This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
Biology 202, Spring 2005
First Web Papers
"I can't control my fingers I can't control my brain"
-- The Ramones ((1))
It was only after attempting unsuccessfully to forge a friendship with a young woman recently diagnosed with bipolar disorder that I was swept into her whirlwind rapid cycling. Sometimes without any prior provocation she would burst into tears making the most light-hearted situations tense. With her pressure cooker emotions leaving me exhausted and confused, I commenced on finding simple answers for complicated processes. The manic-on-top-of-the-world-highs and the-jump-off-a-building-lows were draining for us both. After probing her for information on what lead to her roller coaster emotions and finding she knew little about her own affliction; it lead me to ponder how bipolar disorder affects and alters her brain activity.
Medically defined as intense episodes of mania and depression that disrupt everyday life, each period of emotional instability can last as little as 24 hours, known as rapid cycling, or may stabilize for weeks or months at a time ((2)). Such symptoms are debilitating for sufferers; pushing them from delusional exuberance to suicidal lows. Classified as a mood disorder, bipolar disorder affects normal brain activity in the limbic system ((2)).
From known research, the limbic system appears as a major influence on mood regulation within the brain. This distinct structure is composed primarily of the hippocampus (memory center) and the amygdala (fear center). Gland secretions from the hypothalamus also appear to be an essential component in mood management and stability ((2)). More specifically, the amygdala functions as an epicenter in which the frequency of neuron firings increase when brought into contact with stimuli. If repeated and excessive stimuli exposure occurs in this area the response from the neurons associated with the input becomes increasingly less potent. Thus, as the amygdala acclimates itself with increased stimuli the response time for an output is lengthened and the habituate remains reactive longer ((7)). This process works in conjunction with the hippocampus. In patients not demonstrating bipolar characteristics a layer of the hippocampus is responsible for processing information in such a way as to recognize dangerous situations. When the hippocampus functions erratically or abnormally axon deterioration occurs which stops connections from being made between neurons. As these axon connections no longer situate themselves with the memory center or hippocampus, bipolar sufferers can experience a "constant state of anxiety because [they] can no longer identify safe situations" ((7)).
The abnormal brain activity attributed to bipolar patients has been shown to elevate electrical signals being processed across the cerebral cortex ((4)). This has been evidenced by brain scan reports taken by an imaging technique known as positron emission tomography (PET). One of many techniques for understanding and evaluating brain activity it non-invasively gauges brain metabolism, put more simply it measures brain activity ((8)). With the assistance of PET scans scientists have been able to view and monitor the areas of the brain most active during times of emotional highs and lows. The scans produced by these machines generally display hyperactivity in the brain during manic periods ((4)). Brainplace.com researchers also credit the limbic system with increased metabolism during manic periods as witnessed from scan results. These neuron firings which originate without an input to the central nervous system can be drawn into comparison with similar patterns of activity that occur in the brains of epilepsy patients.
Although controversial and only one way of thinking, some scientists have drawn comparisons between brain activity in bipolar individuals and sufferers of epilepsy. This approach and the similarities that can be established between the two disorders have yet to be scientifically based. This theory may help scientists to critically explore why random cycling of emotions may be so prevalent amongst bipolar individuals. These ideas originating from Dr. Jim Phelps come to focus on the functions of the cingulate which is located in the limbic system. Operating as a metaphorical mediator, allowing an individual to shift their "attention from thing to thing, to move from idea to idea, to see the options in life"; the cingulate appears instrumental in establishing a balanced lifestyle ((5)).
In terms of appearance the cingulate possesses the "same squiggly pattern, even though it is deep in the brain, as the outside part of the brain" ((3)). This "means that limbic cortex is cortex just like "motor cortex" (the outermost part of the brain)" ((3)). This is an important parallel to establish since it is the motor cortex that is affected by abnormally high brain metabolism in epilepsy patients. Thus, if the disturbance that takes place within the motor cortex during an epileptic seizure was moved to the cingulate it can be hypothesized that the same phenomenon of overactive excitatory neuron firing patterns would occur. It is believed this transpires because of a loss of inhibitory neurons. Interestingly, epilepsy.com describes a seizure as "a sudden surge of electrical activity [...] that usually affects how a person feels or acts for a short time" ((6)). This explanation appears almost interchangeable with the known effects of bipolar disorder. This "sudden surge" of electrical activity is the basis of both conditions. Phelps believes there is "no reason to think that [the] cingulate cortex is any less likely than [the] motor cortex to end up having an epileptic area" ((3)). Essentially meaning that instead of an uncontrollable physical seizure that comes from the motor cortex, the disturbance would occur in the limbic system and thus an emotional reaction would come from the increased brain activity. Thus, Phelps explains what would take place as "emotional epilepsy" and therefore an uncontrollable seizure of emotions ((3)).
The concept of "emotional epilepsy" makes further sense when considered in conjunction with the types of medications prescribed to bipolar patients. There is a plethora of possible options all clouted for their minute uniqueness but overall "5 out of the 6 known mood stabilizers are anti-seizure medications" ((3)). Ultimately, bipolar patients are being prescribed known epilepsy medications, ones in which lower the risk of seizures.
These ideas on brain and behavior all work themselves back to being one more instance in which Emily Dickinson's hypotheses hold true since the pattern of neurons is constantly changing within everyone's brain ((9)). The brain to some extent is equivalent to behavior because for bipolar patients it is the excitatory neurons of the brain that prompt their erratic functioning and this constant activity prompts changes in brain structure. Dickinson would say it is these small differences that influence the different behaviors of each person. Thus, each person afflicted with bipolar disorder or epilepsy would have slightly different mood variations/cycling patterns/seizure schedules because their brain composition is not precisely the same as other sufferers.
Ultimately, a vast array of interactions between genetics, environment, and the brain must take place before a person suffers the effects of bipolar disorder. Brain activity alone cannot account for why symptoms of the disorder occur. Everyone experiences manic episodes and depressed states of mind at one point in their lives. So what I am left pondering is what exactly forces the elongation of these episodes in some and not in others. Genetics plays a role in why some people are more predisposed to the disorder but at what point does the brain activity move from normal to abnormal? Understanding the connections that can be drawn between bipolar and epileptic patients shows the essentialness of anatomical specificity in producing specific reactions and behaviors in particular portions of the brain. Thus, if bipolar disorder is in fact connected to epilepsy, sufferers may someday call into their place of employment – "Nope, can't come to work today...Having an emotional seizure... Be back soon."
1. 1) Ramones Lyrics
2. 2) Mood Disorder: Bipolar Disorder , Emedicine website
3. 3)Mood, Jim Phelps, M.D.
4. 4) Images of Bipolar Disorder and Schizophrenia , The Amen Clinics Inc.
5. 5) Brain Function and Physiology , The Amen Clinics Inc.
6. 6) What is a Seizure , The Epilepsy Project
7. 7) Young and Bipolar , Time magazine
8. 8) Open Mind , Mental Health Association of Greater St. Louis
9. 9) Emily Dickinson's The brain is wider than the sky
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