psych 250 exam 3 master list

stimulus

physical event that triggers sensory response

sensory receptor organ

organs specialized to detect certain stimuli

receptor cell

specialized cell within an organ that converts stimuli into an electrical signal

labeled lines

each sensory receptor and its pathway to the brain is “labeled” for a specific type of stimulus and location (the brain knows what kind os sensation you’re experiencing based on which neural pathway is activated, not just the signal itself)

sensory transduction

the process by which a sensory receptor converts a physical or chemical stimulus into an electrical signal (a change in membrane potential) that the NS can interpret

Receptor cells act as

transducers - convert energy from one form to another

receptor (generator) potentials

local changes in resting membrane potential

sequence of events in sensory transduction for the pacinian corpuscle

1. mechanical stimulus applied (pressure or vibration)

2. capsule deformation - the layered structure of the pacinian corpuscle compresses

3. membrane of the sensory neuron is stretched

4. mechanically gated ion channels open

5. Na+ ions enter the neuron —→ creates a receptor (generator) potential

6. if threshold is reached, an action potential is generated in the axon

7. action potentials travel to the CNS where the sensation is interpreted as pressure/vibration

what is the pacinian corpuscle

a specialized mechanoreceptor ion the skin that detects deep pressure and high-frequency vibration

• deep ion the dermis

• onion like layers of connective tissue surrounding a nerve ending

• response

  • rapidly adapting - respond mainly to changes in pressure or vibration, not constant pressure

• converts mechanical deformation into an electrical signal (sensory transduction) sent to the CNS

• basically a vibration and deep pressure sensor that signals quick changes to the NS

adequate stimulus

a type of stimulus for which a given sensory organ is particularly adapted

• each receptor type responds best to one kind of stimulus

  • photoreceptors (rods/cones) —→ light

  • hair cells (auditory) ——> mechanical vibration

  • pacinian corpuscles —→ pressure/vibration

6 aspects of sensory processing

1. coding - how sensory systems represent information about a stimulus, such as its type, intensity, location, or duration

   1. stronger pressure, higher firing rate of a receptor

2. adaptation - the decrease in receptor response when a stimulus is constant. prevents sensory overload and allows the NS to focus on changes or new stimuli

   1. phasic receptors - rapidly adapt (detect changes)

   2. tonic receptors - slowly adapt (monitor continuous stimuli)

3. suppression - when the NS reduces or filters sensory signals, often to prevent overload or ignore irrelevant information

4. pathways - the neural routes sensory information takes from receptors to the brain

   1. various pathways for different types of stimuyli

5. receptive fields - the specific area or set of stimuli that a sensory neuron responds to

   1. a single touch neuron in the skin responds to a patch of skin

6. attention - the brains ability to selectively focus on certain sensory inputs while. ignoring others, enhancing perception of important stimuli

1/6 aspect of sensory processing - coding

how sensory systems represent information about a stimulus, such as its type, intensity, location, or duration

2/6 aspect of sensory processing - adaptation

the decrease in receptor response when a stimulus is constant - prevents sensory overload and allows the NS to focus on changes or new stimuli

1. phasic receptors - rapidly adapt (detect changes)

2. tonic receptors- slowly adapt (monitor continuous stimuli)

3/6 aspect of sensory processing - suppression

when the NS reduces or filters sensory signals, often to prevent overload or ignore irrelevant information

4/6 aspect of sensory processing - pathways

the neural routes sensory information takes from receptors to the brain

1. various pathways for different types of stimuli

5/6 aspect of sensory processing - receptive fields

the specific area or set of stimuli that a sensory neuron responds to

1. a single touch neuron in the skin responds to a patch of skin

6/6 aspect of sensory processing - attention

the brains ability to selectively focus on certain sensory inputs while ignoring others, enhancing perception of important stimuli

1. involves prefrontal cortex (what to focus on)

2. and posterior parietal cortex (where to focus)

6 sensory processing aspects summary

1. coding - how info is represented

2. adaptation - response change

3. suppression - filtering

4. pathways - routes

5. receptive fields - sensory “Area”

6. attention - focus

1/6 sensory processing aspects simple terms - coding

how info is represented

2/6 sensory processing aspects simple terms - adaptation

response change

3/6 sensory processing aspects simple terms - suppression

filtering

4/6 sensory processing aspects simple terms - pathways

routes

5/6 sensory processing aspects simple terms - receptive fields

sensory “area”

