Double dissociation of fornix and caudate nucleus lesions on acquisition of two water maze tasks: Further evidence for multiple memory systems.

Examined the effect of lesions of the caudate nucleus or fimbria-fornix on the acquisition of 2 water maze tasks. In both tasks, 2 rubber balls with different visual patterns were used as cues. The correct cue was attached to a submerged rectangular platform and could be mounted by an animal to escape the water. The incorrect cue was attached to a thin round pedestal and could not be mounted. In a spatial version of the task, the correct cue was located in the same quadrant of the maze on all trials, whereas the visual pattern on the cue was varied from trial to trial. Lesions of the fornix, but not the caudate nucleus, impaired acquisition of this spatial task in relation to control animals. In a simultaneous visual discrimination version of the task, the correct cue on all trials was one with a specific visual pattern, and the spatial location of the correct cue was varied from trial to trial. Lesions of the caudate nucleus, but not the fornix, impaired acquisition of this visual discrimination task in relation to control animals. The double dissociation observed supports the hypothesis that the hippocampus and caudate nucleus are parts of systems that differ in the type of memory they mediate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention impairment by posttraining epinephrine: Role of state dependency and of endogenous opioid mechanisms.

Mice were trained in a step-through inhibitory avoidance task with a 0.6-mA, 60-Hz, 2-s footshock and were tested for retention 3 or 6 hr later. Posttraining intraperitioneal administration of a high dose (25.0 μg per mouse) of epinephrine (Epi) impaired retention; this effect was counteracted by another injection of the same dose of Epi given before retention testing either 3 or 6 hr after training. When administered before the 6-hr test but not the 3-hr test, however, Epi enhanced retention (i.e., above that of controls). The retention enhancement, but not the reversal of impairing effects of posttraining Epi, was antagonized by naltrexone (20.0 μg per mouse). Naltrexone, when administered alone, had no effect on retention when given before testing. However, posttraining administration of naltrexone produced an enhancement of retention detectable 6 but not 3 hr after training. Furthermore, posttraining naltrexone also blocked the impairing effect of posttraining Epi otherwise seen 6 hr after training. Results suggest that the impairment of retention caused by posttraining Epi is attributable to the induction of state dependency based on an Epi state. When the animals are tested 3 hr after training, this effect appears alone. But, when tested 6 hr after training, the Epi effect appears together with an opioid presumably β-endorphin-mediated, state dependency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On Cross-Cultural Similarity of Judged Word Positions in Semantic Space.

Comments on the article by Charles Osgood (see record 1963-00462-001) which examined the generality of affective meaning systems. The commentator notes that Osgood's article was most stimulating. However, a goodly portion of the paper dealt with analyses of subjects' judgments of meaningful words from which Osgood infers a generality in semantic space between various language-culture groups. While Osgood may well be entirely correct in his interpretation of obtained results, there does appear to be a methodological issue with regard to these specific studies, which the commentator highlights. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reversible lesions of the nucleus of the solitary tract attenuate the memory-modulating effects of posttraining epinephrine.

Male rats implanted with cannula tips placed above the nucleus of the solitary tract (NTS) were trained to obtain food pellets placed in 2 arms of a Y-maze and then given a footshock in 1 arm of the maze. Ss then received bilateral injections of lidocaine or buffer into the NTS and peripheral injections of saline or epinephrine (0.01 or 0.05 mg/kg, intraperitoneally [ip]). Two tests were given 24 and 48 hrs after training to assess retention in the presence and absence of contextual cues (the stainless steel floor) associated with the footshock training trial. Epinephrine (0.05 mg/kg) produced a significant enhancement in retention, which was attenuated by injections of lidocaine into the NTS. These findings indicate that the NTS is involved in mediating the memory-modulating effects of peripheral epinephrine and that such effects are initiated at least in part by activation of vagal afferents projecting to the NTS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bicuculline administered into the amygdala after training blocks benzodiazepine-induced amnesia

