Post Hurricane Party Journal Club # 4 William Buchser September

J. Douglas Crawford

Neurophysiology

Relevance - Motor Circuits - Complex Systems - Publishing results that ≠ hypothesis - Protest gels

- Concepts of Eye Movement - Saccades - Head interaction Background

- Superior Colliculus - Vestibuloocular Reflex Eye Movement Head Movement

Hypothesis Based on details from previous studies... This paper hypothesizes Eye – Head Coordination is coded and is adapted downstream of the superior colliculus.

Methods Macaca fascicularis Why monkey as the model? Can do electrophysiology, and in this case, stimulate areas of the brain. Smaller, easier to work with but still same organization.

Methods -Implant “Gaze Coils” -Affix manipulator to skull -“Head Coils” on manipulator

- Behavioral Training - Goggles vs. No Goggles - SC Stimulation - Histological Verification Methods

“Head” – Coils on head mount “Gaze” – Eye Coils “Eye” – Eye relative to head (by head and gaze) Reward: Lost, interesting word beginning with a ‘Q’. If you can identify and define it there is a reward. Clarifications SC Stimulation(Natural) Behavior

- Practical Example - Two Volunteers Needed Methods

Figure 1 Hypothetical Models Original Concept

Figure 2 Behavioral Overview

Figure 3 Behavioral Patterns (2-D) End of Movement Start of Movement 21.8°38.9°

VOR vs. Saccade VOR (Vestibuloocular Reflex) Rapid Eye Saccade Gaze Head Eye

Figure 3 Behavioral Patterns (2-D) Goggle Aperture

Figure 3 - Conclusions In natural (non-stimulated) conditions, head movements are greater with goggles. VOR eye movements are also greater with goggles. VOR movements bring the ‘with goggles’ eye back into the aperture.

Figure 2 Stimulation Overview Back to...

Figure 4 Stimulation Patterns 2-D One SC site Figure 3

Figure 4 - Conclusions The behavioral observations for both natural and stimulation evoked gaze shifts are the same in standard context. With or without goggles, the stimulation paradigm produced similar movements. Skipping Figure 5, 6

Figure 7 - Preface So, is the original hypothesis supported? Can we argue that head and eye movement are coded downstream of the superior colliculus? Lets look at shifts of all different amplitudes and compare the differences.

Figure 7 BehaviorStimulation Goggles Eye No Goggles Eye No Goggles Head Goggles Head

Figure 7 - Conclusions The original hypothesis is not supported by this data It appears that stimulation in the SC cannot evoke the same context dependent head movements (with goggles) Skipping Figure 8,9

Placement of Eye in Aperture End results of movements  Gaze has shifted – is eye in the aperture? Compare with Goggles and without

Figure 10 Gaze shift end point

Figure 11 Gaze shift end point

Figure 12 End Point

Summary 10,11,12 ‘Eye’ component of the eye-head coordination is retained in the ‘with goggles’ stimulation experiment Appears that the ‘eye’ part of the movement is coded downstream of SC. Is this really adaptation and learning, or is it just an interesting phenomenon?

Figure 13 Aperture Switch -This paradigm actually causes an adaptation, which needs to be relearned for new contexts. Proof of Concept [OK]

Summary Eye Return Head Movement Head Movement Eye Return Head Movement Eye Return Head Movement X X √ √ √ X

Figure 1 Conclusion Original Concept New Model