In this brief review of inter-laminar synaptic connections in neocortex a case is made for the hypothesis that axons select their targets, or neurones select their inputs with great specificity. A large part of the data discussed was obtained from dual intracellular recordings in slices of adult neocortex. The neurones innervated in a given layer by a given type of axon were not found to be a random selection of the cells in that layer. Rather in a layer to layer specific fashion, certain types of target cells are densely innervated while others are not contacted or receive only weak inputs. In another layer, the same axons may select other targets.
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http://dx.doi.org/10.1023/a:1024117908539 | DOI Listing |
Front Neuroanat
January 2025
Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
Hodological patterning refers to developmental mechanisms that link the location of neurons in the brain or spinal cord to specific axonal trajectories that direct connectivity to synaptic targets either within the central nervous system or in the periphery. In vertebrate motor circuits, hodological patterning has been demonstrated at different levels, from the final motor output of somatic and preganglionic autonomic neurons targeting peripheral motoneurons and ganglion cells, to premotor inputs from spinal and brainstem neuron populations targeting the somatic motoneurons and preganglionic autonomic neurons, to cortical neurons that delegate movement commands to the brainstem and spinal neurons. In many cases molecular profiling reveals potential underlying mechanisms whereby selective gene expression creates the link between location and axon trajectory.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Translational Neurobiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, 187-8502, Japan.
Caspases are known to mediate neuronal apoptosis during brain development. However, here we show that nonapoptotic activation of caspase-3 at presynapses drives microglial synaptic phagocytosis. Real-time observation and spatiotemporal manipulation of synaptic caspase-3 in the newly established, mouse-derived culture system demonstrate that increased neuronal activity triggers localized presynaptic caspase-3 activation, facilitating synaptic tagging by complements.
View Article and Find Full Text PDFJ Neurosci
January 2025
Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
GABAergic neurons in basal forebrain (BF) nuclei project densely to all layers of the mouse main olfactory bulb (OB), the first relay in odor information processing. However, BF projection neurons are diverse and the contribution of each subtype to odor information processing is not known. In the present study, we used retrograde and anterograde tracing methods together with whole-brain light-sheet analyses, patch-clamp recordings coupled with optogenetic and chemogenetic approaches during spontaneous odor discrimination, and go/no-go odor discrimination/learning tests to characterize the synaptic targets in the OB of BF calretinin-expressing (CR+) GABAergic cells and to reveal their functional implications.
View Article and Find Full Text PDFJCI Insight
January 2025
Gavin Herbert Eye Institute-Center for Translational Vision Research, Depar, University of California Irvine School of Medicine, Irvine, United States of America.
Elevation of intraocular pressure (IOP) due to trabecular meshwork (TM) dysfunction, leading to neurodegeneration, is the pathological hallmark of primary open-angle glaucoma (POAG). Impaired axonal transport is an early and critical feature of glaucomatous neurodegeneration. However, a robust mouse model that accurately replicates these human POAG features has been lacking.
View Article and Find Full Text PDFCell Mol Life Sci
January 2025
School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China.
The selective elimination of inappropriate projections is essential for sculpting neural circuits during development. The class IV dendritic arborization (C4da) sensory neurons of Drosophila remodel the dendritic branches during metamorphosis. Glial cells in the central nervous system (CNS), are required for programmed axonal pruning of mushroom body (MB) γ neurons during metamorphosis in Drosophila.
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