Nature neuroscience
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Nature neuroscience · Feb 2014
ReviewRegulating excitability of peripheral afferents: emerging ion channel targets.
The transmission and processing of pain signals relies critically on the activities of ion channels that are expressed in afferent pain fibers. This includes voltage-gated channels, as well as background (or leak) channels that collectively regulate resting membrane potential and action potential firing properties. ⋯ Over the past few years, a number of different types of ion channels have been implicated in afferent pain signaling. Here we give an overview of recent advances on sodium, calcium, potassium and chloride channels that are emerging as especially attractive targets for the treatment of pain.
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There are many known risk factors for chronic pain conditions, yet the biological underpinnings that link these factors to abnormal processing of painful signals are only just beginning to be explored. This Review will discuss the potential mechanisms that have been proposed to underlie vulnerability and resilience toward developing chronic pain. Particular focus will be given to genetic and epigenetic processes, priming effects on a cellular level, and alterations in brain networks concerned with reward, motivation/learning and descending modulatory control. Although research in this area is still in its infancy, a better understanding of how pain vulnerability emerges has the potential to help identify individuals at risk and may open up new therapeutic avenues.
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Nature neuroscience · Feb 2014
Transcranial focused ultrasound modulates the activity of primary somatosensory cortex in humans.
Improved methods of noninvasively modulating human brain function are needed. Here we probed the influence of transcranial focused ultrasound (tFUS) targeted to the human primary somatosensory cortex (S1) on sensory-evoked brain activity and sensory discrimination abilities. The lateral and axial spatial resolution of the tFUS beam implemented were 4.9 mm and 18 mm, respectively. ⋯ The changes produced by tFUS on sensory-evoked brain activity were abolished when the acoustic beam was focused 1 cm anterior or posterior to S1. Behavioral investigations showed that tFUS targeted to S1 enhanced performance on sensory discrimination tasks without affecting task attention or response bias. We conclude that tFUS can be used to focally modulate human cortical function.
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Nature neuroscience · Jan 2014
Therapeutic activation of macrophages and microglia to suppress brain tumor-initiating cells.
Brain tumor initiating cells (BTICs) contribute to the genesis and recurrence of gliomas. We examined whether the microglia and macrophages that are abundant in gliomas alter BTIC growth. We found that microglia derived from non-glioma human subjects markedly mitigated the sphere-forming capacity of glioma patient-derived BTICs in culture by inducing the expression of genes that control cell cycle arrest and differentiation. ⋯ In mice harboring intracranial mouse or patient-derived BTICs, daily systemic treatment with non-toxic doses of AmpB substantially prolonged life. Notably, microglia and monocytes cultured from glioma patients were inefficient at reducing the sphere-forming capacity of autologous BTICs, but this was rectified by AmpB. These results provide new insights into the treatment of gliomas.
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Nature neuroscience · Nov 2013
Maturation of silent synapses in amygdala-accumbens projection contributes to incubation of cocaine craving.
In rat models of drug relapse and craving, cue-induced cocaine seeking progressively increases after withdrawal from the drug. This 'incubation of cocaine craving' is partially mediated by time-dependent adaptations at glutamatergic synapses in nucleus accumbens (NAc). However, the circuit-level adaptations mediating this plasticity remain elusive. ⋯ As the withdrawal period progressed, these silent synapses became unsilenced, a process that involved synaptic insertion of calcium-permeable AMPA receptors (CP-AMPARs). In vivo optogenetic stimulation-induced downregulation of CP-AMPARs at amygdala-to-NAc synapses, which re-silenced some of the previously silent synapses after prolonged withdrawal, decreased incubation of cocaine craving. Our findings indicate that silent synapse-based reorganization of the amygdala-to-NAc projection is critical for persistent cocaine craving and relapse after withdrawal.