Download
1 / 39
400 likes | 522 Views
Role of Conscious and Biorhythms in Organism’s Activity. Consciousness and its mechanisms.
E N D
Consciousness and its mechanisms • Consciousness is special form of perceiving surroundings and goal-orientated activity of person with interrelation to surroundings. Only social life forms consciousness. It involves life experience of entire society. • This ability of prefrontal areas to keep track of many bits of information could well explain abilities to prognosticate, do plan for the future, delay action in response to incoming sensory signals, consider the consequences of motor actions even before they are performed, solve complicated mathematical, legal, or philosophical problems, correlate all avenues of information in diagnosing rare diseases and control our activities in accord with moral laws.
The process of sensation and perceptual conclusions • The process of sensation results in the transmission of neural messages to the brain, where the psychological process of perception occurs.We actively construct perceptual conclusions about this sensory information. • In arriving at those perceptual conclusions, we are guided by well-established perceptual principles, such as the cues that typically indicate distance, movement, form, and so forth. • But our perceptual conclusions can also be influenced by a variety of psychological factors, including our expectations, learning experiences, and experiences that are unique to our culture.
The nativist position and empiricist position • The Gestalt psychologists believed that perceptual processes are inborn, a viewpoint called the nativist position. According to this position, people everywhere, whatever their background, see the world in the same way because they share the same perceptual rules. • Other psychologists have advocated the empiricist position, believing that people actively construct their perceptions by drawing on their prior learning experiences, including cultural experiences.
Consciousness studying • Wilhelm Wundt’s investigations of consciousness,begun in 1879, were central to the development of psychologyas a field of study. Wundt’s approach, calledstructuralism, sought to determine the structure of consciousnessby recording the verbal descriptions providedby laboratory subjects to various stimuli, a method thatbecame known as introspection. • The next major approachto the study of consciousness was the functionalismof William James, who focused on how consciousnesshelps people adapt to their environment. Behaviorism,pioneered by John B. Watson in the early 1900s,shifted interest from conscious processes to observablebehaviors, and the study of consciousness faded into thebackground for almost half a century, especially in theUnited States, until it was revived by the “cognitive revolution”that began in the 1950s and 1960s.
Consciousness: Sigmund Freud’s model • The existence of different levels of consciousnesswas at the heart of Sigmund Freud’s model of humanmental functioning. • In addition to the conscious level,consisting of thoughts and feelings of which one isaware, Freud proposed the existence of the unconscious,a repository for thoughts and feelings that are repressedbecause they are painful or unacceptable to the consciousmind for some other reason. • He also formulatedthe concept of the preconscious, which functions as anintermediate or transitional level of mind between theunconscious and the conscious. • A preconscious thoughtcan quickly become conscious by receiving attention,and a conscious thought can slip into the preconsciouswhen attention is withdrawn from it. In contrast, the repressed material contained in the unconscious can only be retrieved through some special technique, such as hypnosis or dream interpretation. (What Freud called the unconscious is today referred to by many psychologists as the subconscious.)
Consciousness: Carl Jung’s model • Freud’s contemporary, Carl Jung,posited the existence of a collective unconscious sharedby all people which gathers together the experiences ofprevious generations. • The collective unconscious containsimages and symbols, called archetypes, that Jungfound are shared by people of diverse cultures and tendto emerge in dreams, myths, and other forms. • In Jung’sview, a thorough analysis of both the personal and collectiveunconscious was necessary to fully understandthe individual personality.
Circadian rhythms • In response to morning light,signals from photoreceptors in the eye are relayedvia the optic nerve to the suprachiasmaticnucleus. In turn, the suprachiasmatic nucleuscauses the pineal gland to reduce the productionof melatonin, a hormone that causes sleepiness. • As blood levels of melatonin decrease,mental alertness increases. Daily exposure tobright light, especially sunlight, helps keep thebody’s circadian rhythms synchronized and operatingon a 24-hour schedule.
