1
|
Kaynezhad P, Tachtsidis I, Aboelnour A, Sivaprasad S, Jeffery G. Watching synchronous mitochondrial respiration in the retina and its instability in a mouse model of macular degeneration. Sci Rep 2021; 11:3274. [PMID: 33558624 PMCID: PMC7870852 DOI: 10.1038/s41598-021-82811-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/12/2021] [Indexed: 11/09/2022] Open
Abstract
Mitochondrial function declines with age and in some diseases, but we have been unable to analyze this in vivo. Here, we optically examine retinal mitochondrial function as well as choroidal oxygenation and hemodynamics in aging C57 and complement factor H (CFH-/-) mice, proposed models of macular degeneration which suffer early retinal mitochondrial decline. In young C57s mitochondrial populations respire in coupled oscillatory behavior in cycles of ~ 8 min, which is phase linked to choroidal oscillatory hemodynamics. In aging C57s, the oscillations are less regular being ~ 14 min and more dissociated from choroidal hemodynamics. The mitochondrial oscillatory cycles are extended in CFH-/- mice being ~ 16 min and are further dissociated from choroidal hemodynamics. Mitochondrial decline occurs before age-related changes to choroidal vasculature, hence, is the likely origin of oscillatory disruption in hemodynamics. This technology offers a non-invasive technique to detect early retinal disease and its relationship to blood oxygenation in vivo and in real time.
Collapse
Affiliation(s)
- Pardis Kaynezhad
- Institute of Ophthalmology, University College London, London, EC1V 9EL, UK
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Asmaa Aboelnour
- Histology and Cytology Department, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt
| | - Sobha Sivaprasad
- Institute of Ophthalmology, University College London, London, EC1V 9EL, UK
| | - Glen Jeffery
- Institute of Ophthalmology, University College London, London, EC1V 9EL, UK.
| |
Collapse
|
2
|
Chen Y, Tang J, Chen Y, Farrand J, Craft MA, Carlson BW, Yuan H. Amplitude of fNIRS Resting-State Global Signal Is Related to EEG Vigilance Measures: A Simultaneous fNIRS and EEG Study. Front Neurosci 2020; 14:560878. [PMID: 33343275 PMCID: PMC7744746 DOI: 10.3389/fnins.2020.560878] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 11/11/2020] [Indexed: 12/21/2022] Open
Abstract
Recently, functional near-infrared spectroscopy (fNIRS) has been utilized to image the hemodynamic activities and connectivity in the human brain. With the advantage of economic efficiency, portability, and fewer physical constraints, fNIRS enables studying of the human brain at versatile environment and various body positions, including at bed side and during exercise, which complements the use of functional magnetic resonance imaging (fMRI). However, like fMRI, fNIRS imaging can be influenced by the presence of a strong global component. Yet, the nature of the global signal in fNIRS has not been established. In this study, we investigated the relationship between fNIRS global signal and electroencephalogram (EEG) vigilance using simultaneous recordings in resting healthy subjects in high-density and whole-head montage. In Experiment 1, data were acquired at supine, sitting, and standing positions. Results found that the factor of body positions significantly affected the amplitude of the resting-state fNIRS global signal, prominently in the frequency range of 0.05-0.1 Hz but not in the very low frequency range of less than 0.05 Hz. As a control, the task-induced fNIRS or EEG responses to auditory stimuli did not differ across body positions. However, EEG vigilance plays a modulatory role in the fNIRS signals in the frequency range of less than 0.05 Hz: resting-state sessions of low EEG vigilance measures are associated with high amplitudes of fNIRS global signals. Moreover, in Experiment 2, we further examined the epoch-to-epoch fluctuations in concurrent fNIRS and EEG data acquired from a separate group of subjects and found a negative temporal correlation between EEG vigilance measures and fNIRS global signal amplitudes. Our study for the first time revealed that vigilance as a neurophysiological factor modulates the resting-state dynamics of fNIRS, which have important implications for understanding and processing the noises in fNIRS signals.
