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A DISINHIBITORY MICROCIRCUIT FOR GATED CEREBELLAR LEARNING
Title
A DISINHIBITORY MICROCIRCUIT FOR GATED CEREBELLAR LEARNING.
Creator
Zhang, Ke, Christie, Jason, Dawson-Scully, Ken, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description
Performance motor errors trigger animals’ adaptive learning behaviors to improve the accuracy and efficiency of the movement. The cerebellum is one of the key brain centers for encoding motor performance and motor learning. Climbing fibers relay information related to motor errors to the cerebellar cortex, evoking elevation of intracellular Ca2+ signals at Purkinje cell dendrites and inducing plasticity at coactive parallel fiber synapses, ultimately recalibrating sensorimotor associations to...
Show morePerformance motor errors trigger animals’ adaptive learning behaviors to improve the accuracy and efficiency of the movement. The cerebellum is one of the key brain centers for encoding motor performance and motor learning. Climbing fibers relay information related to motor errors to the cerebellar cortex, evoking elevation of intracellular Ca2+ signals at Purkinje cell dendrites and inducing plasticity at coactive parallel fiber synapses, ultimately recalibrating sensorimotor associations to alter behavior. Molecular layer interneurons (MLIs) inhibit Purkinje cells to modulate dendritic excitability and action potential output. How MLIs contribute to the regulation and encoding of climbing fiber-evoked adaptive movements remains poorly understood. In this dissertation, I used genetic tools to manipulate the activity of MLIs while monitoring Purkinje cell dendritic activity during a cerebellum-dependent motor learning task with different contexts to evaluate how MLIs are involved in this process. The results show that by suppressing dendritic Ca2+ signals in Purkinje cells, MLI activity coincident with climbing fiber-mediated excitation prevents the occurrence of learning when adaptation is not necessary. On the other hand, with error signals present, disinhibition onto Purkinje cells, mediated by MLI-MLI microcircuit, unlocked the ability of climbing fibers to induce plasticity and motor learning.
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Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013526
Subject Headings
Cerebellum, Interneurons, Purkinje cells, Dendrites, Sensorimotor integration, Neuroplasticity
Format
Document (PDF)
MULTISCALE FUNCTIONAL ARCHITECTURE OF NEOCORTEX: FROM CLUSTERS TO COLUMNS
Title
MULTISCALE FUNCTIONAL ARCHITECTURE OF NEOCORTEX: FROM CLUSTERS TO COLUMNS.
Creator
Lee, Kuo-Sheng, Fitzpatrick, David, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
The physical architecture of neural circuits is thought to underlie the computations that give rise to higher order feature sensitivity in the neocortex. Recent technological breakthroughs have allowed the structural and functional investigation of the basic computational units of neural circuits; individual synaptic connections. However, it remains unclear how cortical neurons sample and integrate the thousands of synaptic inputs, supplied by different brain structures, to achieve feature...
Show moreThe physical architecture of neural circuits is thought to underlie the computations that give rise to higher order feature sensitivity in the neocortex. Recent technological breakthroughs have allowed the structural and functional investigation of the basic computational units of neural circuits; individual synaptic connections. However, it remains unclear how cortical neurons sample and integrate the thousands of synaptic inputs, supplied by different brain structures, to achieve feature selectivity. Here, I first describe how visual cortical circuits transform the elementary inputs supplied by the periphery into highly diverse, but well-organized, feature representations. By combining and optimizing newly developed techniques to map the functional synaptic connections with defined sources of inputs, I show that the intersection between columnar architecture and dendritic sampling strategies can lead to the selectivity properties of individual neurons: First, in the canonical feedforward circuit, the basal dendrites of a pyramidal neuron utilize unique strategies to sample ON (light increment) and OFF (light decrement) inputs in orientation columns to create the distinctive receptive field structure that is responsible for basic sensitivity to visual spatial location, orientation, spatial frequency, and phase. Second, for long-range horizontal connections, apical dendrites unbiasedly integrate functionally specialized and spatially targeted inputs in different orientation columns, which generates specific axial surround modulation of the receptive field.
