Differential effects of glucocorticoids on human auditory perception

Basal plasma oxytocin & fecal cortisol concentrations are highly heritable and associated with individual differences in behavior & cognition in dog puppies

Oxytocin and cortisol are hormones that can influence cognition and behavior, but the relationships between endogenous concentrations and individual differences in cognitive and behavioral phenotypes remain poorly understood. Across mammals, oxytocin has important roles in diverse social behaviors, and in dogs, it has been implicated in human-oriented behaviors such as social gaze and point-following. Cortisol, an end-product of the hypothalamic-pituitary-adrenal (HPA) axis, is often studied in relation to temperament and emotional reactivity, but it is also known to modulate executive functions. In this study, we measured basal fecal cortisol (n = 247) and plasma oxytocin (n = 249) in dog puppies from a pedigreed population (Canine Companions ®). We collected cognitive and behavioral data from these subjects (n = 247), including measures of human-oriented social cognition, memory, inhibitory control, perceptual discriminations, and temperament. Oxytocin concentrations were estimated to be very highly heritable (h2 = 0.90-0.99) and cortisol concentrations were estimated to be moderately-highly heritable (h2 = 0.43-0.47). Bayesian mixed models controlling for relatedness revealed that oxytocin concentrations were positively associated with spatial working memory and displayed a negative quadratic relationship with behavioral laterality, but no credible associations were seen for social measures. Cortisol concentrations exhibited a negative linear relationship with performance on an inhibitory control task and a negative quadratic relationship with bold behavioral reactions to a novel object. Collectively, our results suggest that individual differences in oxytocin and cortisol concentrations are under strong genetic control in dogs and are associated with phenotypic variation in aspects of temperament, behavioral laterality, and executive function.

Increased sensitivity to unpleasant odor following acute psychological stress

Previous studies have reported increased sensitivity to malodor after acute stress in humans. However, it is unclear whether stress-related "hypersensitivity" to odors depends on odor pleasantness. Forty participants (mean age 19.13 ± 1.14 years, 21 men and 19 women) completed a stress (Trier Social Stress Test, TSST) and a control session in randomized order. Detection threshold to three odors varying in pleasantness (pleasant: β-Citronellol; neutral: 2-Heptanol; unpleasant: 4-Methylpentanoic acid), odor discrimination, odor identification, sensitivity to trigeminal odor, and suprathreshold odor perception were assessed after participants' completion of the stress or the control tasks. Salivary cortisol, subjective stress, and heart rate were assessed throughout the experiment. After TSST, participants showed an increased sensitivity for the unpleasant odor. Moreover, there were correlations between stress-related salivary cortisol and the increased sensitivity for the unpleasant odor (r = 0.32, p = 0.05) and the neutral odor (r = 0.34, p < 0.05). Besides, salivary cortisol response was correlated to the increased odor discrimination performance (Δ stress - control) (r = 0.34, p < 0.05). The post-TSST perceived stress was correlated with decreased odor identification and decreased sensitivity to the unpleasant odor. After stress, participants rated lower pleasantness for β-Citronellol than the control condition. Overall, these results suggest the impact of acute psychological stress on odor sensitivity depends on the odor valence, and that the stress-related cortisol responses may play an important role in this effect.

Chronic stress induced loudness hyperacusis, sound avoidance and auditory cortex hyperactivity

Hyperacusis, a debilitating loudness intolerance disorder, has been linked to chronic stress and adrenal insufficiency. To investigate the role of chronic stress, rats were chronically treated with corticosterone (CORT) stress hormone. Chronic CORT produced behavioral evidence of loudness hyperacusis, sound avoidance hyperacusis, and abnormal temporal integration of loudness. CORT treatment did not disrupt cochlear or brainstem function as reflected by normal distortion product otoacoustic emissions, compound action potentials, acoustic startle reflexex, and auditory brainstem responses. In contrast, the evoked response from the auditory cortex was enhanced up to three fold after CORT treatment. This hyperactivity was associated with a significant increase in glucocorticoid receptors in auditory cortex layers II/III and VI. Basal serum CORT levels remained normal after chronic CORT stress whereas reactive serum CORT levels evoked by acute restraint stress were blunted (reduced) after chronic CORT stress; similar changes were observed after chronic, intense noise stress. Taken together, our results show for the first time that chronic stress can induce hyperacusis and sound avoidance. A model is proposed in which chronic stress creates a subclinical state of adrenal insufficiency that establishes the necessary conditions for inducing hyperacusis.

