21 research outputs found
Cognitive effects of high-frequency repetitive transcranial magnetic stimulation: a systematic review
Transcranial magnetic stimulation (TMS) was introduced as a non-invasive tool for the investigation of the motor cortex. The repetitive application (rTMS), causing longer lasting effects, was used to study the influence on a variety of cerebral functions. High-frequency (>1Â Hz) rTMS is known to depolarize neurons under the stimulating coil and to indirectly affect areas being connected and related to emotion and behavior. Researchers found selective cognitive improvement after high-frequency (HF) stimulation specifically over the left dorsolateral prefrontal cortex (DLPFC). This article provides a systematic review of HF-rTMS studies (1999â2009) stimulating over the prefrontal cortex of patients suffering from psychiatric/neurological diseases or healthy volunteers, where the effects on cognitive functions were measured. The cognitive effect was analyzed with regard to the impact of clinical status (patients/healthy volunteers) and stimulation type (verum/sham). RTMS at 10, 15 or 20Â Hz, applied over the left DLPFC, within a range of 10â15 successive sessions and an individual motor threshold of 80â110%, is most likely to cause significant cognitive improvement. In comparison, patients tend to reach a greater improvement than healthy participants. Limitations concern the absence of healthy groups in clinical studies and partly the absence of sham groups. Thus, future investigations are needed to assess cognitive rTMS effects in different psychiatric disorders versus healthy subjects using an extended standardized neuropsychological test battery. Since the pathophysiological and neurobiological basis of cognitive improvement with rTMS remains unclear, additional studies including genetics, experimental neurophysiology and functional brain imaging are necessary to explore stimulation-related functional changes in the brain
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Nuclear transformation of a dinoflagellate symbiont of corals
Peer reviewed: TrueDinoflagellates are a diverse and ecologically important group of single-celled eukaryotes. Many are photosynthetic autotrophs while others are predatory, parasitic, or symbiotic. One major group â the Symbiodiniaceae â is well known for its role as coral symbionts that provide the coral host with vital nutrients. While genetic transformation protocols have been published for some non-symbiotic dinoflagellate species, robust methods for genetic manipulation of coral symbionts are lacking, hindering a detailed molecular understanding of this critical symbiotic interaction. Here, we describe the successful transformation of coral symbiont Breviolum minutum (strain SSB01). Using Golden Gate modular plasmid assembly and electroporation, we drove transient NLS-GFP expression from an endogenous dinoflagellate virus nuclear protein (DVNP) promoter and successfully targeted GFP to the dinoflagellate nucleus. We further determined that puromycin can efficiently select transformed cells using the puromycin N-acetyltransferase (pac) resistance gene. Transformed cells could be maintained under antibiotic selection for at least 12 months without losing resistance, albeit with slowly attenuating fluorescence signal. We thus tested the expression of hybrid GFP-2A-PAC polypeptides under the control of a single promoter sequence to overcome loss of fluorescence, but lack of efficient 2A cleavage seemingly hindered antibiotic selection interfering GFP function. Despite this, our transformation approach now allows unanswered questions of dinoflagellate biology to be addressed, as well as fundamental aspects of dinoflagellate-coral symbiosis.</jats:p