Collapse
Affiliation(s)
- Yuxuan Chen
- School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, United States
| | - Julia Tang
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, United States
| | - Yafen Chen
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, United States
| | - Jesse Farrand
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, United States
| | - Melissa A. Craft
- Fran and Earl Ziegler College of Nursing, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Barbara W. Carlson
- Fran and Earl Ziegler College of Nursing, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Han Yuan
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, United States
- Institute for Biomedical Engineering, Science, and Technology, University of Oklahoma, Norman, OK, United States
| |
Collapse
|
3
|
Ghali MGZ, Ghali GZ. Mechanisms Contributing to the Generation of Mayer Waves. Front Neurosci 2020; 14:395. [PMID: 32765203 PMCID: PMC7381285 DOI: 10.3389/fnins.2020.00395] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 03/30/2020] [Indexed: 01/25/2023] Open
Abstract
Mayer waves may synchronize overlapping propriobulbar interneuronal microcircuits constituting the respiratory rhythm and pattern generator, sympathetic oscillators, and cardiac vagal preganglionic neurons. Initially described by Sir Sigmund Mayer in the year 1876 in the arterial pressure waveform of anesthetized rabbits, authors have since extensively observed these oscillations in recordings of hemodynamic variables, including arterial pressure waveform, peripheral resistance, and blood flow. Authors would later reveal the presence of these oscillations in sympathetic neural efferent discharge and brainstem and spinal zones corresponding with sympathetic oscillators. Mayer wave central tendency proves highly consistent within, though the specific frequency band varies extensively across, species. Striking resemblance of the Mayer wave central tendency to the species-specific baroreflex resonant frequency has led the majority of investigators to comfortably presume, and generate computational models premised upon, a baroreflex origin of these oscillations. Empirical interrogation of this conjecture has generated variable results and derivative interpretations. Sinoaortic denervation and effector sympathectomy variably reduces or abolishes spectral power contained within the Mayer wave frequency band. Refractorines of Mayer wave generation to barodeafferentation lends credence to the hypothesis these waves are chiefly generated by brainstem propriobulbar and spinal cord propriospinal interneuronal microcircuit oscillators and likely modulated by the baroreflex. The presence of these waves in unitary discharge of medullary lateral tegmental field and rostral ventrolateral medullary neurons (contemporaneously exhibiting fast sympathetic rhythms [2-6 and 10 Hz bands]) in spectral variability in vagotomized pentobarbital-anesthetized and unanesthetized midcollicular (i.e., intercollicular) decerebrate cats supports genesis of Mayer waves by supraspinal sympathetic microcircuit oscillators. Persistence of these waves following high cervical transection in vagotomized unanesthetized midcollicular decerebrate cats would seem to suggest spinal sympathetic microcircuit oscillators generate these waves. The widespread presence of Mayer waves in brainstem sympathetic-related and non-sympathetic-related cells would seem to betray a general tendency of neurons to oscillate at this frequency. We have thus presented an extensive and, hopefully cohesive, discourse evaluating, and evolving the interpretive consideration of, evidence seeking to illumine our understanding of origins of, and insight into mechanisms contributing to, the genesis of Mayer waves. We have predicated our arguments and conjectures in the substance and matter of empirical data, though we have occasionally waxed philosophical beyond these traditional confines in suggesting interpretations exceeding these limits. We believe our synthesis and interpretation of the relevant literature will fruitfully inspire future studies from the perspective of a more intimate appreciation and conceptualization of network mechanisms generating oscillatory variability in neuronal and neural outputs. Our evaluation of Mayer waves informs a novel set of disciplines we term quantum neurophysics extendable to describing subatomic reality. Beyond informing our appreciation of mechanisms generating sympathetic oscillations, Mayer waves may constitute an intrinsic property of neurons extant throughout the cerebrum, brainstem, and spinal cord or reflect an emergent property of interactions between arteriogenic and neuronal oscillations.
