An Inescapable Cat Odor Exposure Protocol for Studying Innate and Contextual Threat Conditioning in Rats.

Animals respond to threatening situations by exhibiting a number of defensive behaviors, including avoidance, freezing, and risk assessment. An animal model with an ethological approach offers a deeper insight into the biological mechanisms underlying threat responses. This paper describes a methodology to measure defensive behaviors toward both innate and learned aversive stimuli in rats.

Interoceptive insular cortex participates in sensory processing of gastrointestinal malaise and associated behaviors.

The insular cortex plays a central role in the perception and regulation of bodily needs and emotions. Its modular arrangement, corresponding with different sensory modalities, denotes a complex organization, and reveals it to be a hub that is able to coordinate autonomic and behavioral responses to many types of stimuli. Yet, little is known about the dynamics of its electrical activity at the neuronal level.

Interoceptive Insular Cortex Mediates Both Innate Fear and Contextual Threat Conditioning to Predator Odor.

The insular cortex (IC), among other brain regions, becomes active when humans experience fear or anxiety. However, few experimental studies in rats have implicated the IC in threat responses. We have recently reported that inactivation of the primary interoceptive cortex (pIC) during pre-training, or the intra-pIC blockade of protein synthesis immediately after training, impaired the consolidation of auditory fear conditioning.

Effort Displayed During Appetitive Phase of Feeding Behavior Requires Infralimbic Cortex Activity and Histamine H1 Receptor Signaling.

The chances to succeed in goal-directed behaviors, such as food or water-seeking, improve when the subject is in an increased arousal state. The appetitive phase of these motivated behaviors is characterized by high levels of behavioral and vegetative excitation. The key decision of engaging in those particular behaviors depends primarily on prefrontal cortical areas, such as the ventromedial prefrontal cortex.

The activity of discrete sets of neurons in the posterior insula correlates with the behavioral expression and extinction of conditioned fear.

The interoceptive insular cortex is known to be involved in the perception of bodily states and emotions. Increasing evidence points to an additional role for the insula in the storage of fear memories. However, the activity of the insula during fear expression has not been studied.

Plasticity in the Interoceptive System.

The most outstanding manifestations of the plastic capacities of brain circuits and their neuronal and synaptic components in the adult CNS are learning and memory. A reduced number of basic plastic mechanisms underlie learning capacities at many levels and regions of the brain. The interoceptive system is no exception, and some of the most studied behavioral changes that involve learning and memory engage the interoceptive pathways at many levels of their anatomical and functional organization.

The Histaminergic Tuberomamillary Nucleus Is Involved in Appetite for Sex, Water and Amphetamine.

The histaminergic system is one component of the ascending arousal system which is involved in wakefulness, neuroendocrine control, cognition, psychiatric disorders and motivation. During the appetitive phase of motivated behaviors the arousal state rises to an optimal level, thus giving proper intensity to the behavior. Previous studies have demonstrated that the histaminergic neurons show an earlier activation during the appetitive phase of feeding, compared to other ascending arousal system nuclei, paralleled with a high increase in arousal state.

A role for the interoceptive insular cortex in the consolidation of learned fear.

A growing body of evidence suggests that learned fear may be related to the function of the interoceptive insular cortex. Using an auditory fear conditioning paradigm in rats, we show that the inactivation of the posterior insular cortex (pIC), the target of the interoceptive thalamus, prior to training produced a marked reduction in fear expression tested 24h later. Accordingly, post-training anisomycin infused immediately, but not 6h after, also reduced fear expression tested the following day, supporting a role for the pIC in consolidation of fear memory.

Infralimbic cortex activation and motivated arousal induce histamine release.

Appetitive behaviours occur in a state of behavioural and physiological activation that allows the optimal performance of these goal-directed behaviours. Here, we tested the hypothesis that histamine neurons under the command of the infralimbic cortex are important to provide behavioural activation. Extracellular histamine and serotonin were measured by microdialysis of the medial prefrontal cortex in behaving rats in parallel with a picrotoxin microinjection into the infralimbic cortex.

Effect of insular cortex inactivation on autonomic and behavioral responses to acute hypoxia in conscious rats.

The present work was aimed to evaluate the contribution of interoception to the autonomic and behavioral responses to hypoxia. To address this issue, we studied whether the inactivation of the primary interoceptive posterior insular cortex (pIC) may disrupt the autonomic and behavioral effects of hypoxia in conscious rats. Rats were implanted with telemetric transmitters and microinjection cannulae placed bilaterally in the pIC.

Histamine and motivation.

Brain histamine may affect a variety of different behavioral and physiological functions; however, its role in promoting wakefulness has overshadowed its other important functions. Here, we review evidence indicating that brain histamine plays a central role in motivation and emphasize its differential involvement in the appetitive and consummatory phases of motivated behaviors. We discuss the inputs that control histaminergic neurons of the tuberomamillary nucleus (TMN) of the hypothalamus, which determine the distinct role of these neurons in appetitive behavior, sleep/wake cycles, and food anticipatory responses.

The histamine H3 receptor and eating behavior.

Interest in the histaminergic system as a potential target for the treatment of feeding disorders is driven by the unsatisfactory history of the pharmacotherapy of obesity. Eating behavior is regulated by a complex interplay of central neurotransmitter systems, peripheral endocrine stimuli, the circadian rhythm, and environmental cues, all factors that change the behavioral state and alter homeostatic aspects of appetite and energy expenditure. Key factors driving eating behavior are appetite and satiety that are regulated through different mechanisms.

