scholarly journals Water-Diffusion Slowdown in the Human Visual Cortex on Visual Stimulation Precedes Vascular Responses

2009 ◽  
Vol 29 (6) ◽  
pp. 1197-1207 ◽  
Author(s):  
Satoru Kohno ◽  
Nobukatsu Sawamoto ◽  
Shin-ichi Urayama ◽  
Toshihiko Aso ◽  
Kenji Aso ◽  
...  
Keyword(s):  
Diffusion Mri ◽  
Near Infrared ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Optical Signal ◽  
Water Diffusion ◽  
Blood Oxygenation ◽  
Hemoglobin Content ◽  
Vascular Responses ◽  
Total Hemoglobin

We used magnetic resonance imaging (MRI) to investigate the temporal dynamics of changes in water diffusion and blood oxygenation level-dependent (BOLD) responses in the brain cortex of eight subjects undergoing visual stimulation, and compared them with changes of the vascular hemoglobin content (oxygenated, deoxygenated, and total hemoglobin) acquired simultaneously from intrinsic optical recordings (near infrared spectroscopy). The group average rise time for the diffusion MRI signal was statistically significantly shorter than those of the BOLD signal and total hemoglobin content optical signal, which is assumed to be the fastest observable vascular signal. In addition, the group average decay time for the diffusion MRI also was shortest. The overall time courses of the BOLD and optical signals were strongly correlated, but the covariance was weaker with the diffusion MRI response. These results suggest that the observed decrease in water diffusion reflects early events that precede the vascular responses, which could originate from changes in the extravascular tissue.

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

2009 ◽  
Vol 30 (2) ◽  
pp. 449-458 ◽  
Author(s):  
Barış Yeşilyurt ◽  
Kevin Whittingstall ◽  
Kâmil Uğurbil ◽  
Nikos K Logothetis ◽  
Kâmil Uludağ
Keyword(s):  
Brain Function ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Impulse Response Function ◽  
Blood Oxygenation ◽  
Context Dependency ◽  
Oxygenation Level ◽  
Relationship Of ◽  
The Relationship ◽  
The Brain

There is currently a great interest to combine electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to study brain function. Earlier studies have shown different EEG components to correlate well with the fMRI signal arguing for a complex relationship between both measurements. In this study, using separate EEG and fMRI measurements, we show that (1) 0.1 ms visual stimulation evokes detectable hemodynamic and visual-evoked potential (VEP) responses, (2) the negative VEP deflection at ∼80 ms (N2) co-varies with stimulus duration/intensity such as with blood oxygenation level-dependent (BOLD) response; the positive deflection at ∼120 ms (P2) does not, and (3) although the N2 VEP–BOLD relationship is approximately linear, deviation is evident at the limit of zero N2 VEP. The latter finding argues that, although EEG and fMRI measurements can co-vary, they reflect partially independent processes in the brain tissue. Finally, it is shown that the stimulus-induced impulse response function (IRF) at 0.1 ms and the intrinsic IRF during rest have different temporal dynamics, possibly due to predominance of neuromodulation during rest as compared with neurotransmission during stimulation. These results extend earlier findings regarding VEP–BOLD coupling and highlight the component- and context-dependency of the relationship between evoked potentials and hemodynamic responses.

scholarly journals Spontaneous Low-Frequency Oscillations Decline in the Aging Brain

2004 ◽  
Vol 24 (10) ◽  
pp. 1183-1191 ◽  
Author(s):  
Matthias L. Schroeter ◽  
Ole Schmiedel ◽  
D. Yves von Cramon
Keyword(s):  
Near Infrared ◽  
Visual Stimulation ◽  
Vascular System ◽  
Low Frequency ◽  
Aging Brain ◽  
Functional Near Infrared Spectroscopy ◽  
Low Frequency Oscillations ◽  
Total Hemoglobin ◽  
Power Spectral ◽  
Spontaneous Oscillations

