Does the brain predict or react?

Original image from Wikimedia Commons.
Original image from Wikimedia Commons.

We are learning mechanisms. We perceive an effect and trace it back to its cause, forming cognitive connections that the way the world works around us can be forecast in a predictable manner and thus repeated. This is how we learn to function, for better or for worse, in a social setting. Logically, our brains would function in the same way, reacting to stimuli.

Except that that is not quite the case. Researchers long thought that the brain was a collection of synapses and tissue, reacting to nerve stimuli, interpreting and transmitting information. However, new research hints that the brain begins to react to a situation before the stimulus occurs, showing a predictive ability outside what neurologists have expected for years.

The brain’s interpretation of stimuli functions by a process called interoception. It’s a metacommunication process for the senses. Think of the pipelines in buildings that connect ceiling sprinklers: the interoception system connects the senses and regulates internal responses, such as the lining of the respiratory organs and the digestive system. It is not necessarily directly related to how you are feeling your keyboard or phone, but it is related to how you are keeping your balance as you stand or sit. It is related to proprioception, which is your sense of how you fit in space, in that it is also partially responsible for how we “feel,” especially in the physical repercussions of mood changes.

A professor from Northeastern University and a researcher from the Laureate Institute for Brain Research put forward a paper in the journal Nature proposing a model in which the brain’s actions come before the bodily sensations. Called the Embodied Predictive Interoception Coding model, the new model suggests that the limbic tissue of the brain contributes interoceptive information before the body feels it, creating a sort of box for outside stimuli to fill based on previous experiences.

The model hinges on the ability of limbic tissue to make predictions. Limbic tissue, the part of the brain that contains the memory-centric hippocampus and the emotion-centric amygdala, is an old part of the brain and an underlying sensory foundation for much of  how we perceive the world. The researcher from Northeastern, Lisa Feldman Barrett, said the limbic tissue is uniquely contributing to brain function by forming prediction. However, according to her model, it doesn’t react– it only sends predictions. Thus, it has to be making them ahead of time based on previous experiences.

This model could partially explain what we call situational learning. Other mammals with similar brain structures may also be able to perform this predictive brain modeling, and if so, it changes the way we look at how circumstances inform us.

It may also contribute to discussion of how to preserve limbic tissue in those who have lost  it. To lose one’s limbic issue, according to one case study published in the Journal of Clinical Experimental Neuropscyhology, is to suffer massive memory loss. The man in the case study had suffered tissue loss in the 1980s from encephalitis, and he displayed massive global amnesia and ageusia, which is the loss of taste sensation. Surprisingly, the man retained a large number of his executive functions and was still able to work and function, but his IQ dropped significantly.

The most key parts of our brains are still a secret to us. The more we are able to tease apart the disparate components, the more we learn about how we fit into this world around us and how other animals might as well.


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