Jonas Engman

Disruption of Reconsolidation Erases a Fear Memory Trace in the Human Amygdala

Removing Fear Memories Disruption of reconsolidation of an activated fear memory prevents subsequent fear expression. After a memory reminder, extinction training can disrupt fear memory. In rodents, this process is dependent on a brain area called the amygdala. Agren et al. (p. 1550) used functional magnetic resonance imaging and a fear conditioning paradigm to show in humans that, after an associative fear memory was formed, reactivation and reconsolidation left a signature in the basolateral amygdala. This memory trace predicted later fear expression, which was linked to activity in areas forming the fear circuit of the brain. Extinction alone did not change this signal. However, extinction in the reconsolidation window blocked fear expression by erasing the fear memory trace in the amygdala and weakened the connection in the wider fear circuit of the brain. Interfering with memory formation at the right moment removes the signature of fear memories in human brain imaging studies. Memories become labile when recalled. In humans and rodents alike, reactivated fear memories can be attenuated by disrupting reconsolidation with extinction training. Using functional brain imaging, we found that, after a conditioned fear memory was formed, reactivation and reconsolidation left a memory trace in the basolateral amygdala that predicted subsequent fear expression and was tightly coupled to activity in the fear circuit of the brain. In contrast, reactivation followed by disrupted reconsolidation suppressed fear, abolished the memory trace, and attenuated fear-circuit connectivity. Thus, as previously demonstrated in rodents, fear memory suppression resulting from behavioral disruption of reconsolidation is amygdala-dependent also in humans, which supports an evolutionarily conserved memory-update mechanism.

Altered neural correlates of affective processing after internet-delivered cognitive behavior therapy for social anxiety disorder

Randomized controlled trials have yielded promising results for internet-delivered cognitive behavior therapy (iCBT) for patients with social anxiety disorder (SAD). The present study investigated anxiety-related neural changes after iCBT for SAD. The amygdala is a critical hub in the neural fear network, receptive to change using emotion regulation strategies and a putative target for iCBT. Twenty-two subjects were included in pre- and post-treatment functional magnetic resonance imaging at 3T assessing neural changes during an affective face processing task. Treatment outcome was assessed using social anxiety self-reports and the Clinical Global Impression-Improvement (CGI-I) scale. ICBT yielded better outcome than ABM (66% vs. 25% CGI-I responders). A significant differential activation of the left amygdala was found with relatively decreased reactivity after iCBT. Changes in the amygdala were related to a behavioral measure of social anxiety. Functional connectivity analysis in the iCBT group showed that the amygdala attenuation was associated with increased activity in the medial orbitofrontal cortex and decreased activity in the right ventrolateral and dorsolateral (dlPFC) cortices. Treatment-induced neural changes with iCBT were consistent with previously reported studies on regular CBT and emotion regulation in general.

Oral contraceptive use changes brain activity and mood in women with previous negative affect on the pill—A double-blinded, placebo-controlled randomized trial of a levonorgestrel-containing combined oral contraceptive

OBJECTIVE Most women on combined oral contraceptives (COC) report high levels of satisfaction, but 4-10% complain of adverse mood effects. The aim of this randomized, double-blinded, placebo-controlled trial was to investigate if COC use would induce more pronounced mood symptoms than placebo in women with previous history of COC-induced adverse mood. A second aim was to determine if COC use is associated with changes in brain reactivity in regions previously associated with emotion processing. METHODS Thirty-four women with previous experience of mood deterioration during COC use were randomized to one treatment cycle with a levonorgestrel-containing COC or placebo. An emotional face matching task (vs. geometrical shapes) was administered during functional magnetic resonance imaging (fMRI) prior to and during the COC treatment cycle. Throughout the trial, women recorded daily symptom ratings on the Cyclicity Diagnoser (CD) scale. RESULTS During the last week of the treatment cycle COC users had higher scores of depressed mood, mood swings, and fatigue than placebo users. COC users also had lower emotion-induced reactivity in the left insula, left middle frontal gyrus, and bilateral inferior frontal gyri as compared to placebo users. In comparison with their pretreatment cycle, the COC group had decreased emotion-induced reactivity in the bilateral inferior frontal gyri, whereas placebo users had decreased reactivity in the right amygdala. CONCLUSION COC use in women who previously had experienced emotional side effects resulted in mood deterioration, and COC use was also accompanied by changes in emotional brain reactivity. These findings are of relevance for the understanding of how combined oral contraceptives may influence mood. Placebo-controlled fMRI studies in COC sensitive women could be of relevance for future testing of adverse mood effects in new oral contraceptives.

Serotonin Synthesis and Reuptake in Social Anxiety Disorder: A Positron Emission Tomography Study.

