| Abstract: | In 4 experiments, plasticity of the acoustic startle reflex was measured in male albino Sprague-Dawley rats in which a complete transection between the forebrain and midbrain was made. During a period from 60 to 100 min after surgery, startle amplitude in the transected Ss was relatively stable and comparable with that of controls (anesthetized with halothane and placed in a stereotaxic instrument). During this period the transection did not alter the temporal recovery process (with intervals of 2, 4, 8, or 16 sec) or auditory prepulse inhibition (with intervals of 25, 50, 100, 500, or 1,000 msec) or the normal reduction in startle caused by high levels of background noise. The transection did prevent the normal increase in startle caused by moderate levels of background noise and eliminated within-session habituation. The effect on habituation was particularly noticeable since the curves of the transected and nontransected Ss actually crossed. Results are dicussed in terms of how the transection procedure can be used to evaluate various hypotheses about underlying mechanisms of startle plasticity. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
