clamp studies revealed that GnRH neurons expressed both nicotinic (4{beta}2, 3{beta}4, and 7) and muscarinic (M1-M5) ACh receptors. The nicotinic AChRs contributed to the nicotine-elicited inward current and the rise in firing rate. Muscarine via M1 and M3 receptors increased, while via M2 and M4 reduced the frequency of both miniature postsynaptic currents (mPSCs) and firing. Optogenetic activation of channelrhodopsin-2-tagged cholinergic axons modified GnRH neuronal activity and evoked co-transmission of ACh and GABA from a subpopulation of boutons. These findings confirm that the central cholinergic system immensely regulates GnRH neurons and activates the HPG-axis via ACh and ACh/GABA neurotransmissions. Significance statementCholinergic drugs influence reproduction centrally, although the exact neuronal targets and regulatory mechanisms remain unsettled. We found that pharmacogenetic activation of the cholinergic system in vivo evoked an augmented LH release. The study also identified cholinergic cell groups in the mouse forebrain that innervate gonadotropin-releasing hormone (GnRH) neurons, the main hypothalamic regulators of reproduction. We also determined the subtypes of nicotinic and muscarinic receptors involved in neuronal information transmission and explored how their ligands affect the electrophysiological activity of GnRH neurons. A subset of cholinergic neurons was found to co-transmit GABA, which excites GnRH cells via GABA-A receptors. The findings suggest a novel, cholinergic regulation of the adult GnRH system in male mice that activates the pituitary-gonadal axis.

physiology↗

bioRxiv2022

Esr1+ hypothalamic-habenula neurons shape aversive states.

Excitatory projections from the lateral hypothalamic area (LHA) to the lateral habenula (LHb) drive aversive responses. We used Patch-seq guided multimodal classification to define the structural and functional heterogeneity of the LHA-LHb pathway. Our classification identified six glutamatergic neuron types with unique electrophysiological properties, molecular profiles, and projection patterns. We found that genetically-defined LHA-LHb neurons signal distinct aspects of emotional or naturalistic behaviors: Esr1+ LHA-LHb neurons induce aversion, whereas Npy+ LHA-LHb neurons control rearing behavior. Repeated optogenetic drive of Esr1+ LHA-LHb neurons induces a behaviorally persistent aversive state, and large-scale recordings showed a region-specific neural representation of the aversive state in the prelimbic region of the prefrontal cortex. We further found that exposure to unpredictable mild shocks induced a sex-specific sensitivity to develop a stress state in female mice, which was associated with a specific shift in the intrinsic properties of bursting-type Esr1+ LHA-LHb neurons. In summary, we describe the diversity of LHA-LHb neuron types, and provide evidence for the role of Esr1+ neurons in aversion and sexually dimorphic stress sensitivity.

neuroscience↗

bioRxiv2022

High-throughput all-optical postsynaptic plasticity map navigates connectome-guided Voltage-Seq

Understanding the routing of neuronal information requires the functional characterization of connections. Neuronal projections recruit large postsynaptic ensembles with distinct postsynaptic response types (PRTs). PRT is probed by low-throughput whole-cell electrophysiology and is not a selection criterion for single-cell RNA-sequencing (scRNA-seq). To overcome these limitations and target neurons based on specific PRTs for soma harvesting and subsequent scRNA-seq we created Voltage-Seq. To test our methodology, we established all-optical voltage imaging and recorded the PRT of 8347 periaqueductal gray (PAG) neurons evoked by the optogenetic activation of ventromedial hypothalamic (VMH) terminals. PRTs were classified and spatially resolved in the entire VMH-PAG connectome. We built an on-site analysis named VoltView to navigate soma harvesting towards target PRTs guided by a classifier which used the VMH-PAG connectome database as a reference. We demonstrated the agility of Voltage-Seq in locating VMH-driven GABAergic neurons in the PAG, solely guided by the on-site classification in VoltView.

neuroscience↗

bioRxiv2022

A thalamo-preoptic pathway promoting social touch

Social touch is an important form of communication, it is still unknown how it is processed. Here, we discovered a functional role for a neuronal pathway projecting from the posterior intralaminar thalamic nucleus (PIL) to the medial preoptic area (MPOA) in controlling social contact. Neurons in the PIL and the MPOA were activated by physical contact between female rodents and also by chemogenetic stimulation of PIL neurons. Chemogenetic stimulation of PIL neurons tagged by social contact experience increased direct physical interactions between familiar female rats without affecting other forms of social behavior. Furthermore, selective stimulation of the PIL-MPOA pathway, and the local activation of PIL terminals within the MPOA, elevated direct social contact between the animals suggesting the role of pathway-specific activated cell assemblies. Neurons projecting from the PIL to the MPOA contain the neuropeptide parathyroid hormone 2 (PTH2). The expression of the peptide was induced by social housing, the presence of PTH2 receptor was identified in MPOA neurons, and local injection of PTH2 increased the firing rate of identified preoptic area GABAergic neurons via the PTH2 receptor suggesting that PTH2 acts as a neurotransmitter in the PIL-MPOA pathway. We also found a homologous PIL to MPOA neuronal pathway in the human brain. Altogether, we discovered a direct thalamo-preoptic pathway, which bypasses the cerebral cortex and controls social touch. This pathway originates in neurons expressing PTH2, a neuropeptide recently shown in fish to respond to the social environment. These observations provide evidence for common evolutionary-conserved PTH2-containing social-touch specific engram circuits.

neuroscience↗

bioRxiv2020

Somatostatin neurons of the bed nucleus of stria terminalis enhance associative fear memory consolidation in mice

Excessive fear learning and extinction-resistant fear memories are core symptoms of anxiety and trauma-related disorders. Despite significant evidence from clinical studies reporting hyperactivity of the bed nucleus of stria terminalis (BNST) under these conditions, the role of BNST in fear learning and expression is still not clarified. Here, we tested how BNST modulates fear learning in mice using a chemogenetic approach. Activation of GABAergic neurons of BNST during fear acquisition, more specifically the consolidation phase, resulted in enhanced cued fear recall. Importantly, BNST activation had no acute impact on fear expression during conditioning or recalls, but it enhanced cued fear recall subsequently, potentially via altered activity of downstream regions as indicated by c-Fos. Enhanced fear memory consolidation could be replicated by selectively activating somatostatin neurons (but not corticotropin releasing factor neurons), suggesting significant modulation of fear memory strength by specific circuits of BNST.

neuroscience↗