Mental Health

How 'Emotional Hangover' Affects Long-Term Memory: Brain Scans Reveal Emotional Baggage Can Shape Our Future Experiences

Many of us are familiar with the daunting effects of drinking too much the night before — a hangover. We feel weary and apathetic the next morning, scrambling our brains to remember last night's events. Now, researchers at New York University (NYU) suggest emotionally charged experiences too, have a hangover effect on our memory in the future, specifically with how we’ll remember it, known as an “emotional hangover.”

"How we remember events is not just a consequence of the external world we experience, but is also strongly influenced by our internal states--and these internal states can persist and color future experiences," said Lila Davachi, senior author of the study, and an associate professor in NYU's Department of Psychology and Center for Neural Science, in a statement.

Read More: How The Brain Stores And Unlocks Information In The Mind

Previous research has shown emotional experiences are better remembered than non-emotional ones. It is the emotions aroused, not necessarily the personal significance of the event, that makes some experiences easier to remember than others. Moreover, strong emotion can impair our memory for less emotional events, and information experienced at the same time. It is the emotional arousal we experience that aids our recollection.

In the study, published in Nature Neuroscience, researchers investigated how emotional experiences influence how we approach and remember future experiences. A group of participants were recruited to view two sets of images spaced about 10 to 30 minutes apart. One set was from the International Affective Picture System (IAPS), a standard set of images used to elicit emotional reactions; the other set was of neutral (non-emotional) images. Some of the participants viewed non-emotional images first, while others viewed the emotional ones first.

Arousal level was measured by both skin conductance and fMRI brain scans. After six hours, the participants took memory tests to see how many of the images they could recall.

Girl lying on grass with dog Researchers find an "emotional hangover" can have a profound effect on memory formation in the future. Photo courtesy of Yingchou Han, Public Domain

The findings revealed participants' brain activity still showed remnants of the first emotional experience when they viewed the second image. Brain activity seen in several regions, including the amygdala, hippocampus, and medial temporal lobe, was linked to the formation and the duration of emotional memories. The researchers conclude cognition is significantly influenced by previous experiences, and these experiences can trigger emotional brain states that can persist through long periods of time.

It is this persistence that explains how emotional hangovers influence our memory. It was previously known emotional states can last for a few seconds, and affect how people process new information after the experience. However, this study suggests emotional hangovers last longer.

"Emotion is a state of mind," said Davachi.

Events we experience are strongly influenced by our internal states, which can be long lasting, and shape our future experiences.

Read More: Why The Brain Remembers And Forgets, Plus 3 Ways To Improve Memory

This implies that the ways in which the brain is aroused by seeing emotional images persists, and primes the brain for proceeding memories to form. They also are formed more vividly.

Moreover, we know emotional experiences are better remembered than non-emotional ones. The researchers also found non-emotional experiences following emotional ones were better remembered on a later memory test.

For better or worse, holding on to memories of the past can shape our future experiences.

Source: Tambini A, Rimmele U, Phelps EA et al. Emotional brain states carry over and enhance future memory formation. Nature Neuroscience. 2016.

See Also:

What Happens To Forgotten Memories In The Brain?

5 Myths About How The Brain Retains Information And Remembers

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