Interactions between behaviorally relevant rhythms and synaptic plasticity alter coding in the piriform cortex

Area of Science:

• Neuroscience
• Sensory Systems
• Olfactory Processing

Background:

• Neural and behavioral timescales are crucial for understanding cortical activity and stimulus coding.
• Respiratory frequency changes alter temporal patterns of olfactory input in air-breathing animals.
• Olfactory bulb mitral/tufted (M/T) cell spike trains reflect these behavioral timescales.

Purpose of the Study:

• To investigate the interaction between respiratory timescales, spike timing, and short-term synaptic plasticity in shaping cortical olfactory responses.
• To determine how different respiratory frequencies (breathing vs. sniffing) modulate information transfer to the cortex.

Main Methods:

• Quantified short-term synaptic facilitation and depression timescales at M/T cell to cortical neuron synapses in mouse olfactory cortex slices.
• Generated simulated M/T population synaptic currents using quantified plasticity timescales.
• Injected simulated currents into real cortical neurons, modulating input frequencies to mimic passive respiration and active sniffing.

Main Results:

• Short-term synaptic plasticity recruitment differed between breathing and sniffing frequencies.
• Cortical neurons linearly encoded presynaptic firing rate increases with phase-locked firing at sniffing frequencies.
• Cortical responses saturated with presynaptic rate changes at passive breathing frequencies.

Conclusions:

• Differential recruitment of short-term synaptic plasticity gates olfactory information transfer based on respiratory behavior.
• Sniffing facilitates linear stimulus coding, while breathing leads to response saturation, impacting how odor information is relayed to the cortex.