Collapse
Affiliation(s)
- Michael G Z Ghali
- Department of Neurological Surgery, Karolinska Institutet, Stockholm, Sweden.,Department of Neuroscience, University of Helsinki, Helsinki, Finland.,Department of Neurological Surgery, University of Oslo, Olso, Norway.,Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States.,Department of Neurological Surgery, Barrow Neurological Institute, Phoenix, AZ, United States.,Department of Neurological Surgery, Johns Hopkins Medical Institute, Baltimore, MD, United States
| | - George Z Ghali
- Department of Neurological Surgery, Karolinska Institutet, Stockholm, Sweden.,United States Environmental Protection Agency, Arlington, VA, United States.,Department of Toxicology, Purdue University, West Lafayette, IN, United States
| |
Collapse
|
4
|
Merchant S, Medow MS, Visintainer P, Terilli C, Stewart JM. Oscillatory lower body negative pressure impairs working memory task-related functional hyperemia in healthy volunteers. Am J Physiol Heart Circ Physiol 2017; 312:H672-H680. [PMID: 28159806 DOI: 10.1152/ajpheart.00438.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 01/26/2017] [Accepted: 01/26/2017] [Indexed: 11/22/2022]
Abstract
Neurovascular coupling (NVC) describes the link between an increase in task-related neural activity and increased cerebral blood flow denoted "functional hyperemia." We previously showed induced cerebral blood flow oscillations suppressed functional hyperemia; conversely functional hyperemia also suppressed cerebral blood flow oscillations. We used lower body negative pressure (OLBNP) oscillations to force oscillations in middle cerebral artery cerebral blood flow velocity (CBFv). Here, we used N-back testing, an intellectual memory challenge as a neural activation task, to test the hypothesis that OLBNP-induced oscillatory cerebral blood flow can reduce functional hyperemia and NVC produced by a working memory task and can interfere with working memory. We used OLBNP (-30 mmHg) at 0.03, 0.05, and 0.10 Hz and measured spectral power of CBFv at all frequencies. Neither OLBNP nor N-back, alone or combined, affected hemodynamic parameters. 2-Back power and OLBNP individually were compared with 2-back power during OLBNP. 2-Back alone produced a narrow band increase in oscillatory arterial pressure (OAP) and oscillatory cerebral blood flow power centered at 0.0083 Hz. Functional hyperemia in response to 2-back was reduced to near baseline and 2-back memory performance was decreased by 0.03-, 0.05-, and 0.10-Hz OLBNP. OLBNP alone produced increased oscillatory power at frequencies of oscillation not suppressed by added 2-back. However, 2-back preceding OLBNP suppressed OLBNP power. OLBNP-driven oscillatory CBFv blunts NVC and memory performance, while memory task reciprocally interfered with forced CBFv oscillations. This shows that induced cerebral blood flow oscillations suppress functional hyperemia and functional hyperemia suppresses cerebral blood flow oscillations.NEW & NOTEWORTHY We show that induced cerebral blood flow oscillations suppress functional hyperemia produced by a working memory task as well as memory task performance. We conclude that oscillatory cerebral blood flow produces causal reductions of memory task neurovascular coupling and memory task performance. Reductions of functional hyperemia are constrained by autoregulation.