The Biological Clock • A tiny sliver of brain tissue, less than the size of a pinhead, regulates the timing of our bodies. Within this sliver lies a biological clock that keeps track of the time of day, and seasons of the year, and marches our bodies and brains in step. • The small cluster of nerve cells that forms the biological clock is called the suprachiasmatic nucleus (SCN). Its name derives from the location of the SCN, just above where the broad optic nerve trunks cross over each other (a site known as the "optic chiasm") on their way back from the eyes to the visual center of the brain. • The SCN also receives information about light and dark from the eyes, but it has its own dedicated pathway of nerves, the retino-hypothalamic tract (RHT), which is separate from the main nerve bundles carrying visual information to the brain.
The Biological Clock • We know that the SCN is a biological clock because when it is destroyed in an experimental animal by surgical pinpoint lesions of the brain, rhythms in sleep and wake, and many other rhythms, fade away. Interestingly, the animal, minus its SCN, runs, eats and drinks the same total amount each 24 hours, but these activities are now randomly distributed throughout the day and night. • One final fact about human biological clocks -- they actually follow a pattern of about 25 hours. Hence, if someone lives in a cave or an apartment without windows (as people have done), their circadian patterns of sleep and wakefulness shift "westward" by about one hour a day. However, in the regular world, sunlight and darkness serve to "reset" the biological clock every day and keep us on a 24-hour cycle.
Suprachiasmatic nucleus • Circadian rhythms are controlled by a master biological clock-a tiny cluster of neurons in the hypothalamus in the brain. This cluster of neurons is called the suprachiasmatic nucleus. • The SCN is the internal pacemaker that governs the timing of circadian rhythms, including the sleep-wake cycle and the mental alertness cycle. • Keeping the circadian rhythms synchronized with one another and on a 24-hour schedule also involves environmental time cues. The most important of these cues is bright light, especially sunlight. • Normally the sleep-wake cycle, body temperature, and the melatonin cycle are closely coordinated.
Role of melatonin • The decrease in available light is detected by the SCN through its connections with the visual system. In turn, the SCN triggers an increase in the production of a hormone called melatonin. • Melatonin is manufactured by the pineal gland, an endocrine gland located in the brain. Increased blood levels of melatonin make a person sleepy and reduce activity levels. • At night, blood levels of melatonin rise, peaking between 1:00 and 3:00 A.M. Shortly before sunrise, the pineal gland all but stops producing melatonin, and a person soon wakes up. • As the sun rises, exposure to sunlight and other bright light suppresses melatonin levels, and they remain very low throughout the day. In this way, sunlight entrains, or sets, the SCN so that it keeps circadian cycles synchronized and operating on a 24-hour schedule.
Sleep • People experience not only different levels, but alsodifferent states of consciousness, ranging from wakefulness(which may be either active or passive) to deepsleep. Although sleep suspends the voluntary exercise ofboth bodily functions and consciousness, it is a muchmore active state than was once thought. • Tracking brainwaves with the aid of lectroencephalograms (EEGs), researchershave identified six stages of sleep (including apre-sleep stage), each characterized by distinctive brainwavefrequencies.
Theories of sleep • Two theories of sleep, the repair and the adaptivetheories, attempt to explain why sleep occurs. • In therepair theory, sleep serves a biological need, replenishingkey areas of the brain or body which are depletedduring the day. • The adaptive theory suggests that sleepas a function evolved over time because it preventedearly humans from wasting energy and exposing themselvesto nocturnal predators, thus aiding in survival. • REM sleep in particular has been thought to serve specialfunctions. Research subjects whose REM sleepwas interrupted made up for the loss by spending extratime in the REM stage on successive nights. It has alsobeen suggested that REM sleep aids the activity ofneurons that use the neurotransmitter norepinephrine,thus maintaining waking alertness. Persons deprivedof REM sleep have shown poorer retention ofskills learned during the day, leading to the hypothesisthat REM sleep helps in assimilating daytime learningexperiences.