It is well known that aging leads to a degeneration of the vascular system. Hence, one may hypothesize that spontaneous oscillations decrease in the cerebral microvasculature with aging. Accordingly, the authors investigated the age dependency of spontaneous oscillations in the visual cortex during rest and functional activation. Functional near-infrared spectroscopy was used because it is particularly sensitive to the microvasculature. Visual stimulation led to an increase of oxyhemoglobin, total hemoglobin, and a decrease of deoxyhemoglobin, without any influence of age. Peaks of normalized power spectral density were detected for spontaneous low-frequency (0.07 to 0.11 Hz) and very-low-frequency (0.01 to 0.05 Hz) oscillations, with a higher amplitude for oxyhemoglobin than for deoxyhemoglobin. Spontaneous low-frequency oscillations of oxyhemoglobin and deoxyhemoglobin declined strongly with aging during both rest and visual stimulation. Reduction of spontaneous low-frequency oscillations might indicate a declining spontaneous activity in microvascular smooth muscle cells, in conjunction with an increased vessel stiffness with aging.

Interpretation of near-infrared spectroscopy signals: a study with a newly developed perfused rat brain model

2001 ◽  
Vol 90 (5) ◽  
pp. 1657-1662 ◽  
Author(s):  
Yoko Hoshi ◽  
Norio Kobayashi ◽  
Mamoru Tamura
Keyword(s):  
Infrared Spectroscopy ◽  
Rat Brain ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Venous Blood ◽  
Blood Oxygenation ◽  
Direct Effects ◽  
Total Hemoglobin ◽  
Venous Oxygen Saturation ◽  
Hemoglobin Oxygenation

Using a newly developed perfused rat brain model, we examined direct effects of each change in cerebral blood flow (CBF) and oxygen metabolic rate on cerebral hemoglobin oxygenation to interpret near-infrared spectroscopy signals. Changes in CBF and total hemoglobin (tHb) were in parallel, although tHb showed no change when changes in CBF were small (≤10%). Increasing CBF caused an increase in oxygenated hemoglobin (HbO2) and a decrease in deoxygenated hemoglobin (deoxy-Hb). Decreasing CBF was accompanied by a decrease in HbO2, whereas changes in direction of deoxy-Hb were various. Cerebral blood congestion caused increases in HbO2, deoxy-Hb, and tHb. Administration of pentylenetetrazole without increasing the flow rate caused increases in HbO2 and tHb with a decrease in deoxy-Hb. There were no significant differences in venous oxygen saturation before vs. during seizure. These results suggest that, in activation studies with near-infrared spectroscopy, HbO2 is the most sensitive indicator of changes in CBF, and the direction of changes in deoxy-Hb is determined by the degree of changes in venous blood oxygenation and volume.

scholarly journals fNIRS Monitoring of Infant Prefrontal Cortex During Crawling and an Executive Functioning Task

2021 ◽  
Vol 15 ◽  
Author(s):  
Hannah Weibley ◽  
Mina Di Filippo ◽  
Xinran Liu ◽  
Lillian Lazenby ◽  
Jackson Goscha ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Near Infrared ◽  
Brain Activity ◽  
Hemoglobin Concentration ◽  
Blood Oxygenation ◽  
Functional Near Infrared Spectroscopy ◽  
Attention Task ◽  
Total Hemoglobin ◽  
Measured Activity ◽  
Total Hemoglobin Concentration

Functional near-infrared spectroscopy (fNIRS)is a brain-imaging technology used to reveal brain activity by measuring blood oxygenation. Using fNIRS we measured activity in the left prefrontal lobe of 8–14 month-old infants as they crawled or were pushed in a stroller and as they were given a passive attention task or an active executive function (EF) task. For each task, we measured peak total hemoglobin concentration and peak Oxy relative to baseline. Results revealed differences in peak Oxy levels for crawling vs. strolling and between the EF and passive cognitive tasks, with total hemoglobin greater for the EF task than the passive attention task. These results support the theoretical view that both active locomotion and EF engage the prefrontal cortex (PFC) during early development.

scholarly journals Water-diffusion slowdown in the human visual cortex upon visual stimulation precedes vascular responses

2009 ◽  
Vol 65 ◽  
pp. S131 ◽  
Author(s):  
Satoru Kohno ◽  
Nobukatsu Sawamoto ◽  
Shin-ichi Urayama ◽  
Toshihiko Aso ◽  
Kenji Aso ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Water Diffusion ◽  
Vascular Responses ◽  
Human Visual Cortex

scholarly journals Temporal Dynamics and Spatial Specificity of Arterial and Venous Blood Volume Changes during Visual Stimulation: Implication for Bold Quantification

