Synesthesia = mixed senses condition
Transduction = sensory receptors translate stimuli into nerve impulses
Feature detectors = neurons that break down and analyze the specific features of the stimuli.
- Reconstructed into neural representation using previous stored data
- Ppl w/ synesthesia have "cross wiring" in their brain, evoking responses in another part of the brain
dedicated to another sensory modality.
-One theory as to the sensory mixing is that the pruning of neural connections that occurs in infancy has not
occured in people with syn
-Another theory is that w/ syn, theres a deficit in neural inhibitory processes in the brain that ordinarily keep
input from one sensory modality from "overwhelming' into other areas. Both normal perceptual processes
and synesthesia relate in neuroscience called the binding problem.
Sensation = stimulus-detection process by which our sense organs respond to and translate environmental
stimuli into nerve impulses that are sent to the brain.
Perception = making "sense" of what our senses tell us, organizing stimuli and giving them meaning.
- Different animals are more sensitive 2 particular stimuli from adaption 2 environment (IE carrier
pigeons/magnetic field and Sharks/electric current)
- There are more senses than the classical five, such as balance, body position, pressure, pain, temperature,
etc. This scientific area is called psychophysics, which studies relations between the physical characteristics of
stimuli and sensory capabilities.
- Absolute Threshold = the lowest intensity at which a stimulus can be detected correctly 50% of the time.
Thus lower it is = greater the sensitivity.
Signal Detection Theory:
- Ppls sensitivity can fluctuate, with no fixed absolute threshold. People set their own decision criterion, a
standard of how certain they must be that a stimulus is present before they will say they detect it. This can
also change from time to time, due to several factors. Signal detection theory is concerned with these factors
that influence sensory judgements.
- Typical SD experiment: participants told a barely perceptible tone may or may not be presented after light,
creating four outcomes. When there is a sound, they can say yes/no creating a hit/miss, and when it is none
they can say yes (false alarm) or no (correct judgement).
-At low stimulus intensities, increasing rewards and costs for hits and misses will affect performance (generally
Difference threshold = the smallest difference between two stimuli that people can perceive 50% of the time.
This is sometimes called the just noticeable difference. Weber's Law states that the difference threshold, or
jnd, is directly proportional to the magnitude of the stimulus with which the comparison is being made, and
can be expressed by the Weber Fraction.
Sensory Adaption = change over time in the responsiveness of the sensory system to a constant stimulus.
Change over time in the responsiveness of the sensory system to a constant stimulus. Sensory Systems
Vision = Normal stimulus for vision is electromagnetic energy, or light waves, which are measured in
The Human Eye
- Light waves enter cornea > pupil (dilates constricts amount of light entering eye) > pupil size controlled by
muscles in coloured iris > lens (becomes thinners to focus on distant object/thicker vice versa) > retina (light
sensitive multi layered tissue) > lens reverse the image in horizontal/vertical direction but brain reconstructs
Myopia = can see near not far, nearsightedness. Eyeball usually longer bc focus infront retina.
Hyperopia = see near not far, farsightedness. Eyeball shorter bc focus behind retina.
- Aging process usually causes eyeball to shorten, which is why middle aged people get reading glasses.
Photoreceptors: The Rods and the Cones:
- The retina is actually an extension of the brain. It contains two light sensitive receptor cells: rods and cones
(due to their shapes.) 120 mill rods and 6 mill cones in each eye.
Rods = function best in dark, black/white receptors. 500x more sensitive than cones, don’t receive colour
Cones = function best in bright light, animals active during day only have cones = bad night vision
- In humans, rods found everywhere except fovea (small area in center of eye w/ only cones. The peripheral of
eye contains mainly rods.
- Msg > Bipolar cells (synaptic connection) > synapse with
ganglion cells (axons connected in bundle to form optic nerve)
> eventually funneled into only 1 traffic lane from retina
- Rods can combine their individual electrical msgs to the
bipolar cell, where the additive effect of the many signals may
be enough to fire it.
-Cones that line in periphery of retina also share bipolar cells,
but the densely packed cones have their own private line to a
single bipolar cell. This results in visual acuity, or ability to see
in fine detail, is greatest when the visual image projects
directly into fovea.
- Dark adaption is progress improvement in brightness sensitivity that occurs over time under conditions of
low light. Photoreceptors deplete during daytime due to light, but will regenerate when in darkness due to
Trichromatic theory = colour vision is based on the activity of three types of receptors, each with a different
peak sensitivity wavelength. Cones particularly sensitive to blue, green and red.
