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Tectal induction of cortical arousal: evidence implicating multiple output pathways.
P Dean1, M Simkins, L Hetherington
1Department of Psychology, University of Sheffield, England.
Brain Research Bulletin
|January 1, 1991
Summary
Sudden stimuli trigger cortical electroencephalogram (EEG) desynchronization via the superior colliculus. Different layers respond to specific agents, suggesting multiple pathways for this arousal response.
Area of Science:
- Neuroscience
- Physiology
- Behavioral Science
Background:
- The superior colliculus in rodents controls responses to sudden stimuli, including cortical EEG desynchronization.
- Understanding the neural mechanisms of EEG desynchronization is crucial for comprehending arousal and sensory processing.
Purpose of the Study:
- To investigate the role of the superior colliculus in producing cortical EEG desynchronization.
- To determine how different layers and neurochemical agents within the superior colliculus contribute to EEG desynchronization and associated behaviors.
Main Methods:
- Injections of sodium L-glutamate or bicuculline methiodide into the dorsal midbrain of sleeping rats.
- Microinjections targeted various layers of the superior colliculus to assess EEG desynchronization and motor responses.
Main Results:
- Microinjections throughout the superior colliculus successfully desynchronized the cortical EEG.
- Bicuculline was more effective in superficial layers, while glutamate was more effective in deep layers.
- EEG desynchronization occurred with or without defensive/orienting movements, and urethane selectively blocked arousal to superficial glutamate injections.
Conclusions:
- Multiple output pathways from the superior colliculus mediate cortical EEG desynchronization.
- These findings suggest diverse functional roles for EEG desynchronization originating from the superior colliculus.