Altered visual feedback from an embodied avatar unconsciously influences movement amplitude and muscle activity

Evidence suggests that the sense of the position of our body parts can be surreptitiously deceived, for instance through illusory visual inputs. However, whether altered visual feedback during limb movement can induce substantial unconscious motor and muscular adjustments is not known. To address this question, we covertly manipulated virtual body movements in immersive virtual reality. Participants were instructed to flex their elbow to 90° while tensing an elastic band, as their virtual arm reproduced the same, a reduced (75°), or an amplified (105°) movement. We recorded muscle activity using electromyography, and assessed body ownership, agency and proprioception of the arm. Our results not only show that participants compensated for the avatar’s manipulated arm movement while being completely unaware of it, but also that it is possible to induce unconscious motor adaptations requiring significant changes in muscular activity. Altered visual feedback through body ownership illusions can influence motor performance in a process that bypasses awareness

Selective Vulnerability in Striosomes and in the Nigrostriatal Dopaminergic Pathway After Methamphetamine Administration: Early Loss of TH in Striosomes After Methamphetamine

Methamphetamine (METH), a commonly abused psychostimulant, causes dopamine neurotoxicity in humans, rodents, and nonhuman primates. This study examined the selective neuroanatomical pattern of dopaminergic neurotoxicity induced by METH in the mouse striatum. We examined the effect of METH on tyrosine hydroxylase (TH) and dopamine transporter (DAT) immunoreactivity in the different compartments of the striatum and in the nucleus accumbens. The levels of dopamine and its metabolites, 3,4-dihidroxyphenylacetic acid and homovanillic acid, as well as serotonin (5-HT) and its metabolite, 5-hydroxyindolacetic acid, were also quantified in the striatum. Mice were given three injections of METH (4 mg/kg, i.p.) at 3 h intervals and sacrificed 7 days later. This repeated METH injection induced a hyperthermic response and a decrease in striatal concentrations of dopamine and its metabolites without affecting 5-HT concentrations. In addition, the drug caused a reduction in TH- and DAT-immunoreactivity when compared to saline-treated animals. Interestingly, there was a significantly greater loss of TH- and DAT-immunoreactivity in striosomes than in the matrix. The predominant loss of dopaminergic terminals in the striosomes occurred along the rostrocaudal axis of the striatum. In contrast, METH did not decrease TH- or DAT-immunoreactivity in the nucleus accumbens. These results provide the first evidence that compartments of the mouse striatum, striosomes and matrix, and mesolimbic and nigrostriatal pathways have different vulnerability to METH. This pattern is similar to that observed with other neurotoxins such as MPTP, the most widely used model of Parkinson’s disease, in early Huntington’s disease and hypoxic/ischemic injury, suggesting that these conditions might share mechanisms of neurotoxicity

Acute neuropsychological effects of MDMA and ethanol (co-)administration in healthy volunteers

Contains fulltext : 73592.pdf (publisher's version ) (Open Access)RATIONALE: In Western societies, a considerable percentage of young people expose themselves to 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy"). Commonly, ecstasy is used in combination with other substances, in particular alcohol (ethanol). MDMA induces both arousing as well as hallucinogenic effects, whereas ethanol is a general central nervous system depressant. OBJECTIVE: The aim of the present study is to assess the acute effects of single and co-administration of MDMA and ethanol on executive, memory, psychomotor, visuomotor, visuospatial and attention function, as well as on subjective experience. MATERIALS AND METHODS: We performed a four-way, double-blind, randomised, crossover, placebo-controlled study in 16 healthy volunteers (nine male, seven female) between the ages of 18-29. MDMA was given orally (100 mg) and blood alcohol concentration was maintained at 0.6 per thousand by an ethanol infusion regime. RESULTS: Co-administration of MDMA and ethanol was well tolerated and did not show greater impairment of performance compared to the single-drug conditions. Impaired memory function was consistently observed after all drug conditions, whereas impairment of psychomotor function and attention was less consistent across drug conditions. CONCLUSIONS: Co-administration of MDMA and ethanol did not exacerbate the effects of either drug alone. Although the impairment of performance by all drug conditions was relatively moderate, all induced significant impairment of cognitive function

3,4-Methylenedioxymethamphetamine (MDMA) neurotoxicity in rats: a reappraisal of past and present findings