Stage 1 NREM • As the alpha brain waves of drowsiness are replaced by even slower theta brain waves, you enter the first stage of sleep. Lasting only a few minutes, stage 1 is a transitional stage during which you gradually disengage from the sensations of the surrounding world. • Familiar sounds, such as the hum of the refrigerator or the sound of traffic, gradually fade from conscious awareness. During stage 1 NREM, you can quickly regain conscious alertness if needed. Although hypnagogic experiences can occur in stage 1, less vivid mental imagery is common. • Although dreamlike, these images lack the unfolding, sometimes bizarre details of a true dream.
Stage 2 NREM • Stage 2 represents the onset of true sleep. • Stage 2 sleep is defined by the appearance of sleep spindles, brief bursts of brain activity that last a second or two, and K complexes, single but large high-voltage spikes of brain activity that periodically occur. Other than these occasional sleep spindles, brain activity continues to slow down considerably. • Breathing becomes rhythmical. Slight muscle twitches may occur. Theta waves are predominant in stage 2, but large, slow brain waves, called delta brain waves, also begin to emerge. • During the 15 to 20 minutes initially spent in stage 2, delta brain-wave activity gradually increases.
Stage 3 and Stage 4 NREM • Stages 3 and 4 of NREM are physiologically very similar. Both stages are defined by the amount of delta brain-wave activity. In combination, stages 3 and 4 are sometimes referred to as slow-wave sleep. • When delta brain waves represent more than 20 percent of total brain activity, the sleeper is said to be in stage 3 NREM. • When delta brain waves exceed 50 percent of total brain activity, the sleeper is said to be in stage 4 NREM. During the 20 to 40 minutes spent in the night's first episode of stage 4 NREM, delta waves eventually come to represent 100 percent of brain activity. At that point, heart rate, blood pressure, and breathing rate drop to their lowest levels. However, his muscles are still capable of movement. • The sleeper is approximately 70 minutes into a typical night's sleep and immersed in deeply relaxed stage 4 NREM sleep. At this point, the sequence reverses. In a matter of minutes, the sleeper cycles back from stage 4 to stage 3 to stage 2 and enters a dramatic new phase: the night's first episode of REM sleep.
REM Sleep • During REM sleep, the brain becomes more active, generating smaller and faster brain waves. Visual and motor neurons in the brain activate repeatedly, just as they do during wakefulness. • Dreams usually occur during REM sleep. Although the brain is very active, voluntary muscle activity is suppressed, which prevents the dreaming sleeper from acting out those dreams. • REM sleep is accompanied by considerable physiological arousal. The sleeper'seyes dart back and forth behind closed eyelids-the rapid eye movements. Heartrate, blood pressure, and respirations can fluctuate up and down, sometimes extremely. Muscle twitches occur. In both sexes, sexual arousal may occur, which is not necessarily related to dream content. • This first REM episode tends to be brief, about 5 to 15 minutes. From the beginning of stage 1 NREM sleep through the completion of the first episode of REM sleep, about 90 minutes have elapsed.
Beyond the First 90 Minutes • Throughout the rest of the night, the sleeper cycles between NREM and REM sleep. Each cycle lasts about 90 minutes on average, but the duration of cycles may vary from 70 to 120 minutes. • Usually, four more 90-minute cycles of NREM and REM sleep occur during the night. Just before and after REM periods, the sleeper typically shifts position. • Stages 3 and 4 NREM, slow-wave sleep usually occur only during the first two 90-minute cycles. As the night progresses, REM sleep episodes become increasingly longer and less time is spent in NREM. • During the last two 90-minute sleep cycles before awakening, NREM sleep is composed primarily of stage 2 sleep and periods of REM sleep can last as long as 40 minutes.
