Dr. Edward Chang Explores the Basis of Mood Disorders

What They Did: A team of researchers from the University of California, San Francisco led by Professor of Neurological Surgery, neurosurgeon, and NYSCF – Robertson Neuroscience Investigator Edward Chang, MD, have used continuous recording of neural activity to study how our brains behave across different moods. 

What They Found: The team detected a pattern of brain activity common to low mood in people who reported a tendency toward anxiety at the beginning of the study.

Why It Matters: This pattern of activity could serve as a biomarker to help scientists identify and treat mood disorders.

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Understanding mood disorders requires that we understand patterns of activity within our brains, and typically, this activity is recorded in an fMRI scanner. When someone enters an fMRI scanner, scientists can see which parts of the person’s brain start to kick into action during different situations and decipher which brain structures contribute to mood, memory, attention, and other cognitive processes. For example, person in an fMRI scanner might be presented with sad videos, stories, or pictures to induce a depressive or anxious state. Then, the scanner will pick up on their neural activity and tell us which groups of neurons might be associated with negative moods.

But the moods we experience throughout our daily lives encompass a far wider range than what we can engender in a scanner. And if we want to understand the true neural basis behind depression or anxiety, we need to study it as it naturally occurs.

A new study published in Cell from researchers at the University of California, San Francisco (UCSF) including Professor of Neurological Surgery, neurosurgeon, and NYSCF – Robertson Neuroscience Investigator Dr. Edward Chang used surgically implanted brain electrodes to monitor neural activity as people went about normal life, finding that a certain pattern of activity was common to people experiencing low moods.

The subjects involved in the study were patients preparing to undergo a brain surgery for epilepsy. Part of the standard preparation for this surgery involves fitting the brain’s surface, and a few deeper portions, with electrodes. These electrodes can measure brain activity in real-time, telling us when and where neurons start firing.

The researchers tracked the subjects’ neural activity for 10 days, looking closely at brain regions known to play a role in mood disorders. The team also asked subjects to keep a log of their mood throughout each day.

In 13 participants, groups of neurons in brain structures called the hippocampus and amygdala were found to be especially active. The participants all reported high baseline anxiety at the start of the study, and analysis of their mood logs revealed that the increased neuronal activity was highly correlated with instances of low mood. The other 8 participants, all of whom reported low pre-existing anxiety, didn’t show the same brain activity in these areas.

“It is remarkable that we are able to see the actual neural substrates of human mood directly from the brain,” said Dr. Chang in an article released by UCSF. “The findings have scientific implications for our understanding of how specific brain regions contribute to mood disorders, but also practical implications for identifying biomarkers that could be used for new technology designed to treat these disorders.”