A new study maps complex affective states to just 3 centimeters (cm) in size within one brain area.
An innovative new study has unveiled a small area of 3 cm inside the brain where emotions are recorded.
The study examined the correlation of data from two experiments which measured participant responses to the same film.
The first experiment collected self-reported emotional responses to every scene in the film.
The second collected data from a brain imaging study that was measuring activated regions within participants ‘ cortices while watching the film.
Molecular Mind Laboratory (MoMiLab) researchers at the IMT School for Advanced Studies Lucca, Italy, were working on the new study.
They combined the functional MRI (fMRI) data collected during a study at Otto von Guericke University Magdeburg in Germany with data from a behavioral study they performed at IMT at MoMiLab.
The ultimate goal of their research, now published in the journal Nature, was to map and locate cortical regions in which emotions are encoded. Some research efforts were led by doctoral candidates Giada Lettieri and Giacomo Handjaras.
Acting out emotions we see on screen
To evoke an array of emotions from the study participants, MoMiLab’s team showed them a movie that was popular for its emotional storyline.
The authors of the study explain that experiencing others ‘ emotions, even those of actors, may cause us to respond with the same emotions or similar ones. They’re saying:
“To understand our own emotions, as well as those of others, is crucial for human social interactions. Also, witnessing facts and events of others’ life sometimes prompts inner reactions related to the beliefs, intentions, and desires of actors.”
Matching emotions with brain activity
For the study, the researchers gathered emotional reactions from scene to scene that the participants had during the film.
They asked participants to rank out six basic emotions of their responses to each scene: joy, excitement, fear, disappointment, rage, and disgust.
The participants also noticed how intense that feeling was, with a number ranging from 1 to 100.
The team used the available open science data from a German study called “study forrest,” which included brain imaging data from 15 participants ‘ fMRI scans showing which regions were involved during each scene of the same film.
The team finally analyzed the data from both experiments, contrasting the self-reported emotional measures against the data from the fMRI.
Mapping emotions encoded in the brain
Lettieri and team were able to create a topographical map by mapping the participants ‘ emotions, which measured their reactions to the film against the participants ‘ brain imaging data in Germany.
The map shows the arrangement of neuronal receptors in the body— which detects physiological emotional stimuli— with the distribution of neurons serving the same functions within the brain’s cortical sensory regions.
This provided a picture of where the brain encodes certain bodily sensations.
Lettieri and Handjaras called this process “emotionotopy,” in keeping with the related retinotopy technique. This refers to the mapping of how visual data is represented within the brain.
Three gradients of emotion
The IMT team discovered that emotions were encoded within three separate but overlapping gradients by comparing the behavioral ratings with the fMRI scans:
- Polarity. This refers to the opposing measures of positive or negative feeling states.
- Complexity. This refers to the amount of variance between emotions when they combine.
- Intensity. This refers, for example, to the arousal level of each experienced emotion.
Within a particular area of the brain, the researchers mapped these emotional experiences: the right temporoparietal cortex.
The researchers were able to unveil the spatial structures of specific emotions as well as the perceived intensities of those emotions within the brain, armed with the data from the specific moments an emotion was activated.
Connecting feeling states to biology
This study shows how open science data can be used to free up resources and energy to find new ground.
The team has been able to focus their efforts on developing a unique approach to detecting and finding where feelings are represented in the brain by carrying out their own fMRI research.
The research also gives further insight into how psychology and biology interact inside the body.
These results also have real-world consequences for people with mental health problems, states co-author Pietro Pietrini reported.
“Dissecting the brain correlates of elementary factors that modulate our emotional intensity and quality has major implications for understanding what happens when emotions[ become pathological], as in[ the] case of depression and phobia,” Pietrini states.
“These studies are getting psychiatry closer to other fields of medicine in finding objective biological correlates of feelings, which are subjective states.”
– Pietro Pietrini
