perception - exam 5 (final)

life without touch

trouble standing, walking, getting burned; very rare

somatosensory system

touch: pressure, temperature, pain

proprioception: perception of own body; sense of movement and position of limbs

the skin

receptor organ for touch and pain

epidermis

outer layer of the skin

dermis

layer beneath epidermis

mechanoreceptors

receptor cells responding to mechanical stimulation (pressure, stretching, vibration)

4 types of mechanorecpetors

Merkel receptor, Meissner corpuscle, Ruffini cylinder, Pacinian corpuscle

adaption rate

fast adapting and slowly adapting

fast adapting (FA)

fire only at the onset and offset of stimulation; Meissner and Pacinian

proprioception

perception of your own body; sense of movement and position of the limbs

properties of mechanoreceptors

adaptation rate, detail resolution

detail resolution

size of receptive field

merkel receptor

sensitive to fine detail

pacinian receptor

sensitive only to larger grain

primary somatosensory cortex (S1)

receives touch information from the opposite side of the body; each point varies in size

somatotopic map

organization of the primary somatosensory cortex maintaining a representation of the arrangement of the body.

tactile acuity

ability to detect details on the skin

two-point threshold

minimum separation between two points on the skin that when stimulated is perceived as two points

grating acuity

placing a grooved stimulus on the skin and asking the participant to indicate the orientation of the grating

temporary cause of loss of touch sensation

limbs "falling asleep", numbness from cold

permanent cause of loss of touch sensation

damage to brain or spinal cord due to accident or stroke, diseases

phantom limb

when an amputee has the sense that an amputated limb is still attached to their body

two components of pain

responses of pain receptors, cognitive and affective aspects

nociceptors

several types of receptors in skin that are sensitive to extreme heat, cold, pressure, and chemical exposure

gate control theory

the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain

3 input pathways to T cells

S-fibers, L-fibers, central control fibers

S-fibers

carry pain signals from nociceptors

L-fibers

carry info about non-painful tactile simulation

central control fibers

carry signals about cognitive function like expectation, attention, and distraction

Rainville et al. (1997)

manipulated perceived unpleasantness of stimuli (hot water)

Eisenberger et al. (2003)

social pain; participants reporting greater distress → greater activation of ACC

analgesia

inability to feel pain

hyperalgesia

increased sensitivity to pain

haptic perception

the active exploration of the environment by touching and grasping objects with our hands

exploratory procedure

stereotypical hand movement pattern used to contact objects in order to perceive their properties

taste

sensations produced when various substances dissolved in saliva penetrate the taste buds on the tongue and surfaces of the mouth

gustation

technical name for taste

flavor

combination of sensations, including food's taste, smell, temperature, texture, and consistency

5 basic tastes

sweet, sour, salty, bitter, umami

papillae

bumps on tongue

taste buds

cluster of elongated cells in throat, roof of mouth, inside of cheeks (although not inside papillae)

taste receptors

respond to dissolved compounds

microvilli

small threads at end of receptor cell

tongue map

debunked theory of where specifically certain receptors for taste lie on the tongue

specific taste receptors

particular taste receptor cells for particular tastes

tasters

people who can taste PTC

nontasters

people who cannot taste PTC

supertasters

individuals with heightened taste sensitivity

primary taste cortex

identifies and judges intensity of tastes

orbitofrontal cortex

combine with other senses and enables pleasure from food

Rolls (2004)

at first, much neural firing for smell of cream but after eating 50ml, smell produces less firing

Mozel et al. (1969)

smell improved identifying food greatly when tasting it

retronasal olfaction

the perception of odor caused by chewing food in the mouth

specific hungers theory

the idea that deficiency of a given nutrient produces craving for that nutrient

labeled lines theory

each taste fiber carries a particular taste quality

Penfield & Rasmissen (1950)

discovered S1 as somatotopic map; stimulate point on S1 and ask what’s perceived

Singer et al. (2004)

empathetic pain; shock → S1 + ACC, seeing shock → ACC

Melzack & Wall (1965)

gate control system

touch pathway

skin → nerve fibers → spinal cord → ventral posterior nucleus → cortex

anterior cingulate cortex (ACC)

region of the brain associated with perceived unpleasantness of pain sensation

tactile agnosia

inability to identify objects by touch

slow adapting (SA)

fire continuously as long as pressure is applied; Merkel + Ruffini

high acuity

more Merkel receptors + corresponding space in S1