The olfactory mucosa, first actor of olfactory detection, is sensitive to glucocorticoid hormone

The olfactory mucosa (OM) is the primary site of odorant detection, and its axonal projections relay information to brain structures for signal processing. We have previously observed that olfactory function can be affected during a prolonged stress challenge in Wistar rats. The stress response is a neuroendocrine retro-controlled loop allowing pleiotropic adaptive tissue alterations, which are partly mediated through the release of glucocorticoid hormones. We hypothesised that, as part of their wide-ranging pleiotropic effects, glucocorticoids might affect the first step of olfactory detection. To study this, we used a number of approaches ranging from the molecular detection and functional characterisation of glucocorticoid receptors (GRs) in OM cells, to the study of GR acute activation in vivo at the molecular, electrophysiological and behavioural levels. In contrast to previous reports, where GR was reported to be exclusive in olfactory sensory neurones, we located functional GR expression mostly in olfactory ensheathing cells. Dexamethasone (2 mg/kg) was injected intraperitoneally to activate GR in vivo, and this led to functional odorant electrophysiological response (electro-olfactogram) and OM gene expression changes. In a habituation/cross-habituation test of olfactory sensitivity, we observed that DEX-treated rats exhibited higher responsiveness to a complex odorant mixture. These findings support the idea that olfactory perception is altered in stressed animals, as glucocorticoids might enhance odour detection, starting at the first step of detection.

Acute stress enhances pupillary responses to erotic nudes: Evidence for differential effects of sympathetic activation and cortisol

Chronic stress attenuates reproductive behavior in many species, but evidence regarding the impact of acute stress on human sexual arousability is insufficient. Stressor-specific effects might result from divergent roles of both stress response systems. Social self-threat, linked to affiliation-oriented coping, might also influence sexual responsivity. To investigate stress-induced modulation of the processing of sexual cues and its relationship with cortisol, 58 participants underwent either a predominantly sympathetic stressor (3 min sustained handgrip) or similar control procedure. In both conditions, half of the sample was monitored by an opposite-sex person (social evaluation). Pupillary responses to erotic nudes were recorded and dissociated into fast and slow PCA components. Physically stressed participants showed enhanced (slow) dilation to explicit pictures. Cortisol levels after stress negatively predicted rapid responses to opposite-sex and (marginally) explicit stimuli. Our results suggest that acute sympathetic stress exposure facilitates cognitive sexual processing, whereas subsequent HPA-axis activation may induce counteracting effects.

Cellular Mechanisms of Cortisol-Induced Changes in Mauthner-Cell Excitability in the Startle Circuit of Goldfish

Predator pressure and olfactory cues (alarm substance) have been shown to modulate Mauthner cell (M-cell) initiated startle escape responses (C-starts) in teleost fish. The regulation of such adaptive responses to potential threats is thought to involve the release of steroid hormones such as cortisol. However, the mechanism by which cortisol may regulate M-cell excitability is not known. Here, we used intrasomatic, in vivo recordings to elucidate the acute effects of cortisol on M-cell membrane properties and sound evoked post-synaptic potentials (PSPs). Cortisol tonically decreased threshold current in the M-cell within 10 min before trending towards baseline excitability over an hour later, which may indicate the involvement of non-genomic mechanisms. Consistently, current ramp injection experiments showed that cortisol increased M-cell input resistance in the depolarizing membrane, i.e., by a voltage-dependent postsynaptic mechanism. Cortisol also increases the magnitude of sound-evoked M-cell PSPs by reducing the efficacy of local feedforward inhibition (FFI). Interestingly, another pre-synaptic inhibitory network mediating prepulse inhibition (PPI) remained unaffected. Together, our results suggest that cortisol rapidly increases M-cell excitability via a post-synaptic effector mechanism, likely a chloride conductance, which, in combination with its dampening effect on FFI, will modulate information processing to reach threshold. Given the central role of the M-cell in initiating startle, these results are consistent with a role of cortisol in mediating the expression of a vital behavior.

