Sleep and Senses

Circadian Rhythm

The natural internal process that regulates the sleep-wake cycle and other biological processes, roughly repeats every 24 hours.

Our biological clock

Sleep Cycle: Stage 1

The lightest sleep stage, where an individual transitions from wakefulness to sleep, lasting only a few minutes.

Sleep Cycle: Stage 2

A period of light sleep where heart rate slows and body temperature drops, preparing for deeper sleep.

Sleep Cycle: Stage 3 (Deep Sleep)

The stage of deep sleep is characterized by slow delta brain waves, where the body undergoes physical restoration and recovery, and is difficult to awaken from.

As you get older, deep sleep significantly decreases

REM

(Rapid Eye Movement) sleep stage, characterized by vivid dreams, increased brain activity, and temporary muscle paralysis.

Saw-toothed brain waves, heart rate rises, rapid breathing, rapid eye movement; REM tricks brain into responding as if the dreams were real

Alpha Waves

The relatively slow brain waves of a relaxed, awake state

Delta Waves

Slow Wave Deep Sleep: The slow waves linked to deep sleep and unconsciousness

EEG

A test that detects electrical activity in the brain, often used to monitor sleep patterns and diagnose sleep disorders.

Sleep Deprivation

A condition resulting from inadequate sleep, leading to cognitive impairment, mood disturbances, and various health issues.

REM Rebound

The phenomenon where increased REM sleep occurs following periods of sleep deprivation.

Hypnagogic Sensations

Vivid, dream-like experiences that occur during the transition from wakefulness to sleep (the feeling of falling, spinning, and jerking)

Theories on Dream - Activation Synthesis

Proposes that dreams are the brain's attempt to make sense of random neural firings during REM sleep

Theories on Dream - Wish Fulfillment (Freud)

Manifest Content: Storyline of the dream

Latent Content: Underlying meaning of the dream

Suprachiasmatic Nucleus (SCN)

Cell clusters that control circadian rhythm in response to light; less melatonin

Each of a pair of small nuclei in the hypothalamus of the brain, above the optic chiasma, is thought to be concerned with the regulation of physiological circadian rhythms.

Theories on Dream - Consolidation Theory

The process by which newly learned, fragile memories are transformed into stable, long-term memories

Sleep Disorders - Insomnia

Sleep disorder characterized by difficulty falling or staying asleep, resulting in poor sleep quality and daytime impairment

Sleep Disorders - Narcolepsy

Chronic sleep disorder characterized by excessive daytime sleepiness (EDS)

Sleep Disorders - REM Sleep Behavior Disorder

Moving/acting out dreams during REM sleep

Sleep Disorders - Somnabulism

Sleep walking during Stage 3 (Deep Sleep)

Sleep Disorders - Sleep Apnea

Frequent, temporary half of breathing for 15-60 seconds while sleeping

Treated with CPAP machine

What are sleep’s functions?

• Protects

• Helps us recuperate

• Helps restore and rebuilt our fading memories of the day’s experiences

• Feeds creative thinking, supports growth

What happens after sleep deprivation?

Cognitive ability was lower (worse on tests), gave higher ratings on rating their effort, concentration and performance than sleep group

What three steps are basic to all our sensory systems?

All of our sense RECIEVE sensory stimulation, TRANSFORM that stimulation into neural impulses, and DELIVER that neural information to our brain

Transduction

Converting one form of energy to another

Psychophysics

Study of relationship between physical characteristics of stimuli and psychological experience of them

Absolute Thresholds

The minimum stimulus energy needed to detect a particular stimulus 50 percent of the time

Smallest amount of something you can detect

Signal Detection Theory

Detection depends on experiences, background noise, expectations, motivation and alertness

Subliminal

Below absolute threshold for conscious awareness

Difference (Just Noticeable Difference) Threshold

The minimum difference between 2 stimuli required for detection 50 percent of the time

Smallest change you can detect; always changing

Weber’s Law

The principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

Difference threshold is a proportion to be original stimulus

Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation; nerve cells fine less frequently

Sometimes with smell, we can’t go back once we adapted but with other senses we can

Sensory Interaction

How our senses interact: vision and taste, touch and taste, vision and hearing - looking at somebody talking

Synesthesia

Abnormal blending of the senses in which the stimulation of one sense simultaneously produces sensation in a difference sense

Sound and vision often blend together

Prosopagnosia

Face-blindness; difficulty in recognizing faces (including one’s own face)

Blind Sight

Conscious visual field is broken, unconscious part still alive → senses movement but cannot consciously know what they are looking at