- wasn’t consistent b/c ppl with red-green colour blindness
could see yellow, the by product of those 2 colours. An
afterimage would also occur in diff colour after colour stimulus
was viewed steadily and withdrawn.
Opponent-process theory = proposed that each of the three
cone types responds to a red or green, blue or yellow, and
another to black or white. IE, chem reaction to green stimulus
with an opponent process to create red stimulus. This may
explain the colour afterimage. Activation of one member of the
pair inhibits activity in the other. Dual-process theory combines both to account
for the colour transduction process. Cones
contain 3 diff prtein photopigments, diff ratios of
activity can produce any hue in visible spectrum.
Process occurs in the ganglion cells and the visual
cortex of the brain.
Trichromats = norma vision.
Dichromats = deficiency in red-green or blue-
Monochromats = only black-white.
Analysis and Reconstruction of Visual Scenes
- Nerve impulse from optic nerve > thalamus > primary visual cortex. There is a point to point correspondence
between tiny regions of the retina and neurons of the visual cortex. The fovea is represented by a
disproportionately large area, due to its high visual acuity.
- Some of the neurons are organized to receive and integrate sensory nerve impulses originating in specific
regions of the retina, these are feature detectors. Hubel and Wiesel found that certain neurons fired most
frequently when lines of certain orientations were presented. The discovery of these revolutionized vision
research. IE, one neuron may fire more with a horizontal line, another in a vertical line.
- Other classes of feature detectors respond to colour, depth and movement. These subdivide a visual scene
into component dimensions. IE diff colour balls thrown at you, seperate but overlapping modules
simultaneously analyze its colours shape distance and movement by engaging in parallel processing.
- In the Visual association cortex more complex features of the scene are combined and interpreted in light of
our memories. Thus it leads to us catching the ball, as we recognize what it is. Scientists discovered neurons
selectively respond not just to basic stimuli but to complex stimuli which acquired special meaning. IE. single
neuron responded to images of Bill Clinton.
-Stimuli for our sense of hearing are sound waves, a form of mechanical energy. Sound is just pressure waves,
resulting in vibrations. These sound waves have two characteristics: Frequency and Amplitude.
- Frequency is the number of sound waves, or cycles per second. Hertz is the unit of measurement, with one
cycle per second. Higher frequency = higher perceived pitch.
-Amplitude refers to the vertical size of the sound waves - the amount of compression and expansion of the
molecules in the conducting medium. Amplitude = loudness. Unit of measurement is decibels (db)
Auditory Transduction : Pressure to nerve impulses;
- Sound waves > auditory canal > eardrum (movable membrane vibrating to response of sound wave) > middle
ear (hammer, anvil and stirrup amplifies sound waves 30x) > inner ear containing cochlea, filled with fluid and
contains basilar membrane, a sheet of tissue > resting on membrane is organ of Corti which contains hairs that
are sound receptors > tectorial membrane that overhangs basilar membrane along entire length of cochlea >
hairs synapse send impulse to auditory relay station > thalamus > auditory cortex.
- Sound wave strike ear drum > pressure at oval window > sets fluid in cochlea in motion > fluid result in
vibration in basilar membrane and membrane above it causing hair to bend in organ of Corti > trigger
neurotransmitter w/ hair cells into auditory nerve. Coding of pitch and Loudness
- higher amplitude = more bend in hair = more
neurotransmitter substance = higher rate of firing.
Frequency Theory = nerve impulses match frequency of
sound wave, but problem is no frequency can match above
1000hz so how do we perceive higher frequencies like
-Place Theory of pitch perception = specific point in
cochlea where fluid wave peaks and most strongly bends
the hair cell serving as frequency cue. By analyzing specific
location in cochlea where nerve impulses are being
received, brain can code pitches above 1000hz.
Sound Localization = nervous system uses info concerning time and intensity of sounds arrive at both ears to
locate source of sound in space. Sound in front/behind arrive at same time of ear and same intensity so we
can detect where. Any degree in change will tell us the direction it is. Barn owls can pinpoint localization
during night hunting, right ear upward and left ear downward.
Conduction deafness = problems with mechanical system that transmits waves to cochlea (puncture ear drum,
loss of function in tiny bones) use hearing aid.
Nerve deafness = damaged receptors within inner layer or auditory nerve (aging and disease, exposure to loud
noise, repeated exposure to certain freq can cause loss of hair cells for that frequency on basilar membrane.