Moderating Effects of Cortisol on Neural-Cognitive Association in Cognitively Normal Elderly Subjects

Cortisol homeostasis is important for healthy brain and cognitive aging. The aim of the current study is to investigate the role of serum cortisol levels in the relationship between regional brain volumes and cognitive processing speed in a group of cognitively normal elderly subjects. Forty-one healthy elderly participants were from a parallel longitudinal study. The reported data in this study reflects baseline measurements. Whole-brain anatomical scanning was performed using a 3.0 Tesla Philips Medical Systems Achieva scanner. Cognitive processing speed was assessed by the digit-symbol and symbol search tests, from the Chinese version of the Wechsler Adult Intelligence Scale—third edition (WAIS-III). Serum cortisol levels (sampled in the late morning) were measured by ELISA kits. Whole-brain regression analysis revealed that serum cortisol levels positively predicted the white matter volumes (WMV) of the right thalamus, the gray matter volumes (GMV) of the left thalamus and right cerebellar tonsil, and negatively predicted the WMV and GMV of the left middle temporal gyrus (MTG) in 41 healthy elderly participants. Furthermore, serum cortisol significantly moderated the relationship between the GMV of the left MTG and processing speed, as well as the GMV of the left thalamus and processing speed. This study provided the first piece of evidence supporting serum cortisol levels in moderating the relationship between regional brain volumes and processing speed in healthy elderly subjects. This observation enriches our understanding of the role of cortisol in brain morphology and cognitive functioning.

Interplay between stress response genes associated with attention-deficit hyperactivity disorder and brain volume

The glucocorticoid receptor plays a pivotal role in the brain's response to stress; a haplotype of functional polymorphisms in the NR3C1 gene encoding this receptor has been associated with attention-deficit hyperactivity disorder (ADHD). The serotonin transporter (5-HTT) gene polymorphism 5-HTTLPR is known to influence the relation between stress exposure and ADHD severity, which may be partly because of its reported effects on glucocorticoid levels. We therefore investigated if NR3C1 moderates the relation of stress exposure with ADHD severity and brain structure, and the potential role of 5-HTTLPR. Neuroimaging, genetic and stress exposure questionnaire data were available for 539 adolescents and young adults participating in the multicenter ADHD cohort study NeuroIMAGE (average age: 17.2 years). We estimated the effects of genetic variation in NR3C1 and 5-HTT, stress exposure and their interactions on ADHD symptom count and gray matter volume. We found that individuals carrying the ADHD risk haplotype of NR3C1 showed significantly more positive relation between stress exposure and ADHD severity than non-carriers. This gene-environment interaction was significantly stronger for 5-HTTLPR L-allele homozygotes than for S-allele carriers. These two- and three-way interactions were reflected in the gray matter volume of the cerebellum, parahippocampal gyrus, intracalcarine cortex and angular gyrus. Our findings illustrate how genetic variation in the stress response pathway may influence the effects of stress exposure on ADHD severity and brain structure. The reported interplay between NR3C1 and 5-HTT may further explain some of the heterogeneity between studies regarding the role of these genes and hypothalamic-pituitary-adrenal axis activity in ADHD.

Stress lowers the detection threshold for foul-smelling 2-mercaptoethanol

Previous studies have reported enhanced vigilance for threat-related information in response to acute stress. While it is known that acute stress modulates sensory systems in humans, its impact on olfaction and the olfactory detection of potential threats is less clear. Two psychophysical experiments examined, if acute stress lowers the detection threshold for foul-smelling 2-mercaptoethanol. Participants in Experiment 1 (N = 30) and Experiment 2 (N = 32) were randomly allocated to a control group or a stress group. Participants in the stress group underwent a purely psychosocial stressor (public mental arithmetic) in Experiment 1 and a stressor that combined a physically demanding task with social-evaluative threat in Experiment 2 (socially evaluated cold-pressor test). In both experiments, olfactory detection thresholds were repeatedly assessed by means of dynamic dilution olfactometry. Each threshold measurement consisted of three trials conducted using an ascending method of limits. Participants in the stress groups showed the expected changes in heart rate, salivary cortisol, and mood measures in response to stress. About 20 min after the stressor, participants in the stress groups could detect 2-mercaptoethanol at a lower concentration than participants in the corresponding control groups. Our results show that acute stress lowers the detection threshold for a malodor.

