Testosterone administration modulates neural responses to crying infants in young females

Parental responsiveness to infant vocalizations is an essential mechanism to ensure parental care, and its importance is reflected in a specific neural substrate, the thalamocingulate circuit, which evolved through mammalian evolution subserving this responsiveness. Recent studies using functional Magnetic Resonance Imaging (fMRI) provide compelling evidence for a comparable mechanism in humans by showing thalamocingulate responses to infant crying. Furthermore, possibly acting on this common neural substrate, steroid hormones such as estradiol and testosterone, seem to mediate parental behavior both in humans and other animals. Estradiol unmistakably increases parental care, while data for testosterone are less unequivocal. In humans and several other animals, testosterone levels decrease both in mothers and fathers during parenthood. However, exogenous testosterone in mice seems to increase parenting, and infant crying leads to heightened testosterone levels in human males. Not only is the way in which testosterone is implicated in parental responsiveness unresolved, but the underlying mechanisms are fully unknown. Accordingly, using fMRI, we measured neural responses of 16 young women who were listening to crying infants in a double blind, placebo-controlled, counterbalanced, testosterone administration experiment. Crucially, heightened activation in the testosterone condition compared to placebo was shown in the thalamocingulate region, insula, and the cerebellum in response to crying. Our results by controlled hormonal manipulation confirm a role of the thalamocingulate circuit in infant cry perception. Furthermore, the data also suggest that exogenous testosterone, by itself or by way of its metabolite estradiol, in our group of young women acted on this thalamocinculate circuit to, provisionally, upregulate parental care.

Neural mechanisms underlying changes in stress-sensitivity across the menstrual cycle

Hormonal fluctuations across the menstrual cycle are thought to play a central role in premenstrual mood symptoms. In agreement, fluctuations in gonadal hormone levels affect brain processes in regions involved in emotion regulation. Recent findings, however, implicate psychological stress as a potential mediating factor and thus, we investigated whether effects of moderate psychological stress on relevant brain regions interact with menstrual cycle phase. Twenty-eight healthy women were tested in a crossover design with menstrual cycle phase (late luteal versus late follicular) and stress (stress induction versus control) as within-subject factors. After stress induction (or control), we probed neural responses to facial expressions using fMRI. During the late luteal phase, negative affect was highest and the stress-induced increase in heart rate was mildly augmented. fMRI data of the control condition replicate previous findings of elevated amygdala and medial prefrontal cortex responses when comparing the late luteal with the late follicular phase. Importantly, stress induction had opposite effects in the two cycle phases, with unexpected lower response magnitudes in the late luteal phase. Moreover, the larger the increase in allopregnanolone concentration across the menstrual cycle was, the smaller the amygdala and medial prefrontal cortex responses were after stress induction in the late luteal phase. Our findings show that moderate psychological stress influences menstrual cycle effects on activity in the emotion regulation circuitry. These results provide potential insights into how fluctuations in allopregnanolone that naturally occur during the menstrual cycle may change stress vulnerability.

Cortisol administration acutely reduces threat-selective spatial attention in healthy young men

There is mounting evidence that single administrations of glucocorticoids may acutely reduce human fear. We previously reported that administration of cortisol acutely reduced non-spatial selective attention to fearful faces and likewise reduced preferential processing of fearful faces in a spatial working memory task. Here we report the acute effects of 40 mg cortisol (administered in a double-blind, placebo-controlled crossover design) on a different experimental task for measuring threat-selective attention. Twenty healthy young males had to localize a target which was presented in a peripheral location that was either gazed at or not by a preceding dynamic happy or fearful face. This reliable method has been used repeatedly to demonstrate fear-driven selective attention. Present results showed that after placebo, as usual, the fearful gaze cues caused stronger orienting of attention than happy faces. Cortisol abolished this typical anxious response pattern, but only in low anxious participants. These data provide evidence that cortisol acutely influences also spatial threat-selective attention. Possible neuroendocrine mechanisms are discussed.

From specificity to sensitivity: how acute stress affects amygdala processing of biologically salient stimuli

BACKGROUND

A vital component of an organism's response to acute stress is a surge in vigilance that serves to optimize the detection and assessment of threats to its homeostasis. The amygdala is thought to regulate this process, but in humans, acute stress and amygdala function have up to now only been studied in isolation. Hence, we developed an integrated design using functional magnetic resonance imaging to investigate the immediate effects of controlled stress induction on amygdala function.

METHODS

In 27 healthy female participants, we studied brain responses to emotional facial stimuli, embedded in an either acutely stressful or neutral context by means of adjoining movie clips.