Taste and Smell: The chemical Senses
-Gustation and Olfaction (taste and smell respectively) are chem senses cause their receptors are sensitive to
chem molecules rather than energy. They are very intertwined, so enjoying a good meal depends on
simultaneous activity of taste and odour receptors.
- Taste only has four qualities, sweet, sour, salty and bitter. other tastes combines these qualities with other
senses, including touch, temp and smell. Taste buds are chem receptors concentrated along the edges and
back surface of tongue. Each taste bud is responsive to one or two basic taste qualities, and weakly to others.
Umami increase the sensitivity of other taste qualities, caused by certain proteins including MSG. We have
about 9k taste buds consisting of several receptors.
- Olfactory receptors recognize diverse odours individually rather than mixing, have receptor structures similar
to neurotransmitter that fire and send imput to olfactory bulb, a forebrain structure above nasal cavity. Each
oodouros chemical excites only limited portion of bulb, and odors are coded in terms of that specific area.
Pheromones =chem signals in body scents
Menstrual synchrony is the tendency of women who live together or are close friends have similar menstrual
cycles. Experiment: 10 women smell with armpit sweat, and after 3 months they began to coincide.
Skin and Body Senses
- Include touch, kinesthesis, and equilibrium. last two are called body senses as they inform us of position and
movement. Tactile Senses
- pressure, pain, warmth/cold. Conveyed by receptors in skin and internal organs.
- Sometimes the brain locates impossible sensations, known as phantom limb phenomenon (amputees feel
sensations from missing limb).
- Pain receptors are found in all body tissues with the exception of the brain, bones, hair, nails and non=living
parts of the teeth. Free nerve endings in the skin and internal organs respond to intense mechanical, thermal
or chem stimulation and then send nerve impulses into spinal cord, and carry this to the brain.
Spinal and Brain Mechanisms
-Gate control theory = experience of pain results from opening and closing of gating mechanisms in the
nervous system. Events in spinal cord open up the gates and allow nerve impulses to go to the brain. Other
sensory input can partially or fully close gate, ie scratching itch can produce relief.
- Feature of the theory: nerve impulses descending from brain can also influence the spinal gates,
increasing/decreasing pain stimuli. This central control mechanism allows thoughts, emotions and beliefs to
influence feeling pain.
- Research shows that glial cells, which structurally support and service neurons are involved in the creation
and maintenance of pathological pain. Cells activated by immune challenges, and substances by neurones in
pain pathway. They then amplify pain by releasing cytokines that promote inflammation.
- Opiates used for centuries to relieve pain (opium, morphine and heroine) cause they affect the brain pain
pleasure system. These natural opiates are endorphins.
The Body Senses:
Kinesthesis provides us with feedback about our muscles' and joints' position and movements.
Vestibular sense = sense of body orientation and equilibrium. These receptors are in the vestibular apparatus
of the inner ear. Consists of three semicircular canals, filled with fluid, and they only respond to acceleration
and deceleration. The vestibular sacs also contain hair cells responding to the position of the body and tell us
whether we are upright or tilted.
-Experience is not one to one reflection of what is out there, diff people experience different things from the
same raw sensory data. To create perception the brain carries out two diff processing functions. Bottom-up
processing the system takes in individual elements of the stimulus and then combines them into a unified
perception. Your visual system acts in this way (IE look at each letter of word then recombines them). Top-
down processing is when info is interpreted without existing knowledge, concepts and ideas. Top-down
processing is occurring as you interpret the words and sentences constructed by the bottom up process.
Perception is Selective:
- Attention comes two processes of stimuli: focusing on certain ones and filtering out others.
-These processes have been studied through shadowing. Patients use earphones and listen to two messages
simultaneously, one each side. They are asked to repeat one of the messages word for word, but at the cost of
not remembering the other message. We cannot attend completely to more than one thing, but we can switch
back and forth between two. Inattentional Blindness:
- Electircal recording and brain imaging have shown that unattended stimuli register in nervous system but do
not enter into immediate experience. In the visual realm, this has been coined as inattentional blindness, to
refer to failure of unattended stimuli to register in consciousness. We can look right at something without
"seeing" it if we are attending to something else. (IE, first psych class, basketball/gorilla video)
Environmental and Personal Factors in Attention
- Attention is strongly affected both by stimuli and by personal factors, such as intensity novelty movement
contrast and repetition. Sexually oriented stimuli are very attention grabbing. Motives and interests are filters
which influence the stimuli we will notice.
