Publications by Olexiy Kochubey

A posterior insula to lateral amygdala pathway transmits US-offset information with a limited role in fear learning

Ralf Schneggenburger, Olexiy Kochubey, Shriya Palchaudhuri, Denys Osypenko

During fear learning, associations between a sensory cue (conditioned stimulus, CS) and an aversive stimulus (unconditioned stimulus, US) are formed in specific brain circuits. The lateral amygdala (LA) is involved in CS-US integration; however, US pathway ...

2025

Auditory stimuli suppress contextual fear responses in safety learning independent of a possible safety meaning

Ralf Schneggenburger, Olexiy Kochubey, Johanni Michael Brea, Shriya Palchaudhuri, Denys Osypenko, Christos Sourmpis

Safety learning allows the identification of non-threatening situations, a learning process instrumental for survival and psychic health. In contrast to fear learning, in which a sensory cue (conditioned stimulus, CS) is temporally linked to a mildly avers ...

2024

A striatal circuit balances learned fear in the presence and absence of sensory cues

Ralf Schneggenburger, Olexiy Kochubey, Michael Kintscher

During fear learning, defensive behaviors like freezing need to be finely balanced in the presence or absence of threat-predicting cues (conditioned stimulus, CS). Nevertheless, the circuits underlying such balancing are largely unknown. Here, we investiga ...

eLIFE SCIENCES PUBL LTD2023

Stimulation of medial amygdala GABA neurons with kinetically different channelrhodopsins yields opposite behavioral outcomes

Ralf Schneggenburger, Olexiy Kochubey, Aiste Baleisyte

The medial amygdala (MeA) receives pheromone information about conspecifics and has crucial functions in social behaviors. A previous study showed that activation of GABA neurons in the postero-dorsal MeA (MeApd) with channelrhodopsin-2(H)(134R) (ChR2) sti ...

CELL PRESS2022

A VTA to Basal Amygdala Dopamine Projection Contributes to Signal Salient Somatosensory Events during Fear Learning

Ralf Schneggenburger, Olexiy Kochubey, Wei Tang, Michael Kintscher

The amygdala is a brain area critical for the formation of fear memories. However, the nature of the teaching signal(s) that drive plasticity in the amygdala are still under debate. Here, we use optogenetic methods to investigate the contribution of ventra ...

2020

RETRACTED: Insular cortex processes aversive somatosensory information and is crucial for threat learning

Ralf Schneggenburger, Olexiy Kochubey, Wei Tang, Michael Kintscher, Shriya Palchaudhuri, Emmanuelle Marie Brigitte Berret, Denys Osypenko

Learning about threats is essential for survival. During threat learning, an innocuous sensory percept such as a tone acquires an emotional meaning when paired with an aversive stimulus such as a mild footshock. The amygdala is critical for threat memory f ...

American Association for the Advancement of Science2019

Parvalbumin-Interneuron Output Synapses Show Spike-Timing-Dependent Plasticity that Contributes to Auditory Map Remodeling

Ralf Schneggenburger, Olexiy Kochubey, Alex Fratzl, Evan Dean Vickers, Christopher Clark, Denys Osypenko

2018

Synaptotagmin2 (Syt2) Drives Fast Release Redundantly with Syt1 at the Output Synapses of Parvalbumin-Expressing Inhibitory Neurons

Ralf Schneggenburger, Olexiy Kochubey, Enida Gjoni, Brice Antoine Alexandre Bouhours

Parvalbumin-expressing inhibitory neurons in the mammalian CNS are specialized for fast transmitter release at their output synapses. However, the Ca2+ sensor(s) used by identified inhibitory synapses, including the output synapses of parvalbumin-expressin ...

2017

A Synaptotagmin Isoform Switch during the Development of an Identified CNS Synapse

Ralf Schneggenburger, Olexiy Kochubey, Zsolt Norbert Babai

Various Synaptotagmin (Syt) isoform genes are found in mammals, but it is unknown whether Syts can function redundantly in a given nerve terminal, or whether isoforms can be switched during the development of a nerve terminal. Here, we investigated the pos ...

