Midbrain Control of Cold Shivering

这个项目已经明确了无论哪种cold shivering is controlled by midbrain模板or单一gamma efferents were isolated in the preparations of rat whose bilateral preoptic andanterior hypothalamus electrolytically lesioned to eliminate the influences from the highercenter for shivering，and changes in the discharge activity while the midbrain was cooled or warmed by meansa water perfused thermode. Under the normal midbrain temperature，36% of 64 gamma fibers isolated exhibited periodic fluctuations in spontaneous discharge whereas the38 gamma fibers，包含both type Of fibers，examined for thier thermal reaction，71% produced an increase or a decrease in discharge frequency to a fall below or a rise above thenormal midbrain temperature，Temperature dependency of discharge frequency obtained in the range below37.5 C(-1.5<plus-minus>0.1 imp./sec/ C in perfusion temperature) was…More smaller than the one in the range above 37.5 C(2.8<plus-minus>0.5 imp./sec/ C). Thisbehaviour of gamma activity parallels the general pattern of thermoregulatory responses involvedinmaintaining a heat balance, e.g.，heat production is facilitation in the hypothermic range and suppressed in hyperthermic range. theafferent responses from the muscle spindle primary(43) and secondary endings(7) in thegastrocunemius et soleus to stretches of the muscle which were repeatedly applied during midbraincooling or warming were analyzed by measuring peak frequencystatic frequency and the dynamic index in each stretch反应。produced not only dynamic gamma activation but also static gamma activation用former的prevalence of former(63%) over the latter(29%).这些结论indicate that the descendingsignals derived from the thermosensitive structures in the中间brain also influence gamma motoractivities suggesting that shivering threshold could be altered therpmen Less

This project was aimed to clarify whether cold shivering is controlled by midbrain temperature or not. Single gamma efferents were isolated in the preparations of rat whose bilateral preoptic and anterior hypothalamus were electrolytically lesioned to eliminate the influences from the higher center for shivering, and changes in the discharge activity were examined while the midbrain was cooled or warmed by means of a water perfused thermode. Under the normal midbrain temperature, 36% of 64 gamma fibers isolated exhibited periodic fluctuations in spontaneous discharge whereas the rest sustained spontaneous discharge. Of 38 gamma fibers, including both type of fibers, examined for thier thermal reactiveness, 71% produced an increase or a decrease in discharge frequency to a fall below or a rise above the normal midbrain temperature, respectively. Temperature dependency of discharge frequency obtained in the range below 37.5゜C(-1.5<plus-minus>0.1 imp./sec/゜C in perfusion temperature) was … More smaller than the one in the range above 37.5゜C(2.8<plus-minus>0.5 imp./sec/゜C). This behaviour of gamma activity parallels the general pattern of thermoregulatory responses involved inmaintaining a heat balance, e.g., heat production is facilitation in the hypothermic range and suppressed in hyperthermic range. The afferent responses from the muscle spindle primary(43) and secondary endings(7) in the gastrocunemius et soleus to stretches of the muscle which were repeatedly applied during midbrain cooling or warming were analyzed by measuring peak frequency, static frequency and the dynamic index in each stretch response. It was found that midbrain cooling produced not only dynamic gamma activation but also static gamma activation, with the prevalence of former(63%) over the latter(29%). These results indicate that the descending signals derived from the thermosensitive structures in the midbrain also influence gamma motor activities, suggesting that shivering threshold could be altered therpmen Less