Facilitated habituation: Strychnine dose-response effects on neural and behavioral habituation

Abstract

The effects of two doses of strychnine sulfate (0.125 mg/kg and 0.500 mg/kg) on mouse neural and behavioral habituation were assessed. Reliable alterations in concurrent neural (spontaneous and evoked) activity and spontaneous behavioral activity were obtained as the result of training.Neural habituation was characterized by higher frequency, lower amplitude EEG activity, reduced hippocampal theta activity, increased amplitudes in early components of visual evoked responses, and transient increases followed by progressive decreases of late component amplitudes of the visual evoked responses. Behavioral habituation appeared as decreased gross activity and changes in mouse orientation to cogent features of the test chamber.Low strychnine doses (0.125 mg/kg) reliably facilitated habituation to light flashes and produced lessened sensitivity to dishabituation stimuli. High strychnine doses (0.500 mg/kg) disrupted habituation and produced heightened sensitivity to dishabituation stimuli.The results were accommodated by a modified dualprocess theory of habituation; single process views of habituation were inadequate. The significance of these results to drug facilitation was discussed in terms of optimal arousal and the mediation of pro-and retroactive influences on learning. The characterization of processes underlying memory storage seems amenable to further clarification using CNS stimulants known to operate on such processes.Many central nervous system (CNS) stimulants have been useful tools in the investigation of memory storage processes [32]. Appropriately selected doses of these stimulants have allowed the experimental facilitation or disruption of memory storage processes [34]

Drug enhancement of memory consolidation: historical perspective and neurobiological implications

“…Some nonspecific performance effect of the drug might account for the findings of Lashley (1917) as well as the replication of his effects (McGaugh and Petrinovich 1959) and the findings of other maze-learning studies in which the animals received daily injections of strychnine prior to food-rewarded training trials (e.g., McGaugh 1961;McGaugh et al 1962a;Prien et al 1963;Greenough and McGaugh 1965). However, strychnine also enhances the learning of many other kinds of tasks, including a hot-plate escape task (Kelemen and Bovet 1961), appetitively and aversively motivated visual discrimination tasks (Petrinovich 1963;McGaugh and Thomson 1962), and habituation (Andry and Luttges 1971). Clearly, any hypothesis suggesting that the enhanced learning induced by strychnine is due solely to nonspecific performance effects would have difficulty accounting for the enhanced performance obtained with different motivational conditions and with such a wide variety of behaviors used to assess learning.…”

Interactive Effects of Cycloheximide and Puromycin in Altering Brain Polyribosomes and Neural and Behavioural Responses to Electroshock in Mice

“…Mice to be used for electrophysiological analysis were anesthetized with pentobarbital sodium and prepared with chronically indwelling electrodes (ANDRY and LUTTGES, 1971) as well as needle guides. The mice were first generation hybrids (Fl) of C57BL/6Ibg female and DBA/2Ibg male mice.…”

Memory facilitating and anti-amnesic effects of corticosteroids

“…one would not expect them to have anti-amnesic effects. This seems particularly strange since drugs like d-amphetamine, strychnine and picrotoxin act as anti-amnesics in mice given protein synthesis inhibitors (Barondes and Cohen, 1968;Gibbs, 1976;Flood, Jarvik, Bennett, Orme and Rosenzweig, 1977) and also improve retention of non-inh,bited subjects (McGaugh and Petrinovich, 1965;Breen and McGaugh, 1961;Andry and Luttges, 1971;McGaugh and Krivanek, 1970;Krivanek and McGaugh, 1969;Del Rio, 1971;Castellano, 1974).…”