Effective connectivity changes in LSD-induced altered states of consciousness in humans
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Authors: Preller, Katrin H.; Razi, Adeel; Zeidman, Peter; Stampfli, Philipp; Friston, Karl J.; Vollenweider, Franz X.
Abstract
Psychedelics exert unique effects on human consciousness. The thalamic filter model suggests that core effects of psychedelics may result from gating deficits, based on a disintegration of information processing within cortico-striato-thalamo-cortical (CSTC) feedback loops. To test this hypothesis, we characterized changes in directed (effective) connectivity between selected CTSC regions after acute administration of lysergic acid diethylamide (LSD), and after pretreatment with Ketanserin (a selective serotonin 2A receptor antagonist) plus LSD in a double-blind, randomized, placebo-controlled, cross-over study in 25 healthy participants. We used spectral dynamic causal modeling (DCM) for resting-state fMRI data. Fully connected DCM models were specified for each treatment condition to investigate the connectivity between the following areas: thalamus, ventral striatum, posterior cingulate cortex, and temporal cortex. Our results confirm major predictions proposed in the CSTC model and provide evidence that LSD alters effective connectivity within CSTC pathways that have been implicated in the gating of sensory and sensorimotor information to the cortex. In particular, LSD increased effective connectivity from the thalamus to the posterior cingulate cortex in a way that depended on serotonin 2A receptor activation, and decreased effective connectivity from the ventral striatum to the thalamus independently of serotonin 2A receptor activation. Together, these results advance our mechanistic understanding of the action of psychedelics in health and disease. This is important for the development of new pharmacological therapeutics and also increases our understanding of the mechanisms underlying the potential clinical efficacy of psychedelics.
Papillon-Lefevre syndrome with albinism: A review of the literature and report of 2 brothers
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTOLOGY
Authors: Hattab, FN; Amin, WM
Abstract
Background. Papillon-Lefevre syndrome (PLS) is a very rare autosomal recessive disorder characterized by palmoplantar hyperkeratosis and severe early onset of destructive periodontitis leading to premature loss of both primary and permanent dentitions. The etiopathogenesis of the condition suggests that there is a genetic basis for Susceptibility to specific virulent pathogens. Variation in the clinical presentation of PLS has recently been observed. Objective. The objective was to present the first report, which describes the concurrence of PLS and albinism. The etiology, pathology, and management of the condition were reviewed and genetic analysis was performed. Subjects and clinical presentation. The probands are Jordanian brothers aged 13 and 20 years on their initial presentation. The parents were second cousins and not affected. The patients exhibited the typical clinical features of PLS with type 1 oculocutaneous albinism (OCA1). They also had increased susceptibility to infection manifested it) recurrent tonsillitis, respiratory tract infection, pyoderma, onychogryphosis, and other pathosis. Skin biopsy demonstrated hyperkeratosis, focal parakeratosis, hypergranulosis, and acanthosis. Ectopic calcification of the dura was noticed in one of the probands. Hematological parameters tested were within the normal limits. The probands were tested for mutations in the causative genes of PLS and OCA1, cathepsin C (CTSC), and tyrosinase, respectively. independent mutations (c.318-1G > A and c.817G > C/p.W272C) were identified in CTSC and tyrosinase, respectively. The probands were homozygous and their sister who had only PLS was homozygous for the same (CTSC) mutation but heterozygous for tyrosinase gene. Conclusion. We hope that this report of coinheritance PLS and albinism will initiate further investigations to disclose other possible variations that may enhance our knowledge on gene mutations of this intriguing syndrome.