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Author: Ravit Hadar (15)


Jan
2018

Involuntary movements as seen in repetitive disorders such as Tourette Syndrome (TS) results from cortical hyperexcitability that arise due to striato-thalamo-cortical circuit (STC) imbalance. Transcranial direct current stimulation (tDCS) is a stimulation procedure that changes cortical excitability, yet its relevance in repetitive disorders such as TS remains largely unexplored. Here, we employed the dopamine transporter-overexpressing (DAT-tg) rat model to investigate behavioral and neurobiological effects of frontal tDCS.

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Dec
1969

To investigate metabolic changes in brain networks by deep brain stimulation (DBS) of the medial prefrontal cortex (mPFC), nucleus accumbens (NAcc) and dorsomedial thalamus (DM) using positron emission tomography (PET) in naïve rats.
43 male Wistar rats underwent stereotactic surgery and concentric bipolar platinum-iridium electrodes were bilaterally implanted into one of the three brain sites. [18F]-fluoro-2-deoxy-glucose-PET (18FDG-PET) and computed tomography (CT) scans were performed at the 7th (without DBS) and 9th day (with DBS) after surgery.

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Dec
2016

The dopamine transporter (DAT) plays a pivotal role in maintaining optimal dopamine signaling. DAT-overactivity has been linked to various neuropsychiatric disorders yet so far the direct pathological consequences of it has not been fully assessed. We here generated a transgenic rat model that via pronuclear microinjection overexpresses the DAT gene.

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Jul
2017

In recent years schizophrenia has been recognized as a neurodevelopmental disorder likely involving a perinatal insult progressively affecting brain development. The poly I:C maternal immune activation (MIA) rodent model is considered as a neurodevelopmental model of schizophrenia. Using this model we and others demonstrated the association between neuroinflammation in the form of altered microglia and a schizophrenia-like endophenotype.

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Dec
1969

Alcohol use disorder (AUD) is a severe chronic condition characterized by compulsive alcohol use, cravings and high relapse rates even after long periods of abstinence. It is suggested that alterations in neuronal network activity, especially in the reward pathway accompany or even mediate relapse behavior. Here we used a DSM-based rat model to map in a first set of experiments neurochemical alterations in the reward pathway during alcohol relapse.

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Dec
1969

Deep brain stimulation (DBS) of several targets induces beneficial responses in approximately 60% of patients suffering from treatment-resistant depression (TRD). The remaining 40% indicate that these stimulation sites do not bear therapeutic relevance for all TRD patients and consequently DBS-targets should be selected according to individual symptom profiles. We here used two animal models of depression known to have different genetic backgrounds and behavioral responses: the therapy-responsive Flinders sensitive line (FSL) and the therapy-refractory congenitally learned helpless rats (cLH) to study symptom-specific DBS effects i) of different brain sites ii) at different stimulation parameters, and iii) at different expressions of the disease.

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Dec
1969

Schizophrenia is a debilitating psychiatric disorder with a significant number of patients not adequately responding to treatment. Deep brain stimulation (DBS) is a surgical technique currently investigated for medically-refractory psychiatric disorders. Here, we use the poly I:C rat model of schizophrenia to study the effects of medial prefrontal cortex (mPFC) and nucleus accumbens (Nacc) DBS on two behavioral schizophrenia-like deficits, i.

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Sep
2015

To date, the effects of deep brain stimulation (DBS) on hippocampal neurogenesis have been mainly characterized in the context of memory. Acute stimulation (i.e.

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Aug
2015

A growing body of evidence sheds light on the neurodevelopmental nature of schizophrenia with symptoms typically emerging during late adolescence or young adulthood. We compared the pre-symptomatic adolescence period with the full symptomatic period of adulthood at the behavioral and neurobiological level in the poly I:C maternal immune stimulation (MIS) rat model of schizophrenia. We found that in MIS-rats impaired sensorimotor gating, as reflected in disrupted prepusle inhibition (PPI), emerged post-pubertally, with behavioral deficits being only recorded in adulthood but not during adolescence.

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Sep
2015

A significant portion of patients suffering from major depression remains refractory to available antidepressant treatment strategies. This highlights the need for a better understanding of the underlying neuropathology in order to develop rationale-based treatments. Here we aimed to further characterize neurobiological abnormalities of the Flinders Sensitive Line (FSL) rat model of depression.

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Sep
2015

In recent years, deep brain stimulation (DBS) has emerged as a promising treatment option for patients suffering from treatment-resistant depression (TRD). Several stimulation targets have successfully been tested in clinical settings, including the subgenual cingulum (Cg25) and the medial forebrain bundle (MFB). MFB-DBS has led to remarkable results, surpassing the effect of previous targets in terms of response latency and number of responders.

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May
2014

Adult neurogenesis in the hippocampus is impaired in schizophrenic patients and in an animal model of schizophrenia. Amongst a plethora of regulators, the immune system has been shown repeatedly to strongly modulate neurogenesis under physiological and pathological conditions. It is well accepted, that schizophrenic patients have an aberrant peripheral immune status, which is also reflected in the animal model.

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May
2014

One of the two core symptoms of major depression (MD), whether uni- or bipolar, is the inability to experience pleasure, suggested to be triggered by dysregulation within the brain reward system. In recent years, deep brain stimulation (DBS) has evolved as a potential tool to modulate pathological neural activity; stimulation of the subgenual cingulate (Cg25) has been shown to reduce depressive symptoms, including anhedonia. In rodents, the ventromedial prefrontal cortex (vmPFC) is likely to represent the correlate of Cg25 and accordingly, stimulation of vmPFC reduces anhedonia-like behavior in rats.

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Jul
2013

The development of more efficient treatment remains a major unmet need in the realm of schizophrenia disease. Using the maternal immune stimulation and the pubertal cannabinoid administration rat model of schizophrenia, the present study aimed at testing the hypothesis that deep brain stimulation (DBS) serves as a novel therapeutic technique for this disorder.
Adult offspring of dams, treated with the immune activating agent poly I:C (4 mg/kg, n = 50) or saline (n = 50), underwent bilateral stereotactic electrode implantation into one of the following brain regions: subthalamic nucleus (STN, n = 12/10), entopeduncularis nucleus (EP, n = 10/11), globus pallidus (GP, n = 10/10), medial prefrontal cortex (mPFC, n = 8/8), or dorsomedial thalamus (DM, n = 10/11).

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Dec
1969

Memory formation in reversal learning of the honeybee.

Front Behav Neurosci 2010 13;4:186. Epub 2010 Dec 13.
Ravit Hadar, Randolf Menzel
In reversal learning animals are first trained with a differential learning protocol, where they learn to respond to a reinforced odor (CS+) and not to respond to a non-reinforced odor (CS-). Once they respond correctly to this rule, the contingencies of the conditioned stimuli are reversed, and animals learn to adjust their response to the new rule. This study investigated the effect of a protein synthesis inhibitor (emetine) on the memory formed after reversal learning in the honeybee Apis mellifera.

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