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Appropriate/Inappropriate Developed Pain Paths

The organization of the somatosensory input to the dorsal horn of the spinal cord has for a long time been viewed as a somatotopical map of the body that is adult-like already at birth. Recent studies indicate, however, that the adult somatotopic organization in the dorsal horn of the spinal cord emerges from an initial floating and diffuse body representation with many inappropriate connections t

Subacute vessel wall imaging at 7-T MRI in post-thrombectomy stroke patients

PurposeReports from 3-T vessel wall MRI imaging have shown contrast enhancement following thrombectomy for acute stroke, suggesting potential intimal damage. Comparisons have shown higher SNR and more lesions detected by vessel wall imaging when using 7 T compared with 3 T. The aim of this study was to investigate the vessel walls after stent retriever thrombectomy using high-resolution vessel wal

GABA(A) receptor blockade inhibits Aβ fibre evoked wind-up in the arthritic rat

To clarify the mechanisms of allodynia we have examined whether 'wind- up' of nociceptive withdrawal reflexes (NWR), a phenomenon characteristic of nociceptive C fiber spinal processing, can be mimicked by stimulation of tactile Aβ fibers in monoarthritic decerebrate spinal rats. Knee joint monoarthritis was induced by carrageenan/kaolin under halothane anaesthesia 5 h before recordings. In arthri

Silicon sieve electrodes for neural implants - in vitro characterization & in vivo recordings

An in vitro model was developed to characterize the electrical properties of silicon microfabricated recording electrodes, using a Cu-wire mimicing a neural signal source. Phosphorous doped electrodes were used to achieve an all silicon device. The model was used to study signal amplitude as a function of distance between the electrode surface and the signal source. Signal crosstalk to neighbourin

Restrictions on the interpretation of spinal reflex modulation in pain and analgesia research

The use of motor reactions including spinal motor mechanisms, such as tail-flick, hot plate test, and flexion reflexes, in research on pain and analgesia requires some precautions, and results should be interpreted with caution. Nocifensive specificity and analgesic selectivity cannot be established unequivocally by only comparing reflexes evoked by noxious stimuli with monosynaptic reflexes. Rath

First-order nociceptive synapses in rat dorsal horn are blocked by an amino acid antagonist

An antagonist to amino acid evoked excitation, γ-d-glutamylglycine (γ-DGG) inhibits, dose-dependently, nociceptive C-fibre evoked field potentials and neuronal discharges in single nociceptive neurons in rat spinal cord. It is concluded that amino acids are possible transmitter substance(s) in nociceptive afferent C-fibres. These results might be useful for development of centrally acting analgesi

The effects of a distant noxious stimulation on A and C fibre-evoked flexion reflexes and neuronal activity in the dorsal horn of the rat

In the halothane-anaesthetized rat, the responses of 49 neurons in the lumbo-sacral cord and the reflex discharge in the common peroneal nerve following electrical stimulation of the sural nerve were recorded in order to study possible relations between neuronal events and reflex nerve discharges. A distant noxious stimulus (to activate Diffuse Noxious Inhibitory Controls (DNIC) of Le Bars et al.1

Functional and topographical properties of field potentials evoked in rat dorsal horn by cutaneous C‐fibre stimulation.

Extracellular field potentials in the lumbosacral dorsal horn evoked by stimulation of cutaneous C fibres in the sural nerve were explored in the halothane‐anaesthetized rat. C‐fibre‐evoked field potentials were prominent in lamina II and lamina V of the dorsal horn. These potentials had a latency of 80‐130 ms and a duration of more than 200 ms. A peak in the C‐fibre‐evoked field potential, termed

Cutaneous inputs to dorsal horn neurones in adult rats treated at birth with capsaicin

Single unit electrical activity has been recorded from dorsal horn neurons in the lumbar spinal cord of adult rats which had been treated at birth with either capsaicin (50 mg kg-1) or with the solvent-vehicle only. The responses of these neurones to electrical stimulation of A- and C-fibres in the sural nerve and to natural stimulation of their cutaneous receptive fields have been studied. In veh

Activity evoked by A- and C-afferent fibers in rat dorsal horn neurons and its relation to a flexion reflex

The responses of 56 neurons recorded in the lumbosacral spinal cord of halothane-anesthetized rats were studied following the application of mechanical stimuli to the skin on the lateral aspect of the paw or electrical stimulation of the sural nerve. Only neurons driven by A- and C-fiber stimulation were considered. The evoked activity in a nerve supplying flexor muscles, the common peroneal nerve

Segmental action of morphine and acupuncture-like stimulation in the dorsal horn of the rat as visualized by the 14C-2-deoxyglucose method

It is not clear where analgesic measures such as morphine and acupuncture have their sites of action. Since analgesia from acupuncturelike stimulation is reversed by naloxone (Sjolund and Eriksson, Brain Res. 173:295, 1979) it is probably mediated via endorphins. The two analgesic procedures mentioned may thus use similar inhibitory mechanisms. We now present data from autoradiographic measurement

Intrathecally applied morphine inhibits nociceptive C fiber input to the primary somatosensory cortex (SI) of the rat

Nociceptive C fiber input to SI in the halothane-nitrous oxide anesthetized rat was assessed by recording cortical field potentials evoked by noxious thermal cutaneous stimulation with CO2-laser pulses. Morphine topically applied onto the lumbar spinal cord produced a dose-dependent inhibition of nociceptive C fiber input from the hind paw to the contralateral SI. The inhibitory effect of morphine