Browsing by Subject "Interneuron"

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Nanoscale synaptic plasticity of aspiny interneuron dendrites with respect to characteristic fine structures
(2018-10-11) Weisberg, Seth Arthur; Harris, Kristen M.; Zemelman, Boris V; Colgin, Laura L; Nishiyama, Hiroshi; Hofmann, Hans
Long term plastic changes in synaptic function have been reported in GABAergic inhibitory interneurons in the mammalian hippocampus but structural changes associated with plasticity at the predominantly aspiny dendrites is not known. Aspiny dendrites are known to exhibit two distinct morphological types, smooth and varicose. Because of their rarity in neuropil we reimaged tissue in which long-term potentiation (LTP) had been induced by theta-burst stimulation (TBS) in acute hippocampal slices from mature rat using the tSEM method to obtain sufficiently large fields and measured the response of aspiny synapses. We report significant changes in synapse size after potentiation induction in the slice that is influenced by the type of fine structure on which it occurs. We developed quantitative methods to distinguish smooth from varicose aspiny dendrites and within varicose dendrites we found that the varicose and inter-varicose regions could respond differently to TBS. After potentiation induction in the slice synapse ultrastructure and mitochondria distribution changed in different directions in our two experiments but the relationship of synapse change and mitochondrial redistribution was consistent. In both experiments inter-varicose synapses significantly enlarged and were more likely to occur near mitochondria. In one experiment varicose synapses enlarged and were associated with more mitochondria. In the other synapses did not change but were less likely to associate with mitochondria. In smooth type synapses both experiments showed lower association with mitochondria and synapses either did not change or significantly decreased. Our findings of divergent ultrastructural changes among different aspiny dendrite regions may help to reconcile some of the disparate findings showing that similar stimulation protocols can lead to depressed or potentiated responses from inhibitory interneurons.
Neuronal activity in motor neuron and V2a interneuron cultures
(2022-08-03) Somavarapu, Rachel; Sakiyama-Elbert, Shelly E.; Wang, Huiliang (Evan)
The consequences of a spinal cord injury can include paralysis, and loss of motor function, sensory function, and proprioception. Furthermore, spinal cord injuries are often associated with potentially fatal complications, such as pneumonia or sepsis. Spinal cord injuries can take a negative toll on a patient’s life by causing discomfort or by hindering them from living a normal life. Current treatments, such as rehabilitative therapy, electrical spinal cord stimulation, and spinal cord surgery are not effective in treating this condition. However, studying the behavior of cultured neurons in-vitro can help determine what combination of cells are most beneficial for spinal cord transplantation or targeting regeneration of endogenous neural populations. The goal of this project is to study two types of neurons that are found in the spinal cord, motor neurons and V2a interneurons, and examine how these cells behave when they are cultured separately versus cocultured together. Selectable cell lines containing puromycin N-acetyl-transferase (PAC) under the control of either the Hb9 or Chx10 gene regulatory element were induced and selected to form neurons over a 6 day period. The neurons were plated in multielectrode array (MEA) plates or 24 well plates. Collected data regarding the neural firing rate, burst frequency, number of spikes observed, network inter-spike interval coefficient of variation, and synchrony were analyzed to determine differences in activity between mono- and co-cultures.