A dynamical model of the laminar BOLD response

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

High-resolution functional magnetic resonance imaging (fMRI) using blood oxygenation dependent level-dependent (BOLD) signal is an increasingly popular tool to non-invasively examine neuronal processes at the mesoscopic level. However, as the BOLD signal stems from hemodynamic changes, its temporal and spatial properties do not match those of the underlying neuronal activity. In particular, the laminar BOLD response (LBR), commonly measured with gradient-echo (GE) MRI sequence, is confounded by non-local changes in deoxygenated hemoglobin and cerebral blood volume propagated within intracortical ascending veins, leading to a unidirectional blurring of the neuronal activity distribution towards the cortical surface. Here, we present a new cortical depth-dependent model of the BOLD response based on the principle of mass conservation, which takes the effect of ascending (and pial) veins on the cortical BOLD responses explicitly into account. It can be used to dynamically model cortical depth profiles of the BOLD signal as a function of various baseline- and activity-related physiological parameters for any spatiotemporal distribution of neuronal changes. We demonstrate that the commonly observed spatial increase of LBR is mainly due to baseline blood volume increase towards the surface. In contrast, an occasionally observed local maximum in the LBR (i.e. the so-called "bump") is mainly due to spatially inhomogeneous neuronal changes rather than locally higher baseline blood volume. In addition, we show that the GE-BOLD signal laminar point-spread functions, representing the signal leakage towards the surface, depend on several physiological parameters and on the level of neuronal activity. Furthermore, even in the case of simultaneous neuronal changes at each depth, inter-laminar delays of LBR transients are present due to the ascending vein. In summary, the model provides a conceptual framework for the biophysical interpretation of common experimental observations in high-resolution fMRI data. In the future, the model will allow for deconvolution of the spatiotemporal hemodynamic bias of the LBR and provide an estimate of the underlying laminar excitatory and inhibitory neuronal activity.

Original languageEnglish
Article number116209
Number of pages21
JournalNeuroimage
Volume204
Early online date20 Sep 2019
DOIs
Publication statusPublished - 1 Jan 2020

Keywords

  • Laminar
  • Cortical depth-dependent
  • fMRI
  • Modeling
  • BOLD response
  • Transient
  • Steady-state
  • Draining vein
  • Mesoscopic
  • CEREBRAL-BLOOD-FLOW
  • TRANSIT-TIME HETEROGENEITY
  • HUMAN VISUAL-CORTEX
  • POSTSTIMULUS UNDERSHOOT
  • FUNCTIONAL MRI
  • ANALYSIS STRATEGIES
  • OXYGEN UTILIZATION
  • TEMPORAL DYNAMICS
  • NEURONAL-ACTIVITY
  • BALLOON MODEL

Cite this

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title = "A dynamical model of the laminar BOLD response",
abstract = "High-resolution functional magnetic resonance imaging (fMRI) using blood oxygenation dependent level-dependent (BOLD) signal is an increasingly popular tool to non-invasively examine neuronal processes at the mesoscopic level. However, as the BOLD signal stems from hemodynamic changes, its temporal and spatial properties do not match those of the underlying neuronal activity. In particular, the laminar BOLD response (LBR), commonly measured with gradient-echo (GE) MRI sequence, is confounded by non-local changes in deoxygenated hemoglobin and cerebral blood volume propagated within intracortical ascending veins, leading to a unidirectional blurring of the neuronal activity distribution towards the cortical surface. Here, we present a new cortical depth-dependent model of the BOLD response based on the principle of mass conservation, which takes the effect of ascending (and pial) veins on the cortical BOLD responses explicitly into account. It can be used to dynamically model cortical depth profiles of the BOLD signal as a function of various baseline- and activity-related physiological parameters for any spatiotemporal distribution of neuronal changes. We demonstrate that the commonly observed spatial increase of LBR is mainly due to baseline blood volume increase towards the surface. In contrast, an occasionally observed local maximum in the LBR (i.e. the so-called {"}bump{"}) is mainly due to spatially inhomogeneous neuronal changes rather than locally higher baseline blood volume. In addition, we show that the GE-BOLD signal laminar point-spread functions, representing the signal leakage towards the surface, depend on several physiological parameters and on the level of neuronal activity. Furthermore, even in the case of simultaneous neuronal changes at each depth, inter-laminar delays of LBR transients are present due to the ascending vein. In summary, the model provides a conceptual framework for the biophysical interpretation of common experimental observations in high-resolution fMRI data. In the future, the model will allow for deconvolution of the spatiotemporal hemodynamic bias of the LBR and provide an estimate of the underlying laminar excitatory and inhibitory neuronal activity.",
keywords = "Laminar, Cortical depth-dependent, fMRI, Modeling, BOLD response, Transient, Steady-state, Draining vein, Mesoscopic, CEREBRAL-BLOOD-FLOW, TRANSIT-TIME HETEROGENEITY, HUMAN VISUAL-CORTEX, POSTSTIMULUS UNDERSHOOT, FUNCTIONAL MRI, ANALYSIS STRATEGIES, OXYGEN UTILIZATION, TEMPORAL DYNAMICS, NEURONAL-ACTIVITY, BALLOON MODEL",
author = "Martin Havlicek and Kamil Uludag",
note = "Copyright {\circledC} 2019. Published by Elsevier Inc.",
year = "2020",
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day = "1",
doi = "10.1016/j.neuroimage.2019.116209",
language = "English",
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journal = "Neuroimage",
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A dynamical model of the laminar BOLD response. / Havlicek, Martin; Uludag, Kamil.