Disrupting thesleep-wake cycle • As with many other physiological processes, sleep islinked to a 24-hour circadian rhythm and affected by signalssuch as light and dark. The effects of disrupting thesleep-wake cycle can be seen in jet lag, which is characterizedby fatigue, irritability, lack of alertness, andsleeping problems. • A person affected by jet lag feels likesleeping at the wrong times of day. It has been found thatthe body maintains a circadian sleep-wake rhythm evenin the absence of external cues like lightness and darkness,although research subjects deprived of such cueseventually adopt a 25-hour “day.” • The “internal clock”that maintains this pattern is a section of the brain calledthe supra chiasmatic nucleus (SCN), located in the hypothalamus.
Disorders interfering with sleep • Various disorders interfere with sleep. The mostcommon is insomnia, the inability to fall asleep or stayasleep. Nearly one-third of all Americans are affectedby some degree of insomnia. Often associated withmental distress, insomnia is treated with medication,psychotherapy, relaxation techniques, or a combinationof these methods. • The medications most commonly prescribedare benzodiazepines (Valium, Halcyon, Restoril)and barbiturates. While they alleviate insomnia in theshort run, these drugs interfere with normal sleep patterns,and can lead to increased tolerance and dependence. • Researchers and clinicians have had successtreating insomnia with the hormone melatonin, a naturallyoccurring substance related to sleep onset and secretedby the pineal gland.
Sleep disorders • Narcolepsy, a disorder characterized by sudden anduncontrollable occurrences of sleep, afflicts 100,000people in the United States. This condition is geneticallylinked, and may be curable in the future. Individuals affectedby narcolepsy abruptly enter REM sleep statesduring the daytime, collapsing and remaining immobilefor a period of time after awakening. Napping and stimulantshave both been used to treat this condition. • Anotherdisorder associated with sleep is sudden infant deathsyndrome (SIDS), in which a healthy baby stops breathingduring sleep, fails to awaken, and suffocates. Whilethe exact cause of SIDS is unknown, researchers are attemptingto identify and save at-risk infants by studyingthe relationship between the disorder and sleeping patterns. • In sleep apnea, a person repeatedly stops breathingwhile asleep but awakes each time. The disrupted sleepthat results from these multiple awakenings leaves thesleeper fatigued and sleepy during the daytime. • Nightterrors are non-REM dream experiences from which thesleeper never fully awakes and which he or she does notrecall upon awakening. This condition mostly occurs inchildren and can be treated with hypnosis or medicationin severe cases.
Chronicsleep problems • An estimated 15 percent of Americans have chronicsleep problems, while about 10 percent have occasionaltrouble sleeping. • Sleep disorders are listed among theclinical syndromes in Axis I of the American PsychiatricAssociation’s Diagnostic and Statistical Manual of MentalDisorders. • They may be either primary (unrelated toany other disorder, medical or psychological) or secondary(the result of physical illness, psychological disorderssuch as depression, drug or alcohol use, stress, orlifestyle factors, such as jet lag).
Sleep deprivation • Sleep deprivation appears to be a precipitating factor for seizures in some people with epilepsy. The reason why this should be so is unclear. It may be due to neurochemical or hormonal changes or it is possible that the normal increase in protein synthesis that occurs in sleep may be impeded, thereby diminishing cellular repair mechanisms and rendering brain cells more open to epileptic activity. However, sleep deprivation may also be used by doctors to activate EEG abnormalities in patients when a diagnosis of epilepsy is unclear. • In conclusion, people whose seizures are triggered by changes in sleep patterns should be advised to maintain reasonably regular hours of retiring and awakening, to obtain sufficient sleep, and to avoid shift work or other causes of disrupted sleep-waking rhythms. There is not need to exceed average hours of sleep to reduce the chances of seizures occurring.
