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At least 253 records · Page 14Linked to original sources
PubMed1975

Cyclic EEG changes in subacute spongiform and anoxic encephalopathy.

Polygraphic recordings of EEG, EMG, EKG and respiration were made on three patients with histologically verified subacute spongiform encephalopathy and one patient with anoxic encephalopathy both before and after intravenous diazepam. The records showed cyclical activity occurring about every half minute in which the EEG changes were correlated with myoclonus and cardio-respiratory changes. It is suggested that these cycles represent spontaneous cycles of arousal to which the 1/sec sharp waves are related wnd which result from the same mechanisms that produce other cyclical autonomic phenomena.

Acoustic Stimulation↗
PubMed1975

The characteristics of EEG activity and the subjective estimation of time during dreams of different structure.

During dreams evoked by stimuli of a certain duration, the EEF was studied in healthy subjects and in patients with implanted electrodes (EEG, ESCoG (electrosubcorticogram), unit activity). Estimation of the temporal structure of the dream was made from the verbal account of the subject. In the case of an unformed dream the duration of the dream was shown to be adequately estimated, the EEF and ESCoG patterns to be rather variable, and correlation between the bioelectric activities of different structures to be nearly absent. Apparently, in these cases, only some of the structures participate in the formation of dreams, which accounts for their unstructure, with no disorder of temporal and spatial relationships, is accompanied by certain orderly rhythms, similar EEG and ESCoG patterns, and a high correlation between bioelectric processes occurring in the structures under study. Dreams with a complex structure, with simultaneous action in different aspects and with major overestimation of their duration, are accompanied by polymorphous EEG and ESCoG patterns. Almost no correlation is observed between bioelectric processes in different structures. Apparently these dreams are associated with independent activities in different structures and, in the verbal account, the subject tends to place the events in a certain temporal order which creates the effect of considerable acceleration of the time flow.

Alpha Rhythm↗
PubMed1975

[An electrophysiological study of direct occipito-frontal connections in centrum semi-ovale of Papio papio].

1. Evoked responses to single visual stimuli (VEP) and driving by intermittent light stimulation (ILS) were recorded with macroelectrodes from the central white matter (centrum semiovale) of 12 Papio papio baboons. 2. Two types of VEP were identified: VEPs with constant morphology, localized in the long associative bundles connecting the occipital, temporal and frontal lobes; VEPs with variable morphology and without any preferential localization; these probably originate from other types of fibres also belonging to the centrum semi-ovale. 3. Concerning the long associative bundles which have been individualized, they might be the equivalent of the occipito-frontal and the superior and inferior longitudinal bundles well known in man. The fusion frequency observed in these bundles during ILS increases from the frontal to the occipital lobe, because of their involvement (particularly in the parieto-temporal region) with other fibres of the centrum semi-ovale also likely to be driven by ILS. The existence of driving by ILS in these bundles demonstrates an activation of the frontal lobe by visual impulses.

Animals↗
PubMed1982

Human pulvinar units, spontaneous activity and sensory-motor influences.

Unit activity was recorded from the pulvinar nucleus (Pu) in human patients undergoing stereotaxic surgery. Thirty-six units (12 isolated and 12 pairs recorded with the same microelectrode) with a signal-to-noise ratio greater than 5, a stable amplitude, and a sustained discharge rate for more than 1 min, were selected for processing. The following functions were calculated with a digital computer to characterize discharge patterns: interval, autocorrelation and peristimulus time histograms for spikes, cross-correlation histograms between spikes of a pair, and autocorrelation functions and averages of the EEG. In spontaneous conditions, about half of the units fired in rhythmic bursts at the same or half the frequency of the Pu EEG. Most non-rhythmic units showed a "Poisson-like' interval histogram indicating a random firing pattern. Some non-rhythmic units revealed a periodic cross-correlation with the rhythmic Pu EEG, indicating that spikes tend to fire at a preferred phase of the rhythm. About half of the units showed phasic firing rate changes during voluntary movements. In most cells a discharge rate increase was observed. One unit also responded to passive movements of the fingers. Of the neurons tested, 2 out of 3 showed firing rate modulation during voluntary movements of the jaw as well as of the contralateral hand. The above units also increased the impulse rate after visual stimulation. Convergence of the effects of voluntary movements, and visual and auditory stimulation, was demonstrated in one unit. These results indicate the participation of the Pu in sensory-motor integrative functions.

Acoustic Stimulation↗
PubMed1986

Long-lasting EEG reactions in comatose patients after repetitive stimulation.

Twenty patients with severe head injury and a Glasgow Coma Scale of 4-6 were subjects of a multimodality EP study. After EEG recording during rest (control 1) 60 mechanical vibration stimuli and 60 visual stimuli (interstimulus interval 10 sec) were applied. Thereafter a second EEG (control 2) was measured. To quantify a long-lasting stimulated EEG alteration, control 2 was compared with control 1 on the basis of the spectral theta/beta ratio calculated from central derivations. In 50% of the patients the theta/beta ratio was changed in control 2 and therefore a long lasting stimulation effect can be assumed. Stimulus-induced cardiac alterations were also found.

Adolescent↗
PubMed1984

Neuronal activity of the locus ceruleus in awake Macaca arctoides.

