Dennis C. Wright

Retrograde State Dependent Learning

Sodium pentobarbital administered intravenously after acquisition in a one-trial passive avoidance task results in state dependent (drug dissociated) learning in male albino rats. Findings have methodological implications for drug-based research and theoretical implications for drug discrimination studies. Predictions based on a stimulus generalization hypothesis are not supported, whereas those based on an information storage hypothesis are supported.

Memory, Learning Ability, and Neuropathologic Status of Mice with Systemic Lupus Erythematosusa

Abnormal neurologic function and impaired cognition are a major cause of morbidity in patients with the autoimmune disease, systemic lupus erythematosus (SLE).’.2 The causes of the central nervous system dysfunctions that complicate SLE are not understood. It has been postulated that neurologic impairment in SLE is caused by immune complex-mediated vascular lesions, whereas diffuse brain involvement re-

Altered CSF constituents and retrograde amnesia in rats: A biochemical approach

Abstract A parametric estimation was conducted on the concentrations of certain substances in CSF as a function of time after electroconvulsive shock treatment that produced retrograde amnesia in rat. The substances of particular interest were hexoses, and the electrolytes sodium, potassium, calcium and magnesium. The concentrations of each substance were expressed as percent change after treatment from an initial concentration taken from each animal before treatment. Considerable increases in hexose and calcium concentrations were observed at 5 min after electroshock treatment, while concentrations for sodium, potassium and magnesium demonstrated little change at the 5 min observation. Values for all five biochemical variables comparable to their control values were observed at subsequent time intervals. Concentrations for these five biochemical variables were established for both CSF and blood in rat, and compared to those values reported for rabbit. The argument is advanced that protein synthesis inhibition following ECS is secondary to the disruption of membrane surface glycoproteins and that the disruption of these glycoproteins plays a major role in the production of retrograde amnesia.

Latent inhibition from context-dependent retrieval of conflicting information

Rats were trained to lick and were tested for lick suppression to a tone in one apparatus/context. They were conditioned (tone-shock) in a different apparatus/context. Prior to conditioning, they received unreinforced preexposure to the tone (PCE) in the lick test box (Group A), in the conditioning box (Group X), or in a box different from both the test and conditioning boxes (Group B), or they received no PCE (Group N). In both Experiments 1 and 2, Group A was the only group to show latent inhibition (i.e., to show less conditioned lick suppression than did Group N). Context-dependent retrieval of “this CS signals nothing” information acquired during PCE reduces lick suppression when PCE and test contexts match, but not when PCE and conditioning contexts match.

State dependent learning produced by post trial intrathoracic administration of sodium pentobarbital

The state dependent learning paradigm was used with a one-trial, passive avoidance task. Forty male rats were equally distributed among four groups: One group received intrathoracic injections of sodium pentobarbital immediately after the acquisition trial and immediately before the retention test trial; a second group received equivalent injections of 0.9% saline; a third group was drugged after acquisition and given saline prior to retention testing and the fourth group was given saline after acquisition and drug prior to retention testing. All groups showed increased latencies on the retention trial but marked group differences in retention test latencies indicate that there was significantly more retention of training when drug states were the same during the memory storage interval and the memory retrieval interval. Intrathoracic injection proved to be a practical substitute for intravenous injection in assuring rapid onset of drug effect.

Effects of experimentally induced hyperlysinemia on maze learning in mice

Abstract The experiment was designed to test effects of experimentally induced hyperlysinemia on maze learning ability in the mouse. Six% L-lysine was placed in the drinking water during gestation, and/or during nursing and/or during postweaning in a factorial combination. The young were tested at 40 days of age in a water-escape T maze. A week later all animals were retested for retention. Findings revealed that overloads of lysine resulted in temporary impairment, but permanent impairment occurred only if excess lysine was administered during gestation. Biochemical analysis revealed a sharp decrease in urea nitrogen in the urine, and a blood ammonia and lysine increase.

The effect of sodium pentobarbital on attraction in the albino rat

Two “target” rats, one drugged and one undrugged, were tethered on opposite sides of an open arena in which single, undrugged “subject” rats were allowed to roam free. On the last 2 days of testing, the S rats spent significantly more time in physical contact with the undrugged target rat than with the drugged target rat. Prior adaptation to the arena of S rats had no effect on the relative preferences for the target animals.

Preexposure of the conditioning context and latent inhibition from reduced conditioning

Recently, Wright, Skala, and Peuser (1986) reported a failure to find latent inhibition in rats given unreinforced preconditioning exposure to a tone (PCE) when PCE and conditioning (tone-shock) occurred in the same apparatus/context and testing for lick suppression occurred in a different context. The no-PCE control group used for comparison had not been exposed to the tone or the conditioning context prior to conditioning. In the present experiment, the no-PCE control/comparison group received preexposure to the conditioning context, but not to the tone. Although the three groups given 12, 28, or 60 PCEs in the conditioning context did not differ from each other, they all showed less lick suppression in the test context than the no-PCE control group.