Long-Range Gabaergic Projections in the Mouse Auditory Cortex

The auditory cortex is a brain area where many complex auditory signals are processed to enable an organism to understand, learn, and react to the acoustic environment. How neurons connect within the cytoarchitecture of the auditory cortex are responsible for these processes to come to place. Understanding the diversity and interconnectivity of neurons in the auditory cortex and other brain areas advances the understanding of how the auditory system works. There are two types of neurons in the auditory cortex that work together to make the system work properly and efficiently. These are excitatory glutamatergic and inhibitory GABAergic neurons. Classically, glutamatergic neurons in the cortex are considered long-range projecting which transmit signals to other brain areas through excitation whereas GABAergic neurons only project locally and modulate the local neuronal network through inhibition. However, recent evidence shows that cortical GABAergic neurons can not only be local projecting neurons but also be long-range projecting and inhibit other brain areas. Using recent technological advances and classical techniques in neuroscience including transgenic mice, viral and non-viral neuronal tracers, in vitro slice electrophysiology, optogenetics, pharmacology, confocal microscopy, neuronal tracings, and immunohistochemistry allowed the discovery and study of these overlooked neurons. Cortical long-range GABAergic neurons add to the complexity of how cortical circuits processes and transmits neuronal signals throughout the brain. In this dissertation, I describe and explore the characteristics, connectivity, and function of novel long-range GABAergic neurons in the mouse auditory cortex.