Leukocytes in the forestomach mucosa of reindeer (Rangifer tarandus tarandus L.) were investigated by immunoperoxidase staining of cryostat sections, using monoclonal antibodies against antigens on sheep leukocytes. Mucosal samples from three free-ranging reindeer calves were compared with samples from three calves fed baled grass silage previously shown to induce increased frequency of lesions in the ruminal epithelium. In both groups, MHC-II + cells and gamma delta T cells were observed, located within or just below the basal layer of the stratified epithelium. Computer-assisted morphometric analysis showed that the number of gamma delta T cells in the ruminal mucosa was higher in the silage-fed than in the free-ranging animals. No marked difference in number of MHC-II + Langerhans cells was observed between the groups.     

Modified integrated optic Fresnal lens for waveguide-to-fiber coupling

The traditional design procedure for the waveguide Fresnel lens was carried over from those of bulk optics and micro-optics. In this design it is assumed that the lens thickness is negligibly small with respect to the focal length. This criterion does not hold for many integrated optic devices, in particular those with small mode-index modulations and long wavelengths. Under these conditions, the focal properties of the lens become unpredictable and the lens efficiency is reduced, both of which severely limit the usefulness of the lens as a waveguide-to-fiber coupler. To correct for this shortcoming, the standard Fresnel lens design procedure was modified to acocunt for the thickness of the lens explicitly. Both the standard and the modified Fresnel lens designs are outlined. A comparison of the limitations of the two lenses predicts better performance for the modified Fresnel lens. This is supported through computersimulation results for a pair of test lenses.     

Learning theory and behavior therapy: A reply to Rachman and Eysenck.

The importance of distinguishing between learning theory, the practice of behavior therapy, and the effectiveness of treatment is stressed. Rachman and Eysenck's reply (see 40:5) presents no new evidence to remedy the inadequacies of the learning theory espoused by the behavior-therapy group. The claim that behavior-therapy techniques are "based on" learning theory is countermanded by the prior existence of the techniques as well as by the great dissimilarity between what goes on in behavior therapy and in most learning experiments. Finally, the additional references cited by Rachman and Eysenck are reviewed. They are either not relevant to the issues under discussion or are fully subject to the biases discussed in our original paper. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased training in an aversively motivated task attenuates the memory-impairing effects of posttraining N-methyl-D-aspartate-induced amygdala lesions.

Examined the effect of variations in the amount of preoperative training on the retention deficit produced by posttraining lesions of the amygdaloid complex (AC). Rats received 1, 10, or 20 training trials in a footshock-motivated retention escape task 7 days before receiving N-methyl-{d}-aspartate (NMDA) lesions of the AC. Inhibitory avoidance retention performance, which was measured 4 days postoperatively, indicated that increased training improved retention in AC-lesioned animals as well as in control animals. The retention performance of AC-lesioned animals was impaired when compared with that of controls; however, the impairment was partially attenuated by increased preoperative training. The finding that AC-lesioned animals displayed greater locomotor activity on the retention test compared with nonlesioned controls suggests that the increased activity may have contributed to the impaired inhibitory avoidance retention performance. Two days after the retention test, some of the AC-lesioned animals were subsequently trained on a continuous multiple-trial inhibitory avoidance response in the same apparatus. AC lesions did not block acquisition or retention of the task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory of rats with amygdala lesions induced 30 days after footshock-motivated escape training reflects degree of original training.

This experiment was conducted to determine whether the amount of preoperative training influences the effects, on retention, of amygdala lesions induced 30 days after escape training. Rats received 1 or 10 footshock-motivated escape training trials; 30 days later, sham or neurotoxic amygdala lesions were induced. Results of an inhibitory avoidance test performed 4 days after surgery indicated that amygdala lesions impaired retention performance; however, increased preoperative training partially attenuated the retention deficit. Increased preoperative training also attenuated the impairing effects of the lesions on retention assessed in a continuous multiple-trial inhibitory avoidance task given 36 days after the original escape training. The finding that amygdala-lesioned rats remembered the escape training suggests that the amygdala is not a critical locus of the changes underlying the long-term retention of footshock-motivated escape training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)