Interoception and stress

Afferent neural signals are continuously transmitted from visceral organs to the brain. Interoception refers to the processing of visceral-afferent neural signals by the central nervous system, which can finally result in the conscious perception of bodily processes. Interoception can, therefore, be described as a prominent example of information processing on the ascending branch of the brain–body axis. Stress responses involve a complex neuro-behavioral cascade, which is elicited when the organism is confronted with a potentially harmful stimulus. As this stress cascade comprises a range of neural and endocrine pathways, stress can be conceptualized as a communication process on the descending branch of the brain–body axis. Interoception and stress are, therefore, associated via the bi-directional transmission of information on the brain–body axis. It could be argued that excessive and/or enduring activation (e.g., by acute or chronic stress) of neural circuits, which are responsible for successful communication on the brain–body axis, induces malfunction and dysregulation of these information processes. As a consequence, interoceptive signal processing may be altered, resulting in physical symptoms contributing to the development and/or maintenance of body-related mental disorders, which are associated with stress. In the current paper, we summarize findings on psychobiological processes underlying acute and chronic stress and their interaction with interoception. While focusing on the role of the physiological stress axes (hypothalamic-pituitary-adrenocortical axis and autonomic nervous system), psychological factors in acute and chronic stress are also discussed. We propose a positive feedback model involving stress (in particular early life or chronic stress, as well as major adverse events), the dysregulation of physiological stress axes, altered perception of bodily sensations, and the generation of physical symptoms, which may in turn facilitate stress.

Cortisol effects on flow-experience

RATIONALE

Stress affects flow-experience, but the mediating psychobiological mechanisms remain unknown. Previous studies showed an association between flow-experience and endogenous cortisol levels, suggesting an inverted, u-shaped relation between flow-experience and cortisol. However, these studies could not exclude effects of other stress factors.

OBJECTIVES

The aim of this experiment was, therefore, to test the isolated effect of cortisol on flow-experience, independent of concomitant physiological and psychological stress responses, via controlled administration of exogenous cortisol.

METHODS

Sixty-four young healthy subjects (32 males, 32 females) participated in the experiment. According to a double-blind, randomized, placebo-controlled, cross-over design, they received 20 mg oral cortisol on 1 day and placebo on the other day, respectively, with a time distance of 1 week between the experimental days. One hour after cortisol administration, participants engaged in the computer game Pacman. Pacman was delivered in five blocks of randomly differing difficulty levels. One block lasted 5 min. At the end of each block, participants rated flow-experience by the Flow Short Scale. Data was analyzed with hierarchical linear modeling. Subjects were not able to predict whether the pill they received contained cortisol or placebo.

RESULTS

Overall, results revealed a negative effect of oral 20 mg cortisol on flow-experience, with no differences between males and females.

CONCLUSIONS

This study is the first to show that exogenous cortisol in a dose corresponding to a severe stressor impairs flow-experience. The observed negative effect of high cortisol dosage on experienced flow underlines recent findings of an inverted u-shaped relationship between cortisol and flow.

Hormones, stress, and cognition: The effects of glucocorticoids and oxytocin on memory

Hormones have nuanced effects on learning and memory processes. The degree and direction of the effect (e.g., is memory impaired or enhanced?) depends on the dose, type and stage of memory, and type of material being learned, among other factors. This review will focus on two specific topics within the realm of effects of hormones on memory: (1) How glucocorticoids (the output hormones of the hypothalamic-pituitary-adrenal axis) affect long-term memory consolidation, retrieval, and working memory, with a focus on neural mechanisms and effects of emotion; and (2) How oxytocin affects memory, with emphasis on a speculative hypothesis that oxytocin might exert its myriad effects on human social cognition and behavior via impacts on more general cognitive processes. Oxytocin-glucocorticoid interactions will be briefly addressed. These effects of hormones on memory will also be considered from an evolutionary perspective.

PSYCHOPHYSIOLOGICAL CHARACTERISTICS OF WOMEN IN DEPENDENCE ON THE OVARIOHORMONAL CYCLE PHASE AND PROGESTERONE ACTIVITY (PART 1)

With the aim to identify the effects of menstrual cycle phase on the cognitive and psycho-emotional characteristics in 78 women aged 18–27 years were studied in a within-subject design Half the subjects began during their follicular phase and half began during their luteal phase (LP). The level of psycho-emotional tension was lowest, but cognitive performance efficiency is a highest in LP that is associated with the highest saliva progesterone level.

Health anxiety moderates the daytime cortisol slope

OBJECTIVES

Edwards et al. argue that a steeper daytime cortisol slope indicates increased symptom awareness [Edwards S, Hucklebridge F, Clow A, Evans P. Components of the diurnal cortisol cycle in relation to upper respiratory symptoms and perceived stress. Psychosom Med, 2003;65:320-7]. Theory suggests that health anxiety (HA) is associated with increased symptom awareness. Therefore, this study tests the hypothesis that higher levels of HA are associated with a steeper daytime cortisol slope and is the first to examine the daytime diurnal cortisol slope for HA.