2010 ◽  
Vol 31 (5) ◽  
pp. 1211-1222 ◽  
Author(s):  
Tae Kim ◽  
Seong-Gi Kim
Keyword(s):  
Blood Volume ◽  
Cerebral Blood Volume ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Magnetization Transfer ◽  
Venous Blood ◽  
Cortical Layer ◽  
Blood Oxygenation ◽  
Order Of Magnitude ◽  
The Difference

Determination of compartment-specific cerebral blood volume ( CBV) changes is important for understanding neurovascular physiology and quantifying blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI). In isoflurane-anesthetized cats, we measured the spatiotemporal responses of arterial CBV ( CBVa) and total CBV ( CBVt) induced by a 40-second visual stimulation, using magnetization transfer (MT)-varied BOLD and contrast-agent fMRI techniques at 9.4 T. To determine the venous CBV ( CBVv) change, we calculated the difference between CBVt and CBVa changes. The dynamic response of CBVa was an order of magnitude faster than that of CBVv, while the magnitude of change under steady-state conditions was similar between the two. Following stimulation offset, Δ CBVa showed small poststimulus undershoots, while Δ CBVv slowly returned to baseline. The largest CBVa and CBVt response occurred after 10 seconds of simulation in cortical layer 4, which we identified as the stripe of Gennari by T1-weighted MRI. The CBVv response, however, was not specific across the cortical layers during the entire stimulation period. Our data indicate that rapid, more-specific arterial vasodilation is followed by slow, less-specific venous dilation. Our finding implies that the contribution of CBVv changes to BOLD signals is significant for long, but not short, stimulation periods.

scholarly journals Mismatch between Tissue Partial Oxygen Pressure and Near-Infrared Spectroscopy Neuromonitoring of Tissue Respiration in Acute Brain Trauma: The Rationale for Implementing a Multimodal Monitoring Strategy

2021 ◽  
Vol 22 (3) ◽  
pp. 1122
Author(s):  
Mario Forcione ◽  
Mario Ganau ◽  
Lara Prisco ◽  
Antonio Maria Chiarelli ◽  
Andrea Bellelli ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Oxygen Pressure ◽  
Near Infrared ◽  
Optical Signal ◽  
Brain Trauma ◽  
Partial Oxygen Pressure ◽  
Tissue Respiration ◽  
The Brain ◽  
Partial Oxygen

The brain tissue partial oxygen pressure (PbtO2) and near-infrared spectroscopy (NIRS) neuromonitoring are frequently compared in the management of acute moderate and severe traumatic brain injury patients; however, the relationship between their respective output parameters flows from the complex pathogenesis of tissue respiration after brain trauma. NIRS neuromonitoring overcomes certain limitations related to the heterogeneity of the pathology across the brain that cannot be adequately addressed by local-sample invasive neuromonitoring (e.g., PbtO2 neuromonitoring, microdialysis), and it allows clinicians to assess parameters that cannot otherwise be scanned. The anatomical co-registration of an NIRS signal with axial imaging (e.g., computerized tomography scan) enhances the optical signal, which can be changed by the anatomy of the lesions and the significance of the radiological assessment. These arguments led us to conclude that rather than aiming to substitute PbtO2 with tissue saturation, multiple types of NIRS should be included via multimodal systemic- and neuro-monitoring, whose values then are incorporated into biosignatures linked to patient status and prognosis. Discussion on the abnormalities in tissue respiration due to brain trauma and how they affect the PbtO2 and NIRS neuromonitoring is given.

scholarly journals An analysis framework for the integration of broadband NIRS and EEG to assess neurovascular and neurometabolic coupling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Pinti ◽  
M. F. Siddiqui ◽  
A. D. Levy ◽  
E. J. H. Jones ◽  
Ilias Tachtsidis
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Visual Stimulation ◽  
Finite Impulse Response ◽  
Occipital Cortex ◽  
Integrated Analysis ◽  
Impulse Response Functions ◽  
Functional Near Infrared Spectroscopy ◽  
Brain Functioning

