Long-lasting effects of neonatal stimulation on the behavior of rats.

The present study aimed to analyze the effects of neonatal stimulation on species-specific behaviors (defensive reactions to a predator and social interactions) in adult male and female rats. Handling and an unpredictable sequence of aversive stimuli were applied to male and female pups from the 1st to the 10th day after delivery; behavioral inhibition, aggression, and sexual behavior were evaluated in adulthood. Results showed that either neonatal handling or aversive stimulation decreased behavioral inhibition in a novel and potentially harmful situation (open field with a predator) in both male and female rats and increased maternal aggressive behavior. Sexual behavior in both males and females decreased, which could affect reproductive capability. The results could cast doubts on the generalization of beneficial effects of neonatal stimulation on the behavior of adult rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of amygdaloid stimulation on amphetamine-elicited locomotor sensitization

We prospectively assessed the value of anti-neurtrophil cytoplasmic autoantibodies (ANCA) and nuclear or perinuclear anti-neutrophil autoantibodies measured by indirect immunofluorescence microscopy and antimyeloperoxidase autoantibodies measured by a solid-phase assay in the diagnosis of idiopathic (pauci-immune) necrotizing-crescentic glomerulonephritis (NCGN) and renal vasculitis at our institution. A diagnosis was established on the basis of clinical and renal biopsy findings, and follow-up continued for at least 6 months. ANCA were measured at the conclusion of the study. Of the 111 study patients, 28 had NCGN and renal vasculitis. The immunofluorescence assay had 50% sensitivity and 79% specificity. The combination of the enzyme-linked immunosorbent assay for antimyeloperoxidase autoantibodies and the immunofluorescence assay for cytoplasmic ANCA had 78% sensitivity and 84% specificity. A firm diagnosis was established before the determination of ANCA in 26 of the 28 patients with NCGN and renal vasculitis. The antimyeloperoxidase autoantibody values would have suggested the diagnosis in the other two patients. Of these 28 patients, 5 had negative ANCA results. High antimyeloperoxidase autoantibody values were detected in patients with NCGN and renal vasculitis, whereas lower values were less specific and were detected mainly in patients with anti-glomerular basement membrane antibody disease and lupus glomerulonephritis.     

Behavioral and pharmacological specificity of the feeding elicited by cholinergic stimulation of the substantia nigra in the rat.

In 4 experiments, microinjections of the cholinergic agonist carbachol into anterior substantia nigra dose dependently increased food intake in satiated rats (31 male Listar hooded rats and 13 hooded PVG/C rats). This resulted from a prolongation of the duration of eating. In the absence of food, those doses of carbachol that stimulated food intake (.1 and .5 μg) had no effect on any other response examined, including gnawing, drinking, locomotion, grooming, sniffing, and rearing. The effect of carbachol depended on the degree of prior food deprivation, but supra-additive effects of carbachol and deprivation were not observed. These results are contrasted with those of previous studies demonstrating the nonspecific behavioral effects of electrical stimulation of the brain and of studies showing that carbachol has radically different behavioral effects at other CNS sites. Microinjection of an acetylcholine/eserine sulfate mixture also significantly increased food intake. This response was abolished by prior microinjection of the muscarinic receptor antagonist atropine into the substantia nigra, a result that provides evidence for pharmacological specificity of the behavioral effects. Data provide further evidence for the hypothesis that a functional cholinergic system is present within substantia nigra. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociating the anti-fear effects of septal and amygdaloid lesions using two pharmacologically validated models of rat anxiety.

Compared the effects of septal and amygdaloid lesions in 2 models of rat anxiety. Septal lesions decreased burying behavior in the shock-probe burying test and increased open-arm exploration in the elevated plus-maze test, whereas amygdaloid lesions produced neither of these anxiolytic effects. However, amygdaloid lesions increased rats' contacts of the electrified probe, an anxiolytic effect not produced by septal lesions. Each of these distinct, anxiolytic effects of septal or amygdaloid lesions were displayed together in animals with lesions of both structures. Furthermore, the magnitude of these anxiolytic effects after combined lesions were comparable to their magnitude after individual lesions. Taken together, these results suggest that the amygdala and the septum independently control the expression of different fear-related behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of cholinergic mediation of behaviors in the rat.