RESULTS

A variety of physiological and psychological measures confirmed successful induction of moderate levels of acute stress. More importantly, this context manipulation shifted the amygdala toward higher sensitivity as well as lower specificity, that is, stress induction augmented amygdala responses to equally high levels for threat-related and positively valenced stimuli, thereby diminishing a threat-selective response pattern. Additionally, stress amplified sensory processing in early visual regions and the face responsive area of the fusiform gyrus but not in a frontal region involved in task execution.

CONCLUSIONS

A shift of amygdala function toward heightened sensitivity with lower levels of specificity suggests a state of indiscriminate hypervigilance under stress. Although this represents initial survival value in adverse situations where the risk for false negatives in the detection of potential threats should be minimized, it might similarly play a causative role in the sequelae of traumatic events.

Acute psychological stress reduces working memory-related activity in the dorsolateral prefrontal cortex

BACKGROUND

Acute psychological stress impairs higher-order cognitive function such as working memory (WM). Similar impairments are seen in various psychiatric disorders that are associated with higher susceptibility to stress and with prefrontal cortical dysfunctions, suggesting that acute stress may play a potential role in such dysfunctions. However, it remains unknown whether acute stress has immediate effects on WM-related prefrontal activity.

METHODS

Using functional magnetic resonance imaging (fMRI), we investigated neural activity of 27 healthy female participants during a blocked WM task (numerical N-back) while moderate psychological stress was induced by viewing strongly aversive (vs. neutral) movie material together with a self-referencing instruction. To assess stress manipulation, autonomic and endocrine, as well as subjective, measurements were acquired throughout the experiment.

RESULTS

Successfully induced acute stress resulted in significantly reduced WM-related activity in the dorsolateral prefrontal cortex (DLPFC), and was accompanied by less deactivation in brain regions that are jointly referred to as the default mode network.

CONCLUSIONS

This study demonstrates that experimentally induced acute stress in healthy volunteers results in a reduction of WM-related DLPFC activity and reallocation of neural resources away from executive function networks. These effects may be explained by supraoptimal levels of catecholamines potentially in conjunction with elevated levels of cortisol. A similar mechanism involving acute stress as a mediating factor may play an important role in higher-order cognitive deficits and hypofrontality observed in various psychiatric disorders.

Reduced spontaneous facial mimicry in women with autistic traits

Deficits in empathizing and perspective taking are defining characteristics of autism-spectrum disorders. Converging evidence suggests that these socio-emotional abilities are rooted in basic mechanisms that subserve imitative behavior, and may vary with autistic traits across the population as a whole. We investigated this notion by assessing spontaneous and instructed mimicry of facial expressions in healthy male and female volunteers scoring extremely high or low on the autism-spectrum quotient questionnaire. Mimicry was recorded using electromyography of the corrugator supercilii and zygomaticus major. Results show that spontaneous mimicry in the corrugator supercilii was strongest in female participants with low AQ-scores. Mimicry in the zygomaticus major, and in the instructed facial mimicry condition, did not differ between groups. These findings indicate that the degree to which individuals exhibit spontaneous mimicry may vary as a function of both gender and autistic traits.

Enhanced sensitivity with fast three-dimensional blood-oxygen-level-dependent functional MRI: comparison of SENSE-PRESTO and 2D-EPI at 3 T

A major impetus in functional MRI development is to enhance sensitivity to changes in neural activity. One way to improve sensitivity is to enhance contrast to noise ratio, for instance by increasing field strength or the number of receiving coils. If these parameters are fixed, there is still the possibility to optimize scans by altering speed or signal strength [signal-to-noise ratio (SNR)]. We here demonstrate a very fast whole-brain scan, by combining a three-dimensional (3D)-PRESTO (principle of echo shifting with a train of observations) pulse sequence with a commercial eight-channel head coil and sensitivity encoding (SENSE). 3D-PRESTO uses time optimally by means of echo shifting. Moreover, 3D scans can accommodate SENSE in two directions, reducing scan time proportionally. The present PRESTO-SENSE sequence achieves full brain coverage within 500 ms. We compared this with a two-dimensional (2D) echo planar imaging (EPI) scan with identical brain coverage on 10 volunteers. Resting-state temporal SNR in the blood-oxygen-level-dependent (BOLD) frequency range and T-statistics for thumb movement and visual checkerboard activations were compared. Results show improved temporal SNR across the brain for PRESTO-SENSE compared with EPI. The percentage signal change and relative standard deviation of the noise were smaller for PRESTO-SENSE. Sensitivity for brain activation, as reflected by T-values, was consistently higher for PRESTO, and this seemed to be mainly due to the increased number of observations within a fixed time period. We conclude that PRESTO accelerated with SENSE in two directions can be more sensitive to BOLD signal changes than the widely used 2D-EPI, when a fixed amount of time is available for functional MRI scanning.

