Biology subjects

Gonzalez Sabater, V.

Publications and source records attributed to Gonzalez Sabater, V..

3 recordsLinked to original sources

bioRxiv2025

Unreliable homeostatic action potential broadening in cultured dissociated neurons

Homeostatic plasticity preserves neuronal activity against perturbations. Recently, somatic action potential broadening was proposed as a key homeostatic adaptation to chronic inactivity in neocortical neurons. Since action potential shape critically controls calcium entry and neuronal function, broadening provides an attractive homeostatic feedback mechanism to regulate activity. Here, we report that chronic inactivity induced by sodium channel block does not broaden action potentials in neocortical neurons under a wide range of conditions. In contrast, action potentials were broadened in CA3 neurons of organotypic hippocampal cultures by chronic sodium channel block and in hippocampal dissociated cultures by chronic synaptic block. Mechanistically, BK-type potassium channels were proposed to underly inactivity-induced action potential broadening. However, BK channels did not affect action potential duration in our recordings. Our results indicate that action potential broadening can occur in specific neurons and conditions but is not a general mechanism of homeostatic plasticity in cultured neurons.

neuroscience↗

bioRxiv2020

Voltage-gated potassium channels ensure action potential shape fidelity in distal axons

The initiation and propagation of the action potential (AP) along an axon allows neurons to convey information rapidly and across distant sites. Although AP properties have typically been characterised at the soma and proximal axon, the propagation of APs towards distal axonal domains of mammalian neurons remains limited. We used Genetically Encoded Voltage Indicators (GEVIs) to image APs simultaneously at different locations along the long axons of dissociated hippocampal neurons with sub-millisecond temporal resolution. We found that APs became sharper and showed remarkable fidelity as they traveled towards distal axons, even during a high frequency train. Blocking voltage-gated potassium channels (Kv) with 4-AP resulted in an increase in AP width in all compartments, which was stronger at distal locations and exacerbated during AP trains. We conclude that the higher levels of Kv channel activity in distal axons serves to sustain AP fidelity, conveying a reliable digital signal to presynaptic boutons.

neuroscience↗

bioRxiv2018

Homeostatic plasticity rules control the wiring of axo-axonic synapses at the axon initial segment

GABAergic interneurons are chiefly responsible for controlling the activity of local circuits in the cortex1,2. However, the rules that govern the wiring of interneurons are not well understood3. Chandelier cells (ChCs) are a type of GABAergic interneuron that control the output of hundreds of neighbouring pyramidal cells through axo-axonic synapses which target the axon initial segment (AIS)4. Despite their importance in modulating circuit activity, our knowledge of the development and function of axo-axonic synapses remains elusive. In this study, we investigated the role of activity in the formation and plasticity of ChC synapses. In vivo imaging of ChCs during development uncovered a narrow window (P12-P18) over which axons arborized and formed connections. We found that increases in the activity of either pyramidal cells or individual ChCs during this temporal window resulted in a reversible decrease in axo-axonic connections. Voltage imaging of GABAergic transmission at the AIS showed that axo-axonic synapses were depolarising during this period. Identical manipulations of network activity in older mice (P40-P46), when ChC synapses are inhibitory, resulted in an increase in axo-axonic synapses. We propose that the direction of ChC plasticity follows homeostatic rules that depend on the polarity of axo-axonic synapses.

neuroscience↗