Local Optogenetic Induction of Fast (20-40 Hz) Pyramidal-Interneuron Network Oscillations in the In Vitro and In Vivo CA1 Hippocampus: Modulation by CRF and Enforcement of Perirhinal Theta Activity

The neurophysiological processes that can cause theta-to-gamma frequency range (4-80 Hz) network oscillations in the rhinal cortical-hippocampal system and the potential connectivity-based interactions of such forebrain rhythms are a topic of intensive investigation. Here, using selective Channelrhodopsin-2 (ChR2) expression in mouse forebrain glutamatergic cells, we were able to locally, temporally precisely, and reliably induce fast (20-40 Hz) field potential oscillations in hippocampal area CA1 in vitro (at 25 degrees C) and in vivo (i.e., slightly anesthetized NEX-Cre-ChR2 mice). As revealed by pharmacological analyses and patch-clamp recordings from pyramidal cells and GABAergic interneurons in vitro, these light-triggered oscillations can exclusively arise from sustained suprathreshold depolarization (similar to 200 ms or longer) and feedback inhibition of CA1 pyramidal neurons, as being mandatory for prototypic pyramidal-interneuron network (P-I) oscillations. Consistently, the oscillations comprised rhythmically occurring population spikes (generated by pyramidal cells) and their frequency increased with increasing spectral power. We further demonstrate that the optogenetically driven CA1 oscillations, which remain stable over repeated evocations, are impaired by the stress hormone corticotropin-releasing factor (CRF, 125 nM) in vitro and, even more remarkably, found that they are accompanied by concurrent states of enforced theta activity in the memory associated perirhinal cortex (PrC) in vivo. The latter phenomenon most likely derives from neurotransmission via a known, but poorly studied excitatory CA1 -> PrC pathway. Collectively, our data provide evidence for the existence of a prototypic (CRF-sensitive) P-I gamma rhythm generator in area CA1 and suggest that CA1 P-I oscillations can rapidly up-regulate theta activity strength in hippocampus-innervated rhinal networks, at least in the PrC

Substance P and pain chronicity

Substance P (SP) is a highly conserved member of the tachykinin peptide family that is widely expressed throughout the animal kingdom. The numerous members of the tachykinin peptide family are involved in a multitude of neuronal signaling pathways, mediating sensations and emotional responses (Steinhoff et al. in Physiol Rev 94:265-301, 2014). In contrast to receptors for classical transmitters, such as glutamate (Parsons et al. in Handb Exp Pharmacol 249-303, 2005), only a minority of neurons in certain brain areas express neurokinin receptors (NKRs) (Mantyh in J Clin Psychiatry 63:6-10, 2002). SP is also expressed by a variety of non-neuronal cell types such as microglia, as well as immune cells (Mashaghi et al. in Cell Mol Life Sci 73:4249-4264, 2016). SP is an 11-amino acid neuropeptide that preferentially activates the neurokinin-1 receptor (NK1R). It transmits nociceptive signals via primary afferent fibers to spinal and brainstem second-order neurons (Cao et al. in Nature 392:390-394, 1998). Compounds that inhibit SP's action are being investigated as potential drugs to relieve pain. More recently, SP and NKR have gained attention for their role in complex psychiatric processes. It is a key goal in the field of pain research to understand mechanisms involved in the transition between acute pain and chronic pain. The influence of emotional and cognitive inputs and feedbacks from different brain areas makes pain not only a perception but an experience (Zieglgansberger et al. in CNS Spectr 10:298-308, 2005; Trenkwaldner et al. Sleep Med 31:78-85, 2017). This review focuses on functional neuronal plasticity in spinal dorsal horn neurons as a major relay for nociceptive information

Seeing the site of treatment improves habitual pain but not cervical joint position sense immediately after manual therapy in chronic neck pain patients

Background Visual analgesia refers to the phenomena where people report decreased pain intensity when they see the painful or painfully stimulated body part. Alongside pain, sensorimotor impairment (i.e., disturbed proprioception) is also evident in chronic pain. This study aims to investigate whether real-time visual feedback offers additional pain relief and proprioceptive improvement when used in combination with recommended therapies in neck pain patients who received manual therapy with or without real-time visual feedback. Methods A total of 29 neck pain patients were recruited in an outpatient physical therapy practice. Patients were randomly allocated to receive manual therapy of the cervical spine with real-time visual feedback or to a control group where patients received manual therapy without real-time visual feedback. Habitual pain intensity, the pressure pain threshold at the zygapophyseal joint of C2-C3 and the superior angle of the scapulae and cervical proprioception were assessed before and immediately after the intervention by a blinded assessor. Results A between-group comparison revealed a significant reduction in habitual pain in the real-time visual feedback group. No differences were found for the pressure pain threshold or proprioceptive performance. Conclusions Real-time visual feedback combined with manual therapy enhanced the analgesic effect of manual therapy in neck pain patients, but had no positive effect on the pressure pain threshold and cervical joint position sense. The technical demands for integrating real-time visual feedback into daily practice to reduce habitual pain are low, have low costs and are easy to apply. Significance Real-time visual feedback reduces habitual pain immediately after the intervention. Due to its easy integration, it may be an effective adjunct to recommended interventions (i.e., manual therapy) in patients with neck pain

Neuronale Wirkungsmechanismen von Neuropeptiden und Steroiden Abschlussbericht

SIGLEAvailable from TIB Hannover: DtF QN1(35,54) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Differential effects of visually induced analgesia and attention depending on the pain stimulation site

Background The term 'visually induced analgesia' describes a reduced pain perception induced by watching the painful body part as opposed to watching a neutral object. In chronic back pain patients, experimental pain, movement-induced pain and habitual pain can be reduced with visual feedback. Visual feedback can also enhance the effects of both massage treatment and manual therapy. The impact of somatosensory attentional processes remains unclear. Methods In the current study, participants received painful electrical stimuli to their thumb and back while being presented with either a real-time video of their thumb or back (factor feedback). In addition, using an oddball paradigm, they had to count the number of deviant stimuli, applied to either their back or thumb (factor attention) and rate the pain intensity. Results We found a significant main effect for attention with decreased pain ratings during attention. There was no main effect for visual feedback and no significant interaction between visual feedback and attention. Post-hoc tests revealed that the lowest pain intensity ratings were achieved during visual feedback of the back/ thumb and counting at the back/ thumb. Conclusion These data suggest that the modulation of perceived acute pain by visually induced analgesia may be influenced by a simultaneous somatosensory attention task. Significance Somatosensory attention reduced experimental pain intensity in the thumb and back in the presence of both congruent and incongruent visual feedback. We found no significant visual feedback effect on the complex interplay between visual feedback and somatosensory attention

Suchtforschungsverbund Muenchen: Neurobiologisch-pharmakologische Grundlagenforschung zur Suchtentstehung und Drogenabhaengigkeit. Teilprojekt 1: Akute und chronische Wirkungen von Alkohol auf Neurone des Zentralnervensystems. Teilprojekt 2: Alkohol 'Reward' und Sucht. Zentrale NO/cGMP-Rezeptoren bei Aethanolabusus. Die Rolle von Dopoamin- und #mu#-Opioidrezeptoren in der Alkoholsucht: Untersuchungen an rezeptor-defizienten Maeusen und Analyse von Rezeptorpolymorphismen bei Alkoholikern Abschlussbericht

SIGLEAvailable from TIB Hannover: DtF QN1(89,44) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman