Neuroscience letters
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Neuroscience letters · Dec 2010
Nicotine activation of neuronal nitric oxide synthase and guanylyl cyclase in the medulla increases blood flow of the common carotid artery in cats.
Individual activation of nicotinic acetylcholine receptor (nAChR) or nitric oxide (NO) synthase in the dorsal facial area (DFA) increases blood flow of common carotid artery (CCA) supplying intra- and extra-cranial tissues. We investigated whether the activation of nAChR initiated the activation of NO synthase and guanylyl cyclase to increase CCA blood flow in anesthetized cats. ⋯ Control microinjection with d-NAME (an isomer of l-NAME), artificial cerebrospinal fluid or DMSO (a solvent for 7-NI) did not affect resting CCA blood flow, nor did they affect nicotine- or choline-induced response. In conclusion, activation of nAChR, at least α7-nAChR, led to the activation of neuronal NO synthase and guanylyl cyclase in the DFA, which induced an increase in CCA blood flow.
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Neuroscience letters · Dec 2010
Comparative StudyLeft is where the L is right. Significantly delayed reaction time in limb laterality recognition in both CRPS and phantom limb pain patients.
The body schema is based on an intact cortical body representation. Its disruption is indicated by delayed reaction times (RT) and high error rates when deciding on the laterality of a pictured hand in a limb laterality recognition task. Similarities in both cortical reorganisation and disrupted body schema have been found in two different unilateral pain syndromes, one with deafferentation (phantom limb pain, PLP) and one with pain-induced dysfunction (complex regional pain syndrome, CRPS). ⋯ Both healthy subjects and CRPS patients improved during training, but RTs of CRPS patients (1874.5±613.3ms) remain slower (p<0.01) than those of healthy subjects (1280.6±343.2ms) after four-day training. Despite different pathomechanisms, the body schema is equally disrupted in PLP and CRPS patients, uninfluenced by attention and pain and cannot be fully reversed by training alone. This suggests the involvement of complex central nervous system mechanisms in the disruption of the body schema.
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Neuroscience letters · Nov 2010
Study of the origin of short- and long-latency SSEP during recovery from brain ischemia in a rat model.
Somatosensory evoked potentials (SSEPs) have been established as an electrophysiological tool for the prognostication of neurological outcome in patients with hypoxic-ischemic brain injury. The early and late responses in SSEPs reflect the sequential activation of neural structures along the somatosensory pathway. This study reports that the SSEP can be separated into early (short-latency, SL) and late (long-latency, LL) responses using independent component analysis (ICA), based on the assumption that these components are generated from different neural sources. ⋯ With the help of ICA decomposition and corrected peak estimation, the latency of LL-SSEP is shown to be predictive of long-term neurological outcome. Further, it is shown that the recovery processes of SL- and LL-SSEPs follow different dynamics, with the SL-SSEP restored earlier than LL-SSEP. We predict that the SL- and LL-SSEPs reflect the timing of the progression of evoked response through the thalamocortical pathway and as such respond differently depending upon injury and recovery of the thalamic and cortical regions, respectively.
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Neuroscience letters · Nov 2010
Parametric analysis of thermal preference following sleep deprivation in the rat.
A thermal preference task was used to assess the effects of sleep deprivation on nociceptive behavior using hot and cool stimuli. The thermal preference apparatus allowed male rats to move freely from a hot thermal plate (44.7°C) to an adjacent plate at neutral (33.5°C) or cold temperatures (1.3-11°C). Investigators recorded occupancy on the colder side, frequency of movements between the 2 compartments, and first escape latency from the cold side. ⋯ This temperature combination was then used to test the effects of sleep deprivation for 48h using the pedestal-over-water method on response allocation to the 2 temperature zones. Sleep deprivation decreased time spent on the cooled plate. Cumulative occupancy indicated differential effects for sleep deprivation with the rats preferring to remain on the hot side vs. the cold side, suggesting that sleep deprivation increased the nociceptive properties of the cold stimulus.
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Recent brain functional magnetic resonance imaging (fMRI) studies have shown that chronic back pain (CBP) alters brain dynamics beyond the feeling of pain. In particular, the response of the brain default mode network (DMN) during an attention task was found abnormal. ⋯ The alterations were confirmed by the calculation of triggered averages, which demonstrated increased coactivation of the DMN and the former regions. These findings demonstrate that CBP disrupts normal activity in the DMN even during the brain resting state, highlighting the impact of enduring pain over brain structure and function.