Lecture 24 Flashcards
What are voluntary eye movements, and how are they initiated?
Voluntary eye movements are endogenous, self-initiated eye movements that can occur even in the absence of a visual stimulus.
What distinguishes endogenous eye movements from exogenous ones?
Endogenous eye movements are internally initiated, while exogenous eye movements are driven by external stimuli
What is the objective of the experiment involving transcranial magnetic stimulation (TMS)?
The experiment aims to investigate the contributions of the superior prefrontal cortex (SPFC) and the superior parietal lobule (SPL) to the generation of voluntary and visually guided saccades using TMS.
Describe the tasks used in the experiment to study endogenous and exogenous saccades.
The endogenous task involves moving the eyes left or right in response to a central arrowhead, while the exogenous task involves moving the eyes to a peripheral asterisk.
What role does TMS play in this experiment?
TMS is used to apply a magnetic pulse to specific brain regions (SPFC or SPL) to investigate their impact on saccadic eye movements.
What were the results of the experiment regarding endogenous saccades when TMS was applied over the SPFC?
TMS over the SPFC delayed endogenous saccades directed toward the contralateral hemifield.
How did TMS affect exogenous saccades in the experiment?
TMS over neither the SPFC nor the SPL affected the latencies of exogenous saccades.
What conclusion can be drawn from the delayed endogenous saccades associated with TMS over the SPFC?
The delay in contralateral endogenous saccades suggests that the SPFC is involved in generating voluntary saccades.
What brain regions are involved in the control of eye movements, specifically the superior colliculus (SC) and the frontal eye field (FEF)?
The SC and the FEF are involved in controlling eye movements.
What task were participants in the experiment asked to perform, and what were the results for patients with a FEF lesion?
Participants were asked to move their eyes left or right in response to a central arrowhead. Patients with a FEF lesion showed delayed contralateral endogenous saccades.
What conclusion can be drawn from the delayed contralateral endogenous saccades in patients with a FEF lesion?
The delayed contralateral endogenous saccades suggest that the FEF is normally involved in generating voluntary saccades.
What are the differences in the neural circuitry involved in reflexive (exogenous) and voluntary (endogenous) eye movements?
Reflexive eye movements rely more on subcortical structures, while voluntary eye movements depend more on cortical structures.
Why do reflexive eye movements feel easier to execute compared to voluntary eye movements?
Reflexive eye movements require fewer neural connections and involve less processing, making them faster and easier to execute.
How does the simplicity of neural connections explain the speed of reflexive eye movements compared to voluntary ones?
Reflexive eye movements require fewer neural connections and less processing, which leads to faster execution compared to voluntary eye movements.
