Sense and Perception Exam 5 - Touch and Pain

minimal separation when 2 points aren't known as one when close

2 point threshold

a single meissner corpuscle is innervated by #-# ___ _____ nerve fibers

2-6 RA punctuate

sensitivity to vibrotactile stimulation is best for ___ hz and there is _____ sensitivity for low frequencies

200; more

merkel disks are located in the dermis just below epidermis and are found in groups of __ - __

5-10

information about the movement and position of a limb that derives from receptors that are in the muscles, tendons, and joints of that limb

Kinesthesis

the sense that enables one to feel where one's limbs are

Proprioception

sensitivity to very light touch is mediated by ____ fibers

RA

what type of fibers are messier and pacinian corpuscles innervated by?

RA

when ___ fibers are electrically stimulated, there is a vibration sensation on the skin (window screen)

RA

fibers that respond only when the stimulus is first turned on (probe is first applied), and also give brief strong responses when the stimulus is turned off (probe removed)

RA fibers

when you barely detect probe applied to smooth hairless skin on hand, _____ fibers respond (activation of ___ fibers requires stronger tactile stimulation)

RA; SA

what type of fibers are merkel disks and ruffini endings innervated by?

SA

when ___ fibers are electrically stimulated, there is a sensation of light and a uniform pressure (like a brush)

SA

fibers that respond when the stimulus is turned on (probe first applied) and respond more or less constant if pressure is maintained; fires until stimulus is taken away/turned off

SA fibers

fibers that are good at reproducing spatial detail of braille because they carry primary info for tactual formation and roughness perception

SA punctuate

what type of fibers are merkel disks innervated by?

SA punctuate

____ fibers are constantly firing and ____ fibers adapt quickly

SA; RA

what 2 parts of the body have a dull sensitivity to touch?

back and stomach

letters represented by patterns of tangible dots; a good compromise between size and resolution

braille

some types of receptors are surrounded by specialized ______ filled with gel, and their shape, size, and location determines what kinds of touch stimulation will affect receptors within it

capsules

embossed letters have continuous contours, but braille are made from spatially _____ elements, so they are _____ affected by blurring

coarse; less

perceive surface as having _______ roughness regardless of how inspect it, which implies that info from touch receptors is referenced to info about hand motions

constant

loomis found that localization of a point, so discrimination of relative position, is ground by relative responses in array of receptors, and this is known as what?

cross fiber code

receptors within large oval capsule with long axis parallel to skin surface will have a response to ____ along _____ region of capsule

deformation; large

the lower layer of skin that contains mechanoreceptors

dermis

it is ____ to sense undulations in a medium spatial frequency grating

easy

_____ of skin influences perceived roughness and tactile sensitivity

elasticity

outermost layer of skin

epidermis

when is touch acuity its best? why?

fingers move over object; texture

the 2 point threshold is the lowest for ______ and the highest for ______ of the body

fingers; back

receptors that register degree of skin compression give information about what?

firmness

what mechanoreceptors are involved in pain?

free nerve endings

object identification from texture is ______

good

with larger apertures, visual recognition is _____ than tactile recognition, but they're both ______ with small

greater; poor

what is most often the organ of stimulation with touch?

hand

what 2 body parts have the most detailed tactile info?

hand and fingers

it is _______ to sense undulations in a grating with a low spatial frequency and wide grooves

hard

who had the contact comfort experiment with monkeys? and what does this study?

harlow; touch

an object with many grooves that are close together has a ______ spatial frequency, and undulations _____ apparent

high; arent

mechanical blurring eliminates a stimulus' _____ spatial frequency (____ details), reducing the stimulus to ______ version

high; fine; smeared

what occurs when electrical stimulus directly activates fiber thats signaling specific touch sensation?

illusory sensation

perception of tactile stimulation _____ when visual cues supplement info about tactile probe info

increase

4 types of mechanoreceptors respond to _____ or ______ on the skin

indentation, pressure

what finger has the best acuity?

index

diffuse fibers have ____ RFs with ____ defined boundaries; and have _____ spatial discrimination

large, ill; bad

smoother objects (like glass) have _____ fluctuations in skin displacement at a constant frequency, and irregular objects (like sandpaper) have the opposite

less

soft objects offer _____ resistance, so your skin compresses ____

less; less

callus's cause _____ skin elasticity and _____ perceived roughness by _____ pressure changes in skin produced by surface roughness

less; less; decreased

what body part is the best at tactile grating acuity?