Exogenous testosterone enhances responsiveness to social threat in the neural circuitry of social aggression in humans

BACKGROUND

In a range of species, the androgen steroid testosterone is known to potentiate neural circuits involved in intraspecific aggression. Disorders of impulsive aggression in humans have likewise been associated with high testosterone levels, but human evidence for the link between testosterone and aggression remains correlational and inconclusive.

METHODS

Twelve female participants underwent functional magnetic resonance imaging during three sessions while viewing stimuli differing in social threat value: angry and happy facial expressions. The first session served to establish associations between baseline hormone levels and neural activation. Participants were retested in a second and third session after placebo-controlled sublingual administration of .5 mg testosterone.

RESULTS

Findings demonstrate consistent activation to angry versus happy faces in areas known to be involved in vertebrate reactive aggression, such as the amygdala and hypothalamus. Suprathreshold clusters were also found in the orbitofrontal cortex (Brodmann area 47), a region implicated in impulse control in humans. Baseline endocrine profiles of high testosterone and low cortisol were associated with stronger activation in subcortical structures. Neural responses in most activated regions were more persistent after testosterone administration than after placebo.

CONCLUSIONS

These data demonstrate that testosterone enhances responsiveness in neural circuits of social aggression. Based on animal literature, it is argued that actions of testosterone on subcortical reactive aggression circuits give rise to this effect. Implications for our understanding of the pathophysiology of disorders of impulsive aggression are discussed.

Exogenous testosterone attenuates the integrated central stress response in healthy young women

Animal research has shown that the androgen steroid testosterone, the end product of the hypothalamic-pituitary-gonadal (HPG) axis, down regulates the integrated stress response at multiple levels. These effects have been demonstrated at the level of the amygdala and the bed nucleus of the stria terminalis, and along the different nodes of the hypothalamic-pituitary-adrenal (HPA) axis. The present study was designed to assess effects of exogenous testosterone upon reactivity of the autonomic nervous system and modulation of the acoustic startle reflex in humans. Twenty healthy female participants received double-blind, placebo-controlled sublingual administrations of .5mg testosterone. Measurements were made of phasic electrodermal activity, cardiac responses, and startle reflexes to acoustic probes while participants were exposed to pictures with strongly aversive, neutral, or positive content. Subjective reports of mood and picture evaluations were also obtained. Results support the hypothesis of a generally decreased responsiveness of the stress system by showing reduced skin conductance responses as well as reduced affective startle modulation in anxiety-prone participants after administration of testosterone. Candidate neurobiological mechanisms of action are outlined and discussed, and it is argued that androgens promote dynamic regulation of the stress system through actions upon central neuropeptidergic pathways that control corticotropin releasing hormone (CRH) and arginine vasopressin (AVP) expression. The present findings highlight the importance of further investigation of the possible role of the HPG axis in disorders that are associated with HPA axis dysfunctions.

A single administration of cortisol acutely reduces preconscious attention for fear in anxious young men

Chronically elevated HPA activity has often been associated with fear and anxiety, but there is evidence that single administrations of glucocorticoids may acutely reduce fear. Moreover, peri-traumatic cortisol elevation may protect against development of post-traumatic stress disorder. Hypervigilant processing of threat information plays a role in anxiety disorders and although relations with HPA functioning have been established, causality of these relations remains unclear. Presently, self-reported anxiety and response time patterns on a masked emotional Stroop task with fearful faces were measured in 20 healthy young men after double-blind, placebo-controlled oral administration of 40 mg cortisol. The masked fearful Stroop task measures vocal colornaming response latencies for pictures of neutral and fearful faces presented below the threshold for conscious perception. Results showed increased response times on trials for fearful compared to neutral faces after placebo, but this emotional Stroop effect was acutely abolished by cortisol administration. This effect was most pronounced in subjects with heightened anxiety levels. This is the first evidence showing that exogenous cortisol acutely reduces anxiety-driven selective attention to threat. These results extend earlier findings of acute fear reduction after glucocorticoid administration. This suggests interactions of HPA functioning and vigilant attention in the pathogenesis of anxiety disorders. Possible neuroendocrine mechanisms of action are discussed.

