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The complex behavior patterns of the ubiquitous, wild rat have made it almost invulnerable to traditional methods of rat control. The reasons for failure of existing rat control methods were described and it was concluded that a device which could transmit high-intensity, ultrasonic sound over a fairly wide area would not be subject to such shortcomings. Such a device now seems economically feasible with the development of high-intensity, corona-type loudspeakers.

IN clinical and experimental epilepsy, transient fluctuations in susceptibility to seizures have been shown to result from changes in behavioural state. For example, spontaneous electro-encephalographic (EEG) and overt behavioural signs of seizures have been reported more frequently during periods of relaxtion or sleep than during periods of alertness or arousal in epileptic patients1,2. Furthermore, sensory stimuli that produce alerting and orienting responses also interrupt seizure activity in patients3–5and in animals with various types of experimental epilepsy6–11. In addition, seizures produced in cats by subcortical application of aluminum oxide12or systemic injection of metrazol13have been interrupted by electrical stimulation of the mesencephalic reticular formation, a neural network believed to underlie behavioural and EEG arousal14.

SINCE the discovery that electrical stimulation of discrete sites of the brain can influence behaviour, there have been numerous reports of its application1. Such procedures, however, may lead to kindling2; stimulation of some sites at currents initially too low to produce a behavioural response may lead to a gradual development and then intensification of seizures evoked by the stimulation3. Thus when the brain is repeatedly stimulated for therapeutic purposes, seizures may be elicited unless procedures not conducive to kindling are used2. Two questions arise: can kindling leave an organism more susceptible to seizures produced by agents other than local brain stimulation, and are elicited convulsions necessary for this change in susceptibility? Our findings indicate that whether or not overt convulsions are produced by brain stimulation, repeated electrical stimulation of the brain potentiates the effects of subsequent alcohol withdrawal.