METHODS

Forty-two healthy working adults completed measures of HA and neuroticism as well as indices to measure the severity and frequency of symptom reporting. Participants also provided eight consecutive days of salivary cortisol data. Two cortisol measures were taken each day -- once prior to lunch and once in the early evening -- the timing of these was synchronized to waking times. The data were analyzed using multilevel modeling.

RESULTS

The hypothesis was supported, with those scoring higher on HA showing a steeper daytime cortisol slope. There were no significant relationships between cortisol (average production and slope) and either neuroticism or symptom reporting (severity and frequency).

CONCLUSIONS

The results are interpreted as consistent with theories of HA that emphasis increased awareness of nonspecific symptoms.

Reduced auditory processing capacity during vocalization in children with Selective Mutism

BACKGROUND

Because abnormal Auditory Efferent Activity (AEA) is associated with auditory distortions during vocalization, we tested whether auditory processing is impaired during vocalization in children with Selective Mutism (SM).

METHODS

Participants were children with SM and abnormal AEA, children with SM and normal AEA, and normally speaking controls, who had to detect aurally presented target words embedded within word lists under two conditions: silence (single task), and while vocalizing (dual task). To ascertain specificity of auditory-vocal deficit, effects of concurrent vocalizing were also examined during a visual task.

RESULTS

Children with SM and abnormal AEA showed impaired auditory processing during vocalization relative to children with SM and normal AEA, and relative to control children. This impairment is specific to the auditory modality and does not reflect difficulties in dual task per se.

CONCLUSIONS

The data extends previous findings suggesting that deficient auditory processing is involved in speech selectivity in SM.

Predictors of pain behaviors in fibromyalgia syndrome

OBJECTIVE

To evaluate the contributions of physical, pain-related, cognitive, stress-related, affective, and spouse-related variables to differences in pain behaviors in subgroups of patients with fibromyalgia syndrome (FMS).

METHODS

One hundred forty FMS patients underwent medical, physical, and psychological evaluation. Patients and 30 pain-free controls performed a routine physical activity (window-washing task) to elicit pain behaviors with or without the presence of their spouses. The behaviors and spouses' responses during this task were videotaped and subsequently rated. Patients were classified as dysfunctional (DYS), interpersonally distressed (ID), or adaptive copers (AC) based on responses to the Multidimensional Pain Inventory. Hierarchical regression analyses were used to identify predictors of pain behaviors for the total group and subgroups of patients.

RESULTS

Patients classified as DYS demonstrated the highest number of pain behaviors compared with those classified as ID or AC. This difference was observable when the spouse was present. Spouse responses and physical variables were significantly related to pain behaviors in the DYS and ID groups with the model accounting for 77.1% and 41.9% of the variance, respectively. In contrast, for the AC group, stress factors were the most significant predictor of pain behaviors, accounting for 22.8% of the variance.

CONCLUSION

The results indicate that different variables account for the presence of pain behaviors in different subgroups of patients. The data provide support for the heterogeneity of the diagnosis of FMS and have implications for treatment of subgroups of patients.

The Darwinian concept of stress: benefits of allostasis and costs of allostatic load and the trade-offs in health and disease

Why do we get the stress-related diseases we do? Why do some people have flare ups of autoimmune disease, whereas others suffer from melancholic depression during a stressful period in their life? In the present review possible explanations will be given by using different levels of analysis. First, we explain in evolutionary terms why different organisms adopt different behavioral strategies to cope with stress. It has become clear that natural selection maintains a balance of different traits preserving genes for high aggression (Hawks) and low aggression (Doves) within a population. The existence of these personality types (Hawks-Doves) is widespread in the animal kingdom, not only between males and females but also within the same gender across species. Second, proximate (causal) explanations are given for the different stress responses and how they work. Hawks and Doves differ in underlying physiology and these differences are associated with their respective behavioral strategies; for example, bold Hawks preferentially adopt the fight-flight response when establishing a new territory or defending an existing territory, while cautious Doves show the freeze-hide response to adapt to threats in their environment. Thus, adaptive processes that actively maintain stability through change (allostasis) depend on the personality type and the associated stress responses. Third, we describe how the expression of the various stress responses can result in specific benefits to the organism. Fourth, we discuss how the benefits of allostasis and the costs of adaptation (allostatic load) lead to different trade-offs in health and disease, thereby reinforcing a Darwinian concept of stress. Collectively, this provides some explanation of why individuals may differ in their vulnerability to different stress-related diseases and how this relates to the range of personality types, especially aggressive Hawks and non-aggressive Doves in a population. A conceptual framework is presented showing that Hawks, due to inefficient management of mediators of allostasis, are more likely to be violent, to develop impulse control disorders, hypertension, cardiac arrhythmias, sudden death, atypical depression, chronic fatigue states and inflammation. In contrast, Doves, due to the greater release of mediators of allostasis (surplus), are more susceptible to anxiety disorders, metabolic syndromes, melancholic depression, psychotic states and infection.