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Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013327
Subject Headings
Neocortex, Visual Cortex--physiology, Neural circuitry, Dendrites
Format
Document (PDF)
DECIPHERING NEURONAL SIGNALING WITHIN A SINGLE DENDRITIC SPINE IN LONG TERM POTENTIATION
Title
DECIPHERING NEURONAL SIGNALING WITHIN A SINGLE DENDRITIC SPINE IN LONG TERM POTENTIATION.
Creator
Tu, Xun, Yasuda, Ryohei, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description
Organization and function of neuronal circuits require not only the interaction between the intrinsic components of the individual neurons but also the synaptic interactions that incorporate them into functional entities. Dendritic spines are the major sites for excitatory synaptic transmission, and are considered as the basic unit of information transfer in nervous system. Structural plasticity of dendritic spines is highly associated with functional plasticity, playing critical roles in...
Show moreOrganization and function of neuronal circuits require not only the interaction between the intrinsic components of the individual neurons but also the synaptic interactions that incorporate them into functional entities. Dendritic spines are the major sites for excitatory synaptic transmission, and are considered as the basic unit of information transfer in nervous system. Structural plasticity of dendritic spines is highly associated with functional plasticity, playing critical roles in learning and memory. Here, we explored mechanisms underlying PKCα and structural plasticity of dendritic spines. We examined the spatiotemporal activation of actin regulators with 2pFLIM, including small GTPases Rac1, Cdc42 and Ras, in the presence or absence of PKCα during single-spine structural plasticity. Removal of PKCα expression in the postsynapse attenuated Rac1 activation during structural plasticity without affecting Ras or Cdc42 activity. Moreover, disruption of a PDZ binding domain within PKCα led to impaired Rac1 activation and deficits in structural spine remodeling. This work described that PKCα regulates the activation of Rac1, but not Ras or Cdc42, during sLTP of dendritic spines, and this modulation relies on PKCα’s PDZ-binding motif.
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Date Issued
2022
PURL
http://purl.flvc.org/fau/fd/FA00013974
Subject Headings
Dendritic Spines, Neuronal Plasticity, Long-Term Potentiation
Format
Document (PDF)
VISUALIZING NANO-SCALE SYNAPTIC CHANGES DURING SINGLE DENDRITIC SPINE LONG-TERM POTENTIATION BY CORRELATIVE LIGHT AND ELECTRON MICROSCOPY
Title
VISUALIZING NANO-SCALE SYNAPTIC CHANGES DURING SINGLE DENDRITIC SPINE LONG-TERM POTENTIATION BY CORRELATIVE LIGHT AND ELECTRON MICROSCOPY.
Creator
Sun, Ye, Yasuda, Ryohei, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description
Dendritic spines are the major sites for receiving excitatory synaptic inputs and play important roles in neuronal signal transduction, memory storage and neuronal circuit organization. Structural plasticity of dendritic spines is correlated with functional plasticity, and is critical for learning and memory. Visualization of the changes of dendritic spines at the ultrastructural level that specifically correlated with their function changes in high throughput would shed light on detailed...
Show moreDendritic spines are the major sites for receiving excitatory synaptic inputs and play important roles in neuronal signal transduction, memory storage and neuronal circuit organization. Structural plasticity of dendritic spines is correlated with functional plasticity, and is critical for learning and memory. Visualization of the changes of dendritic spines at the ultrastructural level that specifically correlated with their function changes in high throughput would shed light on detailed mechanisms of synaptic plasticity. Here we developed a correlative light and electron microscopy workflow which combines two-photon MNI-glutamate uncaging, pre-embedding immunolabeling, Automatic Tape-collecting Ultramicrotome sectioning and scanning electron microscopy imaging. This method bridges two different visualization platforms, directly linking ultrastructure and function at the level of individual synapses. With this method, we successfully relocated single dendritic spines that underwent long-term potentiation (LTP) induced by two-photon MNI-glutamate uncaging, and visualized their ultrastructures and AMPA receptors distribution at different phases of LTP in high throughput.
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Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013433
Subject Headings
Dendritic Spines, Neuroplasticity, Visualization, Microscopy, Long-Term Potentiation--physiology, Neurons--ultrastructure
Format
Document (PDF)