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Results for “Cortical Synchronization”

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At least 1,027 records · Page 57Linked to original sources
PubMed1982

Arousal a prerequisite for suckling in the conscious rabbit?

Electrocorticographic activity (ECoG) was recorded from the frontal cortex of unanaesthetized, lactating rabbits, and analysed in relation to the suckling behaviour of the animals. Suckling lasted 2--5 minutes each day and was always associated with a desynchronized ECoG. Milk ejection was never seen during slow wave sleep. Mild sedation of the doe caused a dose-dependent block of milk yield but did not affect her willingness to suckle and the ECoG was desynchronized during nursing. In contrast to the rat, but similar to the pig, sleep is not a prerequisite for reflex milk ejection in the rabbit. Evidence presented implies that ECoG arousal may be important for this reflex in the rabbit.

Animals↗
PubMed1996

EEG arousal, sympathetic activity, and brown adipose tissue thermogenesis after conditioned taste aversion.

Conditioned taste aversion was induced in rats by pairing saccharin with intraperitoneal LiCl injection. Animals injected with NaCl served as controls. After evaluating the preference levels for saccharin in rats of both groups, the animals were anesthetized with urethane and the duration of EEG desynchronization, firing rate of sympathetic nerves innervating interscapular brown adipose tissue (BAT), and temperature of the same tissues were recorded, before and after oral stimulation with saccharin or water. The EEG desynchronization was longer in conditioned rats after stimulation with saccharin. Firing rate of sympathetic nerves was higher in conditioned rats after presentation of saccharin. BAT temperature, decreased in conditioned rats after saccharin stimulus, was unchanged in the three other conditions. In a second experiment temperature and firing rate of sympathetic nerves of BAT were recorded after oral presentation of water or saccharin in rats treated as in the first experiment and injected with the alpha 1-adrenergic blocker prazosin. As in the first experiment, saccharin presentation in conditioned animals enhanced the neural sympathetic activity, whereas differently from the first experiment it increased BAT temperature. No changes were found in the same measurements in the three other conditions. The drop in interscapular BAT temperature found in the first experiment, an unexpected finding, probably depends on the use of lithium as unconditioned stimulus, because LiCl interacting with adrenergic receptors changes the two-phase response, normally seen in interscapular BAT after increased sympathetic activity, in a single-phase response.

Adipose Tissue, Brown↗
PubMedDate not supplied

Tolerance development to the arousal effects of nicotine.

To determine if repeated daily doses of nicotine induces tolerance to both its EEG and behavioral activating effects, rats implanted with sets of bipolar cortical elecrodes and carotid cannulae received intracarotid injections of either (1) 6 daily doses of nicotine (as tartrate, 30 mug/kg) (Group 1) or (2) 3 daily doses of saline followed by 4 days of nicotine (Group 2). From an exercise-induced resting state, nicotine produced immediate EEG and behavioral arousal, both of which disappeared in Group 1 by Day 6. Saline administered to Group 2 rats produced little or no response but subsequent nicotine resulted in responses similar to those produced by Group 1 animals. It is concluded that tolerance development to nicotine activation is reflected not only in behavior, but also in the EEG.

Animals↗
PubMed1976

Intraventricular anti-cholinergics do not block cholinergic hippocampal RSA or neocortical desynchronization in the rabbit or rat.

Electroencephalographic (EEG) electrodes and ventricular cannulae were implanted in 8 rabbits and 12 rats. Two anti-cholinergic agents, atropine sulfate and scopolamine hydrobromide, were given systemically (1-50 mg/kg) and intraventricularly (5-800 mug). Systemic but not intraventricular injections blocked sensory stimulation-induced or eserine-induced neocortical desynchronization and hippocampal RSA in rats and rabbits which were immobile and either undrugged or ethanol intoxicated. Systemic injections also blocked hippocampal RSA but not neocortical desynchronization in rats given sensory stimulation under urethane anaesthesia, while intraventricular injections only reduced RSA amplitude. Neither systemic nor intraventricular injections blocked neocortical desynchronization or hippocampal RSA recorded from animals when they walked in a motor driven wheel. These experiments support the hypothesis that there are two types of neocortical desynchronization and hippocampal RSA, one cholinergic and one non-cholinergic. They also suggest that atropine and scopolamine pass more readily to the neural system responsible for cholinergic EEG activity from the capillary bed than from the ventricular fluid.

Animals↗
PubMed1983

Differential clonidine effects on EEG following lesions of the dorsal and median raphe nuclei in rats.

The effects of clonidine on EEG activity and gross behavior were studied in rats with electrolytic lesions of the median (MR) and dorsal (DR) raphe nuclei. Lesioned animals showed significant depletion in forebrain serotonin concentrations. Clonidine (0.1 mg/kg and 0.2 mg/kg IP) produced synchronization in cortical EEG pattern and markedly increased alpha and theta activities in unlesioned animals. Clonidine treatment resulted also in a sedative response. In MR lesioned rats clonidine effect upon EEG was significantly reduced and, additionally, sedative response was not seen. On the other hand clonidine effect on EEG was markedly increased in rats with lesioned DR. These results are discussed on the basis of possible interaction between serotonergic and noradrenergic neurons in the brain.

