Substantia nigra modulates breathing rate via locus coeruleus

Area of Science:

• Neuroscience
• Respiratory Physiology
• Basal Ganglia Function

Background:

• Breathing is an automatic process controlled by hindbrain circuits like the pre-Bötzinger complex.
• The basal ganglia's role in regulating breathing remains largely uncharacterized.
• Substantia nigra (SN) is a key component of the basal ganglia involved in motor control.

Purpose of the Study:

• To investigate the role of substantia nigra (SN) outputs in modulating breathing rate.
• To determine if specific neuronal populations within the SN influence respiratory control.
• To elucidate the neural pathways involved in basal ganglia-mediated breathing regulation.

Main Methods:

• Utilized optogenetics to selectively activate or inhibit neuronal populations in the SN of anesthetized mice.
• Measured breathing rate changes in response to targeted neuronal activation.
• Recorded neural activity in the locus coeruleus (LC) to assess downstream effects.

Main Results:

• Optogenetic activation of glutamic acid decarboxylase 2 (Gad2)-expressing neurons in the SN decreased breathing rate.
• Activation of parvalbumin (Pvalb)-expressing neurons in the SN did not affect breathing rate.
• The observed decrease in breathing rate was associated with the inhibition of neural activity in the locus coeruleus (LC).

Conclusions:

• The substantia nigra (SN) plays a cell-type specific role in modulating breathing rate.
• Gad2-expressing neurons in the SN inhibit locus coeruleus (LC) activity, leading to reduced breathing rate.
• These findings highlight a novel pathway through which the basal ganglia influence respiratory control.