Tel Aviv University researchers have conducted groundbreaking research into the human brain finding that its neural networks preserve memories better than individual neurons. This new understanding could lead to breakthrough in treating debilitating diseases such as Alzheimer’s.
A new study by Dr. Inna Slutsky of Tel Aviv University‘s Sackler Faculty of Medicine and TAU’s Sagol School of Neuroscience finds that homeostatic regulation occurs mainly in groups of neurons rather than in the individual neurons themselves.
Contradicting established assumptions, Edden Slomowitz and Boaz Styr, doctoral students in Dr. Slutsky’s laboratory, discovered that single brain cells, on an individual basis, were unable to autonomously stabilize “spikes” in neuron communication over long periods. “Spikes” or “firing, ” as they are also known, are neurons’ response to stimulation; they relay messages to the rest of the body.
“Neurological and psychiatric disorders often see similar or overlapping neurological symptoms, and the failure of the neuronal homeostatic system may lead to these common endpoints, ” said Dr. Slutsky. “Understanding the principles and mechanisms involved in neuronal homeostasis may lead to new approaches in the treatment of these and other brain disorders like Alzheimer’s disease.”
The brain’s ability to adapt to a constantly changing environment and to form and store memories is due to the extreme flexibility, or plasticity, of its neural network. But the extreme plasticity of the brain also makes it inherently prone to instability and subsequent illnesses and disorders.
“Through homeostasis, organisms are able to maintain a stable internal environment, ” said Slomowitz. “One common example is the secretion of insulin in response to a meal to keep blood sugar levels within the normal range. While there was evidence to support the theory that there were homeostatic mechanisms at work in the brain to stabilize neuronal activity, it was unclear which precise properties were regulated.”
For the purpose of the study, Slomowitz grew a neural network on an array of electrodes and recorded the activity of single individual neurons in the network. He then applied a drug which severely inhibited neural activity. In collaboration with Prof. Eli Nelken of Hebrew University and Dr. Michael
Slutsky of Mantis Vision, Slomowitz found that the network returned to its original firing rate over the course of two days despite the continued presence of the drug — and even though the firing rates and patterns of individual neurons did not reflect homeostatic tendencies.
“These results were unexpected and contradicted the current dogma in the field stating that individual neurons can regulate their own firing rates in an autonomous manner, ” said Dr. Slutsky.