Title:
Towards demystifying the “mysterious creatures of the deep”: corticothalamic feedback in sensory processing
Towards demystifying the “mysterious creatures of the deep”: corticothalamic feedback in sensory processing
Author(s)
Dimwamwa, Elaida
Advisor(s)
Stanley, Garrett B.
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Abstract
Combining incoming sensory information with expectations from our lived experiences, remarkably and effortlessly, we identify and discriminate between objects on a daily basis. While the neuronal processes underlying our ability to complete such sensory-based tasks are canonically studied as feedforward neuronal pathways, numerous feedback pathways interact with the feedforward pathways to enable us to perceive the world through our senses. Corticothalamic feedback from layer 6 of the cortex (L6CT) is one such process that provides copious inputs back to the thalamus, but its function remains elusive. 40-60% of first-order thalamic inputs derive from L6CT neurons, thus positioning L6CT neurons to play an essential role in thalamocortical sensory signaling for sensory perception, which we elucidate through two studies.
Using the somatosensory whisker system of awake, transgenic mice selectively expressing channelrhodopsin-2 in L6CT neurons, we investigate how L6CT neurons modulate thalamic and cortical activity and reveal that L6CT neurons can both enhance and suppress thalamocortical excitability in a manner that is dependent on both the firing rate and synchrony of the L6CT inputs (Chapter 2). We then determine the precise activity patterns of L6CT neurons in mice behaving in a somatosensory detection task and reveal that not only are L6CT neurons sensory responsive in the awake and behaving animal, but that both the sensory response as well as the pre-stimulus synchrony encodes the behavior of the animal (Chapter 3). Taken together, this thesis provides evidence for L6CT neurons as dynamic regulators of thalamocortical excitability that contribute to performance in sensory detection.
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Date Issued
2024-06-27
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Dissertation