Primitive Nervous Systems

Nature ◽  
1968 ◽  
Vol 220 (5167) ◽  
pp. 623-623
Author(s):  
G. A. HORRIDGE
Keyword(s):  
Nervous Systems ◽  
Primitive Nervous Systems

Primitive nervous systems: electrophysiology of the pharynx of the polyclad flatworm, Enchiridium punctatum

1976 ◽  
Vol 65 (3) ◽  
pp. 627-642
Author(s):  
G. Stone ◽  
H. Koopowitz
Keyword(s):  
Motor Activity ◽  
Electrical Activity ◽  
Behavioural Response ◽  
Nervous Systems ◽  
Stimulus Parameters ◽  
Conduction Velocities ◽  
Primitive Nervous Systems ◽  
Behavioural Sequence ◽  
Aperture Closure ◽  
Muscle Potential

1. Electrical activity accompanying motor activity can be recorded from the excised pharynx of Enchiridium punctatum. Multiple stimuli elicit behaviour which consists of an initial aperture closure followed by extension and then peristalsis. If the stimulus parameters are increased the preparation bends from side to side instead of proceeding through the behavioural sequence. Bending appears to inhibit other movements differentially. 2. The conduction involved with peristalsis is polarized and proceeds in a proximal direction. 3. With stimulus intensities greater than those needed to produce the behavioural response an initial muscle potential (IMP) is evoked. The IMP is frequency sensitive. Maximum facilitation occurs within 100 ms and drops to 50% of maximum within 250 ms. 4. Conduction velocities of the IMP range from 0–05 m s-1 to 1-9 m s-1. Conduction velocities appear to increase with facilitation.

Sign in / Sign up

Export Citation Format

Share Document