Chapter 5: Sensation and Perception Flashcards
sensation
the act of using our sensory systems to detect environmental stimuli
perception
the conscious recognition and identification of a sensory stimuli
sensory receptor cells
specialized cells that convert a specific form of environmental stimuli into neural impulses
sensory transduction
the process of converting a specific form of environmental stimuli into neural impulses
absolute threshold
the minimal stimulus necessary for detection by an individual
difference threshold/just noticeable difference
the minimal difference between two stimuli necessary for detection of a different between the two
sensory adaption
the process whereby repeated stimulation of a sensory cell leads to a reduced response
olfactory adaptation
occurs when a change in sensitivity to a particular odour reaches a point where the odour cannot be distinguished after a prolonged exposure to it
how can sensory adaption be overcome?
by providing a stronger stimulus
bottom-up processing
perception that proceeds by transducing environmental stimuli into neural impulses that move into successively more complex brain regions
top-down processing
perception processes led by cognitive processes, such as memory or expectations. involves previously acquired knowledge
perceptual set
readiness to interpet a certain stimulus in a certain way AKA “perceptual expectation”
perceptual sets or expectations come into ambiguous stimuli which is:
stimuli that can be interpreted in different ways
perception involves:
bottom-up and top-down processing occurring at the same time
kinesthetic sense
provides info about body’s movement, posture, and position
vestibular sense
provides info about the head’s position and movement in space, stabilizing gaze as well as maintaining balance and posture
proprioceptive feedback
unconscious awareness of the self and spatial orientation arising from stimulation within the body
chemical senses
involve responses to particular chemicals: includes olfactory and gustatory sense
olfactory sense
our sense of smell
gustatory sense
our sense of taste
odorants
airborne chemicals that are detected as odours
olfactory receptor neurons
sensory receptor cells that convert chemical signals from odorants into neural impulses that travel to the brain
odorants bind to specific receptors on:
olfactory receptor neurons in a “lock-and-key” model
continuous binding of certain odorants will result in:
the fatigue of the olfactory receptor neurons, cell will stop responding to odorant until recovered
if a stimulus is continuously present, the only way the olfactory receptor neuron will respond again is if…
the stimulus increases in magnitude
papillae
bumps on the tongue that contain clumps of taste buds
taste buds
clusters of sensory receptor cells that convert chemical signals from food into neural impulses that travel to the brain
what are the five major kinds of taste receptors?
sweet, sour, bitter, salty, umami; all use a slightly different mechanism for transduction of the food chemicals into neural impulses
taste buds are not evenly distributed:
most are located on the top of the tongue
what is capsaicin?
a chemical that activates pain receptors in tongue (associated with spicy foods)
what is special about olfactory and gustatory sensory receptors?
they can regenerate after being burned or harmed
olfactory bulb
the first region were olfactory information reaches the brain on its way from the nose
the brain is able to recognize/detect certain odours because:
cortex is able to recognize patterns of inputs from a variety of olfactory receptors
taste receptor cells don’t have:
axons, they connect directly with sensory neurons in the tongue to send info to the brain-thalamus-then cerebral cortex
all sensory systems have a main pathway through the thalamus except:
olfaction
which part of the cortex is associated with the emotion of disgust?
the insula
many developmental changes are the result of:
learning, and the gustatory system changes from infancy to adulthood (number of taste buds decline)
exposure to particular odours during childhood lessens the:
reaction to those odours in adulthood
functional differences due to :
differences in concentration of taste buds on the tongue
anosmia
inability to smell
ageusia
inability to taste
what is the leading cause of anosmia and ageusia?
head trauma
reflex epilepsy
will experience a seizure only after exposure to a specific odour
tactile
touch
free nerve endings
located mostly near the surface of the skin and detects touch, pressure, pain, and temperature
Meissner’s corpuscles
transduce information about sensitive touch and are found in the hairless regions of the body, such as fingertips, lips, and palms
Merkel’s discs
transduce info about light to moderate pressure on the skin
Ruffini’s end-organs
located deep in the skin. Register heavy pressure and movement of the joints
Pacinian corpuscles
buried deep in the skin and respond to vibrations and heavy pressure
tactile sensory receptors are:
free nerve endings
skin is not equally sensitive to tactile stimuli due to:
different densities of free nerve endings
can tactile sensations experience sensory adaptation?
yes, reduced tactile sensation from depression of the skin that continues for a period of time
touch info is first received in the:
thalamus before being sent to the somatosensory cortex in the parietal lobe
tactile information is processed:
contralaterally
somatosensory cortex does not have:
equal representation of all parts of the body
how does pain travel to the brain?
2 different types of pain fibres: fast pathway and slow pathway
describe the fast pathway of pain:
along myelinated axons, associated with sharp, localized pain, “withdrawal reflex”
describe the slow pathway of pain:
occurs along unmyelinated axons, input to brain regions that are also involved with emotions, associated with burning pain
can pain system be subjected to adaption?
yes unless it is associated with tissue damage or an abnormality in the pain system
after birth, the ability to recognize and respond to different somatosensory stimuli is dependent on:
further brain development as well as learning
describe reaction to tickling:
activation of somatosensory pathways in an uneven, uncontrollable, and unexpected manner
sensory systems are organized to detect change and are most-tuned to:
stimuli that is unexpected and surprising, doesn’t really notice stimuli that is expected
there is a difference in tactile thresholds with:
age (becomes less sensitive to touch with age)
wat plays a role in the sensation and perception of pain?
learning and physical differences
neuroimaging revealed that people’s brains react differently depending on :
their sensitivity to pain
gat control theory of pain
theory suggesting that certain patterns of neural activity can close a “gate” to keep pain information from travelling to parts of the brain where it is perceived
what are two types of opiates that reduce the feeling of pain?
endorphins and enkephalins
what are endorphins and enkephalins?
naturally occurring pain killing chemicals (neurotransmitters) in the brain
endogenous opiates
opiates that naturally present in the nervous system. Released by neurons after intense physical exercise, stress, and sexual experience
based on gate-control theory, touch sensations on fast fibres can help prevent some:
pain sensations travelling on the slow pathways from reaching areas of the brain where they are perceived. this is because the brain only processes so much input and another stimulus can “distract” the brain
pain is important for:
preventing physical damage to the body
familial dysautonomia
genetic condition associated with an inability to detect pain or temperature
familial dysautonomia can be acquired through:
neuropathies or nerve dysfunction
why do phantom limb sensations occur?
abnormal activity in the somatosensory cortex, somatosensory inputs from intact body parts expand to occupy regions on cortex of the “phantom limbs”