-People are attentive to stimuli that are relevant to their well being. Thus people are quicker to identify an
angry looking face than a smiling face. Baseball players react significantly faster to speeding object toward
their head then if it were to miss their head.
Perceptions have organization and structure
Gestalt Principles of Perceptual Organization
-Early in 20th century psychologists from the german school of Gestalt psych set out to discover ow we
organize the separate parts of perceptual field into a whole. Gestalt means shape/pattern/form. These were
early "champions" of top-down processing.
-They emphasized the importance of figure-ground relations. We perceive borders where there is a distinct
change in the colour or brightness of a visual scene, but interpret these borders as part of the figure. Likewise
music is heard as melody and background noise and harmonies.
-Separating figure from ground can be challenging, yet our perceptual systems are equal to the task. Check
page 173 for diagrams, somewhat helpful.
- Gestalt psychologists are interested in how separate stimuli come to be perceived as parts of larger wholes,
suggesting that people group and interpret stimuli in accordance with four Gestalt Laws: similarity, proximity,
closure and continuity.
- Similarity: parts of a configuration are similar, they belong together.
- Proximity: those objects that are close are together.
- Closure: close the open edges of a figure or fill in gaps to identify form.
- Continuity: Link things together to form line/pattern that makes sense.
Perception Involves Hypothesis Testing
-"Recognizing" stimuli implies that we have a perceptual schema-- a mental representation or image to
compare it with. Schemas contain critical features of objects, events and other phenomena. They allow us to
classify and identify sensory input.
-Someone calls your name. If the stimuli match your inner representation of your friends appearance and
voice closely enough, then you identify the person as your friend. Perception is an attempt to make sense of
stimuli input, to search for the best interpretation of info we can arrive at.
- The perceptual system build up descriptions or hypotheses that best fit the available evidence provided. IE a
picture that may change when right side up and upside down will only be interpreted with right side up photo.
Perception is Influenced by expectations:
- Warship in battle with Iranian gunboats, then fighter plane thought to be Iranian was descending and looked
like it was going to attack. It was shot down and the warship was relieved, though this victory was short lived.
The plane was actually a passenger jet, and it was climbing instead of descending. This incident revealed that
the psychological environment caused the radar operators' eyes to "lie". - It was easy for the operators' observing the plane approaching from a military field to interpret this as a sign
of an air attack. Fear and expectation created a context with the sensory input from the system was
interpreted in a top down process (info interpreted without much existing knowledge etc).
-This perceived "reality" by the operators' is called perceptual set (readiness to perceive stimuli in a particular
way). Believing is seeing.
- Perceptual sets influence our social perceptions as well, demonstrated by Harold Kelly the day he invited a
guest lecturer into his class. Half class was told guest was critcal, determined and a cold person, and the other
half was the same but warm. So half the class rated him bad, the other rated him good, yet it was the same
lecturer, or was it?
Stimuli are Recognizable under Changing conditions: perceptual constancies
- When a closed door swings open, it casts a diff image on our retina, but its still a door. Our perceptual
hypothesis is the same. Perceptual Constancies allow us to recognize familiar stimuli under varying conditions,
otherwise we'd have to rediscover everything under different conditions.
-Shape constancy allows us to recognize people and other objects.
- Brightness constancy is the relative brightness of objects remains the same under diff conditions of light.
- Size constancy is the perception of objects remain semi consant even though images in our retina change in
Perception of Depth, Distance and Movement
- The ability to adapt to a spatial world requires that we make fine distinctions involving distances and
movement of objects. Humans are capable of great precision in such judgements (ie baseball players)
Depth and Distance
- Retina receives info in two dimensions, but translates into three-dimensional perceptions. It does so by using
monocular cues and binocular cues (one eye and both eyes respectively)
Monocular Depth Cues:
-Light and Shadow creates a 3D effect in pictures. Linear Perspective refers to perception that parallel lines
converge or angle toward each other as they recede into distance. Interposition is when objects closer to us
may cut off part of our view of more distant objects. Height on the horizontal plane is another cue (farther
distance = higher on horizontal plane). Texture is the fifth cue, cause texture is finer as distance increases.
Along with this clarity, as nearby objects are more clear. Relative size is another way to judge distance (two
objects are same size, the smaller one is farther away). The final cue is motion parallax, which tells us if we are
moving, nearby objects move faster than far ones.
