Dendritic Spines

Bourne, Jennifer N.; Harris, Kristen M.

doi:10.1002/9780470015902.a0000093.pub2

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…These data support the study of the dendritic spines and the synaptic organization of the human Me. Spines increase the packing density of synapses per tissue volume (Bourne & Harris, ) and are mainly involved with signaling excitatory synaptic inputs (Fortin et al. ; Harnett et al.…”

Section: Introductionmentioning

confidence: 99%

The human medial amygdala: structure, diversity, and complexity of dendritic spines

et al. 2015

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The medial nucleus of the amygdala (Me) is a component of the neural circuit for the interpretation of multimodal sensory stimuli and the elaboration of emotions and social behaviors in primates. We studied the presence, distribution, diverse shape, and connectivity of dendritic spines in the human Me of adult postmortem men. Data were obtained from the five types of multipolar neurons found in the Me using an adapted Golgi method and light microscopy, the carbocyanine DiI fluorescent dye and confocal microscopy, and transmission electron microscopy. Three-dimensional reconstruction of spines showed a continuum of shapes and sizes, with the spines either lying isolated or forming clusters. These dendritic spines were classified as stubby/wide, thin, mushroom-like, ramified or with an atypical morphology including intermediate shapes, double spines, and thorny excrescences. Pleomorphic spines were found from proximal to distal dendritic branches suggesting potential differences for synaptic processing, strength, and plasticity in the Me neurons. Furthermore, the human Me has large and thin spines with a gemmule appearance, spinules, and filopodium. The ultrastructural data showed dendritic spines forming monosynaptic or multisynaptic contacts at the spine head and neck, and with asymmetric or symmetric characteristics. Additional findings included en passant, reciprocal, and serial synapses in the Me. Complex long-necked thin spines were observed in this subcortical area. These new data reveal the diversity of the dendritic spines in the human Me likely involved with the integration and processing of local synaptic inputs and with functional implications in physiological and various neuropathological conditions.

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Section: Introductionmentioning

confidence: 99%

The human medial amygdala: structure, diversity, and complexity of dendritic spines

et al. 2015

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“…The mossy fiber synapses have a very narrow synaptic cleft, measuring less than 20 nm [49][50][51]. For that reason, the movement of released glutamate and zinc, with similar free diffusion coefficients, is very rapid, reaching the opposite side of the cleft in a few microseconds.…”

Section: Introductionmentioning

confidence: 99%

Computer Simulations of Hippocampal Mossy Fiber Cleft Zinc Movements

Freitas¹,

Miraldo²,

Matias³

et al. 2020

Advances in Neural Signal Processing

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Zinc ions have key regulatory, structural, and catalytic functions and mediate a variety of intra-and intercellular processes. The hippocampal mossy fiber boutons contain large amounts of free or loosely bound vesicular zinc, which can be coreleased with glutamate. Zinc can interact with a variety of ionic channels (N-VDCCs, L-VDCCs, K ATP), glutamate receptors (AMPA, KA, NMDA 2A, 2B), glutamate transporters (GLAST, EAAT4), and molecules (ATP). The dynamic properties of cleft free, complexed, and total zinc were addressed, considering the known concentration and affinity of various cleft zinc sensitive sites, mainly in the postsynaptic area and in glial cells. The computer model included three different zinc release processes, with short, medium, and long duration, described, like the uptake ones, by alpha functions. The results suggest that, depending on the amount of release, zinc clearance is largely due, either, to zinc binding to NMDA 2A receptor sites or to glial GLAST transporters.

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Modelling zinc changes at the hippocampal mossy fiber synaptic cleft

et al. 2016

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Zinc, a transition metal existing in very high concentrations in the hippocampal mossy fibers from CA3 area, is assumed to be co-released with glutamate and to have a neuromodulatory role at the corresponding synapses. The synaptic action of zinc is determined both by the spatiotemporal characteristics of the zinc release process and by the kinetics of zinc binding to sites located in the cleft area, as well as by their concentrations. This work addresses total, free and complexed zinc concentration changes, in an individual synaptic cleft, following single, short and long periods of evoked zinc release. The results estimate the magnitude and time course of the concentrations of zinc complexes, assuming that the dynamics of the release processes are similar to those of glutamate. It is also considered that, for the cleft zinc concentrations used in the model (≤ 1 μM), there is no postsynaptic zinc entry. For this reason, all released zinc ends up being reuptaken in a process that is several orders of magnitude slower than that of release and has thus a much smaller amplitude. The time derivative of the total zinc concentration in the cleft is represented by the difference between two alpha functions, corresponding to the released and uptaken components. These include specific parameters that were chosen assuming zinc and glutamate co-release, with similar time courses. The peak amplitudes of free zinc in the cleft were selected based on previously reported experimental cleft zinc concentration changes evoked by single and multiple stimulation protocols. The results suggest that following a low amount of zinc release, similar to that associated with one or a few stimuli, zinc clearance is mainly mediated by zinc binding to the high-affinity sites on the NMDA receptors and to the low-affinity sites on the highly abundant GLAST glutamate transporters. In the case of higher zinc release brought about by a larger group of stimuli, most zinc binding occurs essentially to the GLAST transporters, having the corresponding zinc complex a maximum concentration that is more than one order of magnitude larger than that for the high and low affinity NMDA sites. The other zinc complexes considered in the model, namely those formed with sites on the AMPA receptors, calcium and K channels and with ATP molecules, have much smaller contributions to the synaptic zinc clearance.

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Dendritic Spines

Cited by 3 publications

References 8 publications

The human medial amygdala: structure, diversity, and complexity of dendritic spines

The human medial amygdala: structure, diversity, and complexity of dendritic spines

Computer Simulations of Hippocampal Mossy Fiber Cleft Zinc Movements

Modelling zinc changes at the hippocampal mossy fiber synaptic cleft

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