Collapse
Affiliation(s)
- Sana Merchant
- Department of Pediatrics, New York Medical College, Valhalla, New York
| | - Marvin S Medow
- Department of Pediatrics, New York Medical College, Valhalla, New York.,Department of Physiology, New York Medical College, Valhalla, New York; and
| | - Paul Visintainer
- Director of Epidemiology and Biostatistics, Baystate Medical Center, Tufts University School of Medicine, Springfield, Massachusetts
| | - Courtney Terilli
- Department of Pediatrics, New York Medical College, Valhalla, New York
| | - Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, New York; .,Department of Physiology, New York Medical College, Valhalla, New York; and
| |
Collapse
|
5
|
Stewart JM, Balakrishnan K, Visintainer P, Del Pozzi AT, Messer ZR, Terilli C, Medow MS. Oscillatory lower body negative pressure impairs task related functional hyperemia in healthy volunteers. Am J Physiol Heart Circ Physiol 2016; 310:H775-84. [PMID: 26801310 DOI: 10.1152/ajpheart.00747.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/29/2015] [Indexed: 11/22/2022]
Abstract
Neurovascular coupling refers to the link between an increase in neural activity in response to a task and an increase in cerebral blood flow denoted "functional hyperemia." Recent work on postural tachycardia syndrome indicated that increased oscillatory cerebral blood flow velocity (CBFv) was associated with reduced functional hyperemia. We hypothesized that a reduction in functional hyperemia could be causally produced in healthy volunteers by using oscillations in lower body negative pressure (OLBNP) to force oscillations in CBFv. CBFv was measured by transcranial Doppler ultrasound of the left middle cerebral artery. We used passive arm flexion applied during eight periodic 60-s flexion/60-s relaxation epochs to produce 120-s periodic changes in functional hyperemia (at 0.0083 Hz). We used -30 mmHg of OLBNP at 0.03, 0.05, and 0.10 Hz, the range for cerebral autoregulation, and measured spectral power of CBFv at all frequencies. Arm flexion power performed without OLBNP was compared with arm flexion power during OLBNP. OLBNP power performed in isolation was compared with power during OLBNP plus arm flexion. Cerebral flow velocity oscillations at 0.05 Hz reduced and at 0.10 Hz eliminated functional hyperemia, while 0.03 Hz did not reach significance. In contrast, arm flexion reduced OLBNP-induced oscillatory power at all frequencies. The interactions between OLBNP-driven CBFv oscillations and arm flexion-driven CBFv oscillations are reciprocal. Thus induced cerebral blood flow oscillations suppress functional hyperemia, and functional hyperemia suppresses cerebral blood flow oscillations. We conclude that oscillatory cerebral blood flow produces a causal reduction of functional hyperemia.
Collapse
Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, New York; and Department of Physiology, New York Medical College, Valhalla, New York;
| | | | - Paul Visintainer
- Department of Epidemiology and Biostatistics, Baystate Medical Center, Tufts University School of Medicine, Springfield, Massachusetts; and
| | - Andrew T Del Pozzi
- School of Physical Education Sport & Exercise Science, Ball State University, Muncie, Indiana
| | - Zachary R Messer
- Department of Pediatrics, New York Medical College, Valhalla, New York; and
| | - Courtney Terilli
- Department of Pediatrics, New York Medical College, Valhalla, New York; and
| | - Marvin S Medow
- Department of Pediatrics, New York Medical College, Valhalla, New York; and Department of Physiology, New York Medical College, Valhalla, New York
| |
Collapse
|
6
|
Li Z, Zhang M, Xin Q, Luo S, Zhou W, Cui R, Lu L. Assessment of cerebral oxygenation oscillations in subjects with hypertension. Microvasc Res 2013; 88:32-41. [PMID: 23583904 DOI: 10.1016/j.mvr.2013.04.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/06/2013] [Accepted: 04/01/2013] [Indexed: 11/18/2022]
Abstract
PURPOSE The objective of this study was to assess the spontaneous oscillations in subjects with hypertension based on the wavelet transform of cerebral oxygenation signal measured with near-infrared spectroscopy (NIRS). METHODS Continuous recordings of NIRS and arterial blood pressure (ABP) signals were obtained from simultaneous measurements in 20 healthy subjects (age: 70.8±5.2 years) and 22 subjects with hypertension (age: 72.5±6.8 years). RESULTS Using spectral analysis based on wavelet transform, five frequency intervals were identified (I, 0.4-2 Hz; II, 0.15-0.4 Hz; III, 0.06-0.15 Hz; IV, 0.02-0.06 Hz and V, 0.005-0.02 Hz). The amplitudes of Δ[Hb] and Δ[HbO2] in intervals I, II and III were significantly higher in hypertensive patients, who have increased mean flow velocity in middle cerebral artery (MCA), compared to that in the healthy subjects (p<0.01). The amplitudes of the ABP in frequency intervals III and V were significantly higher in hypertensive patients than in the healthy subjects (p<0.01). CONCLUSIONS The present findings revealed that hypertension and increased mean flow velocity in MCA have significant effect on the cerebral oscillations. The higher cerebral oscillations might be related to the intracerebral atherosclerosis in response to systemic hypertension. In addition, the higher spontaneous oscillations in intervals III and V in ABP indicate a metabolic regulation and myogenic response to hypertension.
