Our long-term goal is to understand how neural circuits support auditory processing. Here, we will explore dynamic aspects of synaptic communication, their neuromodulation and plasticity, in the molecular layer and granule cell regions of the dorsal cochlear nucleus (DCN). The results of this study will reveal novel aspects of DCN circuit elements, information which will add new dimensions to the current picture of auditory and multisensory processing. The DCN functions in sound source localization and the integration of a variety of non-auditory signals, potentially for head/ear orientation or cancelatin of self-generated sound. It is also believed that the DCN plays a role in the maintenance of tinnitus, a widespread and disturbingly chronic clinical condition. The DCN is unique in the lower auditory pathway for showing robust synaptic plasticity - this is plasticity not of the auditory nerve input but rather of multisensory input, highlighting the important role that latter must have in DCN function. This proposal examines two sequential stages of multisensory processing: first in auditory granule cells and then in the DCN molecular layer. All multisensory information enters the DCN through mossy fibers which terminate in seven sub regions of granule cells. Yet, the different roles of these granule regions and what distinct forms of processing occur in each are unknown. We will therefore clarify how granule cells transform signals in order to understand the significance of computations later in the circuit. In the molecular layer, parallel fibers of granule cells terminate onto fusiform principal cells and two interneurons, the cartwheel cell and the superficial stellate cell (SSC). Here we will explore an unexpected function for the SSCs, that they mediate feedback signaling from the principal cells that facilitates activity withi the molecular layer. Lastly, we will determine how processing in granule areas and the molecular layer is controlled by the potent neuromodulators. We will use electrophysiological and optical approaches, and generate new mouse lines in which fluorophores or channelrhodopsin (ChR2) are expressed in specific DCN cell types.
These studies will provide significant new information about how inhibitory and excitatory neurons interact dynamically in a circuit that processes auditory signals. Moreover, the results may offer new insight into the causes of the neuronal hyperactivity associated with tinnitus, and in the design of more effective auditory prosthetic devices.
|Joris, Philip X; Trussell, Laurence O (2018) The Calyx of Held: A Hypothesis on the Need for Reliable Timing in an Intensity-Difference Encoder. Neuron 100:534-549|
|Moore, Alexandra K; Weible, Aldis P; Balmer, Timothy S et al. (2018) Rapid Rebalancing of Excitation and Inhibition by Cortical Circuitry. Neuron 97:1341-1355.e6|
|Lu, Hsin-Wei; Balmer, Timothy S; Romero, Gabriel E et al. (2017) Slow AMPAR Synaptic Transmission Is Determined by Stargazin and Glutamate Transporters. Neuron 96:73-80.e4|
|Irie, Tomohiko; Trussell, Laurence O (2017) Double-Nanodomain Coupling of Calcium Channels, Ryanodine Receptors, and BK Channels Controls the Generation of Burst Firing. Neuron 96:856-870.e4|
|Tang, Zheng-Quan; Trussell, Laurence O (2017) Serotonergic Modulation of Sensory Representation in a Central Multisensory Circuit Is Pathway Specific. Cell Rep 20:1844-1854|
|Moore, Lucille A; Trussell, Laurence O (2017) Corelease of Inhibitory Neurotransmitters in the Mouse Auditory Midbrain. J Neurosci 37:9453-9464|
|Yaeger, Daniel B; Trussell, Laurence O (2016) Auditory Golgi cells are interconnected predominantly by electrical synapses. J Neurophysiol 116:540-51|
|Lu, Hsin-Wei; Trussell, Laurence O (2016) Spontaneous Activity Defines Effective Convergence Ratios in an Inhibitory Circuit. J Neurosci 36:3268-80|
|Balmer, Timothy S; Trussell, Laurence O (2016) Quantum Disentanglement: Electrical Analysis of the Complex Roles of Ions in Filling Vesicles with Glutamate. Neuron 90:667-9|
|Borges-Merjane, Carolina; Trussell, Laurence O (2015) ON and OFF unipolar brush cells transform multisensory inputs to the auditory system. Neuron 85:1029-42|
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