Brain Lateralization of Emotional Processing in Depression

Abstract

There are three major hypotheses regarding the lateralization of emotion in the brainthe right-hemisphere hypothesis (RHH), the valence hypothesis, and the approachwithdrawal hypothesis. The approach-withdrawal hypothesis, which is the most widely accepted, states that emotions that elicit approach behaviors are lateralized to the left hemisphere, while emotions that elicit withdrawal behaviors are lateralized to the right hemisphere. In line with this hypothesis, it has been found that persons with depression show left frontal hypoactivity and right frontal hyperactivity. This hemispheric asymmetry appears not to influence mood but rather emotional reactions to affective stimuli. That is, a person with such an asymmetry does not show a predominant negative mood, but rather heightened negative reactions to occurrences in the environment. The asymmetry may also be a biological marker of depression, with research evidence that it is found in remitted depressives and in infants of depressed mothers. Currently, research in this area focuses on identifying the mechanism underlying the link between the asymmetry and depression.

Middle Cerebellar Peduncle Lesions and Their Relation to Affective and Cognitive Impairment in Multiple Sclerosis

“…As recent evidence exists for the emotional lateralization in the brain, 34 our finding is logical in context of the theory that the right cerebral hemisphere is specialized for perception, expression, and experience of emotion. 35 As the cortico-ponto-cerebellar pathway connects the cerebral hemisphere with the contralateral cerebellum, 36 the left MCP lesions might have disrupted the cerebellar connectivity to the right cerebral hemisphere and consequently impaired patients experience and expression of depressive emotions in our cohort of patients.…”

Oculometric Behavior Assessed by Pupil Response is Altered in Adolescent Depression

“…It is important to note possible relation of between-eyes differences to hemispheric lateralization of valence processing as well as autonomic control. The most recent hypothesis regarding the lateralization of emotions is the approach -withdrawal hypothesis stating that the left prefrontal cortex is associated with intention, planning and regulation that are important for approach behaviors, whereas the right prefrontal cortex is linked to behavioural inhibition important for withdrawal (Pereira and Khan 2017). This hypothesis overlaps with the valence hypothesis reporting that regions of the left hemisphere are specialized for the processing of positive stimuli while processing of negative stimuli involves the right hemisphere (Davidson and Tomarken 1989).…”

Cerebellum and nucleus caudatus asymmetry in major depressive disorder

“…Although asymmetry is a common aspect of the human brain, asymmetry abnormalities are a condition that is particularly emphasized in MDD patients and can be demonstrated by MRI studies in some psychiatric disorders [8]. Studies conducted using neuroimaging techniques and designed on the basis of a hypothesis based on the relationship between emotions and brain lateralization have shown that structural and functional asymmetries between hemispheres can be found in MDD patients [9][10][11][12]. Numerous studies using neurocognitive, electrophysiological, and neuroimaging measurements in MDD patients provide evidence of functional brain asymmetry abnormalities [13].…”

“…Numerous studies using neurocognitive, electrophysiological, and neuroimaging measurements in MDD patients provide evidence of functional brain asymmetry abnormalities [13]. Although the hypothesis that many cognitive and emotional functions are performed asymmetrically between the left and right hemispheres has a long history, this hypothesis should still be evaluated [9]. Some researchers think that brain asymmetry reveals different clinical manifestations of different psychiatric disorders as a result of similar differences in brain function [14,15].…”

“…A recent sMRI study showed that abnormalities in structural asymmetry seen in MDD patients involve the cortico-striatal-pallidalthalamic circuit [14]. Structural hemispheric asymmetry can be a biological marker of MDD as studies showing that this asymmetry is present in patients with MDD in remission, and in babies of mothers with MDD have been published [9]. Recent research has increasingly emphasized the relationship between the cerebellum and MDD; nevertheless, studies examining cerebellar dimensions in MDD are very few [21,22].…”