Module 1.5a Sleep: Consciousness

• consciousness is our subjective awareness of ourselves and our environment, allowing us to make sense of our life in sensations, emotions and choices in the present and future

  • we flit between states of consciousness in various normal waking awareness and various altered states (daydreaming, hallucinations, orgasms, starvation, hypnosis, meditation)

• cognitive neuroscience is the interdisciplinary study of the brain activity linked with cognition (thinking, knowing, remembering, communicating)

  • neuroscientists explore and map conscious functions of the cortex, conscious experience resulting from stimulus crossing a threshold for consciousness

• dual processing is the principle that information is often simultaneously processed on separate conscious and unconscious tracks, the conscious being the reflective and the unconscious the intuitive

• blindsight is the condition which people can respond to a visual stimulus without consciously experiencing it

  • visual perception tracks enable us to think about the world and recognize things for future actions

  • visual action tracks guide our moment-to-moment movements

• parallel processing, processing multiple aspects of a stimulus or problem simultaneously, allows us to take care of routine tasks

• sequential processing, processing one aspect of a stimulus or problem at a time, is best for processing new information or solving difficult problems

Module 1.5b Sleep: Sleep Stages and Theories

• sleep is a periodic, natural loss of consciousness, distinct from unconsciousness resulting from a coma, anesthesia, or hibernation - our consciousness fades as the brain’s cortex stops communicating

  • while sleeping, we retain perception of the world around us and process information

• circadian rhythm is our biological clock or our regular bodily rhythms that occur on a 24-hour cycle

  • our body temperature rises and falls during the day, similar with thinking and processing alertness

  • our age and experiences alter our circadian rhythm, with most young adults being night owls with performance improving across the day while older individuals are more morning birds; we gradually shift through aging thanks to our ancestors hunting food

• we go through 90 minutes of sleep stage cycles, one being REM sleep (rapid eye movement sleep) or the recurring sleep stage in which vivid dreams commonly occur, or paradoxical sleep because the muscles are relaxed while the body systems are active

  • alpha waves are waves our brains admits when awake in a relaxed state, eventually slipping into stage 1 sleep during NREM sleep (non-rapid eye movement sleep) which encompasses all sleep stages except for REM sleep

    • stage 1 sleep may be followed by hallucinations or false sensory experiences like seeing something in the absence of an external visual stimulus

    • stage 1 may also be followed by hypnagogic sensations or bizarre experiences such as jerking or falling then floating, while transitioning into sleep

  • stage 2 sleep is characterized by rapid brain-wave activity that aids memory processing for 20 minutes, processing into stage 3 or deep sleep for 30 minutes where your brain emits delta waves (the large slow brain waves associated with deep sleep) hard to awake

    

• instead of continuing in deep sleep, you return to stage 2 before entering into REM sleep, characterized with rapid brain waves where your heart rate rises and breathing becomes rapid and irregular, followed by darting busts of activity of the eye

  • REM starts the dreams, not actually being real, but convincing the brain to respond if they in fact were

  • REM and stage 2 are most of our sleep period, as stage 3 becomes shorter and irrelevant

    

• sleep patterns are not the same and do not depend only on age, newborns sleeping more than adults, rather influenced genetically and sometimes passing on insomnia and circadian rhythms

  • sleep patterns also depend on cultural, social, and economic environments due to school start times, extracurricular activities, bed times, stress, discrimination, and poverty can disturb sleep

• new stimulus play affect in activating light-sensitive retinal proteins, which send signals to the brain’s suprachiasmatic nucleus (SCN) or a pair of cell clusters in the hypothalamus that control circadian rhythm, decreasing melatonin production from the pineal gland in response to light

  • being deprived of light disrupts the 24-hour biological clock and results in desynchronization, more likely to develop fatigue, heart disease, and more

  • young-adults have adapted to a 25-hour biological clock by staying up too late to get 8 hours of sleep from artificial light delays

    • adjusting sleep schedules results in a similar jet lag until the biological clock becomes reset from changing stimuli

• scientists offer six possible reasons that humans sleep

  • sleep protects us from harm’s way, ancestors sleeping after days to fit the ecological niche we play in the environment

  • sleep restores us and gives our body the chance to repair, require, and reorganize; heal from infection, neurons, and can sweep away free radicals that cause Alzehimer’s

  • sleep consolidates memories and rebuilds our memories of the day into the hippocampus and moves them to storage in the cortex, seeing a performance increase after sleep

  • sleep feeds creativity and allow us to solve difficult problems, make connections, and learn

  • sleep grows us and releases hormones from the pituitary gland for muscle development

  • sleep conserves energy and allows us to preserve our energy for awake times

    • sleep stage 2 and REM build neural connections that build memories and muscle memories
      

