The dorsolateral prefrontal cortex (dlPFC) is important for "cognitive" and "executive" functions such as working memory, intention formation, goal-directed action, abstract reasoning, and attentional control. It is also known that the dorsolateral prefrontal cortex (dlPFC) plays an important role in top-down regulation of emotional processing as part of the more extensive cognitive network that is also critically involved in emotion regulation, particularly by distraction from the emotional stimulus. This dlPFC is important for the reappraisal/suppression of negative affect and a defect in this regulation of negative affect due to a
dysfunction of the dlPFC appears to play a very important role in clinical depression.
Modification of a negative attentional bias by cognitive training alters dlPFC activity in response to emotional stimuli and this is likely the primary result of successful treatment by means of cognitive and cognitive-behavioral psychotherapies. AThe results of a recent study examining the effects of anodal transcranial direct current stimulation (tDCS) of the left dlPFC on temporary reduction of negative attentional bias during learning in depressed versus non-depressed college students supports the suggestion that tDCS may actually enhance the learning of cognitive-behavioural therapeutic strategies.
While there is some strong evidence suggesting that a reduction in dlPFC activity and/or over-activity of the vmPFC may play a major role in the development of depression brain imaging studies continue to reveal other areas of the brain that are also involved in depressed mood and suggest that depression is largely a result of reduced activation/metabolism in a number of brain areas and reports of increased activation of any particular brain area have not consistently been associated with depression. Anxiety, on the other hand, correlates with increased regional cerebral blood flow (rCBF) in posterior cingulate and bilateral inferior parietal lobules. Since comorbid depression and anxiety are quite common, it is important to recognize the different areas that are activated or inhibited by both depression and anxiety.
Electroencephalographic (EEG) studies have largely confirmed these findings by demonstrating increased alpha (8-12 Hz) EEG relative power in the left frontal regions of the brains to be associated with dysthymia and major depressive disorder (MDD) as well as the onset of depression in patients with damage to the left frontal lobe. Since alpha is generally viewed as a cortical idling rhythm and is inversely related to neuronal activity, increased left frontal alpha results in deactivation of the left prefrontal cortex and a functional dominance of the right prefrontal cortex. Indeed, a number of brain researchers have suggested a laterality of the brain’s affective system; with
negative emotions having a bias in activating the right hemisphere and positive emotions activating the left hemisphere. The left frontal lobes may be considered to include an “approach behavior” circuit whereas the right frontal lobes may include an “avoidance-behavior” circuit. As the left becomes more active, we tend to see things as generally more interesting, more rewarding, more approachable (i.e., the cup as half-full). In contrast, activation of the right circuit causes us to see things as potentially more dangerous and less rewarding (i.e., the cup as half-empty). Brain research suggests that a person's mood may largely depend on which side of the prefrontal cortex is more active.
In this vein, Henriques & Davidson (1990, 1991) examined frontal EEG asymmetry in currently depressed versus never depressed individuals and found elevated left frontal alpha power in the depressed individuals. Other researchers have confirmed these findings as well as observing that individual differences in frontal asymmetry emerge early in life and are associated with individual differences in “approach-withdrawal” behavior and the “introversion-extroversion” personality dimension. Taken together, these findings suggest that
EEG asymmetry marked by relative left frontal hypoactivation may be a biological marker of familial and, possibly genetic risk for mood disorders.
EEG biofeedback or Neurofeedback is direct training of brain function, by which the
brain learns to function more efficiently. We observe the brain in
action from moment to moment. We show that information back to the
person. And we reward the brain for changing its own activity to more
appropriate patterns. This is a gradual learning process. It applies to
any aspect of brain function that we can measure. Neurofeedback is also
called EEG Biofeedback, because it is based on electrical brain
activity, the electroencephalogram, or EEG. Neurofeedback is training in
self-regulation. It is simply biofeedback applied to the brain
directly. Self-regulation is a necessary part of good brain function.
Self-regulation training allows the system (the central nervous system)
to function better.
Neurofeedback addresses problems of brain disregulation. These
happen to be numerous. They include the anxiety-depression spectrum,
attention deficits, behavior disorders, various sleep disorders,
headaches and migraines, PMS and emotional disturbances. It is also
useful for organic brain conditions such as seizures, the autism
spectrum, and cerebral palsy.
We offer brainwaves assessment service. It is a tool that designed to give the client’s subconscious mind a voice, and allow the Clinical Hypnotherapist to reveal the various underlying factors that shape the client’s cognitive abilities, emotional responses and automatic behavior. Contact us now for more info.
Source:
http://www.edmontonneurotherapy.com/treatment_depression.html
http://www.eeginfo.com/what-is-neurofeedback.jsp