-3D movies use the principle of binocular disparity, which each eye sees a slightly diff image. Visual input is
analyzed bye feature detectors that are attuned to depth, some only respond to stimuli that are either in front
of or behind the focal point.
-Second cue is convergence, produced by feedback from the muscles that turn your eyes inward to view a
Perception of movement
-Complex process that requires the brain to integrate info from several senses. Primary cue for perceiving
motion of movement of the stimulus across the retina. Illusion of smooth motion can be produced if we
arrange the sequential appearance of multiple stimuli. Max Wertheimer in his studies of stroboscopic
movement, illusionary movement produced with flashing light. This is the principle behind movies, with series of photographs projected onto a screen with dark intervals in between. The rate is important to perceive it as
Illusions: false perceptual hypotheses
-Illusions are compelling but incorrect perceptions. They provide important info about how our perceptual
processes work under normal conditions.
-Distance cues sometimes fool us, and can be manipulated to create other size illusions.
-Our perceptual hypotheses are strongly influenced on context, or surrounding of what causes the stimuli.
Monocular depth cues which are manipulated to produce a figure or scene whose individual parts make sense,
but overall organization is impossible. IE never ending staircase.
Experiences, Critical Periods and Perceptual Development
- By the time they are old enough to crawl, children placed on a visual cliff formed by glass-covered table that
suddenly dropped off will not venture over the glass.
-Story of a Bambuti pygmy named Kenge, who misinterpreted buffalo as insects due to their far distant. Their
culture only lives in densely packed trees, so they never needed to judge size at great distances, as there was
not much open space.
- When light passes thru lens, it is reverse up/down left/right, but if you wore glasses that undid this reversal
what would happen? George Stratton did just that, and had a right side up image on his retina. Gradually he
adapted, and after 8 days he was able to walk and reach for objects.
Cross Cultural Research on Perception
- The culture one grows up in helps determine the kinds of perceptual learning experiences people have. Cross
Cultural research helps identify perceptions in all people regardless of cultures, as well as differences caused
by cultures. More similarities than differences. Some cultures may not have experiences with three
dimensional perceptions in photos, unable to use monocular cues that Westerners may use for the same
photo. All five basic senses are affecting by culture.
States of Consciousness
- States of Consciousness, a pattern of subjective exp, a way of experiencing in/external events. Altered state
of consciousness, altered variations from our normal waking state.
Puzzle of Consciousness
- Consciousness : our moment-to-moment awareness of ourselves/environment. It is intimately connected
with process of selective attention.
-subjective and private. other ppl cannot know what reality is for you, nor other way round.
-dynamic : drift in and out of states throughout each day, exp consciousness as "stream" of mental activity.
- self-reflective and central to our sense of self : aware of its own consciousness, and reflect on "you"
-most common is self report, where ppl describe exp. they offer most direct insight, but are not verifiable.
Physiological measure extablish correspondence btwn bodily states and mental procces. IE EEG recordings.
Behavioural measures are also used, including doing tasks such as the rouge test. Levels of Consciousness: psychodynamic/cognitive perspectives
- Sigmund Freud proposed 3 levels of awareness: conscious mind contains thought/perceptions and current
mental events. Preconscious mind mental events occur outside current awareness, ie not thought about
childhood friend for years, someone brings him up and you remember good times. Unconscious mind is sexual
desire, unacceptable urges, aggression and traumatic events, cannot be brought into conscious mind normally.
Kept out to control arousal, anxiety, guilt, suffering, etc. only good for a broad model, as it was criticized and
Controlled vs automatic processing
- Voluntary use of attention and conscious effort is controlled processing, and those with no conscious effort
is automatic processing. Automatic processing occurs when we carry out routine/well learned tasks. Learning
however is controlled processing. Automatic processing reduces our chances of finding new solutions for
problems, but offers speed and economy of effort.
- Automatic processing controls divided attention, the ability to perform multiple tasks simultaneously.
Without this we could only focus on one thing, but it has limits and gets more difficult when tasks require
similar mental resources. IE shadowing experiment from last chapter.
- Can lead to negative consequences, ie driving while calling/texting (chapter 2 cause and effect lesson)
- Some modern psychodynamic views incorporate info-processing concepts strongly emphasize
emotional/motivational processes operate unconsciously and influence behaviour. IE Chartrand and Bargh
subliminally presented students with nouns that were positive or negative, and after rated their moods.
