Clinical Efficiency and Acceptability of EMDR and MOSAIC Therapy for PTSD.

Eye movement desensitization and reprocessing (EMDR) therapy is one of the therapies recommended by the World Health Organization (2013) to treat posttraumatic stress disorder (PTSD). Although efficient, repeated exposure to the traumatic memory may reduce its acceptability to patients. The therapy "eye movement and alternate stimulation for brain integration" (MOSAIC in French) was developed to improve acceptability and reduce pain by drawing on the patient's internal resources. MOSAIC therapy focuses on the body sensations that the patient wants to experience and avoids having to relive the traumatic memories. This observational study aimed to compare the clinical efficiency of EMDR and MOSAIC therapy for PTSD and to measure the well-being generated by both therapies. Twenty-six PTSD patients (17 females and 9 males, mean age 37.01 years, SD = 13.06) received treatment by psychiatrists and/or psychologists trained with EMDR or MOSAIC therapy. Both patient groups achieved a significant decrease in PTSD symptoms as measured with the PCL-5. However, fewer sessions were required with the MOSAIC therapy than with EMDR therapy. As expected, the level of well-being experienced by the patient during the therapy, assessed using the Lickert scale, was higher with MOSAIC than with EMDR therapy from the first session. These findings provide the first evidence of the efficacy of MOSAIC therapy treatment, which now needs to be corroborated in a larger randomized clinical trial.

MOSAIC: A New Pain-Free Psychotherapy for Psychological Trauma.

Eye movements and alternating stimuli for brain integration (MOSAIC) is a promising but untested new therapy. Its four-step protocol is based on the effects of bilateral alternating stimulation (BAS) (as in eye movement desensitization and reprocessing therapy) on the brain. This solution-oriented therapy promotes experiencing solutions through bodily sensations. Through BAS and bodily sensations, MOSAIC therapy aims to enrich the traumatic memory neuronal network with new information so that the client's psychological trauma is no longer distressing. Thus, MOSAIC can be used to treat psychological trauma without the pain associated with reliving the traumatic situation. This method may be particularly adaptive for patients who have experienced complex trauma and who have dissociative experiences.

Cracking the EMDR code: Recruitment of sensory, memory and emotional networks during bilateral alternating auditory stimulation.

INTRODUCTION: The inability to extinguish a conditioned fear is thought to be at the core of post-traumatic stress disorder. Eye movement desensitization and reprocessing therapy has been efficacious for post-traumatic stress disorder, but the brain mechanisms underlying the effect are still unknown. The core effect of eye movement desensitization and reprocessing therapy seems to rely on the simultaneous association of bilateral alternating stimulation and the recall of the traumatic memory. To shed light on how eye movement desensitization and reprocessing therapy functions, we aimed to highlight the structures activated by bilateral alternating stimulation during fear extinction and its recall. METHODS: We included 38 healthy participants in this study. Participants were examined twice in functional magnetic resonance imaging, over 2 consecutive days. On the first day, they performed two fear conditioning and extinction procedures, one with and one without the bilateral alternating stimulation during the fear extinction learning phase in a counter-balanced order across the participants. On the second day, participants completed the fear extinction recall procedure, in the same order as the previous day. Statistical significance of maps was set at p < 0.05 after correction for family-wise error at the cluster level. RESULTS: The analysis revealed significant activation with versus without bilateral alternating stimulation at the early extinction in the bilateral auditory areas, the right precuneus, and the left medial frontal gyrus. The same pattern was found in the early recall on the second day. The connectivity analysis found a significant increase in connectivity during bilateral alternating stimulation versus without bilateral alternating stimulation in the early extinction and recall between the two superior temporal gyri, the precuneus, the middle frontal gyrus and a set of structures involved in multisensory integration, executive control, emotional processing, salience and memory. CONCLUSION: We show for the first time that in the eye movement desensitization and reprocessing therapy the bilateral alternating stimulation is not a simple sensory signal and can activate large emotional neural networks.

Posttraumatic Stress Disorder is associated with altered reward mechanisms during the anticipation and the outcome of monetary incentive cues.

