Please enable JavaScript.
Coggle requires JavaScript to display documents.
Data analysis - Coggle Diagram
Data analysis
Eye movement
Saccades are rapid eye movements to bring an image onto fovea
Hierachical control of saccades
Brain damage affecting saccades / diangosis signs
Cerebellar damage leads to hypometric saccades
Affects Frontal Eye Fields before it relays t basal ganglia and superior colliculus
Superior colliculus leads to loss of express saccade
saccade in a particular direction decreased.
Basal ganglia leads to difficulty initiating voluntary saccade
Parkinson's disease
Loss of dopaminergic neurones in basal ganglia leading to reduced capacity to inhibit, and thus overall reducing movement
Basal ganglia is a gate controlling selection of visual target, AKA what object of interest to generate a voluntary saccade on.
Prevents unwanted reflexive saccade from focusing vision on disruptive stimuli.
Basal ganglia initiates voluntary saccades in tasks requiring learned or predictive behaviour.
Brain stem damage leads to slow saccade
Motoneuron initiates pulse step control speed and duration of saccade
Pulse is an increased rate of AP firing, overcoming viscous forces of tissue around eye
Step is maintenance of position of eye position against elastic forces
Saccade assisted by other eye movement to keep image onto fovea
When target is non-stationary
When head is moving while viewing image
Vestibulo-ocular reflex
Which way is up / head translation
Sensed by saccule (vertical acceleration) and utricle (horizontal movement)
Where am i going / head rotation
Semicircular canals
14 ms really fast without slow build up
When the object of interest is moving
Smooth pursuit
Requires brain to extimate speed of target
Catch up saccade occur if target moves too fast
Smooth pursuit followed by sharp change as catch up saccade/
On a train, whole visual field is moving
Optokinetic nystagmus
Slow phase followed by fast
Slow build up
Fixational eye movements
microsaccade
drift
Slower than microsaccade
Tremor
Oscillations superimposing with drift
Short latency ~ 200ms
Fast 900 degrees per second
Voluntary movement in response to visual cues
Conjugate - both eyes moving same time same direction
Frontal lobe controls eye movement
foveal pit is mostly densely packed in photoreceptors
Eye movement output
6 traces on y axis
Hor Tar deg
Horizontal stimuli
Hor Lt deg
Horizontal response of left eye to horizontal stimuli
Hor Rt deg
Horizontal response of right eye to horizontal stimuli
Ver Targ deg
Vertical stimuli
Ver Lt deg
Vertical response of left eye
Ver Rt deg
Vertical response of right eye