Corticosterone facilitates retention of contextually conditioned fear and increases CRH mRNA expression in the amygdala

The present study examined the effects of glucocorticoid administration on emotional memory and on corticotropin-releasing hormone (CRH) mRNA expression in the central nucleus of the amygdala (CeA) and the paraventricular nucleus of the hypothalamus (PVN). This was tested by administering repeated corticosterone (CORT) within a contextual fear conditioning paradigm. Rats received 2.5 mg/kg (s.c.) CORT or placebo twice a day for five and a half days and, 2 h after the last injection, rats were given one-trial contextual fear conditioning. When tested for retention of conditioned fear 6 days later, the CORT-treated rats displayed more fear-conditioned freezing in the retention test than vehicle-treated rats, which was not accounted for by an increase in footshock responsivity nor elevated plasma CORT. Another group of rats was fear conditioned prior to CORT administration, followed 24 h later by the five and a half days of CORT, and tested 6 days later; conditioned fear was not enhanced in these rats. Finally, CORT administration produced an increase of CRH mRNA in the CeA and a decrease in the PVN. The data suggest that repeated administration of CORT given before fear conditioning facilitates the acquisition of emotional memory, whereas CORT given after consolidation does not increase emotional memory.

Glucocorticoid regulation of diverse cognitive functions in normal and pathological emotional states

The glucocorticoid hormone cortisol is essential for many forms of regulatory physiology and for cognitive appraisal. Cortisol, while associated with fear and stress response, is also the hormone of energy metabolism and it coordinates behavioral adaptation to the environmental and internal conditions through the regulation of many neurotransmitters and neural circuits. Cortisol has diverse effects on many neuropeptide and neurotransmitter systems thus affecting functional brain systems. As a result, cortisol affects numerous cognitive domains including attention, perception, memory, and emotional processing. When certain pathological emotional states are present, cortisol may have a role in differential activation of brain regions, particularly suppression of hippocampal activation, enhancement of amygdala activity, and dendritic reshaping in these regions as well as in the ventral prefrontal cortex. The coordinated actions of glucocorticoid regulation on various brain systems such as those implicated in emotional processing can lead to perceptual and cognitive adaptations and distortions of events that may be relevant for understanding mood disorders.

Corticosteroids in relation to fear, anxiety and psychopathology

Corticosteroids play extremely important roles in fear and anxiety. The mechanisms by which corticosteroids exert their effects on behavior are often indirect, because, although corticosteroids do not regulate behavior, they induce chemical changes in particular sets of neurons making certain behavioral outcomes more likely in certain contexts as a result of the strengthening or weakening of particular neural pathways. The timing of corticosteroid increase (before, during or after exposure to a stressor) determines whether and how behavior is affected. The present review shows that different aspects of fear and anxiety are affected differentially by the occupation of the mineralocorticoid receptor (MR) or glucocorticoid receptor (GR) at different phases of the stress response. Corticosteroids, at low circulating levels, exert a permissive action via brain MRs on the mediation of acute freezing behavior and acute fear-related plus-maze behavior. Corticosteroids, at high circulating levels, enhance acquisition, conditioning and consolidation of an inescapable stressful experience via GR-mechanisms. Brain GR-occupation also promotes processes underlying fear potentiation. Fear potentiation can be seen as an adjustment in anticipation of changing demands. However, such feed-forward regulation may be particularly vulnerable to dysfunction. MR and/or GR mechanisms are involved in fear extinction. Brain MRs may be involved in the extinction of passive avoidance, and GRs may be involved in mediating the extinction of active avoidance. In the developing brain, corticosteroids play a facilitatory role in the ontogeny of freezing behavior, probably via GRs in the dorsal hippocampus, and their influence on the development of the septo-hippocampal cholinergic system. Corticosteroids can exert maladaptive rather than adaptive effects when their actions via MRs and GRs are chronically unbalanced due to chronic stress. Both mental health of humans and animal welfare is likely to be seriously threatened after psychosocial stress, prolonged stress, prenatal stress or postnatal stress, especially when maternal care or social support is absent, because these can chronically dysregulate the central MR/GR balance. In such circumstances the normally adaptive corticosteroid responses can become maladaptive.