Paired recordings from distant inhibitory neuron pairs by a sequential scanning approach

Area of Science:

• Neuroscience
• Synaptic Physiology
• Auditory Neuroscience

Background:

• Simultaneous recordings from connected neuron pairs provide insights into synaptic communication.
• Traditional patch clamp methods are limited to brain regions with high probability of nearby neuronal connections.
• Recordings from distantly or sparsely connected neuron pairs remain challenging.

Purpose of the Study:

• To present a novel method for dual recordings from remotely connected neuron pairs.
• To enable synaptic recordings in brain areas with low connection probability.
• To investigate the inhibitory pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO).

Main Methods:

• A three-step approach combining focal uncaging of glutamate, pressure application of glutamate, and loose patch recordings.
• Scanning potential presynaptic neurons to identify remotely connected pairs.
• Application in the MNTB-LSO pathway, a key sound localization circuit in the auditory brainstem.

Main Results:

• Successfully achieved recordings from distant, synaptically connected GABA/glycinergic MNTB-LSO neuron pairs.
• Demonstrated highly variable mono-synaptic responses evoked by single MNTB neurons in developing LSO neurons.
• Revealed heterogeneous short-term synaptic dynamics, suggesting local variations in inhibitory connection refinement.

Conclusions:

• The developed method reliably enables dual recordings from remotely connected neuron pairs.
• This technique is valuable for studying synaptic function and plasticity in developing neural circuits.
• The method offers a powerful tool for identifying connected neurons in brain areas with low recording success rates.