David L. Perez

Distinct Neural Signatures for Safety and Danger in the Amygdala and Striatum of the Mouse

The ability to identify, develop, and exploit conditions of safety and security is central to survival and mental health, but little is known of the neurobiology of these processes or associated positive modulations of affective state. We studied electrophysiological and affective correlates of learned safety by negatively correlating an auditory conditioned stimulus (CS) with aversive events (US). This CS came to signify a period of protection, reducing fear responses to predictors of the US and increasing adventurous exploration of a novel environment. In nonaversive conditions, mice turn on the CS when given the opportunity. Thus, conditioned safety involves a reduction of learned and instinctive fear, as well as positive affective responses. Concurrent electrophysiological measurements identified a safety learning-induced long-lasting depression of CS-evoked activity in the lateral nucleus of the amygdala, consistent with fear reduction, and an increase of CS-evoked activity in a region of the striatum involved in positive affect, euphoric responses, and reward.

An Integrative Neurocircuit Perspective on Psychogenic Nonepileptic Seizures and Functional Movement Disorders: Neural Functional Unawareness

Functional neurological disorder (conversion disorder) is a neurobehavioral condition frequently encountered by neurologists. Psychogenic nonepileptic seizure (PNES) and functional movement disorder (FMD) patients present to epileptologists and movement disorder specialists respectively, yet neurologists lack a neurobiological perspective through which to understand these enigmatic groups. Observational research studies suggest that PNES and FMD may represent variants of similar (or the same) conditions given that both groups exhibit a female predominance, have increased prevalence of mood-anxiety disorders, frequently endorse prior abuse, and share phenotypic characteristics. In this perspective article, neuroimaging studies in PNES and FMD are reviewed, and discussed using studies of emotional dysregulation, dissociation and psychological trauma in the context of motor control. Convergent neuroimaging findings implicate alterations in brain circuits mediating emotional expression, regulation and awareness (anterior cingulate and ventromedial prefrontal cortices, insula, amygdala, vermis), cognitive control and motor inhibition (dorsal anterior cingulate, dorsolateral prefrontal, inferior frontal cortices), self-referential processing and perceptual awareness (posterior parietal cortex, temporoparietal junction), and motor planning and coordination (supplementary motor area, cerebellum). Striatal-thalamic components of prefrontal-parietal networks may also play a role in pathophysiology. Aberrant medial prefrontal and amygdalar neuroplastic changes mediated by chronic stress may facilitate the development of functional neurological symptoms in a subset of patients. Improved biological understanding of PNES and FMD will likely reduce stigma and aid the identification of neuroimaging biomarkers guiding treatment development, selection, and prognosis. Additional research should investigate neurocircuit abnormalities within and across functional neurological disorder subtypes, as well as compare PNES and FMD with mood-anxiety-dissociative disorders.

Treatment of Psychogenic Nonepileptic Seizures: Updated Review and Findings From a Mindfulness-Based Intervention Case Series

Psychogenic nonepileptic seizures (PNES) were first described in the medical literature in the 19th century, as seizure-like attacks not related to an identified central nervous system lesion, and are currently classified as a conversion disorder, according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5). While a universally accepted and unifying etiological model does not yet exist, several risk factors have been identified. Management of PNES should be based on interdisciplinary collaboration, targeting modifiable risk factors. The first treatment phase in PNES is patient engagement, which is challenging given the demonstrated low rates of treatment retention. Acute interventions constitute the next phase in treatment, and most research studies focus on short-term evidence-based interventions. Randomized controlled pilot trials support cognitive–behavioral therapy. Other psychotherapeutic and psychopharmacological interventions have been less well-studied using controlled and uncontrolled trials. Within the discussion of acute interventions, we present a preliminary evaluation for feasibility of a mindfulness-based psychotherapy protocol in a very small sample of PNES patients. We demonstrated in 6 subjects that this intervention is feasible in real-life clinical scenarios and warrants further investigation in larger scale studies. The final treatment phase is long-term follow-up. Long-term outcome studies in PNES show that a significant proportion of patients remains symptomatic and experiences continued impairments in quality of life and functionality. We believe that PNES should be understood as a disease that requires different types of intervention during the various phases of treatment.

Motor and Somatosensory Conversion Disorder: A Functional Unawareness Syndrome?

Although conversion disorder is closely connected to the origins of neurology and psychiatry, it remains poorly understood. In this article, the authors discuss neural and clinical parallels between lesional unawareness disorders and unilateral motor and somatosensory conversion disorder, emphasizing functional neuroimaging/disease correlates. Authors suggest that a functional-unawareness neurobiological framework, mediated by right hemisphere-lateralized, large-scale brain network dysfunction, may play a significant role in the neurobiology of conversion disorder. The perigenual anterior cingulate and the posterior parietal cortices are detailed as important in disease pathophysiology. Further investigations will refine the functional-unawareness concept, clarify the role of affective circuits, and delineate the process through which functional neurologic symptoms emerge.

Nonepileptic seizures: an updated review.

