Using Cortical Neuron Markers to Target Cells in the Dorsal Cochlear Nucleus

Area of Science:

• Neuroscience
• Auditory system research
• Tinnitus pathophysiology

Background:

• The dorsal cochlear nucleus (DCN) is crucial for auditory processing and tinnitus research.
• Current limitations in genetic markers impede *in vivo* manipulation of DCN for studying tinnitus.
• Adeno-associated viral vectors (AAV) are explored for targeted gene delivery.

Purpose of the Study:

• To evaluate the efficacy of CaMKIIα promoter and Chrna2-Cre mouse line for targeting DCN populations.
• To investigate the role of specific DCN neuronal populations in auditory processing and tinnitus.
• To identify suitable molecular tools for DCN manipulation in auditory research.

Main Methods:

• Utilized AAV vectors with CaMKIIα promoter to target DCN neurons.
• Employed Chrna2-Cre mouse line and CLARITY technique to identify Cre+ cells in DCN.
• Performed optogenetic stimulation (Channelrhodopsin2, eArch3.0) and electrophysiological recordings.
• Used anterograde labeling in the ventral cochlear nucleus (VCN) to trace projections.

Main Results:

• CaMKIIα promoter did not exclusively target excitatory fusiform DCN neurons, labeling diverse cell types.
• CaMKIIα-driven Channelrhodopsin2 expression showed complex responses to light and sound stimuli.
• Chrna2-Cre mice showed minimal Cre+ cell bodies in DCN but abundant VCN projections to DCN.
• VCN projections identified as excitatory Chrna2+ T-stellate cells; their excitation increased DCN firing.

Conclusions:

• CaMKIIα promoter is unsuitable for precise targeting of specific DCN neuronal populations.
• Chrna2+ T-stellate cells from VCN represent a viable target for DCN manipulation.
• Cortical molecular tools, particularly targeting Chrna2, show potential for DCN manipulation in tinnitus research.