Scientists Find Surprising Neuron Differences Between Primates And Non-Primates

Scientists studying the architecture of neuron cells in the brain have discovered a significant anatomical difference between primates and non-primates in cortical neurons, which are cerebrum cells.

The discoveries provide us a better understanding of this most intricate of organs, as well as how the shape and function of neurons may vary between species. Through the research, we may potentially learn more about human and animal evolution.

The axon fiber, a narrow component of the neuron that transports electrical impulses, is crucial to this variation in neurons. Previously, it was assumed that these axons only came from the cell body, but a new study demonstrates that they may also come from dendrites, the extensions that link nerve cells.

The study revealed that non-primate animals like cats and pigs had a lot more axon-carrying dendrites than primates. The research used aged tissue and specimens and included an examination of almost 34,000 individual neurons.

"A unique aspect of the project is that the team worked with archived tissue and slide preparations, which included material that has been used for years to teach students," says Petra Wahle, a neurobiologist at Germany's Ruhr University Bochum.

Mice, rats, pigs, cats, ferrets, macaque monkeys, and humans were among the animals studied. While axon-carrying dendrites were discovered in all species, non-primates had a much higher number.

The use of the newest high-resolution microscopy techniques to acquire a close-up look at cell growth, which was further highlighted by the use of five distinct staining methods on the cells being investigated, was a critical aspect of the research.

"This allowed the detection of axonal origins accurately tracked at the micrometer level, which is sometimes not so easy with conventional light microscopy," explains Wahle.

More study is needed to figure out why certain species have a larger percentage of axon-carrying dendrites than others, and what evolutionary benefit they may provide to creatures that employ them.

Neurons often operate as gatekeepers, selecting which signals are passed on and which are not based on other inputs they receive. Somatodendritic integration is the term for this. Axon-carrying dendrites appear to have the capacity to escape this gatekeeping and pick which signals make it around the brain network autonomously.

We don't yet completely understand what this entails for brain processing, but we should learn more as time goes on. The amount of these axon-carrying dendrites did not seem to be affected by animal domestication, with pigs and boars having identical proportions. Furthermore, they appear to be born with them rather than developing them as they get older in animals of diverse types.

The brain is a difficult portion of the body to research because there are so many neurons to monitor – tens of billions in certain situations – but that hasn't stopped scientists. We're always discovering new things about how neurons operate and how they're organized.

"Our findings expand the current knowledge regarding the distribution and proportion of axon-carrying dendrite cells in neocortex of non-primate taxa, which strikingly differ from primates where these cells are mainly found in deeper layers and white matter," the researchers write in their report.