Collapse
Affiliation(s)
- Zengyong Li
- School of Mechanical Engineering, Shandong University, Jinan, 250061 PR China.
| | | | | | | | | | | | | |
Collapse
|
7
|
Näsi T, Virtanen J, Noponen T, Toppila J, Salmi T, Ilmoniemi RJ. Spontaneous hemodynamic oscillations during human sleep and sleep stage transitions characterized with near-infrared spectroscopy. PLoS One 2011; 6:e25415. [PMID: 22043284 PMCID: PMC3197192 DOI: 10.1371/journal.pone.0025415] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Accepted: 09/02/2011] [Indexed: 11/18/2022] Open
Abstract
Understanding the interaction between the nervous system and cerebral vasculature is fundamental to forming a complete picture of the neurophysiology of sleep and its role in maintaining physiological homeostasis. However, the intrinsic hemodynamics of slow-wave sleep (SWS) are still poorly known. We carried out 30 all-night sleep measurements with combined near-infrared spectroscopy (NIRS) and polysomnography to investigate spontaneous hemodynamic behavior in SWS compared to light (LS) and rapid-eye-movement sleep (REM). In particular, we concentrated on slow oscillations (3-150 mHz) in oxy- and deoxyhemoglobin concentrations, heart rate, arterial oxygen saturation, and the pulsation amplitude of the photoplethysmographic signal. We also analyzed the behavior of these variables during sleep stage transitions. The results indicate that slow spontaneous cortical and systemic hemodynamic activity is reduced in SWS compared to LS, REM, and wakefulness. This behavior may be explained by neuronal synchronization observed in electrophysiological studies of SWS and a reduction in autonomic nervous system activity. Also, sleep stage transitions are asymmetric, so that the SWS-to-LS and LS-to-REM transitions, which are associated with an increase in the complexity of cortical electrophysiological activity, are characterized by more dramatic hemodynamic changes than the opposite transitions. Thus, it appears that while the onset of SWS and termination of REM occur only as gradual processes over time, the termination of SWS and onset of REM may be triggered more abruptly by a particular physiological event or condition. The results suggest that scalp hemodynamic changes should be considered alongside cortical hemodynamic changes in NIRS sleep studies to assess the interaction between the autonomic and central nervous systems.
Collapse
Affiliation(s)
- Tiina Näsi
- Department of Biomedical Engineering and Computational Science (BECS), Aalto University, Aalto, Espoo, Finland
- BioMag Laboratory, HUSLAB, Helsinki University Central Hospital, Helsinki, Finland
| | - Jaakko Virtanen
- Department of Biomedical Engineering and Computational Science (BECS), Aalto University, Aalto, Espoo, Finland
- BioMag Laboratory, HUSLAB, Helsinki University Central Hospital, Helsinki, Finland
| | - Tommi Noponen
- Department of Nuclear Medicine and Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Jussi Toppila
- Department of Clinical Neurophysiology, Helsinki University Central Hospital, Helsinki, Finland
| | - Tapani Salmi
- Department of Clinical Neurophysiology, Helsinki University Central Hospital, Helsinki, Finland
| | - Risto J. Ilmoniemi
- Department of Biomedical Engineering and Computational Science (BECS), Aalto University, Aalto, Espoo, Finland
- BioMag Laboratory, HUSLAB, Helsinki University Central Hospital, Helsinki, Finland
| |
Collapse
|
8
|
Gommer ED, Shijaku E, Mess WH, Reulen JPH. Dynamic cerebral autoregulation: different signal processing methods without influence on results and reproducibility. Med Biol Eng Comput 2010; 48:1243-50. [PMID: 21049290 PMCID: PMC2993898 DOI: 10.1007/s11517-010-0706-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 10/21/2010] [Indexed: 11/26/2022]
Abstract
Cerebral autoregulation controls cerebral blood flow under changing cerebral perfusion pressure. Standards for measurement and analysis of dynamic cerebral autoregulation (dCA) are lacking. In this study, dCA reproducibility, quantified by intraclass correlation coefficient, is evaluated for different methodological approaches of transfer function analysis (TFA) and compared with multimodal pressure flow analysis (MMPF). dCA parameters were determined in 19 healthy volunteers during three 15-min lasting epochs of spontaneous breathing. Every spontaneous breathing epoch was followed by 5 min of paced breathing at 6 cycles/min. These six measurements were performed in both a morning and an afternoon session. Analysis compared raw data pre-processing by mean subtraction versus smoothness priors detrending. The estimation of spectral density was either performed by averaging of subsequent time windows or by smoothing the spectrum of the whole recording. No significant influence of pre-processing and spectral estimation on dCA parameters was found. Therefore, there seems to be no need to prescribe a specific signal-processing regime. Poor reproducibility of gain and phase was found for TFA as well as for MMPF. Based on reproducibility, no preference can be made for morning versus afternoon measurements, neither for spontaneous versus paced breathing. Finally, reproducibility results are not in favour of TFA or MMPF.
