A gated electronic switch for stimulation and recording with a single electrode
A circuit design is described for an electronic device which is gate controlled to rapidly switch electrode connections between a stimulator and an amplifier. An integrated switch in the circuit is operated by transistor-transistor logic pulses and will conduct analog signals of up to 15 V amplitude. Electrographic records made using the switch show multi-unit spike discharge after repetitive stimulation of the amygdala in the kindled rat.
Cyclic nucleotides in the amygdala of the kindled rat
The basolateral amygdala of rats was stimulated once daily until three successive fully kindled seizures were elicited. Twenty-four hours after the last seizure the rats were sacrificed by focused microwave irradiation to the head. Tissues from homolateral and contralateral amygdala and cerebral cortex were assayed for cAMP and cGMP content. No significant changes in cyclic nucleotides were measured in the kindled animals. These studies indicate that long term changes in the steady-state level of total tissue cyclic nucleotides do not occur concomitant with the persistently altered excitability associated with kindling of the amygdala.
Excitability of the orbicularis oculi reflex in all night sleep: its suppression in non-rapid eye movement and recovery in rapid eye movement sleep.
Abstract The effect of sleep on the orbicularis oculi reflex was studied in 8 normal subjects. Excitability of both the early and late reflexes was markedly reduced during synchronized sleep but was significantly higher in stage REM (rapid eye movement) than in stages II, III or IV. The level of excitability in stage REM was about the same as in stage I but slightly less than in full wakefulness. Some of the late reflexes obtained during stages II, III and IV were of prolonged durations, and some obtained during stage REM were of very prolonged duration. EEG changes in response to shocks appeared less frequently during stage REM than during stages I to II and were at about the same level as those during stage IV. These findings indicate that neither the oligosynaptic nor the polysynaptic component of the orbicularus oculi reflex in man is influenced by sleep in the same way as the monosynaptic spinal reflex (H reflex) in man or as certain monosynaptic or polysynaptic spinal and brain-stem reflexes in cats. It is also noteworthy that the late reflex is consistently absent in coma, suppressed but still frequently evoked by shocks of high intensity in stages II to IV of sleep and freed from the suppression in stage REM, which perhaps may imply different “vigilance levels” between coma and sleep and among stages of sleep. Some of the late reflexes obtained during sleep are much longer in duration than during wakefulness, possibly suggesting that elongated pathways or sustained discharges develop in the pool of interneurons during sleep.