BACKGROUND: Recent studies suggest that Posttraumatic Stress Disorder (PTSD) might be associated with dysfunctional reward circuitry. However, further research is needed to understand the key role of the reward system in PTSD symptomatology. METHODS: Twenty participants with PTSD and 21 Trauma-Exposed matched Controls (TECs) completed the Monetary Incentive Delay (MID) task during an MRI session. Reaction times (RTs) and hit rates were recorded. Brain activity was investigated during the anticipation and the outcome of monetary gains and losses. RESULTS: During the anticipation of monetary loss, PTSD participants had higher RTs than TECs. However, the groups did not differ at the neurofunctional level. During successful avoidance of monetary loss, PTSD patients showed higher activation than TECs in the left caudate nucleus. During the anticipation of monetary gains, no differences in RTs were found between groups. PTSD patients had specific activations in the right amygdala, nucleus accumbens, putamen, and middle frontal gyrus (p < 0.05 family-wise error (FWE)-corrected), while TECs had specific activation in the anterior cingulate cortex. When obtaining monetary gains, PTSD patients had specific activation in the caudate nucleus, while TECs had specific activations in the right hypothalamus, subthalamic nucleus, and left inferior frontal gyrus. CONCLUSION: For the first time, functional brain activation during both the anticipation and the outcome of monetary rewards is reported altered in PTSD patients. These alterations might be associated with the complex symptomatology of PTSD.

Fear extinction learning improvement in PTSD after EMDR therapy: an fMRI study.

Objective: Neurobiological models of Posttraumatic Stress Disorder (PTSD) implicate fear processing impairments in the maintenance of the disorder. Eye Movement Desensitization and Reprocessing (EMDR) is one of the most efficient psychotherapies to treat PTSD. We aimed at exploring the brain mechanisms of the fear circuitry involved in PTSD patients' symptom remission after EMDR therapy. Method: Thirty-six PTSD participants were randomly assigned to either EMDR group receiving EMDR therapy or Wait-List (WL) group receiving supportive therapy. Participants underwent a behavioural fear conditioning and extinction paradigm during functional magnetic resonance (fMRI). In the EMDR group, patients were scanned at baseline, before EMDR and one week after remission. In the WL group, patients were scanned at baseline and within the same time interval as the EMDR group. Results: In the EMDR group after treatment, fear responses in the late extinction were significantly lower than before therapy. In parallel, significant functional activity and connectivity changes were found in the EMDR group versus the WL during the late extinction. These changes involve the fear circuit (amygdalae, left hippocampus), the right inferior frontal gyrus, the right frontal eye field and insula (pFWE < .05). Conclusion: These functional modifications underlie a significant improvement of fear extinction learning in PTSD patients after EMDR therapy.

Objetivo: Los modelos neurobiológicos del TEPT implican deficiencias en el procesamiento del miedo en el mantenimiento del trastorno. EMDR es una de las psicoterapias más eficaces para tratar el TEPT. Nuestro objetivo fue explorar los mecanismos cerebrales de los circuitos de miedo implicados en la remisión de los síntomas de los pacientes con el TEPT después de la terapia EMDR.Método: Treinta y seis participantes con el TEPT fueron asignados aleatoriamente a un grupo EMDR que recibió terapia EMDR o un grupo de Lista de Espera (LE) que recibió terapia de apoyo. Los participantes se sometieron a un paradigma de condicionamiento y extinción del miedo conductual durante la resonancia magnética funcional (fMRI). En el grupo EMDR, los pacientes fueron escaneados al inicio del estudio, antes de EMDR y una semana después de la remisión. En el grupo LE, los pacientes fueron escaneados al inicio y en el mismo intervalo de tiempo que el grupo EMDR.Resultados: En el grupo EMDR después del tratamiento, las respuestas de miedo en la extinción tardía fueron significativamente más bajas que antes de la terapia. En paralelo, se encontraron cambios significativos en la actividad funcional y en la conectividad en el grupo EMDR v/s el grupo LE durante la extinción tardía. Estos cambios involucran el circuito de miedo (amígdala, hipocampo izquierdo), el giro frontal inferior derecho, los campos del ojo frontal derecho y la ínsula (pFWE < .05).Conclusión: Estas modificaciones funcionales subyacen a una mejora significativa del aprendizaje de extinción del miedo en pacientes con el TEPT después de la terapia EMDR.

Subjective and physiological response to emotions in temporal lobe epilepsy and psychogenic non-epileptic seizures.

