Current strategies for optimizing deep brain stimulation (DBS) therapy involve multiple postoperative visits. During each visit, stimulation parameters are adjusted until desired therapeutic effects are achieved and adverse effects are minimized. However, the efficacy of these therapeutic parameters may decline with time due at least in part to disease progression, interactions between the host environment and the electrode, and lead migration. As such, development of closed-loop control systems that can respond to changing neurochemical environments, tailoring DBS therapy to individual patients, is paramount for improving the therapeutic efficacy of DBS. Evidence obtained using electrophysiology and imaging techniques in both animals and humans suggests that DBS works by modulating neural network activity. Recently, animal studies have shown that stimulation-evoked changes in neurotransmitter release that mirror normal physiology are associated with the therapeutic benefits of DBS. Therefore, to fully understand the neurophysiology of DBS and optimize its efficacy, it may be necessary to look beyond conventional electrophysiological analyses and characterize the neurochemical effects of therapeutic and non-therapeutic stimulation. By combining electrochemical monitoring and mathematical modeling techniques, we can potentially replace the trial-and-error process used in clinical programming with deterministic approaches that help attain optimal and stable neurochemical profiles. In this manuscript, we summarize the current understanding of electrophysiological and electrochemical processing for control of neuromodulation therapies. Additionally, we describe a proof-of-principle closed-loop controller that characterizes DBS-evoked dopamine changes to adjust stimulation parameters in a rodent model of DBS. The work described herein represents the initial steps toward achieving a “smart” neuroprosthetic system for treatment of neurologic and psychiatric disorders.

Receptor tyrosine kinases (RTKs) are co-deregulated in a majority of glioblastoma (GBM), the most common and most deadly brain tumor. We show that the RTKs MET, EGFR, and PDGFR regulate microRNA-134 (miR-134) in GBM. We find that miR-134 is downregulated in human tumors and cancer stem cells and that its expression inversely correlates with the activation of MET, EGFR, and PDGFR. We demonstrate that miR-134 inhibits cancer cell and stem-cell proliferation, survival, and xenograft growth, as well as cancer stem-cell self-renewal and stemness. We identify KRAS and STAT5B as targets of miR-134, and establish molecular and functional links between RTKs, miR-134, KRAS/STAT5B and malignancy in vitro and in vivo. We show that miR-134 induction is required for the anti-tumor effects of RTK inhibitors. We also uncover the molecular pathways through which RTKs regulate miR-134 expression and demonstrate the involvement of MAPK signaling and the KLF4 transcription factor. We therefore identify miR-134 as a novel RTK-regulated tumor-suppressive hub that mediates RTK and RTK-inhibitor effects on GBM malignancy by controlling KRAS and STAT5B. Cell Death and Differentiation (2014) 21, 720-734; doi:10.1038/cdd.2013; published online 17 January 2014 microRNAs (miRNAs) regulate a wide variety of physiological and pathological processes. 1-3 miRNAs modulate protein expression by binding to the 3 0 untranslated region (3 0 UTR) of target mRNA and promoting RNA degradation and/or inhibiting translation. Single miRNAs can regulate multiple molecules, highlighting a powerful mechanism for the regulation of redundant and cross-talking signal transduction pathways. 4 miRNA dysregulation is a common feature of neoplasia and numerous miRNAs have been characterized as oncogenes or tumor suppressors in many cancers including in glioblastoma (GBM). 3,[5][6][7][8][9][10][11] microRNA-134 (miR-134) has been implicated in the regulation of physiological and developmental processes. It was shown to promote mouse embryonic stem-cell differentiation, dendritogenesis, and stage-specific cortical development. 12-17 miR-134 is downregulated by SIRT1 and involved in synaptic plasticity and memory formation. 18 miR-134 expression is regulated by MEF2 in dendritogenesis 14 and GBM. 19 GBM is the most common and most deadly primary malignant brain tumor. 20,21 The Cancer Genome Atlas and other studies have shown that aberrant expression or activation of the receptor tyrosine kinases (RTKs) EGFR, MET, and PDGFR occurs in a majority of GBM and correlates with poor prognosis. 22 Importantly, multiple RTKs are co-activated in the same GBM tumors and tumor cells. 23,24 KRAS, STAT3, and STAT5 are activated by RTKs and mediate their oncogenic effects. [25][26][27][28] The failure of current treatments for GBM is arguably due to the presence in the tumors of GBM stem cells (GSCs) that are resistant to radioand chemo-therapy and capable of maintaining and propagating the tumors. 29-31 EGFR, MET, PDGFR, and miRNAs have been implicated in the regulation of GSC f...

Spinal cord injury (SCI) commonly results in permanent loss of motor, sensory, and autonomic function. Recent clinical studies have shown that epidural spinal cord stimulation may provide a beneficial adjunct for restoring lower extremity and other neurological functions. Herein, we review the recent clinical advances of lumbosacral epidural stimulation for restoration of sensorimotor function in individuals with motor complete SCI and we discuss the putative neural pathways involved in this promising neurorehabilitative approach. We focus on three main sections: review recent clinical results for locomotor restoration in complete SCI; discuss the contemporary understanding of electrical neuromodulation and signal transduction pathways involved in spinal locomotor networks; review current challenges of motor system modulation and future directions towards integrative neurorestoration. The current understanding is that initial depolarization occurs at the level of large diameter dorsal root proprioceptive afferents that when integrated with interneuronal and latent residual supraspinal translesional connections can recruit locomotor centers and augment downstream motor units. Spinal epidural stimulation can initiate excitability changes in spinal networks and supraspinal networks. Different stimulation parameters can facilitate standing or stepping, and it may also have potential for augmenting myriad other sensorimotor and autonomic functions. More comprehensive investigation of the mechanisms that mediate the transformation of dysfunctional spinal networks to higher functional states with a greater focus on integrated systems based control system may reveal the key mechanisms underlying neurological augmentation and motor restoration after severe paralysis.