Collapse
Affiliation(s)
- Erik D Gommer
- Department of Clinical Neurophysiology, University Hospital Maastricht, Maastricht, The Netherlands.
| | | | | | | |
Collapse
|
9
|
Scholkmann F, Spichtig S, Muehlemann T, Wolf M. How to detect and reduce movement artifacts in near-infrared imaging using moving standard deviation and spline interpolation. Physiol Meas 2010; 31:649-62. [DOI: 10.1088/0967-3334/31/5/004] [Citation(s) in RCA: 349] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
10
|
Vaurio RG, Simmonds DJ, Mostofsky SH. Increased intra-individual reaction time variability in attention-deficit/hyperactivity disorder across response inhibition tasks with different cognitive demands. Neuropsychologia 2009; 47:2389-96. [PMID: 19552927 DOI: 10.1016/j.neuropsychologia.2009.01.022] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 12/12/2008] [Accepted: 01/02/2009] [Indexed: 10/21/2022]
Abstract
One of the most consistent findings in children with ADHD is increased moment-to-moment variability in reaction time (RT). The source of increased RT variability can be examined using ex-Gaussian analyses that divide variability into normal and exponential components and Fast Fourier transform (FFT) that allow for detailed examination of the frequency of responses in the exponential distribution. Prior studies of ADHD using these methods have produced variable results, potentially related to differences in task demand. The present study sought to examine the profile of RT variability in ADHD using two Go/No-go tasks with differing levels of cognitive demand. A total of 140 children (57 with ADHD and 83 typically developing controls), ages 8-13 years, completed both a "simple" Go/No-go task and a more "complex" Go/No-go task with increased working memory load. Repeated measures ANOVA of ex-Gaussian functions revealed for both tasks children with ADHD demonstrated increased variability in both the normal/Gaussian (significantly elevated sigma) and the exponential (significantly elevated tau) components. In contrast, FFT analysis of the exponential component revealed a significant task x diagnosis interaction, such that infrequent slow responses in ADHD differed depending on task demand (i.e., for the simple task, increased power in the 0.027-0.074 Hz frequency band; for the complex task, decreased power in the 0.074-0.202 Hz band). The ex-Gaussian findings revealing increased variability in both the normal (sigma) and exponential (tau) components for the ADHD group, suggest that both impaired response preparation and infrequent "lapses in attention" contribute to increased variability in ADHD. FFT analyses reveal that the periodicity of intermittent lapses of attention in ADHD varies with task demand. The findings provide further support for intra-individual variability as a candidate intermediate endophenotype of ADHD.