Orexin-B-saporin lesions in the lateral hypothalamus enhance photic masking of rapid eye movement sleep in the albino rat.

The 24-h distribution of rapid eye movement (REM) sleep is known to be deeply reshaped among albino rats with neurotoxic lesions in the lateral hypothalamus (LH) or among rodent models of human narcolepsy-cataplexy, with selective damage of orexinergic neurones. We explored the hypothesis that this phenomenon is explained by an enhancement of REM sleep photic masking, as a consequence of damage in the LH. Orexin-B-saporin neurotoxic lesions were induced in the LH of male Sprague-Dawley rats.

The histaminergic tuberomammillary nucleus is critical for motivated arousal.

Obtaining food, shelter or water, or finding a mating partner are examples of motivated behaviors, which are essential to preserve the species. The full expression of such behaviors requires a high but optimal arousal state. We tested the idea that tuberomammillary nucleus (TMN) histamine neurons are crucial to generate such motivated arousal, using a model of the appetitive phase of feeding behavior.

The parietal association cortex of the rat.

Spatial cognition is a complex higher function in mammals and is involved in a variety of tasks that can be explored in the laboratory. In this review we will discuss the role of the posterior parietal/anteromedial cortex of rodents, also known as the parietal association cortex, and the hippocampal formation in spatial navigation. We will also discuss other higher associational functions of the posterior parietal/anteromedial cortex as they relate to Dr.

Antiribosomal-P autoantibodies from psychiatric lupus target a novel neuronal surface protein causing calcium influx and apoptosis.

The interesting observation was made 20 years ago that psychotic manifestations in patients with systemic lupus erythematosus are associated with the production of antiribosomal-P protein (anti-P) autoantibodies. Since then, the pathogenic role of anti-P antibodies has attracted considerable attention, giving rise to long-term controversies as evidence has either contradicted or confirmed their clinical association with lupus psychosis. Furthermore, a plausible mechanism supporting an anti-P-mediated neuronal dysfunction is still lacking.

Inactivation of the interoceptive insula disrupts drug craving and malaise induced by lithium.

Addiction profoundly alters motivational circuits so that drugs become powerful reinforcers of behavior. The interoceptive system continuously updates homeostatic and emotional information that are important elements in motivational decisions. We tested the idea that interoceptive information is essential in drug craving and in the behavioral signs of malaise.

Maternal melatonin stimulates growth and prevents maturation of the capuchin monkey fetal adrenal gland.

The primate fetal adrenal reaches a large size relative to body weight followed by a rapid decrease in size in the postnatal period. We tested the hypothesis that maternal melatonin stimulates growth and prevents maturation of the primate fetal adrenal gland. We suppressed maternal melatonin by exposing eight pregnant capuchin monkeys to constant light (LL) from 63% to 90% gestation (term 155 days).

The infralimbic cortical area commands the behavioral and vegetative arousal during appetitive behavior in the rat.

The infralimbic cortical area is a good candidate to send processed motivational signals to initiate the arousing and autonomic responses that characterize appetitive behaviors. To test this hypothesis we enticed hungry rats with food while assessing locomotion (as an index of arousal level) and temperature responses, and evaluated Fos immunoreactivity (IR) in the infralimbic area and in subcortical nuclei involved in thermoregulation or arousal. We also recorded from single infralimbic neurons in freely moving rats while enticing them with food.

Specific activation of histaminergic neurons during daily feeding anticipatory behavior in rats.

When food is available during a restricted and predictable time of the day, animals show increased locomotor and food searching behaviors before the anticipated daily meal. We had shown that histamine-containing neurons are the only aminergic neurons related to arousal that become active in anticipation of an upcoming meal. To further map, the brain regions involved in the expression of the feeding-anticipatory behavior, we quantified the expression of Fos in hypothalamic areas involved in arousal.

A review on electron microscopy and neurotransmitter systems.

The purpose of this article is to review the contributions of transmission electron microscopy studies to the understanding of brain circuits and neurotransmitter systems. Our views on the microstructure of connections between neurons have gradually changed, and now we recognize that the classical mental image we had on a chemical synapse is no longer applicable to every neuronal connection. We highlight studies that converge to point out that, while the most prevalent fast transmitters in the brain, glutamate and GABA, are stored in small, clear synaptic vesicles (SSV) and released at synapses, neuropeptides are exclusively stored in large dense core vesicles (LDCV) and released extrasynaptically.

Neurotoxic lesion of anteromedial/posterior parietal cortex disrupts spatial maze memory in blind rats.

The primary visual cortex of rats is surrounded laterally (in Oc2L) and medially (in Oc2M) by several peristriate visual areas. Previous studies from our laboratory demonstrated that bilateral lesions in Oc2L result in visual pattern discrimination deficit, and in failure to solve a conditional discrimination which requires figure-background association. In contrast, neurotoxic lesions of the rostral part of Oc2M (which contains the anteromedial and anterior peristriate visual areas, collectively referred to as AM complex) result in deficits in visuospatial discrimination, and in disruptions in visual tasks involving spatial memory.

The circadian timing system: making sense of day/night gene expression.

The circadian time-keeping system ensures predictive adaptation of individuals to the reproducible 24-h day/night alternations of our planet by generating the 24-h (circadian) rhythms found in hormone release and cardiovascular, biophysical and behavioral functions, and others. In mammals, the master clock resides in the suprachiasmatic nucleus (SCN) of the hypothalamus. The molecular events determining the functional oscillation of the SCN neurons with a period of 24-h involve recurrent expression of several clock proteins that interact in complex transcription/translation feedback loops.