Limbic Structures and Behavior: Endocrine Correlates

Effects of early stimulation and/or perinatal flumazenil on emotional behavior of two psychogenetically-selected rat lines with divergent emotionality profiles

Lesioning of the rat basal forebrain leads to memory impairments in passive and active avoidance tasks

Previous experiments on two-way active avoidance have shown conflicting results after nucleus basalis magnocellularis lesion: disrupting effects with electrolytic lesions and facilitative effects with excitotoxic lesions. To resolve this issue, in this experiment, Wistar rats received pre-training bilateral electrolytic or ibotenic acid lesions and were trained in a massed two-way active avoidance conditioning. In order to test the long-term retention of the learned response, one additional session was conducted 10 days after the acquisition. Results showed that whereas electrolytic lesions did not affect the acquisition, ibotenic acid lesions enhanced it. Retention of active avoidance response was impaired by both electrolytic and ibotenic lesions of the NBM. These results suggest a role of the NBM in the memory consolidation and/or retrieval of two-way active avoidance.

Effects of different handling-stimulation procedures and benzodiazepines on two-way active avoidance acquisition in rats

Analysis of the avoidance learning deficit induced by the serotonin releasing compound p-chloroamphetamine

Effect of reversible inactivation of reuniens nucleus on memory processing in passive avoidance task

The present study examined the role of the 5-HT1B receptor in learning and memory. The ability of the 5-HT1B receptor agonist anpirtoline and the selective 5-HT1B receptor antagonist NAS-181 to affect spatial learning in the water maze (WM) and aversive learning in the passive avoidance (PA) task were examined in the rat. Anpirtoline (0.1-1.0 mg/kg, s.c.) caused a dose-dependent impairment of learning and memory in both the WM and PA tasks. NAS-181 (1.0-10 mg/kg, s.c.) failed to alter performance of the WM task, but produced a dose-dependent (0.1-20 mg/kg) facilitation of PA retention. Furthermore, treatment with NAS-181 (10 mg/kg) fully blocked the impairment of the WM and PA performance caused by anpirtoline (1.0 mg/kg). In contrast, NAS-181 (3.0-10 mg/kg) did not attenuate the spatial learning deficit and the impairment of PA retention caused by scopolamine (0.1 mg/kg in WM task, 0.3 mg/kg in PA task, s.c.), a nonselective muscarinic antagonist. Moreover, a subthreshold dose of scopolamine (0.1 mg/kg) blocked the facilitation of PA retention induced by NAS-181 (1.0-10 mg/kg). In addition, the behavioral disturbances (eg thigmotaxic swimming and platform deflections) induced by anpirtoline and scopolamine were analyzed in the WM task and correlated with WM performance. These results indicate that: (1) 5-HT1B receptor stimulation and blockade result in opposite effects in two types of cognitive tasks in the rat, and that (2) the 5-HT1B antagonist NAS-181 can facilitate some aspects of cognitive function, most likely via an increase of cholinergic transmission. These results suggest that 5-HT1B receptor antagonists may have a potential in the treatment of cognitive deficits resulting from loss of cholinergic transmission.

The effects of excitotoxic lesion of the medial prefrontal cortex on latent inhibition, prepulse inhibition, food hoarding, elevated plus maze, active avoidance and locomotor activity in the rat

Effects of electrical stimulation of the nucleus basalis on two-way active avoidance acquisition, retention, and retrieval

Active and passive avoidance learning in rats neonatally treated with intraventricular 6-hydroxydopamine

The term limbic system refers to a group of forebrain structures that lie beneath the neocortical surface, bordering the neocortex and hypothalamus. Based on this positioning, it was believed that these structures formed the anatomic basis linking subjective emotional experience, mediated by the neocortex, to emotional behaviors, mediated by the hypothalamus and its connections. Modern neuroscience, however, has shown that limbic structures do not serve a unified function and that some limbic structures do not play a predominant role in emotional function. This chapter presents the history of the concept of the limbic system and discusses the function of limbic structures in emotional behaviors and motivational drives, namely the cingulate gyrus, amygdala, nucleus accumbens, and septal nuclei. It also discusses the clinical relevance of these structures, including anterior cingulotomy, Klüver-Bucy syndrome, aggression, fear and anxiety, reward and pleasure, limbic encephalitis, and deep brain stimulation for psychiatric disorders.

Effects of infant and adult amygdaloid lesions upon acquisition of two-way active avoidance by the adult rat: Influence of rearing conditions

Effect of pretraining administration of NC-1900, a vasopressin fragment analog, on memory performance in non- or CO 2-amnesic mice

Memory facilitating and anti-amnesic effects of corticosteroids

In female rats subjected to a 12 hr light-12 hr darkness schedule and fed a semipurified diet containing 10% corn oil, plasma corticosterone concentration showed a monophasic circadian cycle with minimum and maximum concentrations at the start of the light and dark periods, respectively. Adrenal total cholesteryl ester concentration was inversely related to plasma corticosterone, as were those of several of the individual esters; changes in cholesteryl ester concentration appeared to follow rather than precede changes in plasma corticosterone. There was preferential depletion of the cholesteryl esters of 18:1, 18:2omega6, and 20:4omega6 during glucocorticoid secretion. [ EFA, essential fatty acid (s);X:YomegaZ, fatty acid with X carbon atoms and Y olefinic bonds with the terminal double bond Z carbon atoms from the methyl group.] In female rats fed hydrogenated coconut oil (EFA-deficient), a monophasic cycle for plasma corticosterone was also observed, but the peak was much broader than that recorded for rats fed corn oil, although minima and maxima occurred at similar times for the two groups. No significant cycle of adrenal total cholesteryl esters was evident in the deficient rats, but the 20:3omega9 and 22:3omega9 esters did decrease significantly during the period of high plasma corticosterone concentration. Preferential net decreases in adrenal cholesteryl esters during corticosteroidogenesis were more apparent in normal than in EFA-deficient rats.