LECTURE 25 - closed-loop control ** Flashcards
what are four structures that support closed-loop control ?
- vision
- proprioception - muscles spindles, GTO
- vestibular
- somatosensory - haptic
what is the closed-loop control all about ?
regulating an ongoing movement
how does this closed-loop control move ?
system goal → reference mechanism → executive level → effector level → environment (feedback arrow back up to reference mechanism)
what does the closed-loop control monitor ?
the effectiveness of your of your movement while performing the actual task
what are the two pathways of vision in the closed-loop control ?
geniculostriate and retinotectal pathway
what is the genuculostriate pathway ?
a relatively “low-level” visual pathway, involved in the processing of basic visual features and the detection of simple visual stimuli
what is the retinotectal pathway ?
is a neural pathway found in some non-mammalian vertebrates, such as fish, amphibians, reptiles, and birds. It plays a crucial role in the control of visual processing and the guidance of eye movements
how does the genuculostriate pathway travel ?
- begins in the retina (back of the eyes)
- projects to the superior colliculus (structure in the midbrain that is involved in the control of eye movements and other visual behaviors)
- continues to the the thalamus,
- from there, the pathway projects to the visual cortex, where it provides inputs to regions involved in the processing of visual information
how does the retinotectal pathway travel ?
- dynamic visual cue from the visual stimulus
- to the retina
- to the SC
- to the brainstem
- to the eye (dynamic moving stimulus)
what are the two kinds of photoreceptors in vision ?
cones and rods
what are rods ?
- achromatic
- equally dispersed about retina
- low spatial resolution
- respond to low light levels
- provides night vision
- scotopic vision
what are cones ?
- chromatic
- largely located in the center of the retina (central vision)
- high spatial resolution
- do not operate in low light levels
- photopic vision
between cones and rods which are slow acting and fast acting ?
slow acting = rods
fast acting = cones
between cones and rods which are colour and black/white ?
black & white = rods
colour = cones
what is the back of the eye called ?
retina
what is achromatopsia ?
a rare visual disorder that affects color perception
what do individuals with achromatopsia experience ?
have a complete absence or severe reduction in the ability to perceive colors, which can make the world appear in shades of gray and sensitivity to colour
what cause achromatopsia ?
acquired from a injury (e.x., stroke)
perception of colour comes from what pathway ?
ventral visual pathway
what is a way to test for colourblindness ?
The Ishihara test (circular plate with number within)
what are the three cones in the colourblind test?
L-cone, M-cone and S-cones
what colour is the L cone ?
red
what colour is the M cone ?
green
what colour is the S cones ?
blue
does everyone have the same concentration of colour mosaic’s ?
no, people have different concentrations of colour mosaics
what are the two related concepts in vision science that are related to the way the brain processes information from the two eyes ?
binocular rivalry and strereopsis
what is binocular rivalry ?
- seeing two images
- phenomenon in which a visual perception alternates between the different images presented to the eyes
- very small differences between the two eyes yield stereopsis
- eye dominance
what is strereopsis ?
- without stereopsis depth determination is impaired
- motion parallaz
- remember “magic eye” : it is an example of an autosterogram
- refers to the perception of depth or three-dimensionality that arises from the slightly different perspectives provided by each eye
what does enucleated mean ?
an individual has had an eye removed (due to an injury or a disease)
what is it called when an individual has had an eye removed ?
enucleated
what were some in class examples of binocular rivalry ?
- buny or seagull
- vase or faces
- golfer or spartan
what was the “grandparent of them all” in regards to binocular rivalry ?
the necker cube (cube moves ; depth determination)
what is the first region of the brain to receive visual information from the eyes ?
The primary visual cortex (V1)
how does the geniculostriate pathway travel (simple) ?
retina → SC → pulvinar →Posterior parietal cortex
how does the retinotectal pathway travel (simple) ?
retina → LGNd → primary occipital cortec (area V1) → (dorsal) posterior parietal cortex or (ventral) inferotemporal cortex
what is the posterior parietal cortex responsible for ?
action
what is the inferotemporal cortex responsible for ?
perception
what is allocentric frame of reference ?
- objects and locations are described in relation to other objects and locations in the environment, independent of the observer’s own position or movements.
what is vision for perception ?
identify, determine size, shape or properties of object
what is vision for action ?
reach or point to an area in space to control action
what is egocentric frame of reference ?
- representation of space describes objects or locations in relation to the observer’s own body position and movements
what are allocentric and egocentric frame of reference ?
allocentric and egocentric are two different ways of representing spatial information in the brain
