1994 Fiscal Year Final Research Report Summary
Analysis of information processes in pathways concering in orienting and visual discrimination
| Project/Area Number |
05454678
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
神経・脳内生理学
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| Research Institution | TOKYO METROPOLITAN INSTITUTE FOR NEUROSCIENCES |
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Principal Investigator |
SASAKI Shigeto Tokyo Metropolitan Inst.for Neurosciences, 神経生理研究部門, 副参事研究員 (50110490)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Orienting / Superior colliculus / Reticular formation / Cats / Unit activity / Unrestrained animal |
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| Research Abstract |
We have shown that head orienting are principally controlled by two separate pathways, the superior colliculus (SC) -pontomedullary reticular formation-neck motoneurones and SC-Forel's field H neck motoneurones. The former pathway chiefly concerned with control of horizontal head movement, while the latter concerned with the vertical movements. In this study , activities of single or multiple units in the SC and pontomedullary reticular formation were recorded from cats performing headorienting task with an array of movable electrodes implanted chronically.
In the SC,firing patterns differed among the neurones in superficial, intermediate and deep layrs. A group of neurones in the superficial layr (layr I-III) fired vigorously after fixating a target (gaze firing), in contrast to intermediate layr (IV) neurones which are known to discharge in bursts before a movement to a particular visual field (movement field) . Many of the deep layr (V-VI) neurones fired tonically during fixating on a center light waiting for the appearance of a target or during fixating on a target.
Many units in the pontomedullary reticular formation showed activities related to head orienting. They were classified into 3 major types according to the firing pattern. Phasic units fired in a burst manner, initiated firing 20-40 ms prior to movement onset and stopped firing before the end of movement. The number of firing positively related to the maximal angular velocity of head movement. Phasic sustained units fired eariler than phasic units and showed sustained activity during head movement and ceased firing with termination of movement. The activity was more closely related to the duration of movement than the maximal angular velcity. Tonic units showed sustained activity in a particular phase of orienting task, i.e., during fixating a center (fixation) light, target light or during inter-trial intervals.
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