Bio Bases Exam II Flashcards
What percentage of the cerebral cortex plays a direct role in processing visual information
20%
Perceived color of light is determined by three dimensions. What are they
Hue: determined by wavelength, the visible spectrum displays a range of hues that our eyes detect
Saturation: Relative purity of light that is being perceived
Brightness: the intensity of the electromagnetic radiation
- an image must be focused on the ________ for us to see
retina
What is at the back of the retina
- Photoreceptors (rods and cones),
What are the three layers of the retina?
- Outermost: Ganglion cell layer
Transparent & light passes through - Middle: Bipolar layer
Transparent & light passes through - Innermost: photoreceptor layer
Transduce light
What layer of the retina transduces light?
protoreceptor
What are the 2 types of photoreceptors and describe their differences
- cones –
a. 6 million
b. provide us with most of the visual information we see
c. daytime vision
d. color sensitive (color vision)
e. greatest acuity,
f. concentrated in fovea – central area of retina that contains only cones and has greatest visual acuity - rods –
a. 120 million (20 times the amount of cones)
b. light sensitive (not color)
c. mediate vision in dim illumination
d. low activation threshold
e. peripheral vision
What is the fovea
central region of retina, mediates our most acute vision, contains only cones.
Describe the process that happens after light falls on rods and cones
They form synapses with and activate
Bipolar cells that form synapses with and activate
Ganglion cells in the optic nerve
Optic disk is where ganglion cell axon exit eye in optic nerve. Contains no photoreceptors and creates a blind spot.
What is the optic disk?
where ganglion cell axon exit eye in optic nerve. Contains no photoreceptors and creates a blind spot.
What is a receptive field?
the area in the visual field a neuron (photoreceptor) . A neuron’s (ganglion cell) receptive field is determined by the location in the retina of the photoreceptor it is connected with.
what is the optic chaism?
A. Information from each visual field crosses over at the optic chaism and projects to the opposite side of the primary visual cortex
B. neurons carrying information from medial (inner halves or nasal side) cross to contralateral hemisphere
C. (processed contralaterally)- this results in L field information going to R hemisphere and R field information going to L hemisphere throughout rest of visual system
Discuss the 6 layers of the LGN
A. 6 layers plus sublayer
B. 1 and 2 magnocellular layers (large cells)
receive input from rods and are therefore sensitive to light but not color
C. layers 3-6 are parvocellular layers (small cells)
receives input from cones, thus more sensitive to color and less to light
D. koniocellular – between each magno and parvo layer – also receives input from cones
E. each of these layers projects to a specific area in the visual (striate) cortex and the segregation of information they transmit is preserved in the cortex
F. Optic radiations project from LGN to primary visual cortex
Describe the layers of the striate cortex
layer 4 receives input from magno and parvocellular areas of lateral geniculate
layer 2 and 3 receive input from koniocellular
Blobs
color
Interblobs
form, movement
What are magnocellular layers and what layer of the striate cortex do they project to
layes 1,2
(large cells)
receive input from rods and are therefore sensitive to light but not color
project to layer 4 of striate cortex
What are parvocellular layers and what layer of the striate cortex do they project to
layes 3,4,5,6
(small cells)
receives input from cones, thus more sensitive to color and less to light
project to layer 4 of striate cortex
What are konicellular layers and what layer of the striate cortex do they project to
between each magno and parvo layer – also receives input from cones
project to layers 2 and 3 of striate cortex
What is V4 responsible for?
visual association cortex in occipital lobe - color and form
Damage to V4 results in….
achromatopsia -
cannot perceive color
not color blind
Damage to V5/MT results in….
akinetopsia
motion detection
What is Apperceptive visual agnosia
perceptual impairment and visual agnosia
bilateral lateral occipital damage
What is Associative visual agnosia
perception intact with visual agnosia
damage in the anterior ventral (temporal) stream
The lateral occipital cortex has been found to respond to what categories?
Faces (fusoform face area)-ventral stream
Bodies (extrastriate body area)
Scenes
What are the 4 areas of the Intraparietal sulcus and that are they responsible for?
Anterior (AIP) – visual control of grasping and hand movements
Lateral (LIP) and Ventral (VIP) – visual attention and saccadic eye movements (rapid movement of eyes
Medial (MIP) and Ventral (VIP) – visual control of reaching and pointing
Caudal (CIP) – perception of depth from stereopsis
Describe the funcitons of the ear and name the structures involved in this process
- Sound funneled through Pinna through ear canal to
- tympanic membrane. It vibrates (flexes and contracts) with sound waves and transmits (is connecting) to:
- malleus (), incus, stapes – bones in middle ear. Stapes vibrates against membrane in the:
- cochlea – filled with fluid, contains receptors
- Organ of Corti- receptive Oregon
a. Three parts:
a. hair cells are auditory receptor cells and contain cilia between:
b. basilar membrane and tectorial membrane – vibration causes these membranes to flex back and forth sending “waves” through the inner ear fluid causing cilia to bend. This results in action potential in neurons going to cochlear nerve to auditory nerve (cranial nerve 8)
b. specific locations of the basilar membrane flex in response to specific sound frequencies going from low to high in sequential order
Parts of the cochlea and their functions
a. hair cells are auditory receptor cells and contain cilia between:
b. basilar membrane and tectorial membrane – vibration causes these membranes to flex back and forth sending “waves” through the inner ear fluid causing cilia to bend. This results in action potential in neurons going to cochlear nerve to auditory nerve (cranial nerve 8)
What makes up the ossicles?
malleus, incus, stapes
Which way do auditory pathways move?
Afferent
Describe the Auditory pathway
- Medulla
- Bilaterally - but primarily contralaterally – to
a. Cochlear nuclei of the medulla to the
b. superior olivary: complex where perception of sound location is processed - Pass through the lateral lemniscus to the
- Inferior colliculus located at the dorsal midbrain
- Medial geniculate of thalamus
- superior temporal lobe in the lateral fissure – primary auditory cortex
- auditory input projects bilaterally, but is mostly contralateral
What are the regions of the auditory cortex
- Core is primary auditory cortex
- Divided into 3 zones that receive input from 3 different areas of medial Geniculate - Belt – first level of auditory association cortex
- At least 7 divisions
- Receives input from primary auditory cortex and MGB - Parabelt – “highest level” (more complex) of auditory association cortex
- Receives input from belt and MGB
What are somatosenses
provide information relating to events on the skin and to events occurring within the body
What are cutaneous senses
receive various signals from the skin that form the sense of touch
Pressure (touch)
Vibration (touch)
Heating/cooling (temperature)
Stimuli that damage tissue and produce pain (pain)
What is kinesthesia
provides information about the body position and movement
Kinesthetic signals arise from receptors located within the joints, tendons, and muscles
What does touch involve
perception of pressure and vibration of an object on the skin
