Brain's change detection elicited by emotional facial expressions in depressed and non-depressed individuals
Year: 2009
Type: dissertation
Study design: Clinical Trial
Abstract: Previous research has shown that people suffering from depression typically have deficits in emotional information processing.These deficits can be seen in the level of behavior and also in the brain processes.The aim of our study was to investigate with event-related potentials, whether depressed individuals have differences in their brain processes compared to nondepressed individuals when emotional facial expressions are used as stimuli.We applied an oddball paradigm in order to elicit visual mismatch negativity and thus investigate brain's change detection.The brain reacts to infrequently presented stimuli and recognizes the change in the pattern.We also investigated whether short psychotherapy (Acceptance and Commitment Therapy, ACT) alters the brain processes of depressed individuals.Individuals were shown pictures of human faces.In 80% of the faces, the expression was neutral.In the rest of the faces, the expression was emotional.Half of the pictures depicted fearful expression.The other half depicted happy expression.Pictures were presented in quasi-random order on a computer screen.Twenty depressed and ten non-depressed individuals participated in the study.During the experiment, a participant's EEG was recorded with electrodes attached to their scalp.Depressed individuals were randomized in to two groups.The first group received therapy immediately.The second group received therapy after six weeks from the first EEG recording.Those in the immediate treatment group had their EEG recorded twice.Those in the delayed treatment group had EEGs recorded three times.The non-depressed group had an EEG recorded only once.Stimuli were the same in each recording session.The results suggested that depressed and nondepressed individuals processed emotional facial expressions differently.Non-depressed individuals were able to differentiate emotional and neutral expression from one another.In the depressed group, this differentiation did not occur.The P240 component's discriminative power seemed to be lateralized to the posterior parts of right hemisphere, whereas N240's discriminative power was localized in fronto-parietal regions.Component N170 seemed to be the best to reflect a visual mismatch negativity.N170 was able to differentiate between the two emotional expressions which components P240 and N240 were not able to do.These results were in line with previous research which has shown that depression is often characterized by the dysfunctional processing of emotional information.
Author: Kirsti Hannikainen
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2336989366