Animals↗
PubMed1992

Temporal coding in the visual cortex: new vistas on integration in the nervous system.

Although our knowledge of the cellular components of the cortex is accumulating rapidly, we are still largely ignorant about how distributed neuronal activity can be integrated to contribute to unified perception and behaviour. In the visual system, it is still unresolved how responses of feature-detecting neurons can be bound into representations of perceptual objects. Recent crosscorrelation studies show that visual cortical neurons synchronize their responses depending on how coherent features are in the visual field. These results support the hypothesis that temporal correlation of neuronal discharges may serve to bind distributed neuronal activity into unique representations. Furthermore, these studies indicate that neuronal responses with an oscillatory temporal structure may be particularly advantageous as carrier signals for such a temporal coding mechanism. Based on these recent findings, it is suggested here that binding of neuronal activity by a temporal code may provide a solution to the problem of integration in distributed neuronal networks.

Animals↗
PubMed1981

Afferent properties of periarcuate neurons in macaque monkeys. I. Somatosensory responses.

The afferent properties of single neurons of the periarcuate cortex have been studied in the macaque monkey. Most of the recorded neurons responded to stimuli in one or two sensory modalities and, accordingly, they were classified as somatosensory, visual or bimodal (visual and somatosensory) neurons. Visual neurons were located rostral to the arcuate sulcus, whereas the somatosensory and the bimodal neurons were found predominantly caudal to this sulcus. Somatosensory neurons (n = 102) and bimodal neurons (n = 69) had identical somatic afferent properties. They were subdivided into 'tactile' neurons, 'joint' neurons and 'tactile and joint' neurons. 'Tactile' neurons (70%) had their receptive fields formed either by one or by two or more spatially separated responding areas. The parts of the body most represented were the hands and the mouth. 'Joint' neurons (10%) were activated by the rotation of one or, more often, of two or more articulations. The movement of the hand towards the mouth was the most frequently represented movement. 'Tactile and joint' neurons (20%) responded to both tactile and joint stimulation having receptive field locations and properties like those of the other two classes of neurons. Some 'joint' and 'tactile and joint' neurons had summing properties, i.e. their response to tactile or joint stimulation was conditional upon a simultaneous stimulation of another articulation. The data are interpreted as evidence in favor of the existence of an area in the agranular cortex that organizes the mouth and the hand to mouth movements.

Afferent Pathways↗
PubMed1990

Altered diurnal pattern of arousal following naloxone administration in opioid-naive rats.

Heightened arousal occurring in response to physical or psychological stressors in associated with increased levels of endogenous opioid peptides in peripheral circulation and at binding sites in the central nervous system. When administered as a series of bolus injections during active periods, the opioid antagonist naloxone increased delta wave activity and total spectral power in the EEG of opioid-naive rats. A single 1.0 mg/kg injection of naloxone had a similar effect when given at the onset of night-time active periods, but not if administered during the day when rats are normally inactive. These results are consistent with a diminished level of arousal following blockade of endogenous opioid activity, and suggest an excitatory effect of opioid peptides in certain behavioral settings.

Animals↗
PubMed1994

Interhemispheric interaction in children of 7-8: analysis of EEG coherence and finger tapping parameters.

To investigate interhemispheric interaction (IHI), the EEGs of 42 children between the ages of 7-8 years were recorded while they were performing, as fast as possible, both unimanual and bimanual rhythmic tapping tasks. As an EEG index of IHI we used coherence values (Coh) in the alpha band in the pairs of leads F3/F4, C3/C4, P3/P4, O1/O2, and T3/T4 during resting and tapping. The difference between left hand (L-L) and right hand (R-R) intertap intervals in comparable conditions was though to reflect IHI. Interhemispheric alpha Coh increase was only evident in bimanual rhythmic tasks, and was confined to the C3/C4 and P3/P4 regions. Coh in these brain areas correlated negatively with the time difference between the L-L and R-R intertap intervals. The results show that interhemispheric alpha Coh. can be regarded as an index of IHI during bimanual tapping, and support the clinical hypothesis that bimanual versus unimanual tapping might reflect interhemispheric or callosal function.

Alpha Rhythm↗
PubMed1984

Cerebral asymmetry and the psychophysiology of attention.

The literature relevant to psychophysiological aspects of the lateralized control of attention is reviewed. It is argued that the description of attention as a dynamic process tends to obscure examination of the structural determinants of attentional asymmetries. Psychophysiological evidence suggests that a right hemispheric predominance in attention is quite possibly the natural outcome of a similar asymmetry in activational, interoceptive and early visual processes.

Arousal↗