In 6 experiments with 159 immature Sprague-Dawley rats it was found that although scopolamine disrupted discriminative choice behavior in both 15- and 23-day-old pups, it increased latency to choice in 15-day-olds and decreased it in 23-day-olds. This disruption of discriminated choice behavior was not due to differential shock thresholds or differences in locomotor activity between drug-treated and control Ss, nor was it specific to a T-maze shock-escape discrimination task. Results suggest that central cholinergic mediation of different behaviors may mature at different rates. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cytological effects of urecholine stimulation on the rat pancreas

Stimulation of the exocrine pancreas by the secretagogue urecholine caused degranulation of the acinar cells. Under in vivo conditions, this degranulation is not uniform throughout the tissue. Indeed some of the acini are almost completely depleted of their granules while others display the appearance of resting acini. A noticeable feature is that all the cells of the same acinus display a comparable degree of degranulation. Moreover, groups of neighbouring acini seem to respond simultaneously suggesting that the secretory stimulus is propagated from one acinus to the other. In vitro stimulation of dispersed acini also showed that some of the acini are more responsive than others indication that this phenomenon can not be attributed to accessibility of the secretagogue to its receptor. These observations lead us to accessibility of the secretagogue to its receptor. These observations lead us to the concept that the response of the pancreatic acinar cell is controlled at the level of the acinus.     

Fear reduction in the rat following central cholinergic blockade.

In the presence of a natural predator, cat, 92 male Long-Evans hooded rats (in 2 experiments) showed a constellation of responses that was used to define fear: freezing, avoiding the cat, and suppressing consummatory behavior. Compared with controls, Ss treated with an anticholinergic drug, scopolamine, showed significantly less freezing and significantly more approach to the cat; further, these Ss actually engaged in consummatory behavior in proximity to the cat. On a 2nd, undrugged exposure to the cat, the original scopolamine-treated Ss continued to show significantly less freezing, more approach, and more drinking than control Ss. Since methyl scopolamine, which mimics the peripheral actions of scopolamine, had no effect on fear responses, these results implicate a central cholinergic system in fear responses or species-typical defense reactions. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-lasting effects of IMHV lesions on social preferences in domestic fowl.

Imprinting leads to strong filial attachment to the mother. Later it influences mate choice. Although nothing is known about the brain regions involved in adult sexual preferences, a particular region of the domestic chick's forebrain (IMHV) has been implicated in filial imprinting. In the present experiment lesions were placed in this region of female chicks soon after hatching. When these and control birds were adult, their sexual preferences were tested. The sham-operated control females had preferences for a male that differed slightly from one with which they had been reared. In contrast, females with lesions did not show a clear preference. It is suggested that the lesion impairs filial and sexual imprinting by disrupting the ability of chicks to learn the characteristics of individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned effects of kindling three different sites in the hippocampal complex of the rat.

Rats received kindling stimulations to the perirhinal cortex (PRh), ventral hippocampus (VH), or dorsal hippocampus (DH) in 1 environment and an equivalent number of sham stimulations in a 2nd environment. The PRh-kindled rats displayed rapid kindling and a swift emergence of conditioned interictal defensiveness. In contrast, the VH- and DH-kindled rats displayed much slower kindling and slow or no conditioning, respectively. No effects of conditioning on the convulsions, comparable with those associated with amygdala kindling, were observed. These results establish the generality of some of the previously reported kindling-related conditioned effects, confirm the site specificity of some of these effects, and suggest that the convulsions, rather than the stimulations, function as the unconditioned stimuli for the conditioning of interictal behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calbindin-D28K-immunoreactive cells and fibres in the human amygdaloid complex

