Answers to Questions
Answers to Questions
Volz and Gazzaniga (2017) presented the knowledge advancements regarding the split brain phenomenon in the last half century. It is largely established that the human brain is split into 2 hemispheres connected by the corpus callosum, which is a nerve-rich fibrous tissue. The discovery of the split brain phenomenon was advanced by experiments and surgical operation (corpus callosotomy) to treat severe epilepsy. Therefore, the term “split-brain” is also used to mean the partial or full separation of the two brain hemispheres by cutting the corpus callosum (De Haan et al., 2020). Currently, this surgical approach is outdated as more information from research indicated that specific sides on the brain were responsible for different functions in the process called the lateralization of brain function. This notion has been supported by the evidence from latter experiments, which revealed that the two brain hemispheres handle different cognitive functions separately, but combines these disparate perceptions to yield a unified interpretation of the stimuli received by the brain. Guy-Evans (2021) noted that the lateralization of brain function overturned the previous notion explained by the holistic theory of the brain, which posited that the entire brain was involved in thought and action processing. Consequently, research has evidenced that the left brain hemisphere is responsible to language functions, while the right hemisphere controls the visuospartial functions. In addition, the brain has contralateral cortices through which one brain hemisphere controls the functions of the opposite side of the body.
Consequently, advancements in brain function lateralization have revealed the lateralization of the different cognitive functions, such as language, emotion, personality, and gender. In turn, the damage on specific areas in the different lobes of the brain results in specific cognitive malfunctions. For instance, damaged on left frontal lobe destabilizes the personality of an individual just as trauma in the left frontal lobe is associated with depression, while that in the right frontal lobe is associated with manic disorders (Guy-Evans, 2021). These advancements in brain neurology have enabled neuroscientists and psychoanalysts device novel treatments and interventions to cognitive dysfunctions.
Depression is a common and prevalent mental health disorder associated with low mood and a loss of interest often manifested as sad feelings, irritability, hopelessness, and loss of pleasure. The World Health Organization (2021) places the prevalent of depression globally at 3.8% of the global population, which translates to about 280 million people. Depression is a debilitating condition with worrisome outcomes. When severe, depression can lead to dysfunction in daily life and can lead to suicide. The world health organization (2021) rates suicide as the fourth most common cause of fatality among the 15-29-year-old population segment globally, with more than 700,000 people committing suicide annually.
Depression is categorized as mild, moderate or severe based on the frequency and severity of the symptoms. Depression patients experience single or multiple episodes of depressive attacks for extended period, with some severe episodes lasting and entire day to over two weeks. The physiological and behavioral symptoms include the inability to concentrate, guilty feelings, hopelessness, suicidal ideation, sleep disruption, low self-worth, appetite and weight changes, low energy, and perennial fatigue (World Health Organization, 2021). These symptoms differ in severity and frequency.
Family and twin studies have revealed the possible biochemical mechanisms and the likelihood of genes implicated in depressive disorders. Specifically, the monoamine theory and the cytokine theory are biochemical and genetic theories that have been advanced to explain the development and manifestation of depression (Shadrina et al., 2018). Nonetheless, there are several pharmacological and behavioral treatments to alleviate depression. The pharmacological approaches include antidepressant medications, such as tricyclic anti-depressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) (Shadrina et al., 2018). However, depression research is ongoing. Depression research is heavily reliant on the research conducted by biopsychologists and neuroscientists because they unearth new understanding about how depression develops and manifests from at the molecular level and the biomechanical and neurological processes involved in depressive disorders development and advancement. Besides, their studies contribute to the knowledge about the action mechanisms of medication interventions, helping the discovery and design of better pharmacological interventions.
Sleep is a normal regenerative process that occurs in cycles. Disruption of these cycles leads to sleep disorders, which can be manifested physically and psychologically leading to adverse health autcomes. Normal sleep has between 4 and 6 cycles in 24 hour for its restorative benefits to be realized. Each normal cycle lasts an average of 90 minutes. There are 4 stages of normal sleep with three of them belonging to the non-rapid eye movement (NREM) phase and one classified as a rapid eye movement (REM) stage (Patel et al., 2021). The first stage of non-rapid eye movement lasts between 5 and 10 minutes and is characterized by dozing off and commencement of slowed brain and body activity. The second stage of non-rapid eye movement is a pre-deep sleep stage that can last up to 25 minutes. It is characterized by the stoppage of eye movement, lowering of temperature and heart rate, although sleep spindles, which are brain wave burst, occur occasionally. These brainwave bursts are believed to consolidate memory and prevent sleep interruption. The third stage of non-rapid eye movement is considered the deep sleep stage when the eyes and body rest completely. This stage last between 20 and 40 minutes and provides the most restorative benefits. At this state, the body repair, regrowth, and growing mechanisms are most active. It is the most difficult stage to disrupt one’s sleep. The fourth stage is a rapid eye movement one, which lasts 10 minutes. It is the dreaming stage that is characterized by temporary muscle paralysis and rapid eye movement. In addition, the brain activity is high and can equal or exceed that when one is fully awake.
Sleep is often accompanied by dreams, which occur in the rapid eye movement stage. Dreams comprise thoughts, images, and emotions, which can be vague or lucid, and pleasurable or sad. Several theories explain the mechanism and purposes of dreams. For instance Freud’s dream theory explains dreams as wish-fulfillment expressions, while Jung explains them as direct mental expressions. The activation-synthesis dream theory explains dreams as side effects of normal brain activity, while the threat simulation theory explains dreams as a safe-keeping mechanism (Bulkeley, 2017). Insomnia, depression, somnambulism, narcolepsy, and sleep apnea are the common sleep disorders resulting from sleep disruption.
