Oregon Health & Science University
Sensory information is the basis of an integrated perception of reality and allows an organism to make informed decisions based upon events occurring in its surroundings. Mammals are equipped with five sensory modalities to sample the physical and chemical phenomena of the outside world. However, the cellular mechanisms underlying basic sensory processing in the brain are poorly understood. Particularly, an outstanding question is how do heterogeneous groups of cells, e.g. neuronal microcircuits, function in concert to extract and relay meaningful information about sensory inputs? This thesis focuses on a mammalian auditory brainstem region known as the dorsal cochlear nucleus (DCN). Using whole-cell patch clamp electrophysiology and multi-photon imaging in acute brain slices from mouse DCN, the experiments herein focus on inhibition mediated by the neurotransmitters glycine and GABA. Chapter 1 addresses outstanding issues related to the molecular mechanisms involved in the packaging of inhibitory neurotransmitters into synaptic vesicles. Chapters 2-4 focus on the synaptic inputs that control the activity of a previously unstudied inhibitory interneuron in the DCN, the superficial stellate cell. In particular, Chapter 3 describes a novel pathway in the DCN microcircuit that allows excitatory projection neurons to control the activity of stellate cells via gap junction (electrical) coupling. Chapter 4 demonstrates that synaptic inhibition in stellate cells is mediated not only by glycine and GABA, but can be mediated by synaptically-released glutamate deactivating a resting cation conductance in the dendrites of electrically-coupled neurons. These findings are discussed in the context of auditory perception and current theories regarding neuronal microcircuits.
Neuroscience Graduate Program
School of Medicine
Apostolides, Pierre F., "Cellular and network mechanisms for generating inhibition in the mouse dorsal cochlear nucleus" (2014). Scholar Archive. 3500.