Noninvasive Study of Neurovascular Coupling during Graded Neuronal Suppression

Abstract

In this study, the neurovascular coupling relationship was noninvasively studied in the human visual cortex. Graded neuronal/hemodynamic suppression conditions were generated using a paired-stimulus paradigm. Visual evoked potential was measured to quantify neuronal activity. Hemodynamic activities were measured and quantified by perfusion and blood oxygenation leveldependent changes. All quantification was normalized to the same activation condition induced by a single stimulus paradigm within each experimental session. This experiment design eliminated the confounding factors such as anesthesia and inconsistent neurovascular coupling patterns within and/or among tasks. The results reveal that (i) there is a tight neurovascular coupling at graded neuronal suppression conditions; (ii) the neurovascular coupling relationship contains a subtle, but significant, nonlinear component; and (iii) the linear model, nevertheless, is still a good approximation reflecting the neurovascular coupling relationship. This study extends the range of the neurovascular coupling relationship from graded neuronal excitation conditions to graded neuronal suppression conditions.

BOLD Consistently Matches Electrophysiology in Human Sensorimotor Cortex at Increasing Movement Rates: A Combined 7T fMRI and ECoG Study on Neurovascular Coupling

“…Previous studies that have combined electrophysiology and BOLD or blood flow measurements have focused mainly on sensory cortices such as the visual or somatosensory cortex using passive neuronal stimulation, either invasively in rodents or primates, or non-invasively using scalp-based electrophysiology measurements electroencephalography (EEG) in humans. 5,[31][32][33][34][35][36][37] While nonlinearities in hemodynamic and electrophysiological measurements are often reported, two studies on human visual cortex using modulation of the stimulation frequency suggested that the hemodynamic response nonlinearity can potentially be explained by the nonlinear electrophysiological activity as captured by the EEG event-related potentials. 31,32 Electroencephalography measurements, however, do not allow for accurate localization of the source of electrophysiological responses because of the inverse problem.…”

“…5,[31][32][33][34][35][36][37] While nonlinearities in hemodynamic and electrophysiological measurements are often reported, two studies on human visual cortex using modulation of the stimulation frequency suggested that the hemodynamic response nonlinearity can potentially be explained by the nonlinear electrophysiological activity as captured by the EEG event-related potentials. 31,32 Electroencephalography measurements, however, do not allow for accurate localization of the source of electrophysiological responses because of the inverse problem. 38 Moreover, event-related potentials such as those measured by EEG do not map well onto BOLD activity for changing stimulus duration as was recently shown with ECoG, 39 whereas changes in HFB power do, as reported in the same and other data sets.…”

Neurovascular coupling in humans: Physiology, methodological advances and clinical implications

“…[52][53][54][55][56][57][58][59][60][61][62][63] Although there is mechanistic insight provided by the isolated preparations of neurovascular coupling, 41 little is known about which mechanisms are sufficient versus necessary for a functional and effective neurovascular coupling response in humans. The available literature related to this topic is reviewed below.…”

Relationship of the BOLD Signal with VEP for Ultrashort Duration Visual Stimuli (0.1 to 5 ms) in Humans

“…Other studies have also indicated a positive intercept of the BOLD response at the limit of zero SEP (Arthurs and Boniface, 2003). In contrast to these studies, Zhang et al (2008a, b) reported that at the extrapolated limit of zero VEP (defined as the amplitude of the second positive VEP component) using a two-pulse stimulation paradigm, the intercept of CBF and BOLD response is negative. This would imply that for low neural activity, a negative BOLD signal still has to be observed even if an activity is too small to generate a hemodynamic response.…”

“…However, because of its invasive nature, intracortical measurements are not suitable for studies in healthy human subjects. Instead, EEG measurements recorded with the electrodes located at the surface of the scalp can complement fMRI acquisitions, thus providing deeper insights into the relationship between neural and hemodynamic activity in the brain (Arthurs and Boniface, 2003;Kashikura et al, 2001;Wan et al, 2006;Zhang et al, 2008a, b). Similar to the invasive electrophysiology findings, human studies have shown a close relationship between BOLD responses and SEPs as well as VEPs.…”