In: Neuroimage, Vol. 204, 116209, 01.01.2020.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - A dynamical model of the laminar BOLD response

AU - Havlicek, Martin

AU - Uludag, Kamil

N1 - Copyright © 2019. Published by Elsevier Inc.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - High-resolution functional magnetic resonance imaging (fMRI) using blood oxygenation dependent level-dependent (BOLD) signal is an increasingly popular tool to non-invasively examine neuronal processes at the mesoscopic level. However, as the BOLD signal stems from hemodynamic changes, its temporal and spatial properties do not match those of the underlying neuronal activity. In particular, the laminar BOLD response (LBR), commonly measured with gradient-echo (GE) MRI sequence, is confounded by non-local changes in deoxygenated hemoglobin and cerebral blood volume propagated within intracortical ascending veins, leading to a unidirectional blurring of the neuronal activity distribution towards the cortical surface. Here, we present a new cortical depth-dependent model of the BOLD response based on the principle of mass conservation, which takes the effect of ascending (and pial) veins on the cortical BOLD responses explicitly into account. It can be used to dynamically model cortical depth profiles of the BOLD signal as a function of various baseline- and activity-related physiological parameters for any spatiotemporal distribution of neuronal changes. We demonstrate that the commonly observed spatial increase of LBR is mainly due to baseline blood volume increase towards the surface. In contrast, an occasionally observed local maximum in the LBR (i.e. the so-called "bump") is mainly due to spatially inhomogeneous neuronal changes rather than locally higher baseline blood volume. In addition, we show that the GE-BOLD signal laminar point-spread functions, representing the signal leakage towards the surface, depend on several physiological parameters and on the level of neuronal activity. Furthermore, even in the case of simultaneous neuronal changes at each depth, inter-laminar delays of LBR transients are present due to the ascending vein. In summary, the model provides a conceptual framework for the biophysical interpretation of common experimental observations in high-resolution fMRI data. In the future, the model will allow for deconvolution of the spatiotemporal hemodynamic bias of the LBR and provide an estimate of the underlying laminar excitatory and inhibitory neuronal activity.

AB - High-resolution functional magnetic resonance imaging (fMRI) using blood oxygenation dependent level-dependent (BOLD) signal is an increasingly popular tool to non-invasively examine neuronal processes at the mesoscopic level. However, as the BOLD signal stems from hemodynamic changes, its temporal and spatial properties do not match those of the underlying neuronal activity. In particular, the laminar BOLD response (LBR), commonly measured with gradient-echo (GE) MRI sequence, is confounded by non-local changes in deoxygenated hemoglobin and cerebral blood volume propagated within intracortical ascending veins, leading to a unidirectional blurring of the neuronal activity distribution towards the cortical surface. Here, we present a new cortical depth-dependent model of the BOLD response based on the principle of mass conservation, which takes the effect of ascending (and pial) veins on the cortical BOLD responses explicitly into account. It can be used to dynamically model cortical depth profiles of the BOLD signal as a function of various baseline- and activity-related physiological parameters for any spatiotemporal distribution of neuronal changes. We demonstrate that the commonly observed spatial increase of LBR is mainly due to baseline blood volume increase towards the surface. In contrast, an occasionally observed local maximum in the LBR (i.e. the so-called "bump") is mainly due to spatially inhomogeneous neuronal changes rather than locally higher baseline blood volume. In addition, we show that the GE-BOLD signal laminar point-spread functions, representing the signal leakage towards the surface, depend on several physiological parameters and on the level of neuronal activity. Furthermore, even in the case of simultaneous neuronal changes at each depth, inter-laminar delays of LBR transients are present due to the ascending vein. In summary, the model provides a conceptual framework for the biophysical interpretation of common experimental observations in high-resolution fMRI data. In the future, the model will allow for deconvolution of the spatiotemporal hemodynamic bias of the LBR and provide an estimate of the underlying laminar excitatory and inhibitory neuronal activity.

KW - Laminar

KW - Cortical depth-dependent

KW - fMRI

KW - Modeling

KW - BOLD response

KW - Transient

KW - Steady-state

KW - Draining vein

KW - Mesoscopic

KW - CEREBRAL-BLOOD-FLOW

KW - TRANSIT-TIME HETEROGENEITY

KW - HUMAN VISUAL-CORTEX

KW - POSTSTIMULUS UNDERSHOOT

KW - FUNCTIONAL MRI

KW - ANALYSIS STRATEGIES

KW - OXYGEN UTILIZATION

KW - TEMPORAL DYNAMICS

KW - NEURONAL-ACTIVITY

KW - BALLOON MODEL

U2 - 10.1016/j.neuroimage.2019.116209

DO - 10.1016/j.neuroimage.2019.116209

M3 - Article

C2 - 31546051

VL - 204

JO - Neuroimage

JF - Neuroimage

SN - 1053-8119

M1 - 116209

ER -