6/6 sensory processing aspects simple terms - attention

selective focus

tonic receptor

which receptor is

• slow adapting

• fire continuously as long as the stimulus is present

• provide info about duration and intensity

• pain receptors

phasic receptors

which receptor is

• rapidly adapting

• fires briefly at the beginning and sometimes end of a stimulus

• quickly adapts and stops responding if the stimulus stays constant

• pacinian corpuscle

4 types of tactile receptors

1. messier corpuscle

2. merkel disc

3. pacinian corpuscle

4. Ruffini ending

what is a tactile receptor

a nerve ending that converts physical contact with your skin into electrical signals your brain can understand

4 types of tactile receptors extended version

1. messier corpuscle

   1. detect light touch and low-frequency vibration

   2. rapidly adapting (phasic)

   3. found in areas like fingertips

2. merkel disc

   1. detect pressure, texture, and shape

   2. slowly adapting (tonic)

   3. important for fine detail (reading braille)

3. pacinian corpuscle

   1. detect deep pressure and high frequency vibration

   2. rapidly adapting (phasic)

4. Ruffini ending

   1. detect skin stretch and sustained pressure

   2. slowly adapting (tonic)

basically

1. messier - light touch

2. merkel - detail/texture

3. pacinian - vibration

4. Ruffini - stretch

messier corpuscle

type of tactile receptor -

• detect light touch and low frequency vibration

• rapidly adapting (phasic)

• found in areas like fingertips

merkel disc

type of tactile receptor -

1. detect pressure, texture, and shape

2. slowly adapting (tonic)

3. important for fine detail

pacinian corpuscle

type of tactile receptor -

• detect deep pressure and high-frequency vibration

• rapidly adapting (phasic)

Ruffini ending

type of tactile receptor -

• detect skin stretch and sustained pressure

• slowly adapting (tonic)

primary somatosensory cortex (S1)

S1 or S2?

first-stop for touch (raw data). direct input from thalamus, initial processing of tactile information

secondary somatosensory cortex (S2)

S1 or S2?

higher-level interpretation (what the touch means). input from other S and some thalamic area. higher order processing

two brain regions involved in attention

posterior parietal cortex

Cingulate cortex

synesthesia

a stimulus in one modality creates a sensation in another (seeing colors when hearing music, tasting words)

layers of skin

• epidermis - outermost layer; thinnest

• dermis - middle layer; nerve fibers

• hypodermis - innermost layer; anchors muscles, helps shape body

epidermis

outermost and thinnest layer of skin

dermis

middle layer of skin; nerve fibers

hypodermis

innermost layer of skin anchors muscles, helps shape body

somatosensory stimuli/receptor organ/receptor cell/brain pathway

• stimuli —→

• receptor organ (skin, muscles, joints, tendons) —→

• receptor cell ——→

• brain pathway

  • (receptors —→

  • dorsal root ganglion (spinal nerve) ——→

  • ascend via dorsal column-medial lemniscal pathway (fine touch, vibration) or spinothalamic (ventral) tract (pain, temp) ——>

  • thalamus (ventral posterior nuclei) ——>

  • primary somatosensory cortex (s1) ——>

  • secondary somatosensory cortex (S2) for higher order processing

external ear

• pinna, ear canal —→ collect sound

• sound waves hit the tympanic membrane (eardrum) —→ vibration

middle ear

contains two protective muscles

• tensor tympani and stapedius

• when activated —→ stiffen ossicles —→ reduce sound transmission

• protects inner ear from loud sounds

• (ossicles: malleus, incus, stapes) ——> amplify vibration and concentrates vibrations onto the oval window

inner ear (receptor organ)

• the true receptor organ is the cochlea

• within it, the organ contains the hair cells (receptor cells). they concert mechanical vibration into neural signals

• cochlea structure

  • scala vestiboli (vestibular canal)

  • scala media (middle canal) —→ contains organ of cortisol

  • scala tympani (tympanic canal)

two structures in external ear that collect sound

pinna, ear canal

eardrum

tympanic membrane

two protecting muscles in middle ear

tensor tympani, stapedius

what happens when tensor tympani and stapedius stiffen

reduce sound transmission, protects inner ear from loud sounds

receptor organ in inner ear

cochlea

cells that collect auditory info

hair cells

cochlea structure

• scala vestiboli (vestibular canal)

