Regional cerebral blood flow increases during preparation for and processing of sensory stimuli

Knecht, Stefan; Deppe, Michael; Bäcker, Marcus; Ringelstein, E. B.; Henningsen, H.

doi:10.1007/pl00005758

Cited by 32 publications

(30 citation statements)

References 32 publications

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“…Functional imaging of cerebral perfusion by PET or MRI, either by the nature of the technique or by way of the commonly used analysis algorithm, does not usually evaluate the time course of cerebral activation. Conversely, TCD provides continuous information about the hemodynamic response to the neuronal events (27,28). Our TCD study demonstrates that gSW can result in perfusion increases and decreases, which can be separated in time.…”

Section: Discussionmentioning

confidence: 76%

Cerebral Hemodynamic Response to Generalized Spike‐Wave Discharges

Diehl¹,

Knecht²,

Deppe³

et al. 1998

Epilepsia

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Summary: Purpose: Data in the literature concerning metabolic demand during generalized spike-wave activity (gSW) are conflicting. We investigated instantaneous changes in cerebral blood flow velocities (CBFV) in both middle cerebral arteries (MCAs) by transcranial Doppler sonography (TCD) during gSW paroxysms recorded by scalp EEG.Methods: In 13 patients, CBFVs in both MCAs were averaged, time-locked to the occurrence of the gSW; respiratory rate (RR) and end-expiratory pco, were measured in one patient.Results: Nine patients showed significant changes in CBFV during gSW. Four had biphasic flow changes with an initial increase (p < 0.05) and a subsequent decrease (p < 0.01). This was partially paralleled by an increase in RR (p < 0.01) and a Functional imaging is steadily moving toward a larger role in neurologic practice. In the evaluation of epilepsy, it is being used for determination of epileptic foci and for the presurgical mapping of higher cortical functions (1,2). However, several biologic phenomena can affect functional imaging results and interpretation. One such potentially confounding factor in the evaluation of patients with epilepsy is the incidental occurrence of generalized spike-wave activity (gSW). There are conflicting reports on increased and decreased metabolic demands associated with gSW. In several studies, spontaneous and provoked generalized seizures were studied by means of positron emission tomography (PET) and single-photon-emission tomography (SPECT). decrease in pco, (p < 0.01). In three patients, an increase in CBFV that preceded the onset of gSW by several seconds was observed, followed by a decrease in CBFV. Two patients showed a significant decrease only of CBFV. Only gSWs of a median duration of >0.8 s were associated with significant changes in CBFV. Conclusions:We were able to demonstrate that gSWs of several seconds duration lead to cortical perfusion changes. We suggest that the initial increase of CBFV demonstrated in some patients reflects neuronal activation, whereas the subsequent decrease might in part be due to hyperventilation-induced hypocapnia. Key Words: Cerebral blood flow velocitiesTranscranial Doppler sonography-Generalized spike-wave. fusely increased metabolic rates. This discrepancy might be related to the technical constraints of the autoradiographic techniques that measure a metabolic window of -30 min (6) and therefore reflect a mixture a ictal and interictal (i.e., activity without gSW) activity. Moreover, the model for metabolic-rate calculations is based on steady-state conditions whose applicability to rapidly changing physiologic states such as periods of spikewave' discharges is uncertain (7).Flow responses to various stimulations such as hypocapnia as measured by intravenous xenon-133 have shown direct correlation with cerebral blood flow velocity (CBFV) changes as measured by transcranial Doppler sonography (TCD) in the major cerebral arteries (8). Thus TCD allows non-invasive, on-line monitoring of cerebral perfusion changes with a high tempo...

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Section: Discussionmentioning

confidence: 76%

Cerebral Hemodynamic Response to Generalized Spike‐Wave Discharges

Diehl¹,

Knecht²,

Deppe³

et al. 1998

Epilepsia

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“…30 The heart beat, for example, shows a biphasic modulation that is paralleled by biphasic CBFV changes. 31 Autonomic responses are subject to habituation and are thus likely to change from one examination to the next. The cerebral hemodynamic response is also influenced by diurnal fluctuations or by substances such as nicotine.…”

Section: Discussionmentioning

confidence: 99%

Reproducibility of Functional Transcranial Doppler Sonography in Determining Hemispheric Language Lateralization

Knecht

Deppe

Ringelstein

et al. 1998

Stroke

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113

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Background and Purpose-Since functional transcranial Doppler ultrasonography (fTCD) allows convenient and fully automated quantification of language lateralization, it seems ideal for longitudinal studies of perfusion changes during deterioration as well as recovery of language functions. However, during serial examinations, the technical, stochastic, and physiological variabilities of cerebral blood flow velocities (CBFV) have to be considered. Therefore, before fTCD is accepted as a tool for evaluation of changes in lateralization in the diseased state, its reliability in healthy subjects needs to be determined. Methods-We performed fTCD during a word generation task based on a previously validated technique with automated calculation of the averaged CBFV differences in the middle cerebral arteries providing an index of lateralization (LI). Results-(1)The accuracy of the LI as assessed by the confidence interval was better than 1% of the mean hemispheric difference. (2)

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“…Control of attentional shifts is known to be exerted by a lateralized parietal neural network (mostly of the right hemisphere) [Bäcker et al, 1999;Fink et al, 1997;Knecht et al, 1997]. The generalization of training effects indicates an involvement of these lateralized, attention-mediating parietal regions.…”

Section: No Detectable Increase In Cortical Representationmentioning

confidence: 97%

Learning of tactile frequency discrimination in humans

Imai¹,

Kamping²,

Breitenstein³

et al. 2003

Human Brain Mapping

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Learning is based on the remodeling of neural connections in the brain. The purpose of the present study was to examine the extent to which training-induced improvements in tactile frequency discrimination in humans are correlated with an increase of cortical representations in the primary somatosensory cortex. Healthy male subjects (n = 16) were trained in a tactile frequency discrimination task of the left ring finger. During the first 15 days of training, there was a steep improvement in frequency discrimination, which generalized from the trained finger to its homologue on the opposite hand, and to a lesser extent, to the other fingers on both hands. During the following 15 days of training, there was only a minor improvement in tactile frequency discrimination. Retention of improved performance in frequency discrimination 30 days after training was demonstrated for all digits. Cortical finger representation in the primary somatosensory cortex, as measured by magnetic source imaging, did not change during training. Because of the generalized training effect and the lack of detectable increase in the cortical field evoked from the trained finger, we assume that skill improvement was mediated predominantly by regions outside the primary somatosensory cortex.

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Regional cerebral blood flow increases during preparation for and processing of sensory stimuli

Cited by 32 publications

References 32 publications

Cerebral Hemodynamic Response to Generalized Spike‐Wave Discharges

Cerebral Hemodynamic Response to Generalized Spike‐Wave Discharges

Reproducibility of Functional Transcranial Doppler Sonography in Determining Hemispheric Language Lateralization

Learning of tactile frequency discrimination in humans

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