Hypnosis • Certain waking states, which are accompanied bymarked changes in mental processes, are consideredstates of altered consciousness. One of these is hypnosis,a highly responsive state induced by a hypnotist throughthe use of special techniques. While the term “hypnosis”comes from the Greek word for sleep (hypnos), hypnotizedpeople are not really asleep. Their condition resemblessleep in that they are relaxed and out of touch withordinary environmental demands, but their minds remainactive and conscious. • Other characteristics of hypnosisinclude lack of initiative, selective redistribution of attention,enhanced ability to fantasize, reduced realitytesting, and increased suggestibility. Also, hypnosis isoften followed by post-hypnotic amnesia, in which theperson is unable to remember what happened during thehypnotic session. • Hypnosis has proven useful in preventingor controlling various types of pain, including painfrom dental work, childbirth, burns, arthritis, nerve damage,and migraine headaches.
Degrees of hypnosis • There are three degrees of hypnosis. Under lighthypnosis, the subject becomes sleepy and follows simpledirections; under deep hypnosis, the person experiencesdulling of sensory perception, similar to that of anesthesia. • Under deep hypnosis, the subject can move about,open his or her eyes, and can even undergo medical procedureswith no additional anesthetic. Magicians and illusionistsuse deep hypnosis to make a subject behave inunusual ways, such as to suspend the subject’s body betweentwo chairs in a posture that is completely stiff. Themagician suggests that the subject’s body become stiffand rigid, and the result is muscle tension powerfulenough to support the body completely. • Many researcherscontend that the key factor in hypnosis is thesubject’s willingness to cooperate with the hypnotist,combined with the subject’s belief that hypnosis works.People who are easily hypnotized are described as “suggestible”;in fact, if the subject expects to be successfullyhypnotized, it is much more likely that he or she will.
Hypnotic induction • Hypnotic induction is the process by which hypnosisis accomplished. In most situations, an individual performsthe induction on a willing subject. Classical hypnoticinduction involves a series of steps. • First, sensoryinput to the subject is restricted, and the subject is instructedto stop moving. Second, the subject’s focus ofattention is narrowed. This may be accomplished by askinghim or her to focus on a specific point of light or aspot on the wall. • Finally, the hypnotist begins a pattern ofmonotonous repetition.
Employ hypnosis • Doctors also employ hypnosis as a method of painmanagement for chronic headaches, backaches, severeburns, and during childbirth. In cancer treatment, hypnosisis used to control the side effects of chemotherapy and as aself-healing adjunct to chemotherapy. • Hypnosis is alsoused for autoimmune diseases, sleep disorders, and skinailments, including warts and rashes. Some surgeons usehypnosis in the operating room, not only to reduce theamount of anesthesia patients need, but also to lessen anxietyand postoperative swelling and bleeding. • A patient inan hypnotic trance can remain immobile for extended periodsof time, avoiding aggravation of the injury. • Victimsunder a state of shock are also more responsive to hypnoticinduction. Dentists use hypnosis to complete dental workon a relaxed patient without the need for anesthesia.
Professional organizations • A number of professional organizations offer trainingand advanced training in hypnosis. • Among these arethe American Society of Clinical Hypnosis, the AmericanBoard of Medical Hypnosis, the American Board ofPsychological Hypnosis, the American Board of Hypnosisin Dentistry and the American Hypnosis Board forClinical Social Work. The American Psychiatric Association,the American Psychological Association, andthe American Dental Association have all endorsed thetechnique. • Mental health professionals have used hypnosisto treat sexual dysfunction, eating disorders, smokingand other addictions, enuresis and thumb-sucking.
Meditation • In meditation, an altered state of consciousness isachieved by performing certain rituals and exercises.Typical characteristics of the meditative state include intensifiedperception, an altered sense of time, decreaseddistraction from external stimuli, and a sense that the experienceis pleasurable and rewarding. • While meditationis traditionally associated with Zen Buddhism, a secularform called Transcendental Meditation (TM) has beenwidely used in the United States for purposes of relaxation.It has been found that during this type of meditation,people consume less oxygen, eliminate less carbondioxide, and breathe more slowly than when they are inan ordinary resting state.