BACKGROUND: Temporal lobe epilepsy (TLE) and psychogenic non-epileptic seizures (PNES) are conditions frequently associated with dysfunction in emotional regulation leading to increased risk of affective disorders. This study investigates emotional processing with an objective measure of emotional reactivity in patients with TLE and patients with PNES. METHODS: 34 patients with TLE and 14 patients with PNES were evaluated on skin conductance responses (SCR) to emotions induced by short films and compared to 34 healthy controls. An attention and a suppression condition were performed while viewing the films. RESULTS: The both groups of patients disclosed lower SCR to emotions compared to controls, mainly in suppression condition. While TLE patients had lower SCR in attention condition than controls for fear, sadness and happiness, PNES had lower SCR only for happiness. In suppression condition, both had lower SCR than controls except for peacefulness in both groups and sadness in PNES. Subjective evaluations revealed that both patient's groups scored a higher intensity for sadness than controls in attention and lower for in fear and disgust in suppression only in TLE. LIMITATIONS: The sample size in the PNES group and the lack of a control group with similar levels of mood symptoms limited the interpretation of our results. CONCLUSION: As no correlation were found between SCR to emotions and scores of affective disorders, this pattern of responses might be underpinned by specific pathophysiological and cognitive mechanisms related to TLE and to PNES. Thus, therapeutic approaches targeting emotional autonomic responses can be of interest in the management of these conditions.

Brain metabolism and related connectivity in patients with acrophobia treated by virtual reality therapy: an 18F-FDG PET pilot study sensitized by virtual exposure.

BACKGROUND: The aim of this pilot study is to investigate the impact of virtual reality exposure therapy (VRET) on brain metabolism and connectivity. Eighteen patients with acrophobia were assessed by an 18F-FDG PET scan sensitized by virtual exposure before treatment, and nine of them were assessed again after eight sessions of VRET. Statistical Parametric Mapping was used to study the correlations between metabolism and pretherapeutic clinical scores and to compare metabolism before and after VRET (p voxel < 0.005, corrected for cluster volume). Metabolic connectivity was evaluated through interregional correlation analysis. RESULTS: Before therapy, a positive correlation was found between scores on the behavioural avoidance test and left occipital metabolism (BA17-18). After VRET, patients presented increased metabolism in the left frontal superior gyri and the left precentral gyrus, which showed increased metabolic connectivity with bilateral occipital areas (BA17-18-19), concomitant with clinical recovery. CONCLUSIONS: This study highlights the exciting opportunity to use brain PET imaging to investigate metabolism during virtual exposure and reports the involvement of the visual-motor control system in the treatment of acrophobia by VRET.

A case-control study of skin conductance biofeedback on seizure frequency and emotion regulation in drug-resistant temporal lobe epilepsy.

This study investigates the physiological basis of effects of skin conductance biofeedback on anxiety disorders, depressive disorders and stress in drug-resistant temporal lobe epilepsy (TLE). This method presents an interest in seizure reduction and improvement in psychiatric comorbidities frequently associated with TLE. Our goal was to better understand the impact of biofeedback on seizure control and on emotional regulation. Fifteen patients with TLE were treated with 12 skin conductance biofeedback sessions and compared with 15 control TLE patients on a waiting list. They were evaluated in terms of seizure frequency, clinical evaluations of anxiety and depression and skin conductance responses (SCR) to five emotions: fear, disgust, sadness, happiness and peacefulness induced by short films. Biofeedback training significantly reduced seizure frequency with a mean reduction of -47.42% in the biofeedback group, while the control group did not differ at the two time measures. A significant improvement was found for depression and trait-anxiety in the biofeedback group but not in the control group. There were no differences on SCR on any emotion after biofeedback treatment. A correlation was found between mean change in SCR over the biofeedback treatment and the reduction of seizure frequency, but not between SCR changes and scores on psychiatric comorbidities. These results show independent effect of biofeedback on mood and seizure control. Improvements in anxiety and depressive symptoms were not related to SCR, whereas improved seizure control was, suggesting differential mechanisms underlying these two phenomena.

Grey matter density changes of structures involved in Posttraumatic Stress Disorder (PTSD) after recovery following Eye Movement Desensitization and Reprocessing (EMDR) therapy.

Recovery of stress-induced structural alterations in Posttraumatic Stress Disorder (PTSD) remains largely unexplored. This study aimed to determine whether symptoms improvement is associated with grey matter (GM) density changes of brain structures involved in PTSD. Two groups of PTSD patients were involved in this study. The first group was treated with Eye Movement Desensitization and Reprocessing (EMDR) therapy and recovered from their symptoms (recovery group) (n = 11); Patients were scanned prior to therapy (T1), one week (T2) and five months after the end of therapy (T3). The second group included patients which followed a supportive therapy and remained symptomatic (wait-list group) (n = 7). They were scanned at three time-steps mimicking the same inter-scan intervals. Voxel-based morphometry (VBM) was used to characterize GM density evolution. GM density values showed a significant group-by-time interaction effect between T1 and T3 in prefrontal cortex areas. These interaction effects were driven by a GM density increase in the recovery group with respect to the wait-list group. Symptoms removal goes hand-in-hand with GM density enhancement of structures involved in emotional regulation.

Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval.

Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD). Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS) during eye movement desensitization and reprocessing (EMDR) therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to determine if these previous results found in animals can be reproduced in humans. Twenty-two healthy participants took part in a classical fear conditioning, extinction, and extinction recall paradigm. Behavioral responses (fear expectations) as well as psychophysiological measures (skin conductance responses, SCRs) were recorded. The results showed a significant fear expectation decrease during fear extinction with BLS. Additionally, SCR for fear extinction retrieval were significantly lower with BLS. Our results demonstrate the importance of BLS to reduce negative emotions, and provide a successful model to further explore the neural mechanisms underlying the sole BLS effect in the EMDR.

Dissociating Bottom-Up and Top-Down Mechanisms in the Cortico-Limbic System during Emotion Processing.

The cortico-limbic system is critically involved in emotional responses and resulting adaptive behaviors. Within this circuit, complementary regions are believed to be involved in either the appraisal or the regulation of affective state. However, the respective contribution of these bottom-up and top-down mechanisms during emotion processing remains to be clarified. We used a new functional magnetic resonance imaging (fMRI) paradigm varying 3 parameters: emotional valence, emotional congruency, and allocation of attention, to distinguish the functional variation in activity and connectivity between amygdala, anterior cingulate cortex (ACC), and dorsolateral prefrontal cortex (DLPFC). Bottom-up appraisal of negative compared with positive stimuli led to a greater amygdala response and stronger functional interaction between amygdala and both dorsal ACC and DLPFC. Top-down resolution of emotional conflict was associated with increased activity within ACC and higher functional connectivity between this structure, and both the amygdala and DLPFC. Finally, increased top-down attentional control caused greater engagement of the DLPFC, accompanied by increased connectivity between DLPFC and dorsal ACC. This novel task provides an efficient tool for exploring bottom-up and top-down processes underlying emotion and may be particularly helpful for investigating the neurofunctional underpinnings of psychiatric disorders.

Effect of trait anxiety on prefrontal control mechanisms during emotional conflict.

Converging evidence points to a link between anxiety proneness and altered emotional functioning, including threat-related biases in selective attention and higher susceptibility to emotionally ambiguous stimuli. However, during these complex emotional situations, it remains unclear how trait anxiety affects the engagement of the prefrontal emotional control system and particularly the anterior cingulate cortex (ACC), a core region at the intersection of the limbic and prefrontal systems. Using an emotional conflict task and functional magnetic resonance imaging (fMRI), we investigated in healthy subjects the relations between trait anxiety and both regional activity and functional connectivity (psychophysiological interaction) of the ACC. Higher levels of anxiety were associated with stronger task-related activation in ACC but with reduced functional connectivity between ACC and lateral prefrontal cortex (LPFC). These results support the hypothesis that when one is faced with emotionally incompatible information, anxiety leads to inefficient high-order control, characterized by insufficient ACC-LPFC functional coupling and increases, possibly compensatory, in activation of ACC. Our findings provide a deeper understanding of the pathophysiology of the neural circuitry underlying anxiety and may offer potential treatment markers for anxiety disorders.

Acute stress disorder modifies cerebral activity of amygdala and prefrontal cortex.

The diagnosis constraint of acute stress disorder (ASD), consisting of testing individuals in the month following trauma exposure, limits research on the very early and initial stage of the disease. In this regard, this work aims to explore the cerebral mechanism of ASD in a population of fire-fighters before and after trauma exposure. Thirty-six healthy non-traumatized male fire-fighters were explored by an fMRI emotional face-matching task to evaluate the cerebral substrate of emotional recognition. During the two years of the follow-up, two subjects were traumatized, and thus retested, as were 10 non-traumatized subjects among the initial non-exposed ones. In comparison to non-exposed subjects, fire-fighters with ASD had enhanced amygdala, orbitofrontal, and dorsolateral prefrontal BOLD responses to fearful and angry faces (p < .05, FDR-corrected). These results shed new light on the cerebral mechanism associated with ASD. We observed for the first time the existence of an altered fear processing pathway in ASD that is mediated by amygdala and prefrontal cortex hyperactivity, which might be at the core of the disorder.

rTMS in fibromyalgia: a randomized trial evaluating QoL and its brain metabolic substrate.

