However, it may also originate from dendrites, which serve to gather and integrate the inbound synaptic signals. This phenomenon has been termed “axon-carrying dendrites”.
Numerous mammalian types and high-resolution microscopy reveal the variable axonal origin
” An unique element of the task is that the team worked with archived tissue and slide preparations, which included material that has actually been utilized for many years to teach students,” discusses Petra Wahle.
A variety of animals, including rodents (mouse, rat), ungulates (pig), predators (cat, ferret), and macaques and humans of the zoological order primates, were also researched. The scientists concerned the conclusion that there is a species distinction between non-primates and primates through using 5 distinct staining methods and assessment of more than 34,000 nerve cells.
There are visibly less axon-carrying dendrites on excitatory pyramidal neurons in the external layers II and III of the cerebral cortex of primates than on excitatory pyramidal nerve cells in non-primates. In addition, for inhibitory interneurons, considerable variations in the percentage of axon-carrying dendrite cells were found between the cat and human types.
When comparing macaque cortical areas with primary sensory and higher brain functions, no quantitative differences were observed. High-resolution microscopy was of particular significance, as Petra Wahle describes: “This enabled the detection of axonal origins precisely tracked at the micrometer level, which is in some cases not so simple with standard light microscopy.”
Evolutionary advantage still enigmatic
Little is understood about the function of axon-carrying dendrites. Normally, a nerve cell integrates excitatory inputs getting to the dendrites with repressive inputs, a process described somatodendritic integration. The nerve cell then decides if inputs are strong enough and essential adequate to be sent through action potentials to other nerve cells and brain locations.
Axon-carrying dendrites are considered fortunate because depolarizing inputs to these dendrites are able to evoke action potentials directly without the involvement of somatic integration and somatic inhibition. Why this types difference has evolved, and the potential benefit it may have for the neocortical information processing in primates, is yet unidentified.
Referral: “Neocortical pyramidal neurons with axons emerging from dendrites are frequent in non-primates, however uncommon in monkey and human” by Petra Wahle, Eric Sobierajski, Ina Gasterstädt, Nadja Lehmann, Susanna Weber, Joachim HR Lübke, Maren Engelhardt, Claudia Distler and Gundela Meyer, 20 April 2022, eLife.DOI: 10.7554/ eLife.76101.
The study was funded by the German Research Foundation.
The researchers have found out about species-specific differences in nerve cell architecture.
There are distinctions in the neuronal architecture of non-primates and primates.
A multinational research study team has actually now been able to increase their understanding of species-specific variations in the architecture of cortical neurons thanks to high-resolution microscopy.
Scientists from the Developmental Neurobiology research study group at Ruhr-Universität Bochum, led by Professor Petra Wahle, have actually shown that primates and non-primates differ in an important aspect of their architecture: the origin of the axon, which is the process accountable for the transmission of electrical signals called action capacities. The results were just recently published in the journal eLife.
The researchers worked solely with archived tissues and specimens, including specimens that have actually been and continue to be utilized for years for the education of trainees. Credit: RUB, Kramer
Axons can emerge from dendrites
Previously, it was considered book knowledge that the axon constantly, with few exceptions, emerges from the cell body of a nerve cell.