- Mind is a collection of largely separate but interacting modules. These modules act as networks within brain,
and perform tasks related to sensation, perception, memory, problem solving, emotion, motor behaviour, etc.
They process info in parallel.
Keeping Time: Brain / Environment
-Circadian Rhythms are daily bio cycle, regulated by suprachiamatic nuclei (SCN) located in hypothalamus,
confirmed by Martin Ralph. He transplanted normal healthy SCN into animals w/ destory SCN, and restored
their circadian rhythm. These neurons genetically act as a "biological clock," as they link to melatonin, a
hormone that has relaxing effect on the body. SCN is active during day, and reduces melatonin's release from
pineal gland raising body temp and heightening alertness, and at night SCN is inactive which allow melatonin
levels to increase.
- Our clock is biological, but environment affects it, ie day night cycle help keep SCN on 24 hour clock. After
sleep light increases SCN to help reset the clock. If kept in constant dark w/o clocks, people drift into longer
natural cycle called free running circadian rhythm. SCN neurons exhibit this longer cycle even when surgically
removed and kept alive in dishes. Because of free running cycle, they sleep and wake up later each day. They
may not realize they sleep for 12 hours, even during middle of the day.
Early birds/night owls
-Circadian rhythms influence us to be a night or morning person, studies showing older adults are morning
people with 18-30 age group being night people generally. Morning people learn and do tasks better in
morning than night people, and opposite is true for the same tasks done in evening. Environmental Disruptions of Circadian Rhythms
-Seasonal affective disorder (SAD) is cyclic tendency to become depressed during certain months of the year.
Symptoms begin fall/winter, due to shorter periods of daylight, but then lift during spring. Many believe circ
rhythm of SAD may be sensitve to light, so their "onset" time of clocks may be pushed back to unusual degree.
-Jet lag is a sudden circadian disruption caused by flying across several timezones. Flying east = losing hours,
west = more than 24 hours. Symptoms include insomnia, decreased alertness and poorer performance.
Concern for business ppl, athletes, airline crew etc
-Most problematic disruption is caused by night shiftwork, as adjusted to inverted day-night can be difficult.
Solution may be when work sifts change, it is easier to extend waking day then to compress. this is called
Sleep and Dreaming
- Circadian rhythms do not regulate sleep, rather promote readiness to sleep and help determine optimal
period when we can sleep most soundly.
-There are different stages of sleep, in every 90 mins of sleep we cycle through dif stages in which our brain
activity change in a predictable way. When awake we produce beta waves in EEG recordings, and when
feeling relax or drowsy we produce alpha waves. Beta waves have higher frequency.
- As sleep begins, the brainwave pattern becomes theta waves. This is stage 1, form of light sleep you can
easily be awakened from.
-As sleep becomes deeper, sleep spindles, periodic bursts of rapid brainwave activity being to appear, muscles
relax more, breathing and heart rate slow down and its harder to awaken. This is stage 2.
- Stage 3 is marked by appearance of delta waves, which are much slower brainwave patterns. When these
delta waves dominate EEG recording, then Stage 4 has been reached. These two are called slow-1wave sleep,
with brain activity decreased, body is relaxed and its hard to wake up. After 20-30 mins of stage 4 it goes back
to stage 3 and 2.
- There is one stage unlike the rest, called REM sleep, due to rapid eye movements. In REM sleep, those who
are awaken from it always report dreams. During this stage, physiological arousal may increase to daytime
levels, breathing is rapid and irregular, HR increases, brain wave activity is much like an awaken person.
-Brain sends signals making it more difficult for voluntary muscles to contract, therefore become essentially
"paralyzed." This state is called REM sleep paralysis, sometimes called paradoxical sleep. We can dream in
REM or non-REM sleep, but REM dreams are more story like with a perception of reality.
Getting a Night's Sleep
-Brain does not contain a "sleep centre." Sleep is controlled by different brain mechanisms, and it is not just a
matter of turning off certain brain systems.
-Areas of the forebrain and within the brain stem are particularly important in regulating our falling asleep.
Where the reticular formation passes through pons also plays a key role in REM sleep, containing neurons that
initiate the stage, while also activating the other brain systems required for REM sleep.
-Environment affects sleep, ie change of seasons, fall/winter people get 15-60 more mins of sleep.
How much do we sleep? -As we age, we sleep less, REM sleep remains relatively stable after early childhood, and time spent in s