Psychogenic nonepileptic seizures (PNES) are a functional neurological disorder/conversion disorder subtype, which are neurobehavioral conditions at the interface of neurology and psychiatry. Significant advancements over the past decade have been made in the diagnosis, management, and neurobiological understanding of PNES. This article reviews published PNES research focusing on semiologic features that distinguish PNES from epileptic seizures, consensus diagnostic criteria, the intersection of PNES and other comorbidities, neurobiological studies, evidence-based treatment interventions, and outcome studies. Epidemiology and healthcare utilization studies highlight a continued unmet medical need in the comprehensive care of PNES. Consensus guidelines for diagnostic certainty are based on clinical history, semiology of witnessed typical event(s), and EEG findings. While certain semiologic features may aid in the diagnosis of PNES, the gold standard remains capturing a typical event on video electroencephalography (EEG) showing the absence of epileptiform activity with history and semiology consistent with PNES. Medical-neurologic and psychiatric comorbidities are prevalent in PNES; these should be assessed in diagnostic evaluations and integrated into treatment interventions and prognostic considerations. Several studies, including a pilot, multicenter, randomized clinical trial, have now demonstrated that a cognitive behavioral therapy-informed psychotherapy is an efficacious treatment for PNES, and additional efforts are necessary to evaluate the utility of pharmacologic and other psychotherapy treatments. Neuroimaging studies, while requiring replication, suggest that PNES may occur in the context of alterations within and across sensorimotor, emotion regulation/processing, cognitive control, and multimodal integration brain systems. Future research could investigate similarities and differences between PNES and other somatic symptom disorders.

A translational bridge between mouse and human models of learned safety

Abstract Background. Learned safety is established by negatively correlating the occurrence of a neutral stimulus and a noxious stimulus, which renders the previously neutral stimulus a ‘safety signal’. While the neurophysiological and molecular mechanisms have been characterized in mice, it is currently not known how the neural substrates involved compare between mice and people. Methods. Here we attempt to adapt the original animal protocol to humans and use functional magnetic resonance imaging to examine neural responses to the conditioned stimulus in safety conditioned and fear conditioned subjects. Diffusion tensor imaging (DTI) was used in a parallel group of subjects as a first approach to delineate the underlying neural circuitry. Results. Learned safety is associated with dampened amygdala and increased dorsolateral prefrontal cortex and caudate responses and paralleled by pupillary constriction. A neural connection between the amygdala and the dorsolateral prefrontal cortex is suggested by DTI. Conclusion. We present a translational bridge between mouse and human models of learned safety in which cellular and molecular insights from animal experiments are extended to the human neural circuitry. This study provides an example of how animal experiments can be used to inform and target human studies, which in turn can corroborate results obtained in experimental animals.

Pre- and postictal, not ictal, heart rate distinguishes complex partial and psychogenic nonepileptic seizures

Psychogenic nonepileptic seizures (PNES) remain poorly understood neurobiologically. Previously reported work suggests that adjunct ictal heart rates (HRs) may differentiate PNES from complex partial seizures (CPS). We retrospectively reviewed and compared preictal, ictal, and postictal HR differences in patients with PNES (n=42) and CPS controls (n=46) electively admitted for video/EEG monitoring to further characterize PNES autonomic patterns. Statistically significant preictal HR increases (P=0.006) and postictal (P=0.015) HR reductions normalized to baseline were identified in subjects with PNES compared with CPS controls. Ictal HRs were not found to differentiate between PNES and CPS events. This pattern of pre-event HR increases and postevent HR decreases in patients with PNES compared with those with CPS suggests frontolimbic neural circuit dysfunction and merits further exploration.

Frontolimbic neural circuit changes in emotional processing and inhibitory control associated with clinical improvement following transference‐focused psychotherapy in borderline personality disorder

Borderline personality disorder (BPD) is characterized by self‐regulation deficits, including impulsivity and affective lability. Transference‐focused psychotherapy (TFP) is an evidence‐based treatment proven to reduce symptoms across multiple cognitive–emotional domains in BPD. This pilot study aimed to investigate neural activation associated with, and predictive of, clinical improvement in emotional and behavioral regulation in BPD following TFP.

A Neural Circuit Framework for Somatosensory Amplification in Somatoform Disorders

Although somatosensory amplification is theorized to serve a critical role in somatization, it remains poorly understood neurobiologically. In this perspective article, convergent visceral-somatic processing is highlighted, and neuroimaging studies in somatoform disorders are reviewed. Neural correlates of cognitive-affective amplifiers are integrated into a neurocircuit framework for somatosensory amplification. The anterior cingulate cortex, insula, amygdala, hippocampal formation, and striatum are some of the identified regions. Clinical symptomatology in a given patient or group may represent dysfunction in one or more of these neurobehavioral nodes. Somatosensory amplification may, in part, develop through stress-mediated aberrant neuroplastic changes and the neuromodulatory effects of inflammation.

Association of antiepileptic drugs, vitamin D, and calcium supplementation with bone fracture occurrence in epilepsy patients.

The aim of this study is to determine whether calcium and vitamin D supplementation reduces the risk of bone fractures in adult epilepsy patients. Records were obtained on 7716 patients with epilepsy prescribed antiepileptic drugs (AED) from the Veteran Affairs Hospital in Lexington, Kentucky. We performed a single center, retrospective cohort study to examine the proportion of fractures in 3303 patients on AED who took supplements compared to patients on AED not taking supplements. Patients prescribed long-term AEDs taking calcium and vitamin D were as likely to have fractures as those who did not take these supplements (11.7% vs. 9.9%, χ(2)=0.59, p=0.44). Phenytoin use was associated with a statistically significant increased risk of fractures OR=1.55 (1.10-2.24). Thus, in this group of patients with epilepsy on AED, bone fractures were not prevented in individuals taking calcium and vitamin D supplementation.