2016

An Exclusion Zone for Ca2+ Channels around Docked Vesicles Explains Release Control by Multiple Channels at a CNS Synapse

Henry Markram, Ralf Schneggenburger, Felix Schürmann, Yunyun Han, Olexiy Kochubey, Daniel Keller, Zsolt Norbert Babai

The spatial arrangement of Ca2+ channels and vesicles remains unknown for most CNS synapses, despite of the crucial importance of this geometrical parameter for the Ca2+ control of transmitter release. At a large model synapse, the calyx of Held, transmitt ...

Public Library Science2015

Molecular identity of Ca2+ sensors for transmitter release at the developing calyx of Held

Ralf Schneggenburger, Olexiy Kochubey

Wiley-Blackwell2014

An Alien Divalent Ion Reveals a Major Role for Ca2+ Buffering in Controlling Slow Transmitter Release

Ralf Schneggenburger, Olexiy Kochubey, Daniel Keller, Zsolt Norbert Babai

Ca2+-dependent transmitter release occurs in a fast and in a slow phase, but the differential roles of Ca2+ buffers and Ca2+ sensors in shaping release kinetics are still controversial. Replacing extracellular Ca2+ by Sr2+ causes decreased fast release but ...

2014

Munc18-1 is a dynamically regulated PKC target during short-term enhancement of transmitter release

Ralf Schneggenburger, Olexiy Kochubey, Özgür Genç

Transmitter release at synapses is regulated by preceding neuronal activity, which can give rise to short-term enhancement of release like post-tetanic potentiation (PTP). Diacylglycerol (DAG) and Protein-kinase C (PKC) signaling in the nerve terminal have ...

Elife Sciences Publications Ltd2014

Ca2+ channels and transmitter release at the active zone

Ralf Schneggenburger, Yunyun Han, Olexiy Kochubey

Ca2+-dependent transmitter release is the most important signaling mechanism for fast information transfer between neurons. Transmitter release takes places at highly specialized active zones with sub-micrometer dimension, which contain the molecular machi ...

Elsevier2012

Regulation of transmitter release by Ca2+ and synaptotagmin: insights from a large CNS synapse

Ralf Schneggenburger, Olexiy Kochubey

Transmitter release at synapses is driven by elevated intracellular Ca2+ concentration (Ca2+) near the sites of vesicle fusion. Ca2+ signals of profoundly different amplitude and kinetics drive the phasic release component during a presynaptic ac ...

2011

Synaptotagmin increases the dynamic range of synapses by driving Ca2+ - evoked release and by clamping a near-linear remaining Ca2+ sensor

Ralf Schneggenburger, Olexiy Kochubey

Ca2+-evoked transmitter release shows a high dynamic range over spontaneous release. We investigated the role of the Ca2+ sensor protein, Synaptotagmin2 (Syt2), in both spontaneous and Ca2+-evoked release under direct control of presynaptic Ca2+, usin ...

2011

Developmental expression of Synaptotagmin isoforms in single calyx of Held-generating neurons

Heike Runne, Ralf Schneggenburger, Le Xiao, Yunyun Han, Olexiy Kochubey, Heather Mary Elizabeth Murray

The large glutamatergic calyx of Held synapse in the auditory brainstem has become a powerful model for studying transmitter release mechanisms, but the molecular bases of presynaptic function at this synapse are not well known. Here, we have used single-c ...

2010

Interaction between Facilitation and Depression at a Large CNS Synapse Reveals Mechanisms of Short-Term Plasticity

Ralf Schneggenburger, Olexiy Kochubey, Martin Guillermo Mueller

The two fundamental forms of short-term plasticity, short-term depression and facilitation, coexist at most synapses, but little is known about their interaction. Here, we studied the interplay between short-term depression and facilitation at calyx of Hel ...

Society for Neuroscience2010

Developmental regulation of the intracellular Ca2+ sensitivity of vesicle fusion and Ca2+-secretion coupling at the rat calyx of Held

Ralf Schneggenburger, Yunyun Han, Olexiy Kochubey

Developmental refinement of synaptic transmission can occur via changes in several pre- and postsynaptic factors, but it has been unknown whether the intrinsic Ca2+ sensitivity of vesicle fusion in the nerve terminal can be regulated during development. Us ...

2009