A study published in Neuron revealed how different cell types in the cerebral cortex change their activity during general anesthesia. In particular, only one specific cell type called layer 5 pyramidal neurons showed an increase in activity when mice were exposed to different anesthetics. Researchers noticed that changes in layer 5 neurons coincide with the loss and recovery of consciousness. The findings have implications for understanding the neural mechanisms involved in general anesthesia and anesthetic drug discovery.
Patients are commonly given general anesthetics prior to surgery to induce loss of consciousness. This study found that spontaneous activity of mouse layer 5 pyramidal neurons can be synchronized in vivo by anesthetics. Researchers noted that during the transition to and from anesthesia, layer 5 neuron synchrony changes coincide with loss and recovery of consciousness.
Study author Arjun Bharioke uses a helpful sports analogy to explain brain activity that occurs when we are unconscious: “It seems that instead of each neuron sending different pieces of information, during anesthesia all layer 5 pyramidal neurons send the same piece of information. One could think of this as when people in a crowd transition from talking to each other, for example before a soccer or basketball game, to when they are cheering for their team, during the game. Before the game starts, there are many independent conversations. In contrast, during the game, all the spectators are cheering on their team. Thus, there is only one piece of information being transmitted across the crowd.” The layer 5 neurons synchronize messaging activities to carry out a specific mind-body function.
University of Wisconsin researchers have also documented unconscious brain activity in their efforts to understand how the human brain regulates attention and emotion. They found that meditation results in highly synchronized brain activity when they reviewed brain scans from a meditating monk. Fast frequency gamma oscillations can be seen for short durations when reviewing the brain scans of ordinary people. Gamma oscillations of ordinary people last less than one second and do not have large amplitude. However, a monk actively engaged in meditation demonstrated large, highly synchronized brain signals that lasted for many minutes.
Research on the unconscious brain has implications for managing pain, attention and emotion through meditation and drug therapies that promote highly synchronized brain signals.
Source: Neuron