Reduction of habituation of prey-catching activity by alcohol intoxication in the frog

Acute ethanol treatment modifies response properties and habituation of the DR-VR reflex in the isolated frog spinal cord

Ethanol modification of habituation, a fundamental form of behavioral plasticity, was examined in the isolated frog spinal cord preparation. The polysynaptic dorsal root to ventral root (DR-VR) reflex response was assessed in normal Ringer's and at one of four ethanol concentrations. The reflex itself was facilitated at lower levels (0.025%) and depressed at higher levels (0.05-0.5%) of ethanol. Habituation, decrement of the polysynaptic ventral root response to repeated dorsal root stimulation, was reduced at all ethanol concentrations. Understanding the mechanisms of ethanol action involved in the disruption of simple forms of plasticity will help us to explain its actions on more complex forms of associational processes.

Disruption of vertebrate monosynaptic habituation by ethyl alcohol

The effects of ethyl alcohol on neuronal plasticity were examined using a model systems preparation of monosynaptic habituation: the lateral column to motoneuron pathway of the isolated frog spinal cord. Two fundamental effects of alcohol on this system were demonstrated. First, alcohol always depressed the ventral root responses to lateral column stimulation when stimulus intensity was held constant across conditions. This was accompanied by an increase in the amount of habituation produced as training progressed. Second, when stimulus intensity was increased in the alcohol condition so that responses were equated with pre-alcohol response amplitudes, the amount of habituation was markedly decreased. Results are discussed both in terms of proposed mechanisms of habituation and of possible pharmacological interactions with this simple example of response plasticity.

Comparative psychopharmacology

Studies of the effects of psychoactive drugs and neurotransmitters on the behavior of invertebrates and poikilothermic vertebrates are reviewed. Dangers of reductive explanations are pointed out. Results and suggestions are given concerning the use of poikilothermic animals (1) in the development of screening tests, (2) in experiments on the action mechanisms of psychopharmaca, and (3) in the use of psychoactive drugs in the study of the mechanisms of animal behavior.

Enhancement of pseudoconditioning and retardation of escape by low doses of ethanol

Independent groups of mature Wistar rats were injected intraperitoneally with 0.9% NaCl solution or 0.5 g/kg, 1 g/kg or 2 g/kg ethanol prepared from a 30% ethanol solution in 0.9% NaCl. Thirty min later each animal was placed in a two compartment shuttlebox and given 25 trials during which footshock was presented every 60 sec and tones of 8 sec duration were randomly programed. Shock-escape latencies and frequencies of intercompartmental (pseudoconditioned) responses to the tone were measured. The results showed that 1 g/kg and 2 g/kg ethanol significantly retarded escape performance but 2 g/kg ethanol significantly enhanced pseudoconditioning. These findings have implications for the design of experiments concerned with the effects of drugs on learning processes, and for theories of the effects of ethanol on behavior.