Brain lateralization of emotions

As in other brain functions, there is a lateral asymmetry in the neural processing of emotions, since the right hemisphere has a more important role, both in recognition and emotional expression. However, the left hemisphere also participates in the control of emotional information.

Recognition of emotions

It seems that the right hemisphere has a greater capacity to detect visual differences in facial and postural emotional expressions, and also to be able to detect emotional modulation of the voice or prosody with a smaller error rate:

In 1991, Bowers and his colleagues found that patients with lesions in the right hemisphere had difficulty recognizing facially and manually expressed emotions. Likewise, they showed a serious deterioration when describing mental images of emotional expressions.

Neuroimaging studies have shown an increase in the activity of the right prefrontal cortex in the face of emotional recognition from the tone of the voice.

George et al. (1996), by means of a positron emission tomography, observed a frontal activation in both hemispheres in the face of emotional recognition from the meaning of language, but they only saw an activation of the right prefrontal cortex when recognition was given from tone of voice.

The right hemisphere is more important than the left in the recognition and understanding of emotions

Emotional expression

Patients with lesions in the suprasylvian portions of the posterior frontal and anterior parietal lobes of the right hemisphere have difficulties in expressing emotions through modulation of the tone of language.

Aprosodia is a disorder characterized by the tendency to speak in a monotonous way, with the same language pattern, but with a correct cognitive perception of feelings. Thus, a person with aprosodia who, in addition, has suffered the loss of a loved one, can express his emotional pain with the content of the language, but with a tone that would seem of authentic indifference.

Different studies, both in humans and non-human primates, have found lateral asymmetries in the intensity of emotional expression. Thus, facial expressions are manifested more quickly, with more intensity and more completely, in the left facial muscles (which is controlled by the right hemisphere)..

Lesions of the right hemisphere incapacitate subjects to express emotions through facial expressions and / or modulation of the tone of language.

Functional lateralization of the cortex: positive and negative emotions

Different neuroimaging studies support the hypothesis that the prefrontal cortex of the left hemisphere is related to positive emotions, while that of the right would be related to negative emotions.

Electrophysiological studies have shown that the activation of the left prefrontal cortex seems to inhibit negative emotions, and also the subject's disposition to suffer negative emotional states.

Epidemiological analyzes have described that the incidence and severity of depressive symptoms is higher in patients with lesions of the left anterior hemisphere. Likewise, some clinical studies have shown that injuries to the right anterior hemisphere can generate excessive signs of positive emotions.

Different clinical and experimental studies have shown a much more important role for the right hemisphere in the processing of negative emotions and for the left hemisphere in positive ones..

Many patients who are not able to recognize emotions from facial and manual expressions, can do so from the tone of the voice, showing some functional independence between the two systems of emotional understanding..