IMPORTANCE Serotonin is involved in negative affect, but whether anxiety syndromes, such as social anxiety disorder (SAD), are characterized by an overactive or underactive serotonin system has not been established. Serotonin 1A autoreceptors, which inhibit serotonin synthesis and release, are downregulated in SAD, and serotonin transporter availability might be increased; however, presynaptic serotonin activity has not been evaluated extensively. OBJECTIVE To examine the serotonin synthesis rate and serotonin transporter availability in patients with SAD and healthy control individuals using positron emission tomography (PET) with the radioligands 5-hydroxytryptophan labeled with carbon 11 ([11C]5-HTP) and 11C-labeled 3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile [11C]DASB. DESIGN, SETTING, AND PARTICIPANTS We performed a cross-sectional study at an academic clinical research center. Eighteen patients with SAD (9 men and 9 women; mean [SD] age, 32.6 [8.2] years) and 18 sex- and age-matched healthy controls (9 men and 9 women; mean [SD] age, 34.7 [9.2] years) underwent [11C]5-HTP PET imaging. We acquired [11C]DASB PET images for 26 additional patients with SAD (14 men and 12 women; mean [SD] age, 35.2 [10.7] years) and the same 18 sex- and age-matched healthy controls. Participants were recruited through newspaper advertisements. Data were acquired from March 12, 2002, through March 5, 2012, and analyzed from March 28, 2013, through August 29, 2014. MAIN OUTCOMES AND MEASURES The influx rate of [11C]5-HTP as a measure of serotonin synthesis rate capacity and [11C]DASB binding potential as an index of serotonin transporter availability were acquired during rest. We used the Liebowitz Social Anxiety Scale to measure severity of social anxiety symptoms. RESULTS The PET data were not available for analysis in 1 control for each scan. Increased [11C]5-HTP influx rate was observed in the amygdala, raphe nuclei region, caudate nucleus, putamen, hippocampus, and anterior cingulate cortex of patients with SAD compared with healthy controls (P < .05 corrected), supporting an enhanced serotonin synthesis rate. Increased serotonin transporter availability in the patients with SAD relative to healthy controls was reflected by elevated [11C]DASB binding potential in the raphe nuclei region, caudate nucleus, putamen, thalamus, and insula cortex (P < .05 corrected). CONCLUSIONS AND RELEVANCE Neurotransmission in SAD is characterized by an overactive presynaptic serotonin system, with increased serotonin synthesis and transporter availability. Our findings could provide important new insights into the etiology of anxiety disorders.

Remembering our origin: Gender differences in spatial memory are reflected in gender differences in hippocampal lateralization

Gender differences in spatial memory favoring men are frequently reported, and the involvement of the hippocampus in these functions is well-established. However, little is known of whether this behavioral gender difference is mirrored in a gender difference in hippocampal function. Here we assessed hippocampal activity, using functional MRI, while 24 men and women moved through three-dimensional virtual mazes (navigation phase) of varying length, and at the end-point estimated the direction of the starting-point (pointing phase). Men were indeed more accurate than women at estimating direction, and this was especially true in longer mazes. Both genders activated the posterior hippocampus throughout the whole task. During the navigation phase, men showed a larger activation in the right hippocampus than women, while in the pointing phase, women showed a larger activation in the left hippocampus than men. Right-lateralized activation during the navigation phase was associated with greater task performance, and may reflect a spatial strategy that is beneficial in this task. Left-sided activation during the pointing phase might reflect a less efficient post hoc verbal recapitulation of the route. This study is the first to identify neural correlates of the commonly observed male advantage in recalling ones original position, and points to hippocampal lateralization as a possible explanation for this behavioral gender difference.

Amygdala subnuclei resting-state functional connectivity sex and estrogen differences

The amygdala is a hub in emotional processing, including that of negative affect. Healthy men and women have distinct differences in amygdala responses, potentially setting the stage for the observed sex differences in the prevalence of fear, anxiety, and pain disorders. Here, we examined how amygdala subnuclei resting-state functional connectivity is affected by sex, as well as explored how the functional connectivity is related to estrogen levels. Resting-state functional connectivity was measured using functional magnetic resonance imaging (fMRI) with seeds placed in the left and right laterobasal (LB) and centromedial (CM) amygdala. Sex differences were studied in 48 healthy men and 48 healthy women, matched for age, while the association with estrogen was analyzed in a subsample of 24 women, for whom hormone levels had been assessed. For the hormone analyses, the subsample was further divided into a lower and higher estrogen levels group based on a median split. We found distinct sex differences in the LB and CM amygdala resting-state functional connectivity, as well as preliminary evidence for an association between estrogen levels and connectivity patterns. These results are potentially valuable in explaining why women are more afflicted by conditions of negative affect than are men, and could imply a mechanistic role for estrogen in modulating emotion.

