Neuroscience research
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Neuroscience research · Dec 2012
ReviewNon-invasive brain stimulation in the functional evaluation of alcohol effects and in the treatment of alcohol craving: a review.
Acute and chronic consumption of alcohol have direct effects on central nervous system by altering predominantly gamma-aminobutyric acidergic and glutamatergic neurotransmission. Abnormalities in these neurotransmitter systems can be demonstrated by changes in cortical excitability parameters assessed with transcranial magnetic stimulation (TMS). Furthermore, integrated approaches utilizing TMS combined with electroencephalography (EEG) enable the evaluation of the focal effects of alcohol on the human cortex, providing useful information, different from that obtained using other functional brain imaging modalities. ⋯ TMS findings also support the recently emerged theory that abnormal function of glutamate receptors plays a relevant role in the development of alcohol dependence and manifestation of the alcohol withdrawal syndrome. Finally, initial studies provide evidence that non-invasive brain stimulation techniques (rTMS and transcranial direct current stimulation) might represent a potential therapeutic tool to reduce alcohol craving. Future studies with larger sample size evaluating the clinical effects of these neuromodulatory approaches are required to confirm and extend the preliminary findings.
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Neuroscience research · Jun 2006
ReviewTowards the classification of subpopulations of layer V pyramidal projection neurons.
The nature of cerebral cortical circuitry has been increasingly clarified by markers for the identification of precise cell types with specific morphology, connectivity and distinct physiological properties. Molecular markers are not only helpful in dissecting cortical circuitry, but also give insight into the mechanisms of cortical neuronal specification and differentiation. The two principal neuronal types of the cerebral cortex are the pyramidal and GABAergic cells. ⋯ This review will describe the progress made on the correlation of these markers to each other within a specific subtype of layer V neurons with identified, stereotypic projections. Further work is needed to link these data with observations on somatodendritic morphology and physiological properties. The integrated molecular, anatomical and physiological characterisation of pyramidal neurons will lead to a much better appreciation of functional cortical circuits.
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Neuroscience research · Oct 2002
ReviewMolecular mechanisms of analgesia induced by opioids and ethanol: is the GIRK channel one of the keys?
Opioids and ethanol have been used since ancient times for pain relief. Opioid signaling is mediated by various effectors, including G protein-activated inwardly rectifying potassium (GIRK) channels, adenylyl cyclases, voltage-dependent calcium channels, phospholipase Cbeta(PLCbeta), and mitogen-activated protein kinases, although it has been unclear which effector mediates the analgesic effects of opioids. Ethanol induces a variety of physiological phenomena via various proteins, including GIRK channels rather than via membrane lipids. ⋯ This hypothesis is supported by similar findings in GIRK2 knockout mice. Among the various effectors coupled with opioid receptors and various targets of ethanol, GIRK channels are the only molecules whose involvement in opioid- and ethanol-induced analgesia has been demonstrated in vivo. The GIRK channel is potentially one of the key molecules in furthering the understanding of the pain control system and in developing advanced analgesics with fewer adverse effects.
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Neuroscience research · Jun 2002
ReviewFunctional significance of the cortico-subthalamo-pallidal 'hyperdirect' pathway.
How the motor-related cortical areas modulate the activity of the output nuclei of the basal ganglia is an important issue for understanding the mechanisms of motor control by the basal ganglia. The cortico-subthalamo-pallidal 'hyperdirect' pathway conveys powerful excitatory effects from the motor-related cortical areas to the globus pallidus, bypassing the striatum, with shorter conduction time than effects conveyed through the striatum. We emphasize the functional significance of the 'hyperdirect' pathway and propose a dynamic 'center-surround model' of basal ganglia function in the control of voluntary limb movements. ⋯ Then, another corollary signal through the cortico-striato-pallidal 'direct' pathway disinhibits their targets and releases only the selected motor program. Finally, the third corollary signal possibly through the cortico-striato-external pallido-subthalamo-internal pallidal 'indirect' pathway inhibits their targets extensively. Through this sequential information processing, only the selected motor program is initiated, executed and terminated at the selected timing, whereas other competing programs are canceled.