• scala media (middle canal) ——> contains organ of corti

• scala tympani (tympanic canal)

functions of the 3 bones in the middle ear (ossicles)

ossicles - work together to transmit and amplify sound vibrations from the eardrum to the inner ear

• malleus - attached to the tympanic membrane (eardrum); receives vibrations from the eardrum and passes them to the incus

• incus - the middle ossicle; connects the malleus to the stapes and acts as a lever to transmit vibrations efficiently

• stapes - the smallest bone; connects to the oval window of the cochlea; transits vibrations into the fluid of the inner ear, amplifying sound for detection by hair cells

ossicles

3 bones that work together to transmit and amplify sound vibrations from the eardrum to the inner ear

malleus

(bone in inner ear)

attached to the tympanic membrane; receives vibrations from the eardrum and passes them to the incus

incus

(bone in inner ear)

the middle ossicle; connects the malleus to the stapes and acts as a lever to transmit vibrations efficiently

stapes

(bone in inner ear)

the smallest bone; connects to the oval window of the cochlea; transmits vibrations into the fluid of the inner ear, amplifying sound for detection by hair cells.

scala media (part of cochlea) contains

• organ of corti - receptor system that converts vibration into neural activity

• basilar membrane

  • separates scala media and tympani

  • vibrates in réponse to sound

  • hair cells are embedded

  • tip links - thin fibers that connect hair cell stereocelia

• vibration —→ stereo cilia sway —→ tip links move —→ opens ion channels they’re attached to ——> K+ and Ca2+ enter stereo cilia ——→ depolarization, opened Ca2+ channel at cell base —→ neurotransmitters release

organ of corti (part of scala media, which is part of cochlea)

receptor system that converts vibration into neural activity

basilar membrane

• separates scala media and tympani

• vibrates in response to sound

• hair cells are embedded

• tip links - thin fibers that connect hair cell stereocelia

tip links

thin fibers that connect hair cell stereocelia.

auditory system - pathway to brain

• stimulus

• receptor organ

• receptor cell

• brain pathway

  • sound —→ tympanic membrane vibrates —> ossicles (malleus, incus, stapes) amplify

  • stapes pushes on oval window —> fluid movement in cochlea

  • hair cells transduce movement into neural signals

  • signals travel via auditory nerve —→ brainstem (cochlear nuclei) —>

  • superior olivary complex (sound localization) —→

  • inferior colliculus —→ thalamus ——>

  • primary auditory cortex

parts of eye

• cornea - round, transparent front of the eye

• lens - flexible, transparent structure helps focus on an image on the retina

• refraction - bending of light rays by the cornea and lens to form the image on the retina

• fovea - part of the retina where vision is the sharpest

visual receptor organ

eye

cornea

round transparent front of the eye

lens

flexible, transparent structure helps focus on an image on the retina

refraction

bending of light rays by the cornea and lens to form the image on the retina

fovea

part of the retina where vision is the sharpest

photoreceptors

light-detecting cells

rod cells

cells that respond to light of any wavelength, detect lower light level

cone cells

type of cell that responds to different wavelength light, detect color

ganglion cell axons

the fibers of retinal ganglion cells that bundle together to form the optic nerve

retinal circuit

• photoreceptors (rods and cones) —→ detect light and transduce it into electrical signals

• bipolar cells —→ relay signals from photoreceptors

• ganglion cells —→ generate action potentials

output

• axons of ganglion cells form the optic nerve, which carries visual info to the brain

key idea -

photoreceptor —→ bipolar —→ ganglion = flow of visual information out of the retina

photopigments

• light-sensitive molecules in photoreceptors (rods and cones)

• made of opsin and retinal

• absorbs light and starts visual transduction

photopigment = opsin (protein) + retinal (light-reactive part) ——> absorbs light ——> starts vision

retinal

• light-sensitive molecule derived from vitamin A

• changed shape when it absorbs light

• shape change Is what triggers the electrical signal in the photoreceptor

opsin

• a protein that surrounds retinal

• determines which wavelengths of light are absorbed (color sensisitivty in cones)

visual system neural pathway

1. stimuli (light (electromagnetic energy)) ——>

2. receptor organ (eye (specifically retina)) ——>

3. receptor cell (photoreceptors: rods (low light) and cones (color, detail))

