A new study from MIT neuroscientists may help explain human computing power. An innovative neuroscience study represents a breakthrough in understanding the biophysics of the brain’s computing power. In a recent research study published on October 18, 2018 in Cell, a team of researchers from the Massachusetts Institute of Technology (MIT) and Massachusetts General Hospital, discovered distinct characteristics of the human neuron that may help explain why human brains are more powerful than other species. The human cortex is generally the thickest among mammals which indicates that human neurons have rather elongated and compartmentalized dendrites. Dendrites are the long branches that extend from a neuron that function as carriers of electrical signals from synapse (the space between the end of nerve cells) to the neuron’s cell body. In the study, the scientist observed the unique way electrical signals are handled by the dendrites of human neurons compared to rodent neurons. A large part of the challenge of neuroscientific research is the availability of human tissue for experimentation, hence research is mostly conducted on laboratory rodents. So it’s unusual when a research study is conducted on human brain tissue. In the study, the neuroscientists used actual human brain tissue ex vivo, in addition to samples from rodents. These researchers used the brain by-product of surgical treatment for epileptic patients – the healthy brain tissue that had to be removed in order for surgeons to access the diseased portion. The neuroscientists tested the electrical activity of dendrites from these small portions of the human anterior temporal lobe cortex from non-pathologic tissue from epileptic patients, and compared it to rodent dendrites. In the research, the team of scientists discovered that when an electrical current is injected in the human dendrites, there is more electrical compartmentalization, and reduced ion channel densities compared to rodent dendrites. According to the published study, “human dendrites provide limited excitation to the soma, even in the presence of dendritic spikes.” The compartmentalization changes the input-out properties of human neurons, which may play also role in our amplified cognitive abilities. “In human neurons, there is more electrical compartmentalization, and that allows these units to be a little bit more independent, potentially leading to increased computational capabilities of single neurons.” - Mark Harnett, MIT’s McGovern Institute for Brain Research The researchers shows that “that both resistive and capacitive filtering are more pronounced in human neurons due to their increased length and suggest the absence of compensatory mechanisms.” This research study is a milestone in understanding the role dendrites play in human cognition — it’s another clue in unraveling the overall mystery of the human brain. Source