Collapse
Affiliation(s)
- Rebecca G Vaurio
- Kennedy Krieger Institute, Department of Neuropsychology, Baltimore, MD 21211, USA.
| | | | | |
Collapse
|
11
|
Decomposing intra-subject variability in children with attention-deficit/hyperactivity disorder. Biol Psychiatry 2008; 64:607-14. [PMID: 18423424 PMCID: PMC2707839 DOI: 10.1016/j.biopsych.2008.03.008] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 02/13/2008] [Accepted: 03/10/2008] [Indexed: 11/23/2022]
Abstract
BACKGROUND Increased intra-subject response time standard deviations (RT-SD) discriminate children with attention-deficit/hyperactivity disorder (ADHD) from healthy control subjects. The RT-SD is averaged over time; thus it does not provide information about the temporal structure of RT variability. We previously hypothesized that such increased variability might be related to slow spontaneous fluctuations in brain activity occurring with periods between 15 sec and 40 sec. Here, we investigated whether these slow RT fluctuations add unique differentiating information beyond the global increase in RT-SD. METHODS We recorded RT at 3-sec intervals for 15 min during an Eriksen flanker task for 29 children with ADHD and 26 age-matched typically developing control subjects (TDC) (mean ages 12.5 +/- 2.4 and 11.6 +/- 2.5; 26 and 12 boys, respectively). The primary outcome was the magnitude of the spectral component in the frequency range between .027 and .073 Hz measured with continuous Morlet wavelet transform. RESULTS The magnitude of the low-frequency fluctuation was greater for children with ADHD compared with TDC (p = .02, d = .69). After modeling ADHD diagnosis as a function of RT-SD, adding this specific frequency range significantly improved the model fit (p = .03; odds ratio = 2.58). CONCLUSIONS Fluctuations in low-frequency RT variability predict the diagnosis of ADHD beyond the effect associated with global differences in variability. Future studies will examine whether such spectrally specific fluctuations in behavioral responses are linked to intrinsic regional cerebral hemodynamic oscillations that occur at similar frequencies.
Collapse
|
12
|
Koh PH, Glaser DE, Flandin G, Kiebel S, Butterworth B, Maki A, Delpy DT, Elwell CE. Functional optical signal analysis: a software tool for near-infrared spectroscopy data processing incorporating statistical parametric mapping. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:064010. [PMID: 18163826 DOI: 10.1117/1.2804092] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Optical topography (OT) relies on the near infrared spectroscopy (NIRS) technique to provide noninvasively a spatial map of functional brain activity. OT has advantages over conventional fMRI in terms of its simple approach to measuring the hemodynamic response, its ability to distinguish between changes in oxy- and deoxy-hemoglobin and the range of human participants that can be readily investigated. We offer a new software tool, functional optical signal analysis (fOSA), for analyzing the spatially resolved optical signals that provides statistical inference capabilities about the distribution of brain activity in space and time and by experimental condition. It does this by mapping the signal into a standard functional neuroimaging analysis software, statistical parametric mapping (SPM), and forms, in effect, a new SPM toolbox specifically designed for NIRS in an OT configuration. The validity of the program has been tested using synthetic data, and its applicability is demonstrated with experimental data.