Neuronal activity in the locus ceruleus of awake, behaving stump-tailed monkeys increased consistently and vigorously after presentation of mildly aversive and threatening stimuli. These preliminary data increase the range of stimuli reported to elicit locus ceruleus activity in awake monkeys to include nonpainful threat signals and suggest that more studies are needed to be able to categorize locus ceruleus function from its unit activity responses.

Acoustic Stimulation↗
PubMed1988

Hemispheric asymmetry in neglect produced by unilateral lesions of dorsomedial prefrontal cortex in rats.

Unilateral lesions of the medial precentral prefrontal cortex produce severe polymodal neglect which reaches a stable level of recovery over 3 to 4 weeks. Previous research has indicated that neglect is produced by unilateral destruction of this region in either hemisphere, but that the nature of the neglect produced is dependent on the hemisphere damaged. The present study is a further examination of behavioral laterality produced by this unilateral destruction. The results indicated that destruction of medial precentral cortex in the left hemisphere (n = 12) produced severe contralateral multimodal neglect of visual, somatosensory, and auditory stimuli. Identical destruction in the right hemisphere (n = 18) also produced severe neglect, but unlike the left hemisphere operates which always demonstrated contralateral neglect, there were two distinct populations of right hemisphere operates. These subjects demonstrated either ipsilateral neglect or a "switching" response pattern characterized by the initial demonstration of contralateral or ipsilateral neglect and then, during the course of recovery, severe neglect on the opposite body side. Histological analysis indicated that the left and right hemisphere lesions were equivalent, as were the lesions in the two behavioral subcategories of right hemisphere operates. Operated controls (n = 12) did not demonstrate long-standing neglect or this switching pattern. The behavioral laterality observed following unilateral destruction of medial precentral prefrontal cortex is discussed in relationship to the anatomical and neurochemical asymmetries which have been demonstrated in this cortical region.

Acoustic Stimulation↗
PubMed1981

The radiologic anatomy of patients who gag with dentures.

The past dental literature suggests that gagging in dental patients may be due to anatomic causes. Cephalometrically oriented lateral skull radiographs of 53 patients who were gaggers and of matched controls were examined for an anatomic cause of gagging. No evidence was found that the soft palate was especially long or steeply angled in patients who were gaggers. There was no tongue enlargement or reduction of the pharyngeal airway in patients who were gaggers which might render them intolerant of bulky dentures. The postures of the palate, tongue, and hyoid bone were compared in patients with and without their dentures. Wearing dentures caused less modification in the posture of these tissues in the gaggers than in their matched controls. In the absence of either gross abnormality of the radologic anatomy of those who were gaggers, or a marked change of posture of the oral tissues when the patients wore dentures, some other reason for gagging is likely. It is possible that patients who gag may have a more extensive distribution of the vagus nerve. With such an abnormality, physical stimulation of the mucosa in other parts of the mouth would cause gagging.

Cephalometry↗
PubMed1993

Stimulus cancellation by macaques with unilateral frontal or parietal lesions.

Monkeys' spontaneous behaviors in cancelling a variety of visual and somatosensory stimuli were measured before, and acutely after, unilateral periarcuate (N = 16) and inferior parietal (n = 14) cortical removals. Postoperative behavior was analyzed for both severity of change from the preoperative baseline, and for the type of behavior (perceptual or premotor) affected by the lesion. Overall the two lesion groups could not be differentiated by severity or type of deficit. In two tasks, premotor deficits, manifest as extreme disuse of the hand contralateral to the lesion, were significantly worse in the parietal than the frontal group. In a third, the frontal group showed a greater perceptual deficit, manifest as marked preference for acting within ipsilesional space, than the parietal. In the three remaining tasks, premotor and perceptual deficits were equal in the two groups. These quantitative behavioral data suggest that deficits are more highly contingent upon task requirements than upon lesion sites. This in turn suggests that frontal and parietal association cortical fields each play multiple, and sometimes interchangeable, roles in the spatially directed attention and motor behavior of the monkey.

Analysis of Variance↗
PubMed1996

Consequences of covert orienting to non-informative stimuli of different modalities: a unitary mechanism?

Reaction time (RT) to visual targets is lengthened following non-informative cues presented in the same location, or in different locations but in the same hemifield as the targets. RT lengthening is best accounted for by the voluntary suppression of an overt orienting toward the location of the cue: this veto produces an inhibition of the overall motor reactivity towards stimuli presented in the entire hemifield of the cue. This paper shows that ipsilateral inhibition is not unique to the visual system, since the same directional constraints in motor readiness are induced with somatosensory stimulation. RT is slower when a somatic target delivered on a shoulder is preceded by an ipsilateral somatic cue compared to a contralateral one. The neural control of these orienting tendencies may involve the superior colliculus, which contains overlapping maps of the visual, somatosensory and auditory peripheries. This suggestion is reinforced by the presence of cross-modal inhibitory effects in paradigms involving visual cues and somatic targets or somatic cues and visual targets. While the time course of ipsilateral inhibition is similar in the visual and the somatic modalities, cross-modal inhibitory effects are different and somehow complementary when visual cues precede somatic targets (early short-lasting inhibition) or, respectively, somatic cues precede visual targets (late, long-lasting inhibition). An additional finding is that crossed-uncrossed RT differences (CUDs), presumably due to the anatomical relations between stimulus and response, are present in both modalities.

Adult↗