Exogenous cortisol shifts a motivated bias from fear to anger in spatial working memory for facial expressions

Studies assessing processing of facial expressions have established that cortisol levels, emotional traits, and affective disorders predict selective responding to these motivationally relevant stimuli in expression specific manners. For instance, increased attentional processing of fearful faces (attentional bias for fearful faces) is associated with fear and anxiety and diminishes after administration of the anxiolytic hormone testosterone. Conversely, attentional bias for angry faces has been associated with higher levels of approach motivation (e.g. anger) and testosterone, but lower levels of cortisol. This negative relation between cortisol levels and bias for angry faces was also seen in a test of biased working memory performance. However, previous research suggests that exogenous glucocorticoids acutely decrease fearful and inhibited behavior and increase aggressiveness. Hypothesizing from these findings, the present study tested this spatial working memory for faces of various emotional expressions (neutral, happy, fearful, and angry) after double-blind, placebo-controlled administration of 40 mg cortisol in 18 healthy young men. It was predicted that cortisol would acutely attenuate memory bias for fearful expressions while increasing memory bias for angry expressions, in effect creating a shift in biased motivated memory from fear to anger. Results largely confirmed the hypotheses. This is the first causal evidence that cortisol differentially regulates spatial working memory for different facial expressions. Possible biological mechanisms are discussed.

The effects of social stress and cortisol responses on the preconscious selective attention to social threat

The purpose of the present study was to investigate the effects of social stress and stress-induced cortisol on the preconscious selective attention to social threat. Twenty healthy participants were administered a masked emotional Stroop task (comparing color-naming latencies for angry, neutral and happy faces) in conditions of rest and social stress. Stress was induced by means of the Trier social stress test. Based on the stress-induced increase in cortisol levels, participants were allocated post hoc (median-split) to a high and low responders group. In contrast to low responders, high responders showed a negative or avoidant attentional bias to threat (i.e. shorter latencies for angry than neutral faces) in the rest condition. Most importantly, although low responders became avoidant, the high responders became vigilant to the angry faces after stress induction. There were no such effects for happy faces. Our findings are in line with previous studies in both animals and humans, that associate high glucocorticoid stress-responsiveness with diminished avoidance and prolonged freezing reactions during stress.

Toward a framework for defective emotion processing in social phobia

INTRODUCTION

This paper explores and outlines an evolutionary approach to understanding social phobia (SP) as a developmental disorder in brain mechanisms that regulate socioemotional behaviour.

METHODS

A literature review of cognitive, neuronal, and endocrine correlates of SP is presented using an integrative approach.

RESULTS

Social phobia patients present with a specific and developmentally stable functional neuroanatomical and neuroendocrine profile that can be linked to findings of cognitive attentional abnormalities.

CONCLUSIONS

It is argued that SP is the human counterpart to primate sub-ordination stress and develops from clearly identifiable precursors in early child-hood, the understanding of which requires fundamental insights into the regulation of socioemotional behaviour. The current state of knowledge speaks strongly in favour of a diathesis model, in which distorted cognitions that are characteristic of SP are secondary to hyperexcitability of fear circuits that set off at least as early as at preverbal ages and ultimately may lead to the development of SP.

A single administration of testosterone reduces fear-potentiated startle in humans

BACKGROUND

Ample evidence from animal research indicates that the gonadal steroid hormone testosterone has fear-reducing properties. Human data on this topic, however, are scarce and far less unequivocal. The present study therefore aimed to scrutinize anxiolytic effects of a single dose of testosterone, using a direct physiological index of fear in humans.

METHODS

Twenty healthy female participants were tested in a double-blind, placebo-controlled crossover design involving sublingual administration of a single dose of testosterone. Four hours after intake, we assessed effects on baseline startle and fear-potentiated startle in a verbal threat-of-shock paradigm.

RESULTS

In accordance with predictions, testosterone administration resulted in reduced fear-potentiated startle, without affecting baseline startle.

CONCLUSIONS

This study provides direct evidence that a single dose of testosterone reduces fear in humans. The relationship of this effect to previous research on anxiolytic effects of benzodiazepines, as well as possible mechanisms of action, is discussed.

Identity state-dependent attentional bias for facial threat in dissociative identity disorder

Biased attention for threatening stimuli has been associated with many forms of psychopathology. Attention to threatening faces presented below perceptual thresholds was assessed in patients diagnosed with dissociative identity disorder using a pictorial emotional Stroop task. Patients were tested in two different identity states, in one of which they claimed strong awareness of trauma. Attentional bias for social threat proved state-dependent in the patients and deviated from the patterns observed in controls.

