Most approaches to assess brain function and connectivity, including functional magnetic resonance imaging (fMRI) and optical imaging of intrinsic signals (OIS), rely on activity-evoked changes in cerebral blood flow, blood volume and/or blood oxygenation as indirect measures of neural activity. While these hemodynamic methods are immensely valuable to map brain function and connectivity in humans and animals, fundamental gaps remain in our understanding of neuro-vascular mechanisms due to its complexity and methodological difficulties. This gap in knowledge greatly impedes our understanding of the driving neuronal processes behind BOLD fMRI findings of brain function, dysfunction and development. The goal of this proposal is to determine the role of excitatory and inhibitory neuronal activity, including glutamatergic and GABAergic synaptic activity, in vascular regulation and their representation in hemodynamic signals. To activate specific neuronal sub-populations in vivo, novel optogenetic mouse models expressing Channelrhodopsin-2 (ChR2) in cortical excitatory or inhibitory neurons will be used. These optogenetic models will be combined with an innovative approach to concurrently record neural and vascular signals under pharmacological conditions designed to modulate glutamatergic and GABAergic synaptic transmission. Neural activity will be measured by electrophysiology and two-photon calcium imaging. Vascular signals of blood flow will be obtained by laser Doppler flowmetry, while OIS will be used to image changes in cerebral blood volume and blood oxygenation (directly analogous to fMRI). These data will then be used to model and integrate excitatory and inhibitory activity contributions to hemodynamic signals. This work will have a tremendous impact by advancing our understanding of relevant neuro-vascular mechanisms as well as establish a more concrete framework that can allow for a deeper understanding of the neuronal processes behind hemodynamic alterations in brain development and dysfunction.

Public Health Relevance

The hemodynamic response induced by neural activity is the principal means of studying brain function and brain connectivity in humans and animals. Methods like functional magnetic resonance imaging (fMRI) and optical imaging of intrinsic signal (OIS) are now essential in basic science, developmental, cognitive and clinical studies of normal and impaired brain function. This proposal will reveal the contributions of excitatory and inhibitory brain activity on vascular regulation and hemodynamic signals, such as fMRI, and allow us to better understand brain behavior in health and disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS094404-05
Application #
9987715
Study Section
Medical Imaging Study Section (MEDI)
Program Officer
Babcock, Debra J
Project Start
2016-07-15
Project End
2021-06-30
Budget Start
2020-07-01
Budget End
2021-06-30
Support Year
5
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15260
Baranov, Sergei V; Baranova, Oxana V; Yablonska, Svitlana et al. (2018) Mitochondria modulate programmed neuritic retraction. Proc Natl Acad Sci U S A :
Wellman, Steven M; Eles, James R; Ludwig, Kip A et al. (2018) A Materials Roadmap to Functional Neural Interface Design. Adv Funct Mater 28:
Vazquez, Alberto L; Fