Depolarization Of Cortical Neurons Research Articles

Ginkgolide A Prevents the Amyloid-β-Induced Depolarization of Cortical Neurons.

Utilizing the N-methyl-d-aspartate (NMDA) receptor antagonist as a strategy, memantine is the only agent available for clinically treating mild to severe Alzheimer's disease (AD). Our aim was to develop novel similar herb-based drugs. Using a screening platform, ginkgolide A (GA), a pure compound extracted from Ginkgo biloba, was found to attenuate amyloid β (Aβ)-induced abnormal depolarization in mouse primary cortical neurons. Using receptor agonists, it was determined that GA inhibits both NMDA receptors and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. Furthermore, the Aβ-induced increase in c-Jun N-terminal kinase phosphorylation in neurons was prevented by GA. Body weight, glutamate oxaloacetate transaminase, glutamic-pyruvic transaminase, liver histology, and kidney histology were similar when the wild-type/AD animal model mice with and without GA treatment were compared. This pure compound improves the memory of wild-type mice. Our findings indicate that GA has great potential clinically for the treatment of AD because it might target NMDA receptors just like memantine.

Feature Detection in Visual Cortex during Different Functional States.

Cortical activity exhibits distinct characteristics in different functional states. In awake behaving animals it shows less synchrony, while in rest or sleeping state cortical activity is most synchronous. Previous studies showed that switching between functional states can change the efficiency of flowing sensory information. Switching between functional states can be triggered by releasing neuromodulators which affect neurotransmitter release probability and depolarization of cortical neurons. In this work we focus on studying primary visual area V1, by using firing rate ring model with short-term synaptic depression (STD). We show that reconstruction of visual features from V1 activity depends on the functional state, with best precision achieved at the state with intermediate release probability. We suggest that this regime corresponds to the state of maximal visual attention.

1631 – Repetitive transcranial magnetic stimulation (rTMS) as a new supportive tool in the therapy of panic disorder?

With a life-time prevalence of about 3.5 percent, Panic disorder (PD) belongs to the most common anxiety disorders which can often chronify if not treated adequately. Characterized by the sudden onset of unexpected panic attacks it is associated with a significant loss of quality of life. As in other anxiety disorders, inadequate top-down regulation of subcortical structures by the prefrontal cortex (PFC) is assumed to be a core feature. Even though fMRI studies could show that Cognitive Behavioral Therapy (CBT) is an effective treatment method that can normalize prefrontal hypoactivity, the onset of its effect is delayed. Moreover, recent neuroscientific studies indicated a beneficial effect of repetitive transcranial magnetic stimulation (rTMS), which has been shown to modulate neural activity by depolarization of cortical neurons. The goal of this study was, therefore, to investigate the application of a sham (placebo) controlled activating rTMS protocol during CBT. Forty PD patients were assessed with the optical imaging method near-infrared-spectroscopy (NIRS) while performing emotional paradigms as well as a cognitive task before and after receiving 15 sessions of rTMS. Preliminary results show a significant increase in prefrontal activation from the beginning to the end of the treatment period. This effect was even larger in the active rTMS group. It can hence be concluded that it is possible to depict the effects of CBT on a neural level after only three weeks. Furthermore, rTMS seems to serve as a useful tool in terms of supporting the general therapy outcome.

Within-Session Mood Changes From TMS in Depressed Patients

Within-Session Mood Changes From TMS in Depressed Patients

Within-Session Mood Changes From TMS in Depressed Patients

Transcranial magnetic stimulation has become an increasingly well studied tool in neuropsychiatry. It has been applied in neurophysiology and as a treatment modality in various neurological and psychiatric disorders. Regarding the treatment of major depressive disorder, several meta-analyses of a number of randomized sham-controlled trials using repetitive transcranial magnetic stimulation (TMS), 1–6 have produced a significant body of evidence supporting its efficacy. Target areas of repetitive TMS in the treatment of mood disorders are the left and the right prefrontal cortex. The selection of these areas is based on evidence from neuroimaging and neuropsychological studies that suggest that prefrontal cortical areas show significant abnormalities in mood disorders. 7–10 During treatment with TMS, magnetic pulses are applied to the scalp. These pulses induce an electrical current in the underlying cortical tissue which results in depolarization of cortical neurons. Indirectly TMS also has effects on related cortical and subcortical areas as evidenced by studies of the motor cortex. 11,12 TMS studies regarding mood disorders have focused largely on depressed patients during a course of TMS, which usually consists of multiple treatment sessions conducted over several weeks. In contrast, studies regarding immediate effects of TMS on mood and on neural networks have mostly assessed healthy subjects. Reasons for studying healthy subjects rather than depressed patients include concerns about symptom heterogeneity in depression and the impact of psychotropic medications. 13,14