RATIONALE: 3,4-Methylenedioxymethamphetamine (MDMA) is a widely abused illicit drug. In animals, high-dose administration of MDMA produces deficits in serotonin (5-HT) neurons (e.g., depletion of forebrain 5-HT) that have been interpreted as neurotoxicity. Whether such 5-HT deficits reflect neuronal damage is a matter of ongoing debate. OBJECTIVE: The present paper reviews four specific issues related to the hypothesis of MDMA neurotoxicity in rats: (1) the effects of MDMA on monoamine neurons, (2) the use of “interspecies scaling” to adjust MDMA doses across species, (3) the effects of MDMA on established markers of neuronal damage, and (4) functional impairments associated with MDMA-induced 5-HT depletions. RESULTS: MDMA is a substrate for monoamine transporters, and stimulated release of 5-HT, NE, and DA mediates effects of the drug. MDMA produces neurochemical, endocrine, and behavioral actions in rats and humans at equivalent doses (e.g., 1–2 mg/kg), suggesting that there is no reason to adjust doses between these species. Typical doses of MDMA causing long-term 5-HT depletions in rats (e.g., 10–20 mg/kg) do not reliably increase markers of neurotoxic damage such as cell death, silver staining, or reactive gliosis. MDMA-induced 5-HT depletions are accompanied by a number of functional consequences including reductions in evoked 5-HT release and changes in hormone secretion. Perhaps more importantly, administration of MDMA to rats induces persistent anxiety-like behaviors in the absence of measurable 5-HT deficits. CONCLUSIONS: MDMA-induced 5-HT depletions are not necessarily synonymous with neurotoxic damage. However, doses of MDMA which do not cause long-term 5-HT depletions can have protracted effects on behavior, suggesting even moderate doses of the drug may pose risks

Pharmacology of MDMA- and Amphetamine-Like New Psychoactive Substances

New psychoactive substances (NPS) with amphetamine-, aminoindan-, and benzofuran basic chemical structures have recently emerged for recreational drug use. Detailed information about their psychotropic effects and health risks is often limited. At the same time, it emerged that the pharmacological profiles of these NPS resemble those of amphetamine or 3,4-methylenedioxymethamphetamine (MDMA). Amphetamine-like NPS induce psychostimulation and euphoria mediated predominantly by norepinephrine (NE) and dopamine (DA) transporter (NET and DAT) inhibition and transporter-mediated release of NE and DA, thus showing a more catecholamine-selective profile. MDMA-like NPS frequently induce well-being, empathy, and prosocial effects and have only moderate psychostimulant properties. These MDMA-like substances primarily act by inhibiting the serotonin (5-HT) transporter (SERT) and NET, also inducing 5-HT and NE release. Monoamine receptor interactions vary considerably among amphetamine- and MDMA-like NPS. Clinically, amphetamine- and MDMA-like NPS can induce sympathomimetic toxicity. The aim of this chapter is to review the state of knowledge regarding these substances with a focus on the description of the in vitro pharmacology of selected amphetamine- and MDMA-like NPS. In addition, it is aimed to provide links between pharmacological profiles and in vivo effects and toxicity, which leads to the conclusion that abuse liability for amphetamine-like NPS may be higher than for MDMA-like NPS, but that the risk for developing the life-threatening serotonin syndrome may be increased for MDMA-like NPS

Chair-based exercise programs in institutionalized older women: salivary steroid hormones, disabilities and frailty changes

Purpose: Many people experience aging-related losses in different physical domains, which leads to a condition often called physical frailty (PF). The aim of this study was to analyse the effects of two different, 28-weeks, class chair-exercise protocols on salivary steroid hormones (SH), PF, and functional disabilities (FD) in frail older women. Methods: A sample of older frail individuals (n = 60, 817.84 years) participated in the study and were divided into three groups: chair elastic-band muscle strength exercises (CSE), n = 20), chair-multimodal exercise (CME, n = 21) and a control non-exercise group (CGne, n = 19). Both exercise programs consisted of 45 min of supervised chair-based exercise group classes, carried out 3 times/week. CME participants performed a progressive training using walking, mobility and body weight resistance exercises. The CSE participants exercised using an elastic-band system of progressive exercises. Both CSE and CME followed a circuit training protocol. The controls did not change their usual lifestyle. The indicators of PF, FD and SH concentrations were analyzed before and after the intervention. Results: Both exercise programs diminished the PF status showing significant time and time versus treatment interactions (p ne after the same period (p <.05). Both exercise programs decreased the negative scores of several FD domains, specially fear of falling that showed significant effects with time (p <.01), and time vs intervention (p <.05). Conclusion: Both chair-exercise based programs were effective in stimulating positive changes in physical health and in steroid hormone responses, especially in DHEA. The control group did show a negative trend towards an increased PF status and decreased levels of SH. It is crucial for public health to identify the main factors associated with Functional Disability and Physical Frailty that underlie the development of new methods for complementary therapies, such as the use of low doses of hormonal supplementation combined with long-term exercise interventions