4. brain pathway

   1. light —→ cornea —→ pupil —→ lens —→ focused on retina

   2. photoreceptors transduce light ——> signal to bipolar cells —→ ganglion cells

   3. ganglion cell axons form the optic nerve

   4. partial crossing at the optic chasm

   5. —> lateral geniculate nucleus (thalamus)

   6. → primary visual cortex (occipital lobe)

phototransduction (what happens in photoreceptors)

• light enters the eye and hits photoreceptors (rods/cones)

• activates rhodopsin (a photopigment)

• rhodopsin = retinal and opsin

• retinal changes shape when it absorbs light

• triggers a cascade —→ sensory transduction

• leads to hyper polarization of the photoreceptor

what is rhodopsin made of

retinal and opsin

ganglion cells to primary visual cortex

Pathway from ganglion cells to the primary visual cortex

main route for conscious vision

• ganglion cell axons form the optic nerve

  • partial crossing at the optic chasm

  • continue as optic tracts to the lateral geniculate nucleus (thalamus)

  • project via optic radiations to the primary visual cortex (occipital lobe)

the two major visual processing pathways after the primary visual cortex

dorsal stream (where/how pathway)

ventral stream (what pathway)

dorsal stream (where/how pathway)

• path - from visual cortex to parietal lobe

• function - processes motion, location, and spatial relationships

• helps guide actions

• key idea - where is it? how to interact?

ventral stream (what pathway)

• path - from visual cortex to temporal lobe

• function - processes object recognition, shape and color

• helps identify what something is.

• key idea - what is it?

multimodal perception

the brain combines information from multiple senses to form a single, unified, perception.

cross modal phenomenon

one sense influences or alters how another else is perceived.

electrical brain potentials

used to classify levels of arousal, sleep states

3 ways to record sleep

1. electroencephalography (EEG) - records electrical activity in brain

2. electrooculography (EOG) - records eye movements

3. electromyography (EMG) - records muscle activity

electroencephalography (EEG)

records electrical activity in brain

electrooculography (EOG)

records eye movement

electromyography (EMG)

records muscle activity

phases of sleep cycle

• wake - EEG pattern of activity in an awake person contains many frequencies - beta activity of desynchronized EEG

• non-REM - 3 stages, characteristic activity patterns

  • stage 1 - small-amplitude EEG, irregular frequency, lowering heart rate, muscle tension

  • stage 2 - defined by bursts of 14-18 EEG waves - sleep spindles

  • stage 3 slow wave sleep (SWS) - defined by large-amplitude, very slow delta waves

• REM (rapid-eye-movement) sleep

  • EEG activity is like an awake person

  • muscles are relaxed and limp

  • brainstem area inhibits motor neurons

  • characterized by rapid eye movements under closed lids, irregular breathing and pulse rates, vivid dreams.

stage 1 sleep

stage of sleep with small-amplitude EEG, irregular frequency, lowering heart rate, and muscle tension

stage 2 sleep

stage of sleep defined by bursts of 14-18 EEG waves-sleep spindles

state 3 slow wave sleep (SWS)

stage of sleep defined by large-amplitude, very slow delta waves

REM (rapid-eye-movement) sleep

• EEG activity is like an awake person

• muscles are relaxed and limp

• brainstem area inhibits motor neurons

• characterized by rapid eye movements under closed lids, irregular breathing and pulse rates, vivid dreams

Sleep cycles

• 4-5 cycles of sleep stages (90-110 minutes)

• cycles early in the night have more stage 3 SWS

• later cycles have more REM sleep

• the last REM is just before waking up

how do sleep patterns change across the lifespan?

• at puberty - shift in circadian rhythm of sleep —→ get up later in the day

• with age, total time asleep decreases, and number of awakenings increases

• largest decline is the loss of time spent in stage 3

  • at age 60, only half as much time is spent in SWS as age 20

  • at age 90 its gone

vivid dreams in REM

• vivid dreams - REM sleep, visual imagery, sense that dreamer is there

  • predicted if there is rising high-frequency EEG activity in posterior cortex region

  • nightmares - long, frightening dreams awaken the sleeper from REM sleep

  • night terrors - sudden arousals from NREM sleep, marked by fear and autonomic activity

• brain regions most involved

  • amygdala - intense emotions

  • hippocampus - involved in memory and dream content

  • brainstem (especially pons) - generates REM sleep and dreaming activity.

vivid dreams

REM sleep, visual imagery, sense that dreamer is there

• predicted if there is rising high-frequency EEG activity in posterior cortex region