The distribution of calbindin-D28k-immunoreactive cells and fibres in five human amygdalae was analysed from sections that had been stained immunohistochemically with a monoclonal antibody raised against calbindin-D28k. The highest density of calbindin-D28k-positive neurons were found in the anterior cortical, medial, posterior cortical and accessory basal nuclei, in the parvicellular division of the basal nucleus and in the amygdalohippocampal area. The lowest densities of immunopositive neurons were found in the paralaminar nucleus, in the periamygdaloid cortex (PAC1 and PACo) and in some of the intercalated nuclei. The deep nuclei (lateral, basal and accessory basal nuclei) contained a high density of calbindin-D28k-immunoreactive fibres and terminals. The cortical nuclei and the central nucleus were characterized by intense neuropil labelling. Morphologically, a large majority of the calbindin-D28k-immunoreactive neurons were aspiny or sparsely spiny and resembled inhibitory local circuit neurons. A small population of lightly-stained, pyramidal-shaped neurons was also observed. In most of the amygdaloid nuclei, calbindin-D28k-immunoreactive fibres travelled close to each other and formed bundles, which suggests that some of the immunostained neurons were double-bouquet cells. In the paralaminar nucleus, the calbindin-D28k-immunoreactive axons formed tortuous plexus (100-200 microns in diameter) that surrounded several unstained somata. This study provides baseline information on the morphology and distribution of calcium-binding protein-containing inhibitory cells and fibres immunoreactive for calbindin-D28k in the human amygdaloid complex. This information can be used in future studies on the pathogenesis of diseases known to damage the amygdala, such as Alzheimer's disease and temporal lobe epilepsy.     

Competition and summation between rewarding effects of sucrose and lateral hypothalamic stimulation in the rat.

Rats were offered a forced choice between a train of brain stimulation that varied in strength from trial to trial and a fixed standard reward. This standard reward consisted of an intraoral sucrose infusion presented either alone or paired with an equipreferred train of brain stimulation. Postingestional effects were minimized by opening a gastric cannula. The presence of a sucrose standard led the Ss to forgo trains of brain stimulation for which they had responded when the sucrose was absent. The strength of the brain stimulation required to balance the compound reward exceeded the stimulation strength required to balance a reward consisting of sucrose alone. These results imply that the rewarding effects of brain stimulation and intraoral sucrose can be evaluated in a common system of measurement and combined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proactive behavioral effects of theta-driving septal stimulation on conditioned suppression and punishment in the rat.

In 2 experiments, a treatment phase of septal stimulation preceded the acquisition of free operant leverpressing on a random-interval 64-sec reinforcement schedule. 32 male Sprague-Dawley rats were chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode. Ss received (a) low-frequency (7.7 Hz) stimulation, which drove the hippocampal theta rhythm; (b) random-pulse stimulation (average frequency 7.7 Hz), which produced only nonregular waveforms in the hippocampus; or (c) no stimulation. After 12 days of leverpress acquisition, Ss were presented while leverpressing with an auditory signal associated with a particular schedule of shock delivery: In Exp I, shocks occurred despite the S's response strategy; in Exp II, shocks were delivered only if the S pressed the lever. In both experiments, leverpressing was suppressed by the auditory stimulus. Theta-driving but not random-pulse septal stimulation proactively increased behavioral tolerance to the effects of electric shock. Results support the idea that proactive behavioral effects of septal stimulation are a consequence of the production of the hippocampal theta rhythm. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste-potentiated odor aversion learning: Role of the amygdaloid basolateral complex and central nucleus.

Examined the relative contributions of the amygdaloid basolateral complex (ABL) and central nucleus (CN) to taste-potentiated odor aversion (TPOA) learning, an associative learning task that is dependent on information processing in 2 sensory modalities. In Exp 1, rats with neurotoxic lesions of these systems were trained on the TPOA task by presenting a compound taste–odor conditioned stimulus (CS), which was followed by LiCl administration. Results showed that ABL damage caused an impairment in potentiated odor aversion learning but no deficit in the conditioned taste aversion. In contrast, rats with CN damage learned both tasks. Exp 2 examined the effects of ABL damage on TPOA and odor discrimination learning. The odor discrimination procedure used a place preference task to demonstrate normal processing of olfactory information. Results indicated that although ABL-lesioned animals were impaired on TPOA, there was no deficit in odor discrimination learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of electrical stimulation of the amygdaloid central nucleus on neocortical arousal in the rabbit

This study sought to determine whether electrical stimulation of the amygdaloid central nucleus (ACe) produces cholinergically mediated neocortical arousal manifested in the suppression of frontal cortex delta wave (1-4 Hz) activity. Stimulation in both anesthetized and conscious rabbits produced a suppression of delta activity that was accompanied by bradycardia and blocked by cholinergic antagonists. Stimulation of the adjacent putamen did not produce delta suppression, whereas stimulation of the adjacent ventral globus pallidus produced a suppression of shorter duration than that produced by ACe stimulation. The results suggest that the ACe influences neocortical arousal, which may be mediated by its influence on the activity of cholinergic neurons of the nucleus basalis.     

