We modified Ungewitter's (1951) and Beermann and Cassens' (1976) non-selective silver methods for peripheral nerve axons and their terminals by lengthening the time for the prestaining treatment of sections, adjusting the times of various stages of the staining procedures and selecting reagents with minimal chloride and sulphate impurities. These methods were applied to Bouin's fixed material embedded in wax with serial sections up to 100 micron thick, cut longitudinally. The Ungewitter modification stained sensory axons and their terminals very well but failed to give good impregnations of motor fibres. In addition, it marked intrafusal muscle fibres with a peppery silver deposit while sparing extrafusal fibres. The Beermann and Cassens method yielded excellent details of motor axons and their terminals but results were very poor on sensory fibres. Both sensory and motor methods worked regardless of whether the neural elements were mature, regenerating, or neonatal. Both methods consistently yielded pale backgrounds in these thick sections.
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http://dx.doi.org/10.1016/0165-0270(86)90051-8 | DOI Listing |
Mol Psychiatry
January 2025
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.
Age-related dopamine (DA) neuron loss is a primary feature of Parkinson's disease. However, whether similar biological processes occur during healthy aging, but to a lesser degree, remains unclear. We therefore determined whether midbrain DA neurons degenerate during aging in mice and humans.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China.
Horizontal connections in anterior inferior temporal cortex (ITC) are thought to play an important role in object recognition by integrating information across spatially separated functional columns, but their functional organization remains unclear. Using a combination of optical imaging, electrophysiological recording, and anatomical tracing, we investigated the relationship between stimulus-response maps and patterns of horizontal axon terminals in the macaque ITC. In contrast to the "like-to-like" connectivity observed in the early visual cortex, we found that horizontal axons in ITC do not preferentially connect sites with similar object selectivity.
View Article and Find Full Text PDFJ Neurochem
January 2025
Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh, Scotland, UK.
Synaptic vesicle protein 2A (SV2A) is an abundant synaptic vesicle cargo with an as yet unconfirmed role in presynaptic function. It is also heavily implicated in epilepsy, firstly being the target of the leading anti-seizure medication levetiracetam and secondly with loss of function mutations culminating in human disease. A range of potential presynaptic functions have been proposed for SV2A; however its interaction with the calcium sensor for synchronous neurotransmitter release, synaptotagmin-1 (Syt1), has received particular attention over the past decade.
View Article and Find Full Text PDFHeliyon
January 2025
Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy.
Compelling evidence has demonstrated that rehabilitation through physical exercise, a non-invasive and non-surgical intervention, enhances muscle reinnervation and motor recovery after peripheral nerve injury (PNI) by increasing muscle-derived brain-derived neurotrophic factor (BDNF) expression and triggering TrkB-dependent axonal plasticity. Adenosine has been widely acknowledged to trigger TrkB via A2A receptor (A2AR). Since motor nerve terminals co-express TrkBs and A2ARs and depolarizing conditions increase muscle release of BDNF and adenosine, we examined whether A2ARs activation could recapitulate the functional recovery benefits of intermittent exercise after a nerve crush.
View Article and Find Full Text PDFFront Neurol
January 2025
Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States.
Introduction: The brainstem vestibular nuclei neurons receive synaptic inputs from inner ear acceleration-sensing hair cells, cerebellar output neurons, and ascending signals from spinal proprioceptive-related neurons. The lateral (LVST) and medial (MVST) vestibulospinal (VS) tracts convey their coded signals to the spinal circuits to rapidly counter externally imposed perturbations to facilitate stability and provide a framework for self-generated head movements.
Methods: The present study describes the morphological characteristics of intraaxonally recorded and labeled VS neurons monosynaptically connected to the 8th nerve.
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