Module 1.5c Sleep: Sleep Loss, Sleep Disorders, and Dreams

• modern sleep patterns leave us drained and out of sense with our well-being, accumulating sleep debt over the last two weeks: eventually we pay off the sleep debt unhindered until falling back into the normal range feeling more energized and happier

  • students lack sleep and often time get minimal amounts especially with start times leading to deprivation

• tiredness triggers aggression and conflicts, predicts depressive disorders, and often times can predict depression rates among individuals throughout life

  • REM sleep processing of emotion aids against depression and drowsiness, resulting in more sleep, attendance, alertness and better moods

  • sleep loss also messes with hormones and metabolism disrupting and resulting in weight gains:

    • increasing ghrelin; a hunger-arousal hormone that decreases the hunger suppressing hormone leptin

    • increasing cortisol; a stress hormone that stimulates fat production and decreases metabolic rate

    • disrupts gene expression and enhances limbic brain responses to the inability to resist temptation, fatty foods being enticing

• sleep deprivation suppresses immune cells and can make battling viral infections and cancer more of an issue, additionally slowing reaction times and increases issues in the visual attention tasks

  • we sometimes experience microsleep or quick drifts off of consciousness

    

• major sleep disorders can affect individuals and make trying to get sleep an issue

  • insomnia is aggravated by sleeping pills and alcohol causing concentration and memory problems, leading to tolerance

• REM dreams are sequences of vivid images, emotions, and thoughts that pass through a sleeping person’s mind

  • dreams are typically negative emotion associated with failing, attacked, rejected, and misfortune - rarely sexual content

  • dreams often incorporate recent experiences and preoccupations such as trauma (Auschwitz survivors, 9/11), music (musicians report 2x as many music dreams), vision loss (blind individuals uses nonvisual senses but also their vision in dreams), and media experiences (violent media leads to violent dreams, sexual media leads to sexual dreams)

    • our minds intake sensory stimulus around us and incorporate it inside of our dreams

• while dreaming, we do not remember information around us and often fall back asleep

• Sigmund Freud suggests that we sleep to act as a psychic valve; the manifest content (the story line) being a censored version of the latent content (the erotic drives) that would be threatened if expressed (a gun is really a disguised penis)

• scientists have proposed various reasons on why we sleep including:

  • filing away old memories, consolidating our experiences into memory through REM sleep: REM areas become active during sleep that mimic the areas when awake

  • developing and preserving neural pathways, serving as a physiological function to provide the brain with periodic stimulation

  • making sense of neural static, or neural activation from the brainstem in the activation-synthesis theory where dreams are the attempt to synthesize together random neural activity happening; emotional dreams happens from emotion in the limbic system

  • to express cognitive development, overlapping with cognition and speech to simulate reality and engage brain networks to act on top-down control of the dream

• REM rebound is the tendency for REM sleep to increase following REM sleep deprivation

Module 1.6a Sensation: Basic Concepts

• sensation is the process by which our sensory receptors and nervous system receive and represent stimulus energies

  • sensory receptors are sensory nerve endings that detect information and transmit them to the brain

• perception is the process by which our brain organizes and interprets sensory information enabling us to recognize objects and events as meaningful

• our sensory and perceptual processes work together to decipher the world around us

  • bottom-up information processing begins with the sensory receptors and works up to the brain’s integration of sensory information

  • top-down information processing is guided by higher-level mental processes, such as perceptions drawn from experience and expectations

• our sensory systems perform transduction or the conversion of one form of energy into another, transforming physical energy of sights, sounds, and smells into neural impulses (receive sensory, transform to impulses, deliver to our brain)

  • psychophysics study the relation between the physical characteristics of stimuli and their intensity to how we psychologically experience them

• absolute threshold is the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time

  • the signal detection theory predicts how and when we detect the presence of a faint stimulus amid background stimulation; assuming there is no absolute threshold and instead depends on experience, expectations, motivation, and alertness

  • stimuli below absolute threshold for conscious awareness are subliminal

  • priming is the unconscious activation of associations predisposing perception, memory, and response

• difference threshold is the minimum difference between two stimuli required for detection 50 percent of the time

  • Weber’s law dictates that to be perceived as different, two stimuli must differ by a constant minimum percentage

• sensory adaptation is the diminished sensitivity as a consequence of constant stimulation

Module 1.6b Sensation: Vision

• our eyes take in pulses of electromagnetic energy which we perceive as color, ranging from gamma to radio wavelengths

• light travels in waves and the shape of the waves determines what we can see

  • wavelength is the distance from the peak of one light or sound wave to the peak of the next, varying from short gamma waves to long radio transmission pulses

  • the hue is the dimension of color determined by the wavelength of light (colors we know)