Cornea

Clear protective layer; first stage that bends light

Pupil

Hole in the eye that lets light in

Lens

Transparent structure behind pupil that changes shape to focus light

Iris

Controls how big the iris is though muscles

Retina

The projector screen in the back of the eye

Blind Spot

Optic Disc: point where the nerves in the eye attach to the optic nerve

Eye moves three times per second

Visual transduction

The process by which light is converted into electrical signals that can be interpreted by the brain as vision

Visual Nerve

Nerve where the retina connects through the thalamus and into the occipital lobe

Accommodation

Adapting recreation of external world

Rods

Sense black, white, and grey, sensitive to movement, peripheral and twilight vision

Cones

Concentrated near the center of the eye, color and fine detail, daylight and well-lit conditions

Nearsightedness (Myopia)

Can see objects close but not far

Farsightedness (Hyperopia)

Can see objects far but not close

Light Adaptation

Pupils constrict to let less light in

Dark adaptation

Pupils dialate to let more light in

Trichromatic Theory

Color vision depends on three types of cone cells in the retina, each sensitive to different wavelengths of light: red, green, and blue

Opponent-Process Theory

Opposing retinal processes enable color vision

Eye has receptors that make antagonistic responses to 3 pairs of colors (red-green, yellow-blue, black-white)

Evidence: after image effect

Fovia

Highest amount of cones in one spot in the eye; the focus spot

Photoreceptor Cells

Path of Retina: Cones & Rods, Bipolar Cells, then Ganglion Cells

Color-Blindness - Dichromatism

Only two of the three types of color-sensitive cone cells in the eye are functional

Color-Blindness - Monochromatism

Rarer condition where the individual can see only black, white, and gray, because either no cones or only one type of cone is present

Afterimage Effect

A visual illusion where you see a faint image after looking away from the original stimulus. This happens because of prolonged stimulation of the eye's photoreceptors, causing temporary fatigue and leading to a lingering perception of the image, or its complementary color

Ganglion Cells

A type of neuron located in the retina, the light-sensitive layer at the back of the eye. They play a crucial role in vision by receiving and transmitting visual information from the photoreceptor cells (rods and cones) to the brain.

Feature Detectors

Nerve cells in the brain’s visual cortex that respond to specific features of stimulus → shape, angle, movement

Pitch

A tone’s experienced highness or lowness; depends on frequency → short wave = high frequency

Loudness (Amplitude)

The height of the sound waves

Pitch Perception

The ability to differentiate pitches from one another

Place Theory

The pitch we hear is linked to where the cochlea is stimulated

Frequency Theory

The rate of nerve impulses traveling up the auditory nerve matches the frequency of the tone, thus enabling us to sense its pitch; how many hairs are hit in the cochlea help us determine the pitch; more are hit, higher pitch

Volley Theory

Nerves fire in a volley to create a higher perceived frequency of more than 1000 waves per second

Sound Localization

The brain’s ability to understand where a sound is coming from due to analyzing its volume; difference between strength of each ear to determine where the sound is coming from → why we have two earsC

Conduction Deafness

Hearing loss caused by damage to mechanical systems that conducts soundwaves to cochlea; no damage to nerves in cochlea

Sensorineural Deafness

Hearing loss caused by damage to cochlea’s receptor cells or auditory nerves; “nerve deafness“

Olfactory Stimuli

Chemical molecules in the air that are detected by the nose and trigger the sense of smell

Olfactory Cilia

Smell receptors; hairs in nasal passage; sends message to forebrain first (not through thalamus); responds differently to different odors

Gustation

The sense of taste, which allows the brain to identify the flavors of food and drink

Types of Taste Buds

Sweet, sour, salty, bitter, umami (savory), oleogustus (fatty)

Supertasters

Heightened sense of taste

Non-Tasters

Someone with lower taste perception, particularly for bitter compounds

Warm and Cold Receptors in Skin

In the skin, warm and cold receptors are specialized nerve endings called thermoreceptors that detect changes in temperature

Pain

Release of Substance P

Gate-Control Theory

How non-painful input can close the neural "gates" in the spinal cord to block pain signals from reaching the brain

Phantom Limb Sensation

The perception of sensations, such as pain, tingling, numbness, or movement, in a limb that has been amputated

Semicircular Canals

Three tiny, fluid-filled tubes in the inner ear that help control balance by detecting rotational movements of the head

Kinesthetic System

Monitors positions of various parts of the body

Receptors in joints & muscles; transmit to brain

Vestibular System

Monitors position of the body in space; provides sense of balance (equilibrium)

Located in semicircular canals of ear

Fast Pathway

Registers localized pain; relays to brain in fraction of a second (pricked finger)

Slow Pathway

Conveys less localized, longer-lasting, aching pain after an injury (lags seconds behind fast pathway)

Pain Dispersed Throughout Body

Head: 21%
Trunk (Torso): 38%
Arms: 13%
Hands: 5%
Upper Legs: 15%
Lower Legs: 8%