Rubow Tine K, Bass Andrew H
Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
J Exp Biol. 2009 Oct;212(Pt 20):3252-62. doi: 10.1242/jeb.032748.
Seasonal and circadian rhythms control fundamental physiological processes including neural excitability and synaptic plasticity that can lead to the periodic modulation of motor behaviors like social vocalizations. Parental male midshipman fish produce three call types during the breeding season: long duration (min to >1 h) advertisement 'hums', frequency and amplitude modulated agonistic 'growls' (s), and very brief (ms) agonistic 'grunts' produced either singly or repetitively as ;grunt trains' for up to several minutes. Fictive grunts that establish the temporal properties of natural grunts are readily evoked and recorded in vivo from vocal occipital nerve roots at any time of day or year by electrical microstimulation in either the midbrain periaqueductal gray or a hindbrain vocal pre-pacemaker nucleus. Now, as shown here, the longer duration fictive growls and hums can also be elicited, but are restricted to the nocturnal reproductive season. A significant drop in call threshold accompanies the fictive growls and hums that are distinguished by their much longer duration and lower and more regular firing frequency. Lastly, the long duration fictive calls are dependent upon increased stimulation time and intensity and hence may result from activity-dependent changes in the vocal motor circuit that are themselves modulated by seasonal and circadian rhythms.
季节性和昼夜节律控制着包括神经兴奋性和突触可塑性在内的基本生理过程，这些过程可导致诸如社会发声等运动行为的周期性调节。雄性琵琶鱼在繁殖季节会发出三种叫声：持续时间较长（数分钟至超过1小时）的求偶“嗡嗡声”、频率和振幅调制的争斗性“咆哮声”（秒），以及非常短暂（毫秒）的争斗性“咕噜声”，“咕噜声”可单独发出，也可重复发出形成“咕噜声序列”，持续数分钟。用于确定自然咕噜声时间特性的虚构咕噜声，在一年中的任何时候，通过对中脑导水管周围灰质或后脑发声前起搏器核进行电微刺激，都能在体内从枕部声带神经根轻松诱发和记录。现在，如下所示，持续时间较长的虚构咆哮声和嗡嗡声也能被诱发，但仅限于夜间繁殖季节。与虚构咆哮声和嗡嗡声相伴的是叫声阈值的显著下降，它们的特点是持续时间长得多，且放电频率更低、更规律。最后，持续时间较长的虚构叫声依赖于增加的刺激时间和强度，因此可能是由季节性和昼夜节律调节的、依赖于活动的发声运动回路变化导致的。
