NEURO- MUSCULAR ORGANIZATION OF SHIVERING 
animals by a noxious stimulus (pinching the skin) irrespective of 
rectal temperature (Fig. 8). Sometimes the rectal temperature 
continued to fall but at a slower rate after such noxious stimulus 
induction of active and continuous shivering. When the animals 
were at a lig^t enough anesthetic level to display a conjunctival 
reflex, shivering weakened, and it was evident only during inspiration 
and sometimes it was coupled with limb extension, twitches, or loco- 
motor movements. 
Effect of Vagotomy on Shivering 
Respiratory movements became mild, absent, or irregular im- 
mediately post bilateral vagotomy (Fig. 9). While respiration was so 
disturbed shivering was completely depressed and its return was 
concomitant with the recovery of regular respiration. 
Effects of Acetylcholine (ACH) and Epinephrine on Shivering 
Twenty seconds after the I. V. or I. P. injection of acetylcholine 
(5 mg/kg) the blood pressure of shivering animals fell 30 mm Hg. 
approximately for about 10 minutes or more. Respiration rate then 
rose from 9to20breaths/min. Immediately after the blood pressure 
fell, shivering became feeble and was depressed completely within 
5 to 50 seconds. Shivering did not return post ACH injection until 
respiration and blood pressure returned to pre- injection levels. 
Epinephrine injection (30 mg subcutaneous) facilitated the recovery 
of shivering after ACH induced inhibition (Fig. 10) After ACH in- 
jection, cortical, thalamic, and subthalamic brain w^ves did not 
illustrate any remarkable changes in wave frequency but wave amp- 
litudes were somewhat depressed (Fig. 11). There seemed to be a 
relationship between the disappearance of shivering after ACH 
injection and the decrease in cortical EEG wave amplitudes and 
subsequent appearance of cortical barbiturate spindling. However, 
203 