  • the intensity is the amount of energy in a light or sound wave which influences what we perceive as brightness or loudness on amplitude

    

• the eye is how we transform physical energy into color, meaning, and depth

  • the cornea, the eye’s clear protective outer layer covering the pupil and iris, lets in light to bend it into focus

  • the light then passes into the pupil, the adjustable opening in the center of the eye which allows light through

    • the pupil opens because of the the ring of muscle tissues that controls the size of the opening, the iris, which also forms eye color

    • the iris constricts and dilates based on cognitive and emotional states alongside the outside stimuli entering it

  • after the pupil, light enters the lens or the transparent structure behind the pupil that changes shape to focus images onto the retina

    • the retina is the light-sensitive back inner surface of the eye which contains receptor rods and cones alongside neurons that process the visual information

    • the retina undergoes accommodation where the lens of the eye changes shapes to focus images of near or far objects onto it

      • myopia - nearsightedness can be fixed with contacts

  • the eye processes the millions of neural energy impulses, which the brain then assembles them into what we perceive

• inside of the retina, photoreceptor cells convert light energy into chemical changes to activate the nearby bipolar cells, activating their neighboring ganglion cells, and then forming the optic nerve or the nerve that carries neural impulses to the brain

  • rods are retinal receptors that detect black, white, and gray that are sensitive to movement allowing us peripheral and twilight vision

    • rods cluster in the retina’s outer regions, pooling faint energy output to a single bipolar cell to relay to the visual cortex

  • cones are retinal receptors that are concentrated near the center and function in daylight or lit conditions, giving us detail and color

    • cones cluster around the fovea or the focal point of the retina, transmitting one message to a single bipolar cell to relay to the visual cortex

      

• our eye’s blind spot is the point where the optic nerve leaves the eye creating a blind spot since no receptor cells are located there

  • our retina also analyzes and encodes sensory information to the occipital lobes after crossing the optic chiasm

    

• color is perception; light waves have no color but our brain creates the experiences of sight

  • the Young-Helmholtz trichromatic theory suggests that the retina contains three different types of color receptors, sensitive to either red, green, or blue, which stimuli can produce in combination the perception of any color

• color-deficient vision results in a lack of functioning of red or green cones, which prompts the question why individuals can still see yellow and purple

  • afterimages and opponent colors resulted in the opponent-process theory that suggests that opposing retinal processes (red-green, blue-yellow, white-black) enable our color vision from tiring the other

• feature detectors are nerves in the brain’s visual cortex that responses to specific features of stimuli, such as shape, angle, and movement

  • feature detectors pass the specific information to supercell clusters in the cortical areas

  • specialized cells in supercell clusters integrate one type of stimulus to fire only when the cues indicate to do so

    • the fusiform face area of the temporal love helps us recognize faces, and reveals that our perception of other objects occur separately in various regions of the brain

• our brains take advantage of parallel processing, or processing multiple aspects of a stimulus or problem simultaneously, to construct the different subdimensions of vision

Module 1.6c Sensation: Hearing

• audition is the sense or act of hearing

• sound waves very in height, amplitude, depends on the perceived loudness

  • frequency is the number of complete wavelengths that pass a point in a given time (Hz)

  • pitch is the tones experienced highness or lowness, depending on frequency
    

    

  • sound intensity is measured in decibels, zero decibels represent the absolute threshold with 60 decibels around the normal conversation

  

• when soundwaves strike your eardrum, the membrane vibrates and triggers nerve impulses to decode as sounds

  • the middle ear is the chamber between the eardrum and the cochlea containing three tiny bones that concentrate the vibrations of the eardrum on the cochlea’s oval window

  • the piston is composed of the hammer, anvil, and stirrup

    • the piston picks up vibrations and transmits them to the cochlea, the coiled bony fluid-filled tube in the inner ear where sound waves travel through cochlear fluid to trigger nerve impulses

    • the inner ear is the innermost part of the ear containing the cochlea, semicircular canals, and vestibular sacs

• the basilar membrane ripples and bends the hair cells with cilia, triggering impulses to the auditory nerve to be carried to the thalamus and auditory cortex

• sensorineural hearing loss is damage to the cochlea’s receptor cells or the auditory nerve, the most common and known as nerve deafness

• conduction hearing loss is damage to the eardrum and bones that conduct sound waves to the cochlea

• a cochlear implant is a device that converts sounds into electrical signals and stimulates the auditory nerve through electrodes threaded into the cochlea

  • hearing has a critical period which allow proficient learning and restoration, leading to less social isolation and depression

    

• loudness is interpreted from the number of activated hair cells, and the loss of sensitivity to soft sounds is the only difference in terms of loudness

  • place theory (place coding) assumes that the pitch we hear is a result of sound waves triggering different areas of the cochlea’s membrane (high frequencies produce large vibrations near the base of the cochlea’s membrane)

