How does the brain handle uncertainty?

Whether investing in the stock market, buying your first house, or pursuing a terminal degree, your brain helps you navigate the world’s complexities by processing uncertainty. But how does the brain achieve this extraordinary ability?

In this article, we will dive into the neurobiology that governs how the brain handles uncertainty in our daily lives. Let’s start by understanding what areas of the brain help us make decisions during uncertainty.

The brain during uncertainty

Dr. Micheal Halassa and his postdoc Dr. Arghya Mukherjee at MIT’s McGovern Institute for Brain Research have identified key brain circuits that help direct decision-making when presented with moments of uncertainty. The work, performed by Mukherjee and colleagues, consisted of beautifully designed studies investigating how mice interpret ambiguous sensory cues (Mukherjee et al., 2021).

Before we learn about their discovery, we must first understand what regions of the brain become activated when humans are presented with uncertainty.

Active regions of the human brain during uncertainty

Functional brain imaging studies demonstrate that when people are asked to study a scene and purposely left uncertain as to what they should focus on, an area of the brain called the mediodorsal thalamus becomes activated (Kosciessa et al., 2021). The less context subjects are given (and thus more uncertainty), the more active this brain region becomes.

While scientists understand that the mediodorsal thalamus and prefrontal cortex interact to resolve uncertainty, the precise mechanism of this interaction remained a mystery. That is until recent work by Mukherjee and colleagues provided some clues.

Let’s revisit the details of their study.

How the mediodorsal circuits of the thalamus influence decision-making during uncertainty

Dr. Mukherjee identified two phenotypically distinct sets of mediodorsal circuits in the thalamus. One set releases excitatory neurotransmitters in the prefrontal cortex while the other releases inhibitory neurotransmitters. Together, these neuronal circuits either amplify or suppress activity in the prefrontal cortex during moments of uncertainty.

Think of the mediodorsal region of the thalamus as a group of neurons acting as the telephone switchboard operator of the brain (pictured above). These cells determine which sensory messages should be sent to the decision center of the brain (prefrontal cortex) and which should be suppressed.

When presented with moments of uncertainty, this neurological switchboard works overtime. The more uncertain we are, the more these neurological activations present or suppress sensory information.

Why are some sensory cues suppressed by the mediodorsal thalamus?

The easiest way to answer this question is by understanding what happens in the brain of individuals suffering from schizophrenia.

Schizophrenia is a mental disorder categorized by recurring psychosis episodes including hallucinations, delusions, and paranoia. For instance, a schizophrenic patient might think hidden messages are being recorded in TV episodes or that restaurant patrons are mumbling the plans of a secret plot to kill them. Those without schizophrenia would quickly dismiss these thoughts as insignificant and irrational.

New evidence suggests that individuals suffering from schizophrenia spectrum disorders have a less active mediodorsal thalamus. It sends non-important sensory signals to the prefrontal cortex (Giraldo-Chica et al., 2018). These sensory cues are normally suppressed in a healthy brain.

Therefore, it is important to understand how the switchboard operator (mediodorsal region) of the thalamus controls which sensory information should be acted upon and which should be ignored.

How the mediodorsal circuits of the thalamus influence decision-making during uncertainty

As mentioned previously, there are two distinct sets of mediodorsal circuits in the thalamus that are phenotypically distinct. One set releases excitatory neurotransmitters in the prefrontal cortex while the other releases inhibitory neurotransmitters. Together, these neuronal circuits will either amplify or suppress activity in the prefrontal cortex during moments of uncertainty.

The inhibitory neuronal circuit, therefore, plays an important role in preventing the healthy brain from focusing on irrelevant sensory information. However, evidence suggests that individuals suffering from schizophrenia have less active inhibitory neurons in the mediodorsal thalamus.

How exercise could help scientists study uncertainty

Studies show that exercise therapy can improve the symptoms of schizophrenia (Girdler et al., 2019). However, the role exercise plays in alleviating these symptoms has only been studied in the context of the hippocampus and the neurotransmitters dopamine, serotonin, gamma-aminobutyric acid (GABA), and norepinephrine.

Scientists have yet to investigate how exercise influences the neuronal activity of inhibitory neurons in the mediodorsal thalamus among healthy and schizophrenic subjects.

Evidence demonstrates that exercise can help restore the atrophy (shrinking) of the thalamus in at least one neurological disease, multiple sclerosis (MS; Sandroff et al., 2022). Similar to MS, the brain of individuals with schizophrenia has been reported to exhibit atrophy of cortical matter (Andreone et al., 2019).

How a mobile EEG device can help scientists study uncertainty

Could exercise help individuals with schizophrenia restore the activity of inhibitory neurons in the thalamus and thus properly suppress activity in the prefrontal cortex?

It is an impossible question to answer without the proper experimental design and equipment such as a mobile EEG machine.

Historically EEG machines are heavy, large, and bulky. Even portable EEG machines are limited by their ability to collect quality data with minimal background noise.

Until now.

Mentalab’s mobile EEG system, Explore Pro, is a valuable tool used to study how the brain processes uncertainty in healthy and diseased brains. This transportable EEG unit can help neuroscientists capture the brain’s electrical activity inside and outside the lab quickly.

Mobile EEG devices: unlocking the potential of brain research

The mediodorsal thalamus is a crucial area of the brain that determines which sensory messages should be sent to the decision center of the brain (prefrontal cortex) and which should be blocked.

Mobile EEG devices have opened up a new world of possibilities for scientists studying the human brain. They provide new avenues for research and allow data to be gathered in real-world environments, under diverse experimental parameters, and for extended periods of time.

The potential applications of mobile EEG devices are limitless, and they promise to expand our understanding of the final frontier in biology – the human brain.