-
the primary _____ cortex is organized tonitopically
auditory
-
the inferior colliculi and medial geniculate nuclei are components of the ______ system
auditory
-
what seperates the left and right cerebral hemispheres?
the cerebral commissures
-
what is the most highly lateralized of all cognitive abilities?
language
-
aphasia
brain damage produced defecit in the ability to produce or comprehend language - left hemisphere damage/Broca's area
-
where is Broca's area?
inferior prefrontal cortex
-
apraxia
associated with left hemisphere damage, but the symptoms are bilateral. difficulty performing movements when asked to perform them out of context
-
left hemisphere functions
language, voluntary movement
-
what were the results of the cat experiments by Myers and Sperry?
the function of the corpus callossum is to transfer learned information between hemispheres. when it is cut, each hemisphere can function independently. one hemisphere working alone can learn simple tasks as rapidly as two. transferring the eye patch, however, tested the other hemisphere and performance immediately dropped
-
cross cuing
the means by which the two hemispheres communicate through indirect pathways through the brain stem/external route
-
lateralization of function: VISION
- left: words, letters
- right: faces, geometric patterns, emotional expression
-
lateralization of function: AUDITORY
- left: language sounds
- right: nonlanguage sounds, music
-
left hemisphere interpreter
a cognitive approach/hypothetical neuronal mechanism that asseses patterns of events and tries to make sense of them
-
what do free nerve endings detect?
temperature and pain
-
outer ear (three parts)
pinna, ear canal, tympanic membrane
-
what is the difference between the dorsal column-medial lemniscus system and the anterolateral system?
- DCMLS: touch and proprioception
- Anterolateral system: temperature and pain
-
What is the difference b/w pacinian corpuscles, ruffini corpuscles, and merkel's disks
- pacinian corpuscles: rapid response, deeper pressure
- Ruffini corpuscles: slower response, shallow pressure
- Merkel's disks slower response, stretching
-
Cortex of the left inferior prefrontal lobe is known as
Broca's area
-
damage to the ____ hemisphere is more likely to produce ipsilateral motor problems
left
-
musical ability, spatial ability,and _____ are viewed as right-hemisphere specialization
emotions
-
three common theories of cerebral lateralization are analytic synthetic theory, the motor theory, and the ____ theory
linguistic
-
alexia v. agraphia
- alexia: inability to read
- agraphia: inability to write
-
what is the role of the left angular gyrus in language?
posterior to wernicke's area, comprehending language related visual input
-
conduction aphasia
damage to the pathway connection Broca's and Wernicke's area (arcuate fascilculus). difficulty repeating words that had just been heard, although comprehension and spontaneous speech would be intact
-
the ____ gyrus translates the visual form of a read word into an auditory code
angular
-
the ____ cortex controls the muscles of articulation
primary motor
-
the ____ cortex perceives the written word
primary visual
-
the ____ gyrus translates the visual form of a read word into an auditory code
angular
-
the _____ cortex perceives the spoken word
primary auditory
-
unilateral neglect syndrome
- lack of attention to the left half of things
- neglect usually dissipates over a few months
- right parietal lobe damage
-
opponent process theory
complementary afterimages
-
-
-
ocular dominance columns
striate cortex
-
the axons of retinal ganglion cells leave the eyeball at the
blind spot
-
the area of the retina tha tmediates high acuity vision is the
fovea
-
cones are the receptors of the ____ system, which functions only in good lighting
photopic
-
the retinal ganglion cells from the nasal hemiretinas decussate via the
optic chiasm
-
the photopigment of rods is
rhodopsin
-
the high degree of _____ characteristic of the scotopic system increases its sensitivity but decreases its acuity
convergence
-
areas of the cortex that receive input from more than one sensory system are called
association
-
the three principles of sensory system organization
- 1. hierarchical organization
- 2. functional segregation
- 3. parallel processing
-
the middle ______ is is the incus
ossicle
-
the auditory nerve is a branch of cranial nerve VIII via the _____ nerve
auditory vestibular
-
the axons of the auditory nerves synapse n the ipsilateral ____ nuclei
cochlear
-
one function of the superior olives is sound _____
localization
-
many studies of visual auditory interactions have focused on association cortex in the ________
posterior parietal lobe
-
the inferior colliculi and medial geniculate nuclei are components of the ______ system
auditory
-
the dorsal column medial lemniscus system and anterolateral system are pathways of the _________
somatosensory system
-
the ventral posterior nuclei, the intralaminar nuclei, and the parafasicular nuclei are thalamic nuclei of the ____ system
somatosensory
-
one pathway of the ____ system projects from the amygdala and piriform cortex to the orbitofrontal cortex
olfactory
-
unlike the neuronal projections of all other sensory systems those of the ________ are primarily ipsilateral
gustatory
-
rods versus cones
rods: 120 million/abundant in PERIPHERAL retina/best for low light conditions/detect brightness and movement/low acuity
cones: 6 million/abundant in fovea/best for bright light conditions/detect color/high acuity
-
magnocelluar / parvocellular/ koniocellular
- magnocellular: lower two layers of LGN
- parvocellular: top 4 LGN layers
- koniocellur: ventral to each layer
-
primary sensory cortex
- the area of sensory cortex that receives most of its input directly from
- the thalamic relay nuclei of that system. For instance, the primary visual
- cortex is the area of the cerebral cortex that receives most of its input from
- the lateral geniculate nucleus of the thalamus.
