Mechanisms of Perception Flashcards
Primary sensory cortex
input mainly from thalamic relay nuclei
-lowest level of processing
Secondary sensory cortex
input mainly from primary and secondary cortex
Association sensory cortex
input from more than one sensory system, usually secondary
Disruption of lower levels of the cortex lead to loss of _______
sense perception
Disruption of higher levels of the cortex lead to ________
complex deficits (man who mistook wife for hat)
Where is the primary visual cortex located (V1)
posterior occipital lobe
Scotoma
area of blindness resulting from damage to visual cortex
-may not be detected due to completion
Blindsight
ability to respond to a visual stimulus even with no conscious awareness due to scotoma
-may be because some connections still exist in V1
Agnosia
failure of recognition
Visual agnosia
ability to see but not recognize
Prosopagnosia
inability to recognize and differentiate faces
-bilateral damage to ventral stream
Fusiform face area
activity is increased during facial recognition but not recognition of other objects
Frequency
number of complete wavelengths that pass a point in a given time
Pitch
tones highness or lowness which depends on frequency
Middle ear
between eardrum and cochlea containing ossicles that concentrate the vibrations of the eardrum on the ovals window
Inner ear
cochlea, semicircular canals, vestibular sacs
Tympanic membrane
eardrum
Cochlea
contains organ of Corti, hair cells, auditory receptors and is highly sensitive
Oval window
on cochlea where stapes presses
Superior olivary complex
group of nuclei in medulla which code for spatial location
Lateral lemniscus
band of fibres that carry auditory info through medulla and pons to inferior colliculus
Inferior colliculus
involved in sensory reflexes (startle to unexpected noise)
Phase difference
- difference in arrival times of sound waves at each eardrum
- detected by medial superior olivary complex
- it is difficult to determine whether sound is directly in front or behind
Conductive deafness
ossicle damage
Nerve deafness
cochlea or auditory nerve damage
-major cause is a loss of hair cells
Divisions of exteroreceptive system
touch (mechanical)
temp (thermal)
pain (nociceptive)
Free nerve endings
temp and pain
-no specialized structures
Pacinian corpuscles
adapt rapidly, large and deep
-sudden displacements of skin
Merkels disks
gradual skin indentation
Ruffini endings
gradual skin stretch
Stereognosis
identifying objects by touch (manipulate object so pattern of stimulation changes)
Dermatome
area of the body innervated by the L and R dorsal roots of a given segment of spinal cord
Ascending somatosensory pathways
- dorsal column medial lemniscus system
- anterolateral system
Dorsal medical lemniscus system
-touch and proprioception
Anterolateral system
- pain and temp
- 3 tracts: spinothalmic, spinoreticular, spinotectal
Asterognosia
inability to recognize objects by touch
Asomatognosia
failure to recognize parts of ones own body
- unilateral L side of body
- damage to R temporal and posterior parietal lobe
- accompanied by anosognosia (can’t recognize ones symptoms)
Descending pain control states pain can be suppressed by ______ and ______ factors
cognitive and emotional
Discoveries supporting descending pain control
- electrical stim of PAG has pain blocking effects
- PAG and other areas have opiate receptors for pain relief drugs such as morphine
- existence of endogenous opiates- endorphins
What is the only sensory system whose pathway reaches the cerebral cortex without passing through thalamus
olfaction
How is the olfactory system organized
chemotopically
-according to map of odors
Metabotropic mediated tastes
sweet
umami
bitter
(receptor causes ion channel to open)
Ionotropic mediated tastes
salty
sour
(don’t have receptors and therefore act on ion channels)
Anosmia
inability to smell
-blow to the head which damages olfactory nerves
Ageusia
inability to taste
- damage to ear on same side of the body can cause limited ageusia
- rare due to multiple taste pathways
Exogenous attention
bottom up
- external events
- drawn to table since cat knocked lamp off it
Endogenous attention
top up
- internal cognitive processes
- focused on table since you are trying to find keys
Change blindness
no memory of which that is not attended to
-doesn’t occur without brief intervals since memory isn’t needed
Cocktail phenomenon
indicates there is processing of info not attended to
-unconsciously monitoring contents of one convo while consciously listening to another
Simultanagnosia
difficulty attending to more than one visual object at once
-damage to dorsal stream (localizing objects)
Visual neglect
receive info from L side but neglect it since there is damage to L side structures
