The brain is a complex network containing billions of neurons (nerve cells). The soma of each of these neurons (communicates simultaneously with thousands of others via their synapses and collects incoming signals through several very long, branched arms called dendritic trees.
New kinds of experiments show that many neuronal features commonly attributed to the soma actually originate from dendritic mechanisms and that this understanding could impact research on the origin of degenerative diseases, as well as sleep-and-awake states of brain activity.
For the last 75 years, a core hypothesis of neuroscience has been that the basic computational element of the brain is the neuronal soma, where the long dendritic trees are only cables that enable them to collect incoming signals from its thousands of connecting neurons. This long-lasting hypothesis has now been called into question.
In an article just published in Physica A under the title “Neuronal plasticity features are independent of neuronal holding membrane potential,” researchers from Bar-Ilan University (BIU) in Ramat Gan reveal that many dynamic features that are commonly attributed to the soma may stem from dendritic mechanisms.
“Typically, in-vitro experiments examine nerve cells using a fixed holding-membrane potential, imitating the physiological conditions of intact brains in an awake state,” said Prof. Ido Kanter of BIU’s physics department and the Gonda (Goldschmied) Multidisciplinary Brain Research Center who led the research. “We went against conventional wisdom and performed new types of experiments, violating the physiological conditions of the brain. Results showed that neuronal features are independent of these physiological conditions – a finding that strongly pinpoints dendrites as the segments controlling neuronal plasticity features such as the neuronal firing frequency and the stimulation threshold of the neuron.”Presented experimental evidence supports previous research by Kanter and his experimental research team that was led by Dr. Roni Vardi and indicated indicating efficient dendritic-tree-learning evidence for sub-dendritic adaptation using neuronal cultures, together with other properties of neurons.
The new results call for a re-examination of the origin of degenerative diseases because the origin of many neuron functions are beyond the traditional framework and must be attributed to the dendrites instead of the soma. In addition, results question the origin of the brain’s awake-and-sleep states that are commonly attributed to the level of the somatic membrane potential.