-
secondary sensory cortex
- comprises the areas of the sensory cortex that receive most
- of their input from the primary sensory cortex of that system or from other
- areas of the secondary sensory cortex of the same system.
-
association cortex
- any area of cortex that receives input from more than one sensory
- system. Most input to areas of association cortex come from areas of secondary
- sensory cortex.
-
Parallel systems
- ystems in which information flows through the components over multiple
- pathways. Parallel systems feature parallel processing, the simultaneous analysis
- of a signal in different ways by the mulitpl eparallel pathways of a neural
- network.
-
frontal operculum
- the area of frontal lobe cortex that lies just in front of the face area of the primary motor cortex. in the left hemisphere it is the location of brocas area.
- anatomical assymetry b/w hemispheres
-
planum temporale
posterior region of lateral fissure; role in comprehension of language (wernicke's area)
-
heschl's gyrus
lateral fissure anterior to planum temporale in temporal lobe- location of primary auditory cortexes
-
process of auditory hearing w/in ear
vibrations in stapes trigger vibration sof the oval window, which transfers vibration to the fluid of the cochlea. teh cochlea has an internal membrane called the organ of corti
-
organ of corti
auditory receptor organ
-
basilar membrane/tectorial membrane
- basilar membrane: auditory receptors are mounted here
- tectorial membrane: rests on the hair cells
-
round window
vibrations of cochlear fluid are dissipated by round window, as elastic membrane in cochlea wall
-
semicircular canals
receptive orans of the vestibular system, which carries information about the direction and intensity of head movements, maintainting balance
-
network of auditory pathways
axons of each auditory nerve synapse in the ipsilateral cochlear nuclei, from which many projections lead to the superior olives on both sides of the brain stem at the same level the axons of the olivary neurons project via the lateral lemniscus to the inferior colliculi, where they synapse on neurons that project to the medial geniculate nuclei, which project to the primary auditory cortex. signals are transmitted to both ipsilateral and contralateral cortices.
-
primary auditory cortex
receives input from medial geniculate nucleus, located in temporal lobe, within lateral fissure. surround by "belt" of secondary cortex.
-
primary auditory cortex organization
functional columns. all neurons encountered tend to respond optimally to same-frequency sounds; organized tonotopically, on the basis of frequency
-
where are auditory signals ultimately conducted to?
association cortex: prefrontal cortex and posterior parietal cortex
-
auditory cortex damage
- complicated because most auditory cortex is in the lateral fissure; few permanent hearing deficits following lesions. system is partially contralateral.