The effect of premenstrual dysphoric disorder and menstrual cycle phase on brain activity during response inhibition

BACKGROUND Premenstrual dysphoric disorder (PMDD) has generally not been associated with impulsive behavior. However, some studies suggest that women with PMDD have higher impulsivity scores than healthy controls and that brain activity during response inhibition may vary across the menstrual cycle. Therefore, our aim was to unravel potentially important cognitive aspects of PMDD by investigating brain activity during response inhibition in women with PMDD and healthy controls in relation to menstrual cycle phase. METHODS Fourteen PMDD patients and 13 healthy controls performed a Go/NoGo task to measure brain activity during response inhibition by use of event-related functional magnetic resonance imaging. RESULTS Women with PMDD displayed decreased activity during both menstrual cycle phases compared to healthy controls in several task-related parietal areas. A significant group by phase interactions was found in the left insula, driven by enhanced activity among healthy controls in the follicular phase and by enhanced insula activity during the luteal phase among PMDD patients. LIMITATIONS The limitations of the present study are the relatively limited sample size, the relatively small number of NoGo trials and the lack of a baseline contrast for the NoGo trials. CONCLUSIONS During response inhibition women with PMDD have reduced activity in areas associated with attention and motor function which is unrelated to menstrual cycle phase. Insular cortex activity, involved in both affective and cognitive processing, was significantly activated during the luteal phase among PMDD women. These findings are relevant for the understanding of how ovarian steroids influence mood symptoms in women.

Disruption of Memory Reconsolidation Erases a Fear Memory Trace in the Human Amygdala: An 18-Month Follow-Up.

Fear memories can be attenuated by reactivation followed by disrupted reconsolidation. Using functional magnetic resonance imaging we recently showed that reactivation and reconsolidation of a conditioned fear memory trace in the basolateral amygdala predicts subsequent fear expression over two days, while reactivation followed by disrupted reconsolidation abolishes the memory trace and suppresses fear. In this follow-up study we demonstrate that the behavioral effect persists over 18 months reflected in superior reacquisition after undisrupted, as compared to disrupted reconsolidation, and that neural activity in the basolateral amygdala representing the initial fear memory predicts return of fear. We conclude that disrupting reconsolidation have long lasting behavioral effects and may permanently erase the fear component of an amygdala-dependent memory.

Age, sex and NK1 receptors in the human brain — A positron emission tomography study with [11C]GR205171

The substance P/neurokinin 1 (SP/NK1) system has been implicated in the processing of negative affect. Its role seems complex and findings from animal studies have not been easily translated to humans. Brain imaging studies on NK1 receptor distribution in humans have revealed an abundance of receptors in cortical, striatal and subcortical areas, including the amygdala. A reduction in NK1 receptors with increasing age has been reported in frontal, temporal, and parietal cortices, as well as in hippocampal areas. Also, a previous study suggests sex differences in cortical and subcortical areas, with women displaying fewer NK1 receptors. The present PET study explored NK1 receptor availability in men (n=9) and women (n=9) matched for age varying between 20 and 50years using the highly specific NK1 receptor antagonist [¹¹C]GR205171 and a reference tissue model with cerebellum as the reference region. Age by sex interactions in the amygdala and the temporal cortex reflected a lower NK1 receptor availability with increasing age in men, but not in women. A general age-related decline in NK1 receptor availability was evident in the frontal, temporal, and occipital cortices, as well as in the brainstem, caudate nucleus, and thalamus. Women had lower NK1 receptor availability in the thalamus. The observed pattern of NK1 receptor distribution in the brain might have functional significance for brain-related disorders showing age- and sex-related differences in prevalence.

Enlargement of visual processing regions in social anxiety disorder is related to symptom severity

Social anxiety disorder (SAD) is associated with altered brain function and structure, but most structural studies include small samples and findings are mixed. This study compared regional gray matter volume between 48 SAD patients and 29 healthy controls (HC) as well as the relationship between volume and symptom severity. Structural magnetic resonance images from SAD patients and HC were evaluated using standard voxel-based morphometry (VBM) processing in the SPM8 software package. Social anxiety symptom severity was rated in SAD patients by a clinician using the Liebowitz Social Anxiety Scale (LSAS). SAD patients had greater regional gray matter volume in the lingual gyrus and lateral occipital cortex than the controls, and within the SAD group a positive correlation was found between symptom severity and regional gray matter volume in the lingual gyrus and the retrosplenial cortex. These findings replicate and extend earlier reports of enlarged visual processing areas in SAD. Increased gray matter volume in regions involved in visual processing and self-consciousness could underlie, or be the result of, abnormal emotional information processing and self-focused attention previously demonstrated in patients with SAD.