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Smoking restores impaired LTD-like plasticity in schizophrenia: a transcranial direct current stimulation study.

ABSTRACT: Impaired neuroplastic responses following noninvasive brain stimulation have been reported repeatedly in schizophrenia patients. These findings have been associated with deficits in GABAergic, glutamatergic, and cholinergic neurotransmission. Although various neurophysiological studies have indicated a relationship between nicotine and neuroplasticity in healthy individuals, the present study is the first investigation into the impact of nicotine on LTD-like plasticity in patients with schizophrenia. Cortical excitability and cortical plasticity were explored in 30 schizophrenia patients (17 smoker, 13 nonsmoker) and 45 healthy controls (13 smoker, 32 nonsmoker) by using single-pulse transcranial magnetic stimulation (TMS) before and following cathodal transcranial direct current stimulation (tDCS) applied to the left primary motor cortex. Our analysis revealed abolished LTD-like plasticity in nonsmoking schizophrenia patients. However, these plasticity deficits were not present in smoking schizophrenia patients. In healthy controls, significant MEP reductions following cathodal tDCS were observed in nonsmoking individuals, but only trend-level reductions in smokers. In smoking schizophrenia patients, the severity of negative symptoms correlated positively with reduced neuroplasticity, whereas nonsmoking patients displayed the opposite effect. Taken together, the data of our study support the notion of an association between chronic smoking and the restitution of impaired LTD-like plasticity in schizophrenia patients. Although replication and further research are needed to better understand this relationship, our findings indicate that nicotine intake might stabilize the impaired inhibition-facilitation balance in the schizophrenic brain through a complex interaction between cortical plasticity, and GABAergic and cholinergic neurotransmission, and might explain the reduced prevalence of negative symptoms in this population.

SUBMITTER: Strube W

PROVIDER: S-EPMC4330512 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Smoking restores impaired LTD-like plasticity in schizophrenia: a transcranial direct current stimulation study.

Strube Wolfgang W Bunse Tilmann T Nitsche Michael A MA Wobrock Thomas T Aborowa Richard R Misewitsch Kristina K Herrmann Maximiliane M Falkai Peter P Hasan Alkomiet A

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 20141013 4

Impaired neuroplastic responses following noninvasive brain stimulation have been reported repeatedly in schizophrenia patients. These findings have been associated with deficits in GABAergic, glutamatergic, and cholinergic neurotransmission. Although various neurophysiological studies have indicated a relationship between nicotine and neuroplasticity in healthy individuals, the present study is the first investigation into the impact of nicotine on LTD-like plasticity in patients with schizophr ...[more]

PMID: 25308351

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Project description:Patients with schizophrenia spectrum disorder often demonstrate impairments in action-outcome monitoring. Passivity phenomena and hallucinations, in particular, have been related to impairments of efference copy-based predictions which are relevant for the monitoring of outcomes produced by voluntary action. Frontal transcranial direct current stimulation has been shown to improve action-outcome monitoring in healthy subjects. However, whether transcranial direct current stimulation can improve action monitoring in patients with schizophrenia spectrum disorder remains unknown. We investigated whether transcranial direct current stimulation can improve the detection of temporal action-outcome discrepancies in patients with schizophrenia spectrum disorder. On 4 separate days, we applied sham or left cathodal/right anodal transcranial direct current stimulation in a randomized order to frontal (F3/F4), parietal (CP3/CP4) and frontoparietal (F3/CP4) areas of 19 patients with schizophrenia spectrum disorder and 26 healthy control subjects. Action-outcome monitoring was assessed subsequent to 10 min of sham/transcranial direct current stimulation (1.5 mA). After a self-generated (active) or externally generated (passive) key press, subjects were presented with a visual outcome (a dot on the screen), which was presented after various delays (0-417 ms). Participants had to detect delays between the key press and the visual consequence. Symptom subgroups were explored based on the presence or absence of symptoms related to a paranoid-hallucinatory syndrome. In general, delay-detection performance was impaired in the schizophrenia spectrum disorder compared to the healthy control group. Interaction analyses showed group-specific (schizophrenia spectrum disorder versus healthy control group) and symptom-specific (with/without relevant paranoid-hallucinatory symptoms) transcranial direct current stimulation effects. Post hoc tests revealed that frontal transcranial direct current stimulation improved the detection of long delays in active conditions and reduced the proportion of false alarms in undelayed trials of the passive condition in patients. The patients with no or few paranoid-hallucinatory symptoms benefited especially from frontal transcranial direct current stimulation in active conditions, while improvement in the patients with paranoid-hallucinatory symptoms was predominantly reflected in reduced false alarm rates in passive conditions. These data provide some first evidence for the potential utility of transcranial direct current stimulation in improving efference copy mechanisms and action-outcome monitoring in schizophrenia spectrum disorder. Current data indicate that improving efference copy-related processes can be especially effective in patients with no or few positive symptoms, while intersensory matching (i.e. task-relevant in passive conditions) could be more susceptible to improvement in patients with paranoid-hallucinatory symptoms.

Project description:Introduction: Conventional transcranial direct current stimulation (tDCS) and high-definition tDCS (HD-tDCS) may improve motor learning in children. Mechanisms are not understood. Neuronavigated robotic transcranial magnetic stimulation (TMS) can produce individualised maps of primary motor cortex (M1) topography. We aimed to determine the effects of tDCS- and HD-tDCS-enhanced motor learning on motor maps. Methods: Typically developing children aged 12-18 years were randomised to right M1 anodal tDCS, HD-tDCS, or Sham during training of their left-hand on the Purdue Pegboard Task (PPT) over 5 days. Bilateral motor mapping was performed at baseline (pre), day 5 (post), and 6-weeks retention time (RT). Primary muscle was the first dorsal interosseous (FDI) with secondary muscles of abductor pollicis brevis (APB) and adductor digiti minimi (ADM). Primary mapping outcomes were volume (mm2/mV) and area (mm2). Secondary outcomes were centre of gravity (COG, mm) and hotspot magnitude (mV). Linear mixed-effects modelling was employed to investigate effects of time and stimulation type (tDCS, HD-tDCS, Sham) on motor map characteristics. Results: Twenty-four right-handed participants (median age 15.5 years, 52% female) completed the study with no serious adverse events or dropouts. Quality maps could not be obtained in two participants. No effect of time or group were observed on map area or volume. LFDI COG (mm) differed in the medial-lateral plane (x-axis) between tDCS and Sham (p = 0.038) from pre-to-post mapping sessions. Shifts in map COG were also observed for secondary left-hand muscles. Map metrics did not correlate with behavioural changes. Conclusion: Robotic TMS mapping can safely assess motor cortex neurophysiology in children undergoing motor learning and neuromodulation interventions. Large effects on map area and volume were not observed while changes in COG may occur. Larger controlled studies are required to understand the role of motor maps in interventional neuroplasticity in children.

Dataset Information

Smoking restores impaired LTD-like plasticity in schizophrenia: a transcranial direct current stimulation study.

Publications

Smoking restores impaired LTD-like plasticity in schizophrenia: a transcranial direct current stimulation study.

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