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Unit Recordings (unit + recording)

Distribution by Scientific Domains
Medical Sciences50%
Life Sciences50%

Kinds of Unit Recordings

  • single unit recording
    		•

    Selected Abstracts

    Thalamic sensitization transforms localized pain into widespread allodynia

    ANNALS OF NEUROLOGY, Issue 1 2010
    Rami Burstein PhD
    Objective Focal somatic pain can evolve into widespread hypersensitivity to nonpainful and painful skin stimuli (allodynia and hyperalgesia, respectively). We hypothesized that transformation of headache into whole-body allodynia/hyperalgesia during a migraine attack is mediated by sensitization of thalamic neurons that process converging sensory impulses from the cranial meninges and extracephalic skin. Methods Extracephalic allodynia was assessed using single unit recording of thalamic trigeminovascular neurons in rats and contrast analysis of blood oxygenation level-dependent (BOLD) signals registered in functional magnetic resonance imaging (fMRI) scans of patients exhibiting extracephalic allodynia. Results Sensory neurons in the rat posterior thalamus that were activated and sensitized by chemical stimulation of the cranial dura exhibited long-lasting hyperexcitability to innocuous (brush, pressure) and noxious (pinch, heat) stimulation of the paws. Innocuous, extracephalic skin stimuli that did not produce neuronal firing at baseline (eg, brush) became as effective as noxious stimuli (eg, pinch) in eliciting large bouts of neuronal firing after sensitization was established. In migraine patients, fMRI assessment of BOLD signals showed that brush and heat stimulation at the skin of the dorsum of the hand produced larger BOLD responses in the posterior thalamus of subjects undergoing a migraine attack with extracephalic allodynia than the corresponding responses registered when the same patients were free of migraine and allodynia. Interpretation We propose that the spreading of multimodal allodynia and hyperalgesia beyond the locus of migraine headache is mediated by sensitized thalamic neurons that process nociceptive information from the cranial meninges together with sensory information from the skin of the scalp, face, body, and limbs. ANN NEUROL 2010 [source]

    Effects of cannabinoids on prefrontal neuronal responses to ventral tegmental area stimulation

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2001
    Marco Pistis
    Abstract Cannabinoids activate the firing of mesoprefrontocortical dopamine neurons and release dopamine in the prefrontal cortex. This study was undertaken with the aim of clarifying the interaction between cannabinoids and mesocortical system in the prefrontal cortex. The effect of ,9 -tetrahydrocannabinol (,9 -THC) and the synthetic CB1 agonist WIN55,212,2 (WIN) was studied by extracellular single unit recordings, in chloral hydrate anaesthetised rats, on the spontaneous activity of pyramidal neurons and on the inhibition produced on these neurons by the electrical stimulation of the ventral tegmental area (VTA). Intravenously administered ,9 -THC and WIN (1.0 and 0.5 mg/kg, respectively), increased the firing rate of pyramidal neurons projecting to the VTA. VTA stimulation produced a phasic inhibition (167 ± 6 ms) in 79% of prefrontal cortex pyramidal neurons. ,9 -THC and WIN reverted this inhibition in 73% and 100% of the neurons tested, respectively. The subsequent administration of the selective CB1 antagonist SR141716A (1 mg/kg) readily suppressed the effects of both cannabinoids and restored the inhibitory response to VTA stimulation. Moreover, when administered alone, SR141716A prolonged the inhibition in 55.6% of the neurons tested. The results indicate that stimulation of CB1 receptors by cannabinoids results in an enhanced excitability of prefrontal cortex pyramidal neurons as indexed by the suppression of the inhibitory effect of VTA stimulation and by the increase in firing rate of antidromically identified neurons projecting to the VTA. Furthermore, our results support the view that endogenous cannabinoids exert a negative control on dopamine activity in the prefrontal cortex. This study may be relevant in helping to understand the influence of cannabinoids on cognitive processes mediated by the prefrontal cortex. [source]

    Dopaminergic Neurons in the Ventral Tegmental Area of C57BL/6J and DBA/2J Mice Differ in Sensitivity to Ethanol Excitation

    ALCOHOLISM, Issue 7 2000
    Mark S. Brodie
    Background: The mesolimbic dopamine pathway that originates in the ventral tegmental area (VTA) is important for the rewarding effects of ethanol. Ethanol has been shown to excite dopaminergic neurons of the VTA, both in vivo and in vitro, in rats. Behavioral differences in the rewarding effects of ethanol have been observed between C57BL/6J and DBA/2J mice. The present electrophysiological study examined the effect of ethanol on individual dopaminergic VTA neurons from these two inbred mouse strains. Methods: Extracellular single unit recordings of spontaneous action potentials were made from dopaminergic VTA neurons in brain slices from either C57BL/6J or DBA/2J mice. Ethanol (10 to 160 mM) was administered in the superfusate and the mean change in firing rate produced by ethanol was measured. Results: There was no significant difference in basal spontaneous firing rate of dopaminergic VTA neurons between these two mouse strains. Ethanol caused a concentration-dependent increase in the firing rate of neurons from both mouse strains. Ethanol excited dopaminergic VTA neurons from DBA/2J mice more potently than those from C57BL/6J mice. Conclusions: The difference in sensitivity to ethanol excitation of dopaminergic VTA neurons in C57BL/6J and DBA/2J mice may contribute to differences in their behavioral response to ethanol. The fact that a given concentration of ethanol causes greater excitation of dopaminergic VTA (reward) neurons in DBA/2J mice than in C57BL/6J mice could explain why DBA/2J mice show much stronger place preference conditioning with ethanol. The higher voluntary intake of ethanol by C57BL/6J mice may be partly due to the insensitivity of their dopaminergic VTA neurons that requires them to drink a lot of ethanol to achieve sufficient excitation of reward neurons, whereas DBA/2J mice avoid oral ingestion of ethanol, despite its rewarding effect, because of their aversion to its taste. [source]

    Select spinal lesions reveal multiple ascending pathways in the rat conveying input from the male genitalia

    THE JOURNAL OF PHYSIOLOGY, Issue 7 2010
    C. H. Hubscher
    The specific white matter location of all the spinal pathways conveying penile input to the rostral medulla is not known. Our previous studies using rats demonstrated the loss of low but not high threshold penile inputs to medullary reticular formation (MRF) neurons after acute and chronic dorsal column (DC) lesions of the T8 spinal cord and loss of all penile inputs after lesioning the dorsal three-fifths of the cord. In the present study, select T8 lesions were made and terminal electrophysiological recordings were performed 45,60 days later in a limited portion of the nucleus reticularis gigantocellularis (Gi) and Gi pars alpha. Lesions included subtotal dorsal hemisections that spared only the lateral half of the dorsal portion of the lateral funiculus on one side, dorsal and over-dorsal hemisections, and subtotal transections that spared predominantly just the ventromedial white matter. Electrophysiological data for 448 single unit recordings obtained from 32 urethane-anaesthetized rats, when analysed in groups based upon histological lesion reconstructions, revealed (1) ascending bilateral projections in the dorsal, dorsolateral and ventrolateral white matter of the spinal cord conveying information from the male external genitalia to MRF, and (2) ascending bilateral projections in the ventrolateral white matter conveying information from the pelvic visceral organs (bladder, descending colon, urethra) to MRF. Multiple spinal pathways from the penis to the MRF may correspond to different functions, including those processing affective/pleasure/motivational, nociception, and mating-specific (such as for erection and ejaculation) inputs. [source]