  • frequency theory (temporal coding) suggests the rate that nerve impulses travel up the auditory nerve matches the frequency of the tone

    • the two theories create the volley theory, where the two theories work together to create a combined frequency

• our ears allow us to have stereophonic, or 3D hearing based on how fast sound travels into our ears

  • the supersensitive auditory system detects a noticeable difference in the direction of two sound sources based on how intense a sound arrives into your ear (time)

    

Module 1.6d Sensation: Skin, Chemical, and Body Senses and Sensory Interaction

• touch, our tactile sense, is vital in aiding our development and well-being

  • our “sense of touch” is a mixture of sensitivity to pressure, warmth, cold, and pain - all other sensations being variations on our skin activating various receptors and pain spots

  • touch sensation also involves cognition in our brain’s influence of the sensory response, such as a a straight man being caressed by a woman versus a guy

• pain is our body’s way of telling us something is wrong, enhancing our self-awareness and arousing and promoting empathetic social connections

• pain is an approach from bottom-up sensations and top-down cognition, in a biopsychosocial approach

  • nociceptors in the skin, muscles, and organs detect harmful temperatures, pressure, or chemicals

    

  • pain depends partly on genes you inherit and your physical characteristics like gender, the gate-control theory suggesting that the spinal cord contrails a neurological “gate” that blocks pain signals or allows them to pass to the brain, opened by the activity of signals in small nerve fibers and closed by larger fibers or information from the brain

    • chronic pain can therefore be treated with gate-closing stimulation like massage and acupuncture

    • endorphins respond to pain and can either boost the response to pain or disrupt the circuit not bringing pain

• the brain can create pain, such as phantom limb sensations, when it lacks normal sensory input and interprets CNS activity

  • hearing loss similarly creates tinnitus, the phantom ringing in the ears not produced by the vibrating air molecules - vision loss creating phantom sights - taste damage creating phantom tastes and smalls

• the perception of pain depends on the attention we focus on it, and can be altered by the memories of pain based on the pain’s peak moment and amount of pain in the end

• our expectations and culture varies our perception of pain, tending to perceive more pain when others also experience similar pain

• pain control therapies can treat the psychological phenomenon, such as placebos that dampen the CNS’s attention and responses to experiences mimicking painkillers

  • drawing attention away from pain activates brain pathways that inhibit pain and increase tolerance - immersing oneself is an effective distraction

• gustation, our sense of taste, involves sensations of sweet, sour, salty, and bitter - later identifying savory umami, and oleogustus or the taste of fat

  • taste-exposure allows us to develop preference after extensive exposure, since our biology has us programmed to avoid bitter foods

  • sweet detects energy, salty detects sodium, sour detects acid, bitter detects poison, umami detects proteins, and oleogustus detects fats for energy and cell growth

  • the thousands of bumps contain pores that bind to food chemicals and release neurotransmitters to matching cells in our temporal lobes

    • expectations also influence taste of various items

• olfaction is our sense of smell, and is also a chemical sense in the sense molecules of a substance reach receptor cells in the nasal cavity

  • olfactory neurons bypass the thalamus because of biological developments to smell food, and the pheromones (olfactory chemical messages) secreted as sexual attractants

  • odor molecules use different receptors to detect them, slipping into receptors that trigger combinations for the olfactory cortex to process into odors

    • people in relationships learn to recognize their scents and drop stress levels as a result of our learned associations

  • the appeal depends on learned associations, however often times it is harder to describe and recall smells

• our brain is able to recognize odors and associate memories to them, bringing trauma and nostalgia to the limbic and nose areas

• position and motion sensors in muscles tendons, and joins known as proprioceptors provide feedback and enable our sense of kinesthesis, or our movement sense responsible for sensing position and movement of individual body parts

  • our vestibular sense (our balance sense) monitors the head and body’s position and movement, coming from two structures in the inner ear - faster than all other senses

    • semicircular canals filled with fluid and calcium crystal filled vestibular sacs stimulate hair-like receptors that send signals to the cerebellum

• sensory interaction is the principle that one sense can influence another, such as when smell of food influences taste

  • food molecules released by chewing rise into your nasal cavity for example, and influences the smell receptors to perceive our taste of the food

  • vision and hearing interact when light becomes more visible accompanied by a short bust of sound and vice versa - such as closed captions

• the McGurk effect is the phenomenon where we perceive and blend the stimulus we hear and see when talking with people

• the bottom-up sensations and top-down cognitions form our embodied cognition, or the influence of bodily sensations, gestures, and states on our cognitive preferences and judgments

  • sometimes the brain circuits become joined in synesthesia, which stimulates one of the senses triggered by experiencing another (hearing activates color, color activates tastes)