Abstract
Purpose: :
To examine the regularity and adaptability of the field potential response inductions by flash stimulations over the successive time series and across the different layers of the superior colliculus, in the rat.
Methods: :
The four regularly-spaced thread electrodes were permanently implanted in the superior colliculus of the anesthetized male albino Wistar rats. After the minimum recovery period of two weeks the visual responses for the free-field white-light flashes (0.5 ms square-pulse) of different intensities were recorded from the unrestrained and non-drugged animals, for the spontaneous alert immobile behavioural state.
Results: :
The typical up (positive) and down (negative) biphasic field potential responses were evoked by the flash stimulations. The amplitudes of these response components gradually inceased to the saturating maximum, but were relatively smaller in the deeper layers of the superior colliculus. The associated latencies respectively gradually reduced to the minimum with the greatest stimulus intensity, or increased to the maximum by the intermediate stimulus intensity and after that diminished up to the maximal stimulus intensity. These processes happened within the period of 100 ms, from the stimulus moment. There appeared another down (negative) response deflection with the outstanding latency decreases, within the period of 100-200 ms, by the increasing stimulus intensity, these responses being, in contrary to the above, the greatest in amplitudes within the deepest layers of the superior colliculus.
Conclusions: :
These records from the superior colliculus, as measured from the freely behaving animals by applying a visual stimulator device, suggest the idea that the information properties of the given state of the system adaptability, over the successive and possibly folded time series but within the limited time frames, reflect the inherent spread of information in (and to) the superior colliculus, as would be the case for the transmissions of the given adaptive information property of the system state from the retina to the most superficial parts of the superior colliculus, in the rat.
Keywords: electrophysiology: non-clinical • signal transduction: pharmacology/physiology • superior colliculus/optic tectum