AbstractWith the rapid growth of optical-based neuroimaging to explore human brain functioning, our research group has been developing broadband Near Infrared Spectroscopy (bNIRS) instruments, a technological extension to functional Near Infrared Spectroscopy (fNIRS). bNIRS has the unique capacity of monitoring brain haemodynamics/oxygenation (measuring oxygenated and deoxygenated haemoglobin), and metabolism (measuring the changes in the redox state of cytochrome-c-oxidase). When combined with electroencephalography (EEG), bNIRS provides a unique neuromonitoring platform to explore neurovascular coupling mechanisms. In this paper, we present a novel pipeline for the integrated analysis of bNIRS and EEG signals, and demonstrate its use on multi-channel bNIRS data recorded with concurrent EEG on healthy adults during a visual stimulation task. We introduce the use of the Finite Impulse Response functions within the General Linear Model for bNIRS and show its feasibility to statistically localize the haemodynamic and metabolic activity in the occipital cortex. Moreover, our results suggest that the fusion of haemodynamic and metabolic measures unveils additional information on brain functioning over haemodynamic imaging alone. The cross-correlation-based analysis of interrelationships between electrical (EEG) and haemodynamic/metabolic (bNIRS) activity revealed that the bNIRS metabolic signal offers a unique marker of brain activity, being more closely coupled to the neuronal EEG response.

Cerebral oxygenation changes in response to motor stimulation

1996 ◽  
Vol 81 (3) ◽  
pp. 1174-1183 ◽  
Author(s):  
H. Obrig ◽  
C. Hirth ◽  
J. G. Junge-Hulsing ◽  
C. Doge ◽  
T. Wolf ◽  
...  
Keyword(s):  
Time Course ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Motor Task ◽  
Hemoglobin Concentration ◽  
Hemodynamic Response ◽  
Blood Oxygenation ◽  
Initial Increase ◽  
Cerebral Hemodynamic ◽  
Course Changes

We studied cerebral hemodynamic response to a sequential motor task in 56 subjects to investigate the time course and distribution of blood oxygenation changes as monitored by near-infrared spectroscopy (NIRS). To address whether response is modulated by different performance velocities, a group of subjects (n = 12) was examined while performing the motor task at 1, 2, and 3 Hz. The results demonstrate that 1) the NIRS response reflects localized changes in cerebral hemodynamics, 2) the response, consisting of an increase in oxygenated hemoglobin concentration [oxy-Hb] and a decrease in deoxygenated hemoglobin concentration ([deoxy-Hb]), is lateralized and increases in amplitude with higher performance rates, and 3) changes in [oxy-Hb] and [deoxy-Hb] differ in time course. Changes in [oxy-Hb] are biphasic, with a fast initial increase and a pronounced poststimulus undershoot. The stimulus-associated decrease in [deoxy-Hb] is monophasic, and response latency is greater. We conclude that NIRS is able to detect even small changes in cerebral hemodynamic response to functional stimulation.

Temporal Dynamics of Shape Analysis in Macaque Visual Area V2

2004 ◽  
Vol 92 (5) ◽  
pp. 3030-3042 ◽  
Author(s):  
Jay Hegdé ◽  
David C. Van Essen
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Signal To Noise Ratio ◽  
Stimulus Onset ◽  
Visual Area ◽  
Response Modulation ◽  
Population Response ◽  
Area V2

The firing rate of visual cortical neurons typically changes substantially during a sustained visual stimulus. To assess whether, and to what extent, the information about shape conveyed by neurons in visual area V2 changes over the course of the response, we recorded the responses of V2 neurons in awake, fixating monkeys while presenting a diverse set of static shape stimuli within the classical receptive field. We analyzed the time course of various measures of responsiveness and stimulus-related response modulation at the level of individual cells and of the population. For a majority of V2 cells, the response modulation was maximal during the initial transient response (40–80 ms after stimulus onset). During the same period, the population response was relatively correlated, in that V2 cells tended to respond similarly to specific subsets of stimuli. Over the ensuing 80–100 ms, the signal-to-noise ratio of individual cells generally declined, but to a lesser degree than the evoked-response rate during the corresponding time bins, and the response profiles became decorrelated for many individual cells. Concomitantly, the population response became substantially decorrelated. Our results indicate that the information about stimulus shape evolves dynamically and relatively rapidly in V2 during static visual stimulation in ways that may contribute to form discrimination.

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