It is a mystery we all experience without fully understanding. How does our brain command our body to move?
The answer may lie in the spontaneous activity of our neurons, whose slowness intrigues researchers.
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Since the 1960s, neuroscientists have observed a gradual rise in brain activity just before a spontaneous movement. But the origin of this activity remained unclear. A discovery by a team at the Brain Institute of Chapman University has changed that.
By simulating the spontaneous activity of neural networks, the researchers compared this data with recordings of human brains in action. They found that interactions between neurons, which at first appear fast and disordered, ultimately produce a slow, large-scale fluctuation.
It is this slow fluctuation that could be the key. The researchers explain that it allows the crossing of a threshold, triggering movement. A delay of 1 to 2 seconds appears to be necessary between the beginning of the fluctuation and the crossing of the threshold, resulting in the actual movement. This discovery sheds new light on the phenomenon of brain preparation.
Even more intriguingly, this slow rise in activity is not limited to physical actions. It is also present during other spontaneous processes, such as creativity or memory.
Thus, the crossing of this neuronal threshold seems to be a fundamental phenomenon in various human behaviors, far beyond simple movement. Research continues to further unravel these hidden mechanisms.
What is the neuronal threshold?
The neuronal threshold is the critical level of excitation that a nerve cell (or neuron) must reach to trigger an action. Neurons continuously receive electrical signals. If these signals exceed a certain level, called the "threshold," the neuron responds by sending a signal.
When this threshold is crossed in the motor cortex, movement is initiated. Before reaching this threshold, neuronal activity rises slowly, a phenomenon often observed before spontaneous actions. These slow fluctuations, although produced by individual neurons with fast activity, seem crucial for initiating movement.