6A: Sensing the environment Flashcards
Sensation
conversion of physical, electromagnetic, auditory, and other info from our internal and external environment to electrical signals in the nervous system
threshold
min amount of a stimulus that renders a difference in perception
absolute threshold
min amount of stimulus energy that is needed to activate a sensory system
Weber’s Law
there is a constant ratio between the change in stimulus magnitude needed needed to produce a jnd (just noticeable difference) and the magnitude of the original stimulus
difference threshold (just noticeable difference, JND)
min difference in magnitude between two stimuli before one can perceive this difference
signal detection theory
changes in perception of the same stimuli depending on both internal (psychological) and external (environmental) context
reponse bias
tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors
adaptation
two parts: physiological (sensory) component - when pupils of the eyes will dilate in the dark and contract in the light, psychological (perception) component - once we have clothes on, we stop feeling the clothes on us
psychophysics
the branch of psychology that deals with the relationships between physical stimuli and mental phenomena
sensory receptors
neurons that respond to the stimuli and trigger electrical signals
sensory pathways
signals from stimuli must pass through specific sensory pathways: different types of receptors, nerve endings or specific sensory cells, receive stimulus, transmit data to CNS through sensory ganglia (collection of neuron cell bodies found outside CNS), once transduced, electrochemical energy is sent along neural pathways to projection areas
photoreceptors
respond to EM waves in visible light: sight
hair cells
respond to movement of fluid in inner ear structures: hearing, rotational, linear acceleration
Nocireceptors
respond to painful or noxious stimuli: somatosensory
thermoreceptors
respond to changes in temp: somatosensory
osmoreceptors
respond to osmolarity of blood: water homeostasis
olfactory receptors
respond to volatile compounds: smell
taste receptors
respond to dissolved compounds: taste
eye
specialized organ used to detect light in the form of photons
sclera
exposed portion of eye is covered by this, thick structural layer (white of the eye); does not cover cornea (front most portion of eye)
choroidal vessels/retinal vessels
supplies nutrients to eyes
retina
innermost layer of eye, contains photoreceptors that transduce light into electric info. considered part of CNS. has two types of photoreceptors: light/dark, color detection
cornea
light passes through here first; clear domelike window in front of eye and it focuses and gathers light
anterior chamber
one division of the front of the eye, lies in front of the iris and posterior chamber
posterior chamber
division of front of eye, in between iris and lens
iris
colored part of eye made up of dilator pupillae (opens pupil during sympathetic stimulation) and constrictor pupillae (constricts pupil during parasympathetic stimulation) continuous with choroid
choroid
makes aqueous humor
ciliary body
part of eye that includes ciliary muscle
aqueous humor
bathes front part of eye before draining into canal of Schlemm
lens
controls refraction of light
ciliary muscle
contraction is under parasympathetic control, when it contracts it pulls on suspensory ligaments and changes shape of lens (accommodation)
vitreous humor
lies behind lends, supports retina, transparent gel
Cones
6 million, used for color vision and fine details. best in bright light. 3 forms: short (blue), medium (green), large (red)
rods
120 mil, functional, allow sensation of light and dark because they contain rhodopsin, low sensitivity to details, permit night vision
macula
center section of retina, high [cones]
fovea
center most point of macula, only cones, best visual acuity
optic disk
blind spot where optic nerve leaves the eye, no photoreceptors
retinal pathway
rods & cones connect with bipolar cells then ganglion cells; amacrine and horizontal cells are before GC’s
bipolar cells
highlight gradients between adjacent rods and cones
ganglion cells (GC)
group together to form optic nerve, more receptors than GC’s, each GC has to represent the combined activity of many rods and cones (lose resolution) # of cones converging
amacrine/horizontal cells
receive input from multiple retinal cells in same area before the info is passed on to ganglion cells; accentual slight differences between visual info in each bipolar cell. important for edge detection, increase perception of contrasts
visual pathways
refer to both physical anatomical connections between eyes and brain and flow of visual info along these connections.
optic chiasm
fibers from nasal half cross paths (carry temporal visual field - further toward side of head from each eye) since temporal fibers (carry nasal visual field) don’t cross, all fibers corresponding the left visual field from both eyes goes to right brain vice versa.