Time structure of self-grooming in the rat: Self-facilitation and effects of hypothalamic stimulation and neuropeptides.

Specific brain manipulations, such as stimulation of the paraventricular nucleus of the hypothalamus (PVH) or injections of neuropeptides, increase self-grooming in the rat. Such manipulations also affect the different movements that constitute grooming. Using models to assess the time structure of these movements, the authors demonstrate that the rules that control the time structure within grooming are different from the ones that control its initiation. This study also showed that grooming is self-facilitating and that different brain manipulations in the same hypothalamic area induce structurally different kinds of grooming. The authors suggest that this part of the hypothalamus is not only involved in setting priorities to grooming, relative to other behaviors, but is also involved in the timing of different grooming components. These findings suggest that different neural mechanisms may be involved in the initiation and internal time structure of grooming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The cholinergic agent physostigmine enhances short-term-memory-based performance in the developing rat.

There are age-related differences in the rat's short-term memory processes. Rats 24–25 days old are 90% correct when the delay interval separating the forced run and choice run of a trial is either 10 or 30 s, but they perform at chance when the delay interval is 60 s. In contrast, the choice performance of 30-day-old rats remains constant across all delay intervals. It is reported that the cholinergic agent physostigmine dramatically improved the short-term-memory-based performance of rats 24–25 days old such that they displayed no loss in choice accuracy even when the delay interval was 60 s. No such enhanced performance was seen in rats treated with neostigmine, a peripherally acting anticholinesterase. The results support the hypothesis that postnatal maturational differences in central cholinergic systems may contribute to age-related differences in short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociations among the anxiolytic effects of septal, hippocampal, and amygdaloid lesions.

Fear reactions of rats given bilateral lesions to the septum, hippocampus, or amygdala were compared with those of rats given sham lesions, in 2 animal models of anxiety: the shock-probe burying test and the elevated plus-maze test. Septal lesions produced anxiolytic effects in both tests (i.e., an increase in open-arm activity and a decrease in burying), whereas hippocampal and amygdaloid lesions produced neither of these effects. On the other hand, hippocampal and amygdaloid lesions impaired rats' passive avoidance of the electrified shock-probe, whereas septal lesions did not. These dissociations suggest that limbic structures such as the septum, amygdala, and hippocampus exert parallel but distinct control over different fear reactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-lasting effects of briefly flashed words and pseudowords in ultrarapid serial visual presentation.

Our ability to identify even complex scenes in rapid serial visual presentation (RSVP) is astounding, but memory for such items seems lacking. Rather than pictures, we used streams of more than 200 verbal stimuli, rushing by on the screen at a rate of more than 12 items per second while participants had to detect infrequent names (Experiments 1 and 2) or words written in capitals (Experiment 3). By direct and indirect tests, we investigated what is remembered of these masses of task-irrelevant distractor words and pseudowords embedded in an RSVP stream. Lexical decision, the indirect test applied either immediately after each stimulus train or with a delay, revealed strong long-term priming effects. Relative to stimuli not shown before, lexical decisions were faster and more accurate to words but slower to pseudowords. The size of these effects mirrored how often words and pseudowords had occurred in a stream, suggesting that memory traces are strengthened with successive presentations and survive for several minutes at least. Moreover, in a direct test (old–new categorization), words as well as pseudowords benefited from prior occurrence in an RSVP stream if they had occurred more than once. These findings parallel recent physiological and behavioral evidence for memory consolidation of distractor pictures in RSVP and highlight that, despite huge numbers of interfering stimuli, distractor words and pseudowords exhibit long-lasting memory effects. Consolidation seems to progress at higher cognitive levels at the same time that subsequent stimuli are perceptually processed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)