lips

what 2 parts of the body are very sensitive to touch?

lips and fingers

when stimulus applied to skin within area, location touched can be judged accurately

localization ability

what type of cells are RA fibers related to in vision?

magno

what type of cells are diffuse fibers related to in vision?

magno

touch is triggered by ________ of skin produced by physical object contact, but varies depending on physical properties and _____ exploration

mechanical disturbance; tactile

on the human hand, what allow for the exploration of touch?

mechanoreceptors

receptors sensitive to mechanical pressure or deformation of skin; code touch info

mechanoreceptors

acute, high sensitivity areas have densely packed ________ and have a disproportionally large representation in the _________

mechanoreceptors; cerebral cortex

what nerve runs along the top of the arm down to the thumb side of the hand?

median

located in the dermis just below epidermis; long axis perpendicular to skin's surface; each tucked into small papillae that line grooves in skin of palm and fingers

meissner corpuscles

what mechanoreceptor is involved in perceived roughness and are what really give us sensitivity?

merkel disks

what 2 mechanoreceptors are nonencapsulated?

merkel disks and ruffini endings

what are the four types of mechanoreceptors that respond to indentation or pressure on the skin?

merkel disks, ruffini ending, messier corpuscle, pacinian corpuscle

what 2 mechanoreceptors are involved when gripping something?

messier and merkel

what 2 mechanoreceptors are encapsulated?

messier and pacinian corpuscles

if you apply more pressure when you touch your chin, there will be ______ touch sensation

more

is touch a near or far sense?

near

if signals from the hand to the brain aren't sent, what may occur?

numbness

the ability to resolve fine spatial details with fingers depends on _______ of spatial frequency grooves relative to that (blank) of the finger

orientation

what part of the body has the greatest sensitivity to vibrations?

palm

what type of cells are SA fibers related to in vision?

parvo

what type of cells are punctuate fibers related to in vision?

parvo

tactile resolution is the best when grating undulations run ______ to long axis of finger

perpendicular

what is texture determined by?

physical characteristics of object surface

when the skin is cooled, touch sensitivity dulls because the skin is less _____

pliant

if an object has a smooth and round shape, the forces against skin are the same as you move it in your hand, but a sharp and irregular object have abrupt _____ changes against skin

pressure

what are the 2 spatial property fibers?

punctuate and diffuse

the degree of callus varies with the frequency of finger use, so what finger would result in the surface to feel the most rough? why?

ring; use less

the sounds that are produced when you rub a surface give clues about the degree of _______

roughness

mechanoreceptor that is located deeper in the dermis and is elongated parallel to the surface

ruffini ending

places with good touch acuity also have greater of what 2 characteristics?

sensitivity, localization

loomis measured minimal ______ and minimal _______

separation; lateral displacement

what has a large touch receptor surface?

skin

what is the largest organ in the body that protects the organism?

skin

if you gradually move your fingers across a surface, there is a ____ modulation in pressure

slow

what are the 2 temporal property fibers?

slowly and rapidly adapting

punctuate fibers have ____ RFs with ____ defined boundaries; and have ______ sensitivity

small, sharply; uniform

how do shallow grooves feel?

smooth

the ability to discriminate relative location of 2 probes on the skin is better than ________ measured by the 2 point technique

spatial resolution

what are merkel disks activated by?

steady pressure of small object

adjusting the ____ pattern of stimulation applied to single location on immobile fingertips mimics the effect of moving a fingertip across some pattern

temporal

touch fibers are categorized into 4 groups based on ______ & ______ response properties allowing them to respond to different types of stimuli within receptive fields

temporal, spatial

what is the most reliable of the sense modalities?

touch

ability to distinguish a small separation between 2 closely adjacent stimuli applied to skin

touch acuity

meissner corpuscles respond best to ______ stimulation (e.g., something rubbing/moving over skin)

transient

fibers carrying touch information from hands pass signals to spinal chord along what 2 nerves?

ulnar and median

skin _____ frequency give information about an objects smoothness by rubbing your hand across the object

undulation

what sense is touch closely related to?

vision

what can be used to measure tactile sensitivity? which found that short and thick hair yield ______ pressure

von frey hairs; more

if you move your fingers horizontally across the letter O, your fingers are stimulated twice, separated by an interval that reflects the ____ of letter and speed of _____

width; movement

when you squeeze a hard object, it _____ yield to pressure, so your skin ______

won't; compresses