optic tracts
after cross occurs in chiasm, reorganized pathways that leave the chiasm
lateral geniculate nucleus
where info goes after chiasm; of the thalamus
visual cortex
where info goes after chiasm; in occipital lobe, info reaches here through radiations in the temporal and parietal lobes
superior colliculus
where info goes after chiasm; controls responses to visual stimuli and reflexive eye movements
parallel processing
ability to simultaneously analyze and combine info regarding color, shape, and motion
feature detection
process by which pathways contain cells specialized in detection of either color, shape, or motion
parvocellular cells
detect shape, high color spatial resolution (see very fine detail), low temporal resolution (only work with slow moving/still objects)
magnocellular cells
movement, high temporal resolution, low spatial resolution, rich detail lost
ear
three parts: outer, middle, inner
pinna/auricle
sound wave first reaches here, cartilaginous, channels sound waves to tympanic membrane
tympanic membrane (ear drum)
membrane vibrates in phase with incoming sound waves (freq of sound determines rate of vibration: high freq - faster vibration), divide outer ear from middle
intensity
increase amplitude of vibration, louder sounds have greater
middle ear
ossicles here
ossicles
help transmit and amplify vibrations from the tympanic membrane to inner ear
malleus (hammer)
affixed to tympanic membrane, acts on incus (anvil)
incus (anvil)
acts on stapes
stapes
base plate rests in oval window of cochlea, entrance of inner ear
eustachian tube
connects middle ear to nasal cavity, equalizes pressure between middle ear and enviro
inner ear
bony labyrinth: cochlea, vestibule, semicircular canals. structures continuous with each other and form membranous labyrinth
endolymph
fills membranous labyrinth, K rich
perilymph
membraneous labyrinth is suspended in bony labyrinth by thin layer of this. transmits vibrations from outside world and cushions inner ear structures
cochlea
spiral shaped organ divided into 3 parts: scalae, that run the entire length of cochlea, top and bottom have perilymph, tonotopically organized: hair cells vibrating gives brain indication of pitch
middle scala
houses actual hearing apparatus , endolymph
organ of corti
hearing apparatus, rests on basilar membrane, composed of 1000s of hair cells bathed in endolymph
basilar membrane
thin, flexible membrane, base of organ of corti, changes thickness depending on location of cochlea. high freq close to oval window, low freq causes vibration near apex
tectorial membrane
immobile membrane on top of organ of corti
round window
membrane covered hole in the cochlea, permits perilymph to move within cochlea
hair cells of organ of corti
convert physical stimuli into electrical signals which is carried to CNS by auditory (vestibulocochlear) nerve
vestibule
portion of bony labyrinth that contains utricle and saccule - sensitive to linear acceleration, used as a part of balancing apparatus. contains otoliths
otoliths
modified hair cells in utricle and saccule. resist motion. stimulates underlying hair cells
semicircular canals
sensitive to rotational acceleration. arranged perpendicularly to each other and each ends in ampulla
ampulla
swelling at the end of semicircular canals that contain hair cells, when head rotates, endolymph in the semicircular canal resists this motion, stimulates underlying hair cells
auditory pathways
more complex than visual, sound info to vestibulocochlear nerve, to brain stem, to medial geniculate nucleus (MGN) of thalamus then to auditory cortex
superior olive
sound info sent here to localize the sound
inferior colliculus
sound info sent here, involved in the startle reflex and helps keep eyes fixed on point while head is turned (vestibulo-ocular reflex)
hair cells of ear
long tufts of stereocilia on top surface, once basilar membrane vibrates, stereocilia swap back and forth within endolymph - causes opening of ion channels
somatosensation
all modalities of touch
smell
chemical sense, respond to volatile aerosolized compounds
olfactory chemoreceptors (olfactory nerves)
located in olfactory epithelium, upper nasal cavity, chemical stimuli must bind to respective chemoreceptors to cause signal
phermones
secreted by one person or animal, once bonded with CR, compel/urge another to behave in specific way
olfactory pathway
odor molecules inhaled into nasal passages and then contact olfactory nerves in olfactory epithelium, receptor cells activated and send signals to olfactory bulb, then signal relayed via olfactory tract to higher brain regions/limbic region
taste
five basic tastes: sweet, sour, salty, bitter, umami
chemoreceptors of taste
sensitive to dissolved compounds, flavors are triggered by specific molecules binding to receptors, send to taste center in thalamus
taste buds
group of cells that are receptors for taste
papillae
little bumps where taste buds are located on tongue
somatosensation
four modalities: pressure, vibration, pain, temp
Pacinian corpuscles
respond to deep pressure and vibration
Meissner corpuscles
respond to light touch
Merkle discs
respond to deep pressure and texture
Ruffini endings
stretch
free nerve endings
pain and temp
somatosensory cortex
in parietal lobe, where touch info sent in CNS
two point threshold
refers to minimum distance necessary between 2 points of stimulation on the skin such that 2 points felt as two distinct stimuli
physiological zero
temperature judged relative to this, normal temp of skin
gate theory of pain
special gating mechanism that can turn pain signals on or off affecting whether or not we perceive pain
kinesthetic sense (proprioception)
ability to tell where one’s body is in space
perception
refers to processing of info make sense of its significance
bottom up processing
refers to object recognition by parallel processing and feature detection; data driven; brain takes individual sensory stimuli and combines them to make a cohesive image
top down processing
driven by memories and expectations that allow brain to recognize whole object and then recognize components based on these expectations
perceptual organization
ability to use bottom up and top down processing in tandem with all other sensory clues about an object to create complete picture or idea
gestalt principles
using available info in terms of depth, form, motion, and constancy to fill in gaps of info
law of proximity
elements close to one another tend to be perceived as unit
law of similarity
objects that are similar are grouped together
law of good continuation
elements appear to follow in the same pathway are grouped together
subjective contours
perceiving contours, aka shapes that aren’t actually present
law of closure
space is enclosed by contour it tends to be perceived as complete figure
law of pragnanz
gestalt principles governed by this, perceptual organization will always be as regular, simple, and symmetric as possible