OBJECTIVE: This double-blind, randomized, placebo-controlled study investigated the impact of repetitive transcranial magnetic stimulation (rTMS) on quality of life (QoL) of patients with fibromyalgia, and its possible brain metabolic substrate. METHODS: Thirty-eight patients were randomly assigned to receive high-frequency rTMS (n = 19) or sham stimulation (n = 19), applied to left primary motor cortex in 14 sessions over 10 weeks. Primary clinical outcomes were QoL changes at the end of week 11, measured using the Fibromyalgia Impact Questionnaire (FIQ). Secondary clinical outcomes were mental and physical QoL component measured using the 36-Item Short Form Health Survey (SF-36), but also pain, mood, and anxiety. Resting-state [(18)F]-fluorodeoxyglucose-PET metabolism was assessed at baseline, week 2, and week 11. Whole-brain voxel-based analysis was performed to study between-group metabolic changes over time. RESULTS: At week 11, patients of the active rTMS group had greater QoL improvement in the FIQ (p = 0.032) and in the mental component of the SF-36 (p = 0.019) than the sham stimulation group. No significant impact was found for other clinical outcomes. Compared with the sham stimulation group, patients of the active rTMS group presented an increase in right medial temporal metabolism between baseline and week 11 (p < 0.001), which was correlated with FIQ and mental component SF-36 concomitant changes (r = -0.38, p = 0.043; r = 0.51, p = 0.009, respectively). QoL improvement involved mainly affective, emotional, and social dimensions. CONCLUSION: Our study shows that rTMS improves QoL of patients with fibromyalgia. This improvement is associated with a concomitant increase in right limbic metabolism, arguing for a neural substrate to the impact of rTMS on emotional dimensions involved in QoL. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that rTMS compared with sham rTMS improves QoL in patients with fibromyalgia.

Relationship between emotional experience and resilience: an fMRI study in fire-fighters.

Resilience refers to the capacity to cope effectively in stressful situations or adversity. It may involve the ability to experience emotions matching the demands of environmental circumstances. The brain mechanisms underlying resilience remain unclear. In this study, we aim to investigate the relationship between the neural basis of emotional experience and resilience. Thirty-six fire-fighters were included. They performed an fMRI script-driven paradigm comprising relaxing and trauma-related scripts to evaluate the cerebral substrate of emotional experience (p<0.05, FDR-corrected). Correlations were examined between fMRI activations and the resilience DRS15 scale (p<0.05). Resilience was positively correlated with the right amygdala and left orbitofrontal activations when performing the contrast of trauma vs. relaxing script. The present study provides neural data on the mechanisms underlying resilience and their relationship with emotional reactivity, suggesting that appropriate emotional response in stressful situations is essential for coping with aversive events in daily life.

Neuroticism modifies psychophysiological responses to fearful films.

BACKGROUND: Neuroticism is a personality component frequently found in anxious and depressive psychiatric disorders. The influence of neuroticism on negative emotions could be due to its action on stimuli related to fear and sadness, but this remains debated. Our goal was thus to better understand the impact of neuroticism through verbal and physiological assessment in response to stimuli inducing fear and sadness as compared to another negative emotion (disgust). METHODS: Fifteen low neurotic and 18 high neurotic subjects were assessed on an emotional attending task by using film excerpts inducing fear, disgust, and sadness. We recorded skin conductance response (SCR) and corrugator muscle activity (frowning) as indices of emotional expression. RESULTS: SCR was larger in high neurotic subjects than in low neurotics for fear relative to sadness and disgust. Moreover, corrugator activity and SCR were larger in high than in low neurotic subjects when fear was induced. CONCLUSION: After decades of evidence that individuals higher in neuroticism experience more intense emotional reactions to even minor stressors, our results indicate that they show greater SCR and expressive reactivity specifically to stimuli evoking fear rather than to those inducing sadness or disgust. Fear processing seems mainly under the influence of neuroticism. This modulation of autonomic activity by neurotics in response to threat/fear may explain their increased vulnerability to anxious psychopathologies such as PTSD (post traumatic stress disorder).

Attentional bias in post-traumatic stress disorder diminishes after symptom amelioration.