Collapse
Affiliation(s)
- Peck H Koh
- University College London, Department of Medical Physics and Bioengineering, Biomedical Optics Research Laboratory, Gower Street, London WC1E 6BT United Kingdom. pkoha.medphys.ucl.ac.uk
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Rovati L, Salvatori G, Bulf L, Fonda S. Optical and electrical recording of neural activity evoked by graded contrast visual stimulus. Biomed Eng Online 2007; 6:28. [PMID: 17610733 PMCID: PMC1934360 DOI: 10.1186/1475-925x-6-28] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 07/04/2007] [Indexed: 11/12/2022] Open
Abstract
Background Brain activity has been investigated by several methods with different principles, notably optical ones. Each method may offer information on distinct physiological or pathological aspects of brain function. The ideal instrument to measure brain activity should include complementary techniques and integrate the resultant information. As a "low cost" approach towards this objective, we combined the well-grounded electroencephalography technique with the newer near infrared spectroscopy methods to investigate human visual function. Methods The article describes an embedded instrumentation combining a continuous-wave near-infrared spectroscopy system and an electroencephalography system to simultaneously monitor functional hemodynamics and electrical activity. Near infrared spectroscopy (NIRS) signal depends on the light absorption spectra of haemoglobin and measures the blood volume and blood oxygenation regulation supporting the neural activity. The NIRS and visual evoked potential (VEP) are concurrently acquired during steady state visual stimulation, at 8 Hz, with a b/w "windmill" pattern, in nine human subjects. The pattern contrast is varied (1%, 10%, 100%) according to a stimulation protocol. Results In this study, we present the measuring system; the results consist in concurrent recordings of hemodynamic changes and evoked potential responses emerging from different contrast levels of a patterned stimulus. The concentration of [HbO2] increases and [HHb] decreases after the onset of the stimulus. Their variation shows a clear relationship with the contrast value: large contrast produce huge difference in concentration, while low contrast provokes small concentration difference. This behaviour is similar to the already known relationship between VEP response amplitude and contrast. Conclusion The simultaneous recording and analysis of NIRS and VEP signals in humans during visual stimulation with a b/w pattern at variable contrast, demonstrates a strong linear correlation between hemodynamic changes and evoked potential amplitude. Furthermore both responses present a logarithmic profile with stimulus contrast.
Collapse
Affiliation(s)
- Luigi Rovati
- Department of Information Engineering, University of Modena and Reggio Emilia, Via Vignolese 905, I-41100 Modena, Italy
| | - Giorgia Salvatori
- Department of Information Engineering, University of Modena and Reggio Emilia, Via Vignolese 905, I-41100 Modena, Italy
| | - Luca Bulf
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, I-41100 Modena, Italy
| | - Sergio Fonda
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, I-41100 Modena, Italy
| |
Collapse
|
14
|
Tachtsidis I, Elwell CE, Leung TS, Lee CW, Smith M, Delpy DT. Investigation of cerebral haemodynamics by near-infrared spectroscopy in young healthy volunteers reveals posture-dependent spontaneous oscillations. Physiol Meas 2004; 25:437-45. [PMID: 15132309 DOI: 10.1088/0967-3334/25/2/003] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Autonomic reflexes enable the cardiovascular system to respond to gravitational displacement of blood during changes in posture. Spontaneous oscillations present in the cerebral and systemic circulation of healthy subjects have demonstrated a regulatory role. This study assessed the dynamic responses of the cerebral and systemic circulation upon standing up and the posture dependence of spontaneous oscillations. In ten young healthy volunteers, blood pressure and cerebral haemodynamics were continuously monitored non-invasively using the Portapres and near-infrared spectroscopy (NIRS), respectively. Oscillatory changes in the cerebral NIRS signals and the diastolic blood pressure (DBP) signal have been identified by the fast Fourier analysis. Blood pressure increased during standing and returned to basal level when volunteers sat on a chair. The mean value of cerebral tissue oxygen index (TOI) as measured by NIRS did not demonstrate any significant changes. Oscillatory changes in DBP, oxyhaemoglobin concentration [O2Hb] and TOI showed a significant increase when subjects were standing. Investigation of the low frequency component (approximately 0.1 Hz) of these fluctuations revealed posture dependence associated with activation of autonomic reflexes. Systemic and cerebral changes appeared to preserve adequate blood flow and cerebral perfusion during standing in healthy volunteers. Oscillatory changes in [O2Hb] and TOI, which may be related to the degree of cerebral sympathetic stimulation, are posture dependent in healthy subjects.
Collapse
Affiliation(s)
- Ilias Tachtsidis
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6JA, UK.
| | | | | | | | | | | |
Collapse
|
15
|
Tachtsidis I, Elwell CE, Lee CW, Leung TS, Smith M, Delpy DT. Spectral Characteristics of Spontaneous Oscillations in Cerebral Haemodynamics are Posture Dependent. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 540:31-6. [PMID: 15174599 DOI: 10.1007/978-1-4757-6125-2_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- Ilias Tachtsidis
- Department of Medical Physics & Bioengineering, University College London, London WC1E 6JA, UK.
| | | | | | | | | | | |
Collapse
|