Pinpointing consciousness in animal brain using mouse 'brain map'

A recent research finds the brain's network cores that have robust bidirectional connectivity.

The location of consciousness in the brain may be becoming more clear to science. A recent research demonstrates the significance of certain brain connections in defining consciousness.

Jun Kitazono, a corresponding author and project researcher in the Department of General Systems Studies at the University of Tokyo, directed the study, which was published in Cerebral Cortex.

The study's corresponding author and leader of the lab that conducted the research, Associate Professor Masafumi Oizumi, stated that "where in the brain consciousness lives has been one of the largest puzzles in science." Even if we haven't come to a definitive conclusion, there is a lot of empirical data that has been gathered in the process of looking for the brain correlates of consciousness or the bare minimum processes required for conscious experience.

With this research, the scientists made a first step in pinpointing the brain regions that are bare-bones enough to allow conscious experience.

The researchers searched for a particular characteristic of consciousness inside the neural networks of the brain: bidirectional pathways, in order to pinpoint the regions of the brain where awareness dwells. Our brains process information when we see something or feel a sense. This is referred to as a feed-forward signal, although being aware of such signals alone does not constitute awareness. Additionally, our brains must provide feedback, or information that is sent back. Not all brain regions are capable of receiving feed-forward information and providing feedback in return. These connections in both directions, according to researchers, are a crucial characteristic of the regions of the brain involved in awareness.

"For participants to consciously perceive stimuli, feed-forward processing is inadequate; feedback is also required, demonstrating the necessity for bidirectional processing. The feedback component vanishes not only when particular conscious contents are lost in awake states, but also in unconscious states like general anesthesia, sleep, and vegetative states, when conscious experiences are often lost "Kitazono added. He also added that the bidirectionality of processing is crucial whether you are looking at a person, a monkey, a mouse, a bird, or a fly.

To test this hypothesis, researchers employed computational methods and a mouse connectome. The connections in the brain are shown in great detail in a connectome. They first created an effective method to extract the complexes, or regions of the brain with strong bidirectional connections. The mouse connectome was then subjected to the algorithm.

The retrieved complexes with the greatest degree of bidirectionality, according to Kitazono's research, are concentrated in the cortical and thalamic regions rather than being distributed equally throughout all main brain areas. "On the other hand, there is little bidirectionality in the other main locations. Particularly, there is substantially less bidirectionality in the cerebellum."

These findings support the location in the brain where scientists have long hypothesized consciousness to dwell. The cerebral cortex, which is found on the outside of the brain, has sensory, motor, and association regions that are considered to be crucial for experiencing consciousness. The thalamus, which is situated in the center of the brain, has also been linked to consciousness. In particular, the thalamo-cortical loop, which is the connection between the thalamus and cortical areas, is regarded to be crucial for consciousness. These findings lend credence to the notion that locating the location of consciousness requires understanding the brain network's bidirectionality.

Researchers stressed that they are still trying to pinpoint where awareness is located.

"Only "static" anatomical connections between neurons or brain regions are the subject of this investigation. However, awareness is "dynamic," shifting based on neuronal activity from one moment to the next ""Oizumi" remarked. We need to actively analyze the dynamics of neuronal activity to determine the location of awareness at any particular time, even though physical connections explain how neural activity would spread and how different brain regions would interact.

He stated that as a subsequent step, the group is now reviewing activity-based networks of the brain in various kinds of neural recordings.

Finding the mathematical connection between awareness and the brain is the ultimate objective of our work, according to Oizumi. "In this study, we tried to link the location of awareness to the network features of the brain. In order to achieve our ultimate objective, we will continue to research the connection between consciousness and the brain."

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Materials provided by University of Tokyo. Note: Content may be edited for style and length.