New insights on how internal brain conditions influence decision making

Reviewed by Emily Henderson, B.Sc.August 17, 2020

Matthew Smith and Byron Yu in biomedical engineering, and former PhD student Ben Cowley (School of Computer Science ’18), study the neural foundations that internal states of the brain influence for long-term decision-making. did. By simultaneously recording the activity of a population of neurons in two brain regions, they were able to gain unprecedented insight into how increasing or decreasing mental status affects our decision making.

“Internal state” or impulsivity is a term more commonly discussed in psychology or neuroscience, but the concept is familiar to everyone. You do not have to be a psychologist to know that conditions such as hunger and fatigue affect your thinking and decision making. These are examples of internal states. However, the biological mechanisms by which these states influence critical thinking and decision-making abilities are still poorly understood.

Although long-term studies are rare in neuroscience, and it is even rarer to measure multiple areas of the brain simultaneously, this is exactly what Smith is good at. The team presented the subjects with a simple visual task and simultaneously measured the prefrontal cortex. Another area of ​​the brain related to decision making and another related to vision. Their goal was to measure how the activity of this “decision circuit” was altered by repeating this task for several hours. `

What they could observe during the task was what they called a “slow nerve drift” of brain activity. Subject’s decisions changed slowly over time, which allowed the team to observe synchronized brain activity drifts across multiple brain regions. This is related to changes in internal state over time. Their observations on the effects of slow neural drift on subject behavior provide insights into how these internal states physically influence decision making. These findings indicate an important role for internal states in understanding the biological work of brain decision circuits and how they change over time.

We all tend to shift over time. It varies from the time we wait very patiently to the time impulsive and easy to guess. It was found that this tendency was woven into the activity of the subject’s entire brain. “

Carnegie Mellon University, Biomedical Engineering, Matthew Smith

Since decision making is one of the most basic cognitive processes, this study could have broad implications for future research in neuroscience and psychology. Several medically defined mental states, such as schizophrenia, attention deficit disorder (ADD) and Tourette’s syndrome, affect impulsivity in a manner comparable to these internal states. The range is diverse, but each condition affects decision making. This may be elucidated through long-term, multi-regional studies of decision circuits such as Smith, Yu, and Cowley. It can be a particularly useful tool in understanding the pharmacological effects of various drugs and how they affect brain function.

There is much to learn about the brain-computer interface (BCI) and the human-machine interface. The increase or decrease in mental status observed by the team over time can reduce the accuracy with which the BCI can read a person’s thoughts or movement intent. Their work will impact the design of more robust BCI and human-machine interfaces in the future.

Similarly, with respect to education, everyone experienced a decline and flow of mental state while sitting through lectures. Understanding how these changes in mental status result can help develop better teaching and learning methods, such as presenting important material only when students are most likely to pay attention. I will.

The logical next step of Smith, Yu, and Cowley is to better characterize slower nerve drift in electroencephalography (EEG), identify which brain regions are responsible for slower nerve drift, and A study is to emphasize the importance of longer timescales.

The team’s contribution represents a major advance in the understanding of the function of the brain’s deterministic circuits over time. Their discovery of how internal states cause the phenomenon of slow neural drift greatly influences how future neuroscientists and psychologists understand decision making and impulsivity.