Testosterone shifts the balance between sensitivity for punishment and reward in healthy young women

Animal research has demonstrated reductions in punishment sensitivity and enhanced reward dependency after testosterone administration. In humans, elevated levels of testosterone have been associated with violent and antisocial behavior. Interestingly, extreme forms of violent and antisocial behavior can be observed in the psychopath. Moreover, it has been argued that reduced punishment sensitivity and heightened reward dependency are crucially involved in the etiology and maintenance of psychopathy. A task that has been proven to be capable of simulating punishment-reward contingencies is the IOWA gambling task. Decisions to choose from decks of cards become motivated by punishment and reward schedules inherent in the task. Importantly, clinical and subclinical psychopaths demonstrate a risky, disadvantageous pattern of decision-making in the task, indicating motivational imbalance (insensitivity for punishment and enhanced reward dependency). Here, in a double-blind placebo-controlled crossover design (n = 12), whether a single administration of testosterone would shift the motivational balance between the sensitivity for punishment and reward towards this tendency to choose disadvantageously was investigated. As hypothesized, subjects showed a more disadvantageous pattern of decision-making after testosterone compared to placebo administration. These findings not only provide the first direct evidence for the effects of testosterone on punishment-reward contingencies in humans, but they also give further insights into the hypothetical link between testosterone and psychopathy.

Low cortisol levels and the balance between punishment sensitivity and reward dependency

The neuro-endocrinological basis of psychopathy, a disorder characterized by lack of fear, is relatively unknown. However, low levels of cortisol may result in fearlessness and have been observed in individuals with psychopathic tendencies. Low fear models state that psychopaths are not motivated to avoid punishment, especially when reward is pending. In agreement, disadvantageous decision making on the IOWA gambling task in psychopaths and psychopathic analogous, indicates low punishment sensitivity and high reward dependency. Here, it was investigated whether low basal cortisol levels predicted the balance between punishment sensitivity and reward dependency in the same manner. As hypothesized, the most disadvantageous pattern of decision making was found in the subjects with the lowest cortisol levels. These findings suggest that low levels of cortisol may set the balance between the sensitivity for punishment and reward dependency towards a pre-disposition for psychopathy.

Defective somatic markers in sub-clinical psychopathy

Damasio's somatic marker hypothesis is argued to be specifically applicable to psychopathy, though evidence has been meager until now. The principal evidence for the somatic marker hypothesis is based on findings in patients with orbitofrontal lesions, showing absent punishment learning on the Iowa gambling task. Interestingly, neuroimaging studies indicate orbitofrontal dysfunction in psychopathy also. Here we investigated the somatic marker hypothesis in subjects selected on low and high psychopathic behavioral characteristics from the outer extreme ranges of a large subject pool (n = 525). The low psychopathic subject group (n = 16) showed intact punishment learning, suggesting somatic markers came to guide their decisions in the course of the game. In contrast, such punishment learning was not observed in the high psychopathic subject group (n = 16), who mimicked the gambling behavior of orbitofrontal patients. These findings provide further evidence for the hypothesized link between psychopathy and orbitofrontal dysfunction.

A left-prefrontal lateralized, sympathetic mechanism directs attention towards social threat in humans: evidence from repetitive transcranial magnetic stimulation

The prioritized processing of threat is suggested to be motivated by anxiety, regulated by the parasympatheticus, and biased to the right hemisphere. However, according to an anterior dimensional model of negative affect this is unlikely to be true when threat is of social origin. Social threat is communicated by the angry facial expression, and recent research indicates that prioritized processing of angry faces is motivated by anger. Anger is a sympathetically dominated emotion, and for its expression and experience, neuroimaging data have demonstrated anterior lateralization to the left hemisphere. To scrutinize the above diverging statements, suprathreshold low-frequency repetitive transcranial magnetic stimulation (rTMS) was applied over the right and the left prefrontal cortex (PFC) of ten healthy subjects during 15min continuously, and the subsequent effects on sympathetic and parasympathetic activity of the heart, and selective attention to angry facial expressions were investigated. Combined rTMS-neuroimaging studies have shown contralateral excitation after unilateral supratheshold low-frequency rTMS, hence the strengthening of contralaterally mediated emotion functions. The earlier reported increases in selective attention to angry facial expressions after right-PFC rTMS were found to be accompanied by and significantly associated with elevations in sympathetic activity. Our data suggest that a left-PFC lateralized, sympathetic mechanism directs attention towards the angry facial expression.