In this second video, we will look at the brain areas that play an important role in emotion. Traditionally, the limbic system, which is a group of structures in the forebrain that forms a border around the brainstem, is considered the most important brain area for emotions. The limbic system consists of the amygdala, fornix, thalamus, and cingulate gyrus. Research on brain structures involved in emotional experiences is mostly focused on the amygdala, which is an almond-shaped structure in the limbic system that plays an important role in feeling both positive and negative emotions.
Many research has looked at the role of the amygdala in the experience of negative emotions, especially fear. Joseph Ledoux and his colleagues, for example, found that the amygdala is extremely important for the control of fear. When the amygdala receives a signal about potential danger in the environment, it reacts quickly to protect the organism from harm. This system of fear evolved to enable an organism to detect and rapidly respond to threats to the organism's own safety.
The brain circuit for fear is believed to consist of two pathways. The first is the direct pathway from the thalamus to the amygdala, which sends information to the amygdala relatively quickly, but in less detail. The speed of the transmission of information along this pathway provides an advantage when an organism's safety is threatened. The second one, the indirect pathway, brings information from the thalamus to the sensory cortex, which then delivers the information to the amygdala.
The indirect pathway carries nerve impulses from sensory organs, such as the eyes and ears, to the thalamus, which is a relay station for all sensory information except for the sense of smell. From the thalamus, these nerve impulses travel to the sensory cortex, which subsequently sends the corresponding signals to the amygdala. The amygdala itself is able to retain learned associations about fear for a relatively long period of time, and as such, once we've learned to fear a particular stimulus, we don't need to relearn the same information in the future.
But on the flip side of that, since the amygdala retains this fear information, fear of a particular stimulus would be difficult to forget. We will discuss the relationship between the amygdala and fear in greater detail in later videos in this week's series. Contemporary research has also found the role of some neurotransmitters in emotions. Among these, dopamine and endorphins have been found to be associated with positive emotions such as happiness. Norepinephrine, on the other hand, has been found to play a role in the regulation of anxiety.
In addition to the limbic system, researchers have also found that the cerebral cortex also responds to emotional situations. PET and fMRI studies suggest that there is wide variability in the cortical areas that process different emotions. The experimental procedure usually involves asking participants to view emotional pictures or to listen to emotional stories while participants'brain activities are recorded.
In the image on your screen, each colored dot represents one study that managed to find significant activation of that particular cortical area during the experience of a specific emotion. Perhaps the most striking conclusion that can be made from this picture is the wide variability of locations for any one particular emotion. This variation can perhaps be attributed to differences in the research procedures employed in each study.
It's important to note that even though studies have found that the amygdala is important for perceiving emotions, especially fear and anxiety in someone's expression, when it comes to experiencing emotions, with the exception of happiness, there does not seem to be a specific area in the cortex that's important for experiencing a particular emotion. Perhaps one of the most frequently debated questions in the research on emotions is whether or not we have basic universal emotions that are commonly perceived and experienced by all people in all cultures. The primary idea that supports the notion of universal emotions is the early finding that in general there are six basic emotions that appear to be expressed universally throughout the world. namely happiness, anger, sadness, surprise, disgust, and fear. When people of different ethnic backgrounds are shown a set of photographs of a group of individuals displaying different facial expressions, as the one you see on the screen, most people, regardless of their ethnic background, are able to correctly label the emotions shown in each picture.
Yet many other experts in the field are unconvinced with the idea of the universality of emotional expressions, because the emotional expressions portrayed in the photographs shown to study participants were posed and rather exaggerated to maximize recognition of emotion when people are shown spontaneous facial expressions that we commonly see in daily life it's more likely for observers to identify two or more emotional expressions within the same photo and the identified emotions may not necessarily be consistent with the one that the person in the photo is actually expressing. That wasn't the only problem though. When participants are asked to match a photograph with the name of an emotion selected from a list of available emotions, and each photograph of a facial expression is also presented simultaneously with other photos of emotional expressions, it would automatically become easier for the participants to identify an emotion in the photo simply because there are other emotional expressions to compare it to.
For example, if a study participant initially identifies the picture on the bottom right as fear, and they know that another photograph should be labeled surprise, then the participant would automatically identify the bottom left photograph as surprise. But if the participant sees the bottom left photograph on its own, without other photos to compare it to, it could be that the participant would label the bottom left photo as fear similarly if a participant sees the bottom center photo by itself perhaps the photo may be labeled as anger instead of disgust another weakness with the experimental procedure used to investigate the universality of emotions has to do with how Experimental subjects were found to recognize expressions common to their own culture better than those from other cultures. Furthermore, when applied in a real-world situation, we rarely identify a person's emotion simply from their facial expression.
When participants in a study were asked to observe a photograph of a tennis player who either just won or just lost a difficult match, they were generally better able to more accurately identify the emotion as either happy or sad from photos of body postures than they were from photos of facial expressions alone another study also found that both children and adults perceived the expressions of intense pleasure as similar to intense pain an alternative idea to the concept of universal basic emotions is the notion that perhaps emotions vary along one or more continuous dimensions, such as weak versus strong, or pleasant versus unpleasant. One such continuum that's been studied and that seems to be supported by experimental evidence is the continuum of activation versus inhibition. In particular, it's been found that there is a difference in the activities of the left and right hemispheres in emotion.
especially in the frontal and temporal lobes. Activation of the left hemisphere is associated with the behavioral activation system, which is marked by low to moderate autonomic arousal and with a tendency to approach, which could characterize either happiness or anger. On the other hand, activation of the right hemisphere has been linked to the behavioral inhibition system, increases attention and arousal, inhibits action, and stimulates emotions like fear and disgust.
Differences between the hemispheres also appear to be related to personality. In general, individuals with greater activity of the frontal cortex of the left hemisphere tend to be happier, more outgoing, and more fun-loving. while individuals with greater activity of the right hemisphere tend to be more socially withdrawn, less satisfied with life, and prone to experiencing unpleasant emotions. In line with this idea, it was also discovered that when study participants are shown a picture of an emotional expression to only one hemisphere of the brain, the left hemisphere is faster and more accurate at identifying happy faces, while the right hemisphere is faster and more accurate at identifying sad and frightened faces.