Emotions are powerful intuitive and instinctive feelings derived from moods, circumstances, and relationships. Several theories have been advanced to explain emotions. There are three theoretical categories explaining emotions are cognitive, neurological, and physiological theories, which explain emotions as being caused by thoughts, brain activity, and bodily responses respectively. Notable theories of emotions include the evolutionary, James-Lange, Cannon-Bard, Schachter-Singer, cognitive appraisal, and Facial-Feedback theories of emotions. The evolutionary theory explains emotions as a survival mechanism that has evolved over time. It separates the feelings of love and affection from those of fear, which induce mate-seeking or flight, respectively. The James-Lange theory is a physiological theory which explains emotions as interpretations of physical reactions to external stimuli. However, Cannon-Bard theory of emotions, another physiological one, contradicts the James-Lange one by noting that many physical reactions are not connected to emotions and emotional reactions are very rapid and can precede the emotional feelings. The theory connected the mechanisms in the thalamus as the processes that transform emotions to physiological reactions. Contrastingly, Schachter-Singer theory and cognitive appraisal theories are renowned examples of genitive theories of emotions. Schachter-Singer theory suggests that thoughts generate emotions although physiological reactions can cause different emotions, a notion that is similar to that held by the Cannon-Bard theory. Contrastingly, the cognitive appraisal theory posits that the brain assesses the situation before translating the response into an emotion. The Facial-Feedback theory is a neurological theory of emotions which links the facial expressions to emotions neurologically. The theory posits that facial muscles are linked to emotions through the nervous system. Consequently, happy facial expressions lead to positive emotions while sad facial expressions lead to negative emotions.
I think the Schachter-Singer theory provides the best explanation of emotions because it combines arguments from the James-Lange and Cannon-Bard theories. The theory prioritizes the situation and context, and the mental interpretation labeling the emotion. I find this a more holistic approach to explaining emotions compared to the individual theories considered separately. Besides, I find the Schachter-Singer theory to present a more realistic representation of emotions that related with my reality.
Although it is well established that sleep is beneficial to the brain and its processes, it is also recognized that the brain play a primary role on controlling and regulating sleep. Several brain parts and regions are associated with sleep control and regulation. For instance, hypothalamus is considered to the sleep and arousal control center. It hosts the suprachiasmatic nucleus (SCN), which translate light stimuli to behavioral rhythms. Consequently, damage to the hypothalamus leads to erratic sleep (Falup‑Pecurariu et al., 2021). The brain stem works alongside the hypothalamus to regulate the wake and sleep cycles. Similarly, the basal forebrain releases adenosine and regulates the wakefulness and sleep cycles along with the hypothalamus and the brain stem. The thalamus is another brain part critical for relaying information to the cerebral cortex. It is inactive during the non-rapid eye movement and activated during the rapid eye movement phase of sleep. Its primary role is to facilitate dream visualization. The pineal gland, located between the two brain hemispheres, is critical for inducing sleep when light is put off and darkness is induced (Falup‑Pecurariu et al., 2021). This light-related sleep cycle is mediated by melatonin, which is a hormone produced by this gland.
Circadian rhythms are the biological cycles controlled by light and darkness within 24 hours. Notably, there are others that occur annually, monthly, and in less than 24 hours. However, the human body and mind responses to light and darkness by adjusting the behavioral, mental and physical activities, accentuating some with light and other with darkness (Tähkämö et al., 2019). These regulations are controlled by neurochemicals such as melatonin and adenosine, which are triggered glands responding the light and darkness stimuli, perceived through the eyes. This is why blind people have irregular circadian rhythms because they lack the visual stimuli.
Bulkeley, K. (2017). An introduction to the psychology of dreaming. ABC-CLIO.
De Haan, E. H., Corballis, P. M., Hillyard, S. A., Marzi, C. A., Seth, A., Lamme, V. A., … & Pinto, Y. (2020). Split-brain: What we know now and why this is important for understanding consciousness. Neuropsychology Review, 30(2), 224-233. https://doi.org/10.1007/s11065-020-09439-3
Falup‑Pecurariu, C., Diaconu, Ș., Țînț, D., & Falup‑Pecurariu, O. (2021). Neurobiology of sleep. Experimental and Therapeutic Medicine, 21(3), 1-8.
Guy-Evans, O. (2021). Lateralization of brain function. Simply Psychology, Retrieved from www.simplypsychology.org/brain-lateralization.html.
Patel, A. K., Reddy, V., & Araujo, J. F. (2021). Physiology, sleep stages. In StatPearls [Internet]. StatPearls Publishing.
Shadrina, M., Bondarenko, E. A., & Slominsky, P. A. (2018). Genetics factors in major depression disease. Frontiers in Psychiatry, 9, 1-18.
Tähkämö, L., Partonen, T., & Pesonen, A. K. (2019). Systematic review of light exposure impact on human circadian rhythm. Chronobiology international, 36(2), 151-170.
Volz, L. J., & Gazzaniga, M. S. (2017). Interaction in isolation: 50 years of insights from split-brain research. Brain, 140(7), 2051-2060.
World Health Organization (2021). Depression. Retrieved from https://www.who.int/news-room/fact-sheets/detail/depression.