Pinpointing consciousness in animal brain using mouse brain map: New study identifies network cores of the brain with strong bidirectional connections

Science may be one step closer to understanding where consciousness resides in the brain. A new study shows the importance of certain types of neural connections in identifying consciousness.

The research, published in Cerebral Cortex, was led by Jun Kitazono, a corresponding author and a project researcher in the Department of General Systems Studies at the University of Tokyo.

“Where in the brain consciousness resides has been one of the biggest questions in science,” said Associate Professor Masafumi Oizumi, corresponding author and head of the lab conducting the study. “Although we have not reached a conclusive answer, much empirical evidence has been accumulated in the course of searching for the minimal mechanisms sufficient for conscious experience, or the neural correlates of consciousness.”

For this study, the team took a step toward identifying the minimally sufficient subnetworks in the brain that support conscious experience.

To identify the areas of the brain where consciousness resides, the researchers looked for one specific hallmark of consciousness within the neural networks of the brain: bidirectional pathways. When we see something or experience a sensation, our brains take in information. This is called a feed-forward signal, but receiving such feed-forward signals is not enough for consciousness. Our brains also need to send information back, in what is called feedback. Not every part of the brain can both receive feed-forward and return feedback information. Researchers hypothesized that these bidirectional connections are an essential hallmark of the parts of the brain responsible for consciousness.

“Feed-forward processing alone is insufficient for subjects to consciously perceive stimuli; rather, feedback is also necessary, indicating the need for bidirectional processing. The feedback component disappears not only during the loss of specific contents of consciousness in awake states, but also during unconscious states where conscious experiences are generally lost, such as general anesthesia, sleep and vegetative states,” said Kitazono. He also explained that it does not matter if you are looking at a human, monkey, mouse, bird or fly; the bidirectionality of processing remains essential.

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