BACKGROUND: Avoidance and hypervigilance to reminders of a traumatic event are among the main characteristics of post-traumatic stress disorder (PTSD). Attentional bias toward aversive cues in PTSD has been hypothesized as being part of the dysfunction causing etiology and maintenance of PTSD. The aim of the present study was to investigate the cognitive strategy underlying attentional bias in PTSD and whether normal cognitive processing is restored after a treatment suppressing core PTSD symptoms. METHODS: Nineteen healthy controls were matched for age, sex and education to 19 PTSD patients. We used the emotional stroop and detection of target tasks, before and after an average of 4.1 sessions of eye movement desensitization and reprocessing (EMDR) therapy. RESULTS: We found that on both tasks, patients were slower than controls in responding in the presence of emotionally negative words compared to neutral ones. After symptoms removal, patients no longer had attentional bias, and responded similarly to controls. CONCLUSION: These results support the existence of an attentional bias in PTSD patients due to a disengagement difficulty. There was also preliminary evidence that the disengagement was linked to PTSD symptomatology. It should be further explored whether attentional bias and PTSD involve common brain mechanisms.

Amygdala activity correlates with attentional bias in PTSD.

Post-traumatic stress disorder (PTSD) is an anxiety disorder arising in the aftermath of a traumatic event. The most prevalent hypothesis is that of an increased amygdala activity to threat cues. The amygdala has also shown an implication in orienting attention toward threat. The aim of the study was to explore the correlations between amygdala activity, symptom severity and attentional bias in PTSD. Patients and healthy controls were assayed on an fMRI emotional face matching task and an attentional detection of target (DOT) task. The amygdala showed enhanced activity in PTSD (vs. controls). It positively correlated with anxiety scores and PTSD symptomatology. It also positively correlated with the disengagement index. Mostly, these results provide preliminary support for an implication of the amygdala in attention orientation to threat in PTSD. These results are further discussed in light of recent theories concerned with cortico-limbic functioning.

Pure-tone auditory thresholds are decreased in depressed people with post-traumatic stress disorder.

BACKGROUND: Depression has been related to sensory modulation and notably to auditory modifications such as alterations in auditory event-related potentials, abnormal patterns of auditory habituation, increased activation of primary and secondary auditory cortex, and higher bilateral auditory thresholds. However, few experiments have considered the exploration of the auditory system in depression. The aim of the experiment is to further explore auditory thresholds across a higher number of frequencies than has previously been undertaken in depressed subjects, to determine whether thresholds are modified as compared to controls, and if so, at which frequencies. METHODS: 25 pure-tones covering a large range of frequencies from 125Hz to 8kHz were used to measure both air and bone conduction (AC and BC respectively) hearing thresholds. 13 patients with depression and post-traumatic disorder matched for age, sex and education level with 13 healthy subjects, were tested. RESULTS: Hearing thresholds were found to be significantly poorer in depressed participants than in controls for frequencies from 2.75Hz to 8kHz in BC, and for 0.5, 0.75, 0.875 and 2.0-8.0kHz pure-tone frequencies in AC. LIMITATIONS: Given that the depressed patients also had comorbid post-traumatic disorder, it should be verified whether their modified pure-tone audiometry is only related to depression. CONCLUSIONS: The AC and BC pure-tone auditory threshold measurement may provide new and different insights into the aetiology and evolution of depression.

Hypo-retrieval and hyper-suppression mechanisms in functional amnesia.

Functional amnesia (FA) is characterized by an extensive retrograde memory loss in the absence of detectable structural brain damage. The two main hypotheses put forward to explain this disturbance involve a global retrieval deficit (affecting both pre- and post-onset memories) and a selective inability to explicitly retrieve pre-onset memories. Here, we extensively examined P.P., a patient with FA, with a view to obtaining additional insights into the cognitive and neural mechanisms underlying this disorder. In Experiments 1 and 2, post-onset memories were assessed using tasks focusing on the state of consciousness associated with their retrieval. Although subtle deficits in the ability to recollect post-onset personal events were detected, P.P.'s performances were normal when the encoding of the event was monitored in a laboratory setting. In Experiment 3, implicit recognition of pre-onset memories was tested using skin conductance responses. Results showed that P.P. responded implicitly to photographs of personal pre-onset events that were not explicitly recognized. In Experiment 4, designed to assess the patient's ability to suppress newly acquired information, P.P. suppressed more items than controls. Additionally, while no grey matter loss was evidenced with voxel-based morphometry, magnetic resonance spectroscopy and magnetization transfer imaging showed significant metabolic and structural changes within the white matter of the right prefrontal lobe. In conclusion, our results suggest that FA may result from a combination between two processes, a "hypo-retrieval" of pre-onset memories, tentatively due to white matter tract damage, and a "hyper-suppression" mechanism, concomitantly preventing the retrieval of pre-onset memories.