John D. Pettigrew and Steven M. Miller argue that the underlying pathophysiology for Bipolar Disorder remains elusive, the disorder being strongly heritable but acknowledging that genetics are complicated. Pettigrew and Miller use the term inter-hemispheric switching which looks at trait-dependent biological markers associated with bipolar disorder. Proposing that bipolar disorder is the product of genetic propensity of slow inter-hemispheric switching mechanisms which can become ‘stuck’ in one particular state. Pettigrew and Miller state that slower switches are more ‘sticky’ in contrast to faster switches, hypothesising that the clinical manifestations of bipolar disorder can possibly be explained by hemispheric activation, which could be caught on the right (depression) or the left (mania). The research is based on rates of perceptual alteration in binocular rivalries that appears to be slower in bipolar disorder subjects who are in euthymic states in contrast to the normal controls.
The research data showed that bipolar disorder patients clustered on the tail end of the distribution indicating a slower alternation rate. The Rivalry Alternation Rates: Bipolar Affective Disorder (n = 18) vs Non-Clinical Controls (n = 49). Subsequently the euthymic state of the bipolar subjects at the time of testing suggests that slower rivalry rates can be a trait marker for bipolar disorder. Limitations of this study are related to subjects that have unipolar depression who demonstrated slower rivalry rates, although these subjects were to a lesser extent in contrast to bipolar subjects. The model of “bipolar disorder slow switches are ‘sticky’ switches because the intrinsic channel abnormalities that cause the slow oscillation rate also make the switch more likely to be held down in one state by external synaptic inputs”. A neuronal sensitivity with bipolar disorder argues that it would “lead to increased hemispheric output (in response to a stressor) and might therefore increase the likelihood that the switch will be held down (‘stuck’) on the side favouring that hemisphere”.
Pettigrew and Miller propose that the data suggests that bipolar patients have an increased ‘stickiness’ due to reduced intrinsic currents and greater extrinsic synaptic inputs from stressors, resulting in the patients being ‘stuck’ in a depressive or manic episode as a consequence of a stressor. The research proposes that the wide variety of data is indicative of hemispheric asymmetries of mood and mood disorders. Overall the results of the tests in inter-hemispheric switching might also be applicable to understanding the physiological rhythms of mood, cognitive style and other aspects of human brain function. Pettigrew and Miller outline that there have been reports that creativity is enhanced in subjects with mood disorders and also their relatives in contrast to the general population. The controversial reports of increased creativity raise the potential for an understanding of the consequences associated with slower inter-hemispheric switching and the rhythms of cognitive style that could reveal neural mechanisms of human creativity.
Please note: this is not an academic essay merely a series of different research I found interesting.
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