Rapid Neuromodulation of Layer 1 Interneurons in Human Neocortex

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• Inhibitory interneurons are crucial for neocortical computations and are modulated by neurotransmitters.
• While rodent interneuron mechanisms are well-studied, their equivalents in the human neocortex remain largely unknown.
• Specific interneurons rapidly convert neuromodulatory signals influencing sensory processing during attention and learning.

Purpose of the Study:

• To investigate the physiological and genetic features of human layer 1 interneurons (L1-INs).
• To determine if rapid neuromodulatory mechanisms observed in rodents are conserved in the human neocortex.
• To characterize the responses of human L1-INs to neuromodulators like nicotinic and HTR3 receptors.

Main Methods:

• Whole-cell recordings from human L1-INs.
• Application of neuromodulatory agonists.
• Utilizing transgenic mouse lines for comparison.
• In situ hybridization for gene expression analysis.
• Unbiased clustering for cell type classification.

Main Results:

• All human L1-INs showed significant nicotinic receptor-mediated recruitment.
• A small subset of L1-INs co-expressed the ionotropic HTR3 receptor.
• Two distinct, conserved L1-IN types were identified in both human and mouse neocortex.
• Evidence for conserved rapid neuromodulation of human neocortical circuits via layer 1.

Conclusions:

• Human L1-INs are rapidly modulated by nicotinic pathways.
• Conserved interneuron subtypes and neuromodulatory mechanisms exist in human and rodent layer 1.
• These findings suggest conserved rapid neuromodulation underlies human neocortical circuit function.