Kristen M. Harris

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Neurotrophins regulate neuronal survival, differentiation, and synaptic function. To understand how neurotrophins elicit such diverse responses, we elucidated signaling pathways by which brain-derived neurotrophic factor (BDNF) activates gene expression in cultured neurons and hippocampal slices. We found, unexpectedly, that the transcription factor cyclic(More)
Dendritic spines are micron-sized membrane protrusions receiving most excitatory synaptic inputs in the mammalian brain. Spines form and grow during long-term potentiation (LTP) of synaptic strength. However, the source of membrane for spine formation and enlargement is unknown. Here we report that membrane trafficking from recycling endosomes is required(More)
Dendritic spines are the primary recipients of excitatory input in the central nervous system. They provide biochemical compartments that locally control the signaling mechanisms at individual synapses. Hippocampal spines show structural plasticity as the basis for the physiological changes in synaptic efficacy that underlie learning and memory. Spine(More)
Dendritic spines are the primary site of excitatory input on most principal neurons. Long-lasting changes in synaptic activity are accompanied by alterations in spine shape, size and number. The responsiveness of thin spines to increases and decreases in synaptic activity has led to the suggestion that they are 'learning spines', whereas the stability of(More)
Complete reconstructions of vertebrate neuronal circuits on the synaptic level require new approaches. Here, serial section transmission electron microscopy was automated to densely reconstruct four volumes, totaling 670 μm(3), from the rat hippocampus as proving grounds to determine when axo-dendritic proximities predict synapses. First, in contrast with(More)
Altered dendritic spines are characteristic of traumatized or diseased brain. Two general categories of spine pathology can be distinguished: pathologies of distribution and pathologies of ultrastructure. Pathologies of spine distribution affect many spines along the dendrites of a neuron and include altered spine numbers, distorted spine shapes, and(More)
Endosomes are essential to dendritic and synaptic function in sorting membrane proteins for degradation or recycling, yet little is known about their locations near synapses. Here, serial electron microscopy was used to ascertain the morphology and distribution of all membranous intracellular compartments in distal dendrites of hippocampal CA1 pyramidal(More)
The presence of polyribosomes in dendritic spines suggests a potential involvement of local protein synthesis in the modification of synapses. Dendritic spine and synapse ultrastructure were compared after low-frequency control or tetanic stimulation in hippocampal slices from postnatal day (P)15 rats. The percentage of spines containing polyribosomes(More)
Design and Measurements: Volumes are reconstructed by defining transformations that align the entire area of adjacent sections. Whole-field alignment requires rotation, translation, skew, scaling, and second-order nonlinear deformations. Such transformations are implemented by a linear combination of bivariate polynomials. Computer software for generating(More)
Kristen M. Harris,1,2,3 Elizabeth Perry,2 Jennifer Bourne,1,2 Marcia Feinberg,3 Linnaea Ostroff,3 and Jamie Hurlburt2,3 1Section of Neurobiology and Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712, 2Department of Neurology, Synapses, and Cognitive Neuroscience Center, Medical College of Georgia, Augusta, Georgia 30912,(More)