Neuroimaging, neuropsychiatric and brain stimulation studies of depression indicate the location of depression lies in multiple brain regions (Pandya, Altinay, Malone, & Anand, 2012).
It has been suggested that corticolimbic connectivity abnormalities are a primary cause of a number of psychiatric illnesses including depression and that psychotherapy can assist in the modulation of dysfunctional networks within the corticolimbic system (Leisman & Melillo, 2013).
The corticolimbic system consists of several brain regions that include:
The anterior cingulate cortex – processes emotional experiences at the conscious level and selective attentional responses. The anterior cingulate cortex is divided anatomically into dorsal (cognition) and ventral (emotion) components.
The ventromedial prefrontal cortex – plays a role in the inhibition of emotional responses, decision-making, and the processing of risk and fear.
The dorsolateral prefrontal cortex – involved in higher cognitive functions such as working memory, abstract reasoning, and inhibiting inappropriate responses
The amygdala – processes and regulates emotional responses to stimuli so that an individual may recognize similar events in the future.
The hippocampus – involved in spatial learning, memory, and behavioral regulation.
One potential cause for many of the core symptoms of depression – particularly those associated with negative emotional experiences – is inefficient cortical control over brain regions that respond to emotional stimuli. Psychotherapy has broadly been hypothesized to remediate these neural abnormalities and reduce symptoms by strengthening the cortical emotion regulatory processes.
Improved prefrontal cortex and cortical function lead to enhanced regulation over limbic regions, thereby constricting emotional reactions to negative stimuli (Pandya, Altinay, Malone, & Anand, 2012).
Goldapple et al, (2004) used functional neuroimaging in order to measure changes in limbic and paralimbic activity after CBT treatment in depressive patients. When compared to the pharmaceutical treatment they found that patients who underwent CBT showed elevated activity in their hippocampus, parahippocampus, and dorsal cingulate – areas that play key roles in learning, memory, and cognition.
Conversely, those who received only pharmaceutical treatment showed less elevated activity in the same regions.
The neural mechanisms of psychodynamic psychotherapy (PDT) in relieving the symptoms of depression have also been indicated through neuroimaging. The metabolic activities within the amygdala, hippocampus, and dorsal prefrontal cortex in depressive patients after PDT become similar to that of ‘healthy’ people when patients are exposed to attachment-related stimuli (Buchheim et al, 2012).
A large and growing body of research implicates the ventromedial and dorsolateral sectors of the prefrontal cortex as key neural substrates underlying depression (Koenigs & Grafman, 2009).
The use of MRI technology to compare levels of brain activity in depressive individuals pre- and post-CBT identified increased activity within the dorsolateral prefrontal cortex, and decreased activity in the limbic system, particularly the amygdala (Höflich et al., 2012). (article taken from Positivepsychology.com)