- -conductive deafness: ossicle damage
- -nerve deafness: cochlea/auditory nerve
-
free nerve endings
simplest cutaneous receptors; neuron endings with no specialized structures. sensitive to temperature change and pain
-
two major somatosensory pathways
- dorsal column medial lemniscus system: touch and prioception
- -enter via a dorsal root
- -ascend ipsilaterally in dorsal columns
- -synapse in dorsal column nuclei of medulla
- -decussate and ascend in medial lemniscus to contralateral ventral posterior nucleus of thalamus
- -also input from trigeminal nerve
- -most neurons project to primary somatosensory cortex
anterolateral: pain and temporature
-
bimodal neurons
posterior parietal cortex: respond to activation of 2 different sensory systems (somatosensory and visual)
-
hemianopsia
a scotoma covers half the visual field
-
somatosensory agnosia (2 types)
1. asterognosia: inability to recognize objects by touch
2. asomatognosia: inability to reconize parts of one's own body (unilateral-left side) damage to right posterior parietal
-
paradox of pain
- 1) adaptiveness of pain: important for survival
- 2) lack of clear cortical representation of pain- areas of activation vary from person to person. removal of somatosensory cortex to not change the threshold for pain.
- 3) descending pain control: pain can be supressed by cognitive and emotional factors
-
gate control theory
ability of cognitive and emotional factors to block pain; signals coming from brain can activate neural gating circuits in spinal cord to block incoming pain signals
-
cortical area most associated with pain
anterior cingular cortex (cortex of anterior cingulated gyrus) -EMOTIONAL reaction to pain rather than the perception of pain itself
-
the chemical senses
olfaction and gustation; function is to mnitor the chemical content of the environment.
-
phemones
chemicals that influence the physicology and behavior of others in the same species
-
olfactory receptors
upper part of the nose, dendrites in nasal passages. axons pass through skull enter olfactory bulbs, synapse on neurons thea tproject via olfactory tracts to the brain
-
one olfactory receptor one neuron rule
each olfactory receptor cell contains only one type of receptor protein molecule. receptors are scattered throughout olfactory mucosa,
-
where does each olfactory tract project to?
- medial/temporal lobes
- AMYGDALA
- PIRIFORM CORTEX
-
olfactory system is the only major sensory system whose major sensory pathway reaches the cerebral cortex without first passing through the
Thalamus
-
two major olfactory pathways leaving the amygdala-piriform area
- 1) projects diffusely to limbic system
- 2) projects via medial dorsal nuclei to orbitofrontal cortex
-
gustatory system
- taste receptors (clusters of 50) located around papillae
- do not have their own axons; each neuron that carries impulses away from ataste bud receives input from many receptors
-
anosmia/ageusia
- anosmia: inability to smell
- ageusia: inability to taste
-
selective attention
we can only perceive a small amount of the many stimuli that excite our sensory organs at any time; ignore the rest
-
properties of light
- wavelength: perception of color
- intensity: perception of brightness
-
binocular disparity
difference in position of the same image on two retinas
-
retina layers
- -receptors
- -horizontal cells
- -bipolar cells
- -amacrine cells
- -retinal ganglion cells
-
retinal ganglion cells
axons project across teh inside of th retina before gathering in a bundle and leaving eyeball (through blind spot)
-
amacrine and horizontal cells
lateral communication: communication across the major channels of sensory input
-
"inside out" arrangement
light reaches receptors after passing through the other four layers, then the message goes back through the layers to the retinal ganglion cells, then through those axons in a bundle out of the eyeball
-
problems with inside out arrangement
- 1) incoming light is distorted by retinal tissue it has to first pass through
- -fovea helps: indentations specialized for high acuity, retinal ganglion layer in very thin here
- 2) for bundle of retinal ganglion axons to exit eyeball t here must be a blind spot
- -completion: filling in. visual system fills in gaps in retinal images
-
surface interpolation
how we perceive surfaces; visual system extracts information about edges and fills it in
-
convergence: rods/cones
retinal ganglion cells may receive signals from hundreds of diff. rods, but signals from only a few cones. effect of dim lighting stimulating tons of rods can summate in the firing of a retinal ganglion cell when the same stimulation in cones does not summate to the same degree
-
cones and rods distribution on retina
- only cones in fovea, no rods
- more rods in nasal hemiretina than temporal hemiretina
-
spectral sensitivvity
lights of same intensity but different wavelengths differ in brightness due to visual system not being equally sensitive to all wavelengths in the visual spectrum
-
spectral sensitivity curve
- a graph of the relative brightness of lights of the same intensity at different wavelengths
- -visual system is most sensitive to wavelengths (yellow, bright warm colors) - will look the brightest
- -in scotopic conditions, most sensitive to cool blue/violet colors
-
purkinje effect
- before dusk, yellow and red flowers seem brighter than blue ones
- at night, blue flowers seem brighter than yellow
-
how do we see color and acuity when cones are crammed into fovea at center of visual field?
eyes continuously scan the visual field, and our visual perception at any instant is the summation of recent visual information (TEMPORAL INTEGRATION)
-
fixational eye movements
- tremor
- drifts
- saccades: small jerky movements
- visual neurons respond to change
-
rhodopsin
- g protein receptor responding to light rather than neurotransmitters.
