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Lecture

NROC64: Lec 9: Gaze Control and Spatial Constancy (nearly word-for-word what was said in lec)

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Department
Neuroscience
Course
NROC64H3
Professor
Niemier
Semester
Winter

Description
Lec 9 Gaze Control and Spatial Constancyusually eye movements correspond with attentioneye movements are motor control that are fairly simple 3 pairs of agonistantagonist muscles onlymore simpler than having multiple joints and arm movement etchow motor control works specifically oculomotor control is quite simple topiceye movements special in another way eye mvts are almost exclusively meant to adjustyour sensation for perception meant to change visionvery impt for visionwill moveyour fovea to regions where you want to look atnot necessarily the same as hand mvts you may use your hands to touch something sensation but then you would also use it for other thingsopen door etcShort Answer QuestionWhy is motor control considered to be redundant Give an exampleAnswerExample with Duchenne genuine assoc w emotions smile and fake smile 2 patients that had difficulties with facial muscles one patient could do Duchenne smile but not the voluntary smile while the other patient could do fake smile but not the Duchenne smile Its redundant because both are similar functions and its innervating for the same facial muscles for the mouth Slide 6 Six kinds of eye movementsBring fovea to the target and keep it thereoEx reading and want to look at a wordSaccadesfixations 2 eye mvts that go togetheroMove fovea to targetoUp to 900 degsoSaccade amplitude under voluntary control not velocitypicture diagram used as a stimulus for research oMirrors on side of eyes with light shined onto light movement of eye would be detected by crystal surface which would be superimposed onto the image itselfoPicture of little girl and superimposed are traces of eye mvtsoSeen are saccadic eye mvtslines that connect the knots the knots are fixationsoFixationvery little eye mvt because the eye never stands still form thick knots on pictures because eyes arent completely stable theyre moving a little bitoGraph right eye movement as a fxn of time smooth transition from some position relatively to the left to some position relatively to the rightThis phase here in terms of ms is pretty quickless than 50 msSaccadic mvts can be btn 2ms20 ms depending on how large the eye mvts are Graph shows that most of the time eye isnt movingfixation time period this is so we get the best possible visionSaccades are meant to move the eye as quickly as possible but during this phase vision is blurred this time period is very shortNormally head movements are smooth but in ppl who have problems with eye muscles their head mvts are jerky bc lack of eye mvt controloNormal ppl do these jerky mvts if they have a tube thru which eye is looking thru since only looking thru small aperture must make jerky head mvts eye mvts dont really help anymorethese are like saccadesSaccades can be voluntary or spontaneousYou cannot determine how fast the saccade will be theres not quite a linear relationship between saccade amplitude and velocityThats whats plotted here during the saccade theres a spike of velocitySlide 7 Six kinds of eye movementsEye mvt 3 smooth pursuit is also meant to have the fovea on a target of interest that is moving ex reading the letters of a truck thats going byhave to follow the letters on the truck with your eyesDashed line is the stimulus that the participant is supposed to fixate on right where the eye is looking at then stepping to 10 degrees to the right side and then slowly moving to the left sideTheres a little delay the computer will measure rxn timeThe saccade catches up with the stimulus and then pretty much matches the position and velocity of the stimulusOne of the things that neurologist would test in a patient because normally able to do that unless youre older aging effect or have some neurological deficitSlide 8 Six kinds of eye movements4 Vesibuloocular reflexBrings fovea to the target outside in the world and keeps it there compensates for the head movementsHolding camera sitting on chair and turning himself around notice that the eyes are continuously moving as hes turning bc its trying to focus on somethingGraph sawtooth patternoPlotted as fxn of time vertical is horizontal eye positionoThere are periods where the eye is moving slowly and theres a quick phase saccade back to some other position and then slow phase and another quick phase and so onsawtooth patternoKind of combo of smooth pursuit and saccadeDriven by the vestibular systemSo trying to keep your eyes stable your trying to look straight ahead but since your head moves to one side when youre spinning the vestibular system causes your eyes to counterrotatethis is the slow phase the velocity during this time would try to match the velocity of your head rotations but in exact opposite direction
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