- rods are in darkness: sodium channels are partially open which keeps them slightly depolarized, allows a steady flow of excitatory glutamate to come from them
- light: series of events closes sodium channels and hyperpolarizes the rods, reducing release of glutamate
-
retinal geniculate striate pathways
- conduct signals from each retina to primary visual cortex via lateral geniculate nuclei of the thalamus
- 90 percent of axons become part of RGS pathways; no other sensory system has such a predominant pair of pathways
-
lateral geniculate nuclei
6 layers, each layer receiving input ffrom all parts of the contralateral visual field (three from one eye, three from the other)
-
retinotopic organization
- RGS system
- each level of the system is organized like amap of the retina
- disproportionate representation of the fovea in the Primary visual cortex (25 %)
-
M and P channels
- two parallel channels of communication through each LGN
- parvocellular: small cell bodies
- -top 4 layers
- -fien pattern details
- -stationary, slow moving objects
- -CONES
- M layers
- bottom two
- movement
- RODS
-
edges
- define extent and position of objects
- perception of contrast between two adjacent areas of visual field
- LATERAL INHIBITION
- mach bands
-
receptive fields of the RGS system
- -receptive fields in th efoveal area of the retina were smaller than the periphery, consistent with high-acuity in fovea
- -all neurons have circular receptive fields
- -all neurons were monocular (field in one eye)
- -excitatory and inhibitory area
-
one function of neurons in RGS System
respond to degree of brightness contrast between 2 areas in receptive field
-
columnar organization of primary visual cortex
- 1) characteristics of receptive fields can be attributed to flow of signals from neurons with simpler receptive fields to more complex. on center/off center in lower layer IV---simple cells---complex cells
- 2) primary visual cortex neurons are grouped in functional vertical columns
-
ocular dominance colummns
alternating areas of left eye and right eye dominance
-
implications of plasticity in visual system
- -research on reactions to simple stimuli cannot provide a complete explanation of how visual system works
- visual neurons are plastic, capable of changing structure/function
- -receptive field properties of each neuron change with the elements in the scene
-
component/trichromatic theory of color vision
- three different types of cones, each with a differetn spectral sensitivity
- color of stimulus is encoded byt he ratio of activity in three kinds of receptors
- three is the minimum number of different wavelengths needed to match every color
-
opponent process theory of color vision
- two different classes of cells- BRIGHTNESS v COLOR
- each classes encoded two complementary color perceptions
- -red: hyperpolarization green:hypopolaraization
- complementary colors: produce white or gray when combined in equal measures
-
color constancy
perceived color of an object is not a simple function of the wavelengths reflected; its the tendency for an object to stay the same color despite changes in the waelengths of light that it reflects
-
retinex theory
color of an object is determined by its reflectance; proportion of light of diff wavelenghts that a surface reflects. efficiency in ABSORBING each wavelength and reflecting unabsorbed does not change
-
dual opponent color cells
- respond ON when center is illuminated with one wavelength and suround is stimulated with another wavelength
- respond OFF when pattern is reversed
not evenly distributed; concentrated in BLOBS
-
blobs
- cytochrome oxidase
- columsn
- dual opponent color cells
-
what happens as you move up primary visual---secondary---association cx
- larger receptive fields
- stimuli to which neurons respond are more specific/complex
-
blindsight
- damage to the PVC
- ability to respond to visual stimuli in scotomas even though they have no conscious awareness
- Perception of MOTION most likely to survive damage
-
dorsal stream versus ventral stream
- dorsal: primary visual---- dorsal prestriate cortex----posterior parietal cortex
- SPATIAL STIMULI (location/direction of movement)
- ventral: primary visual----ventral prestriate cortex---inferotemporal cortex
- CHARACTERISTICS
-
control of behavior v. conscious perception
- dorsal: behavioral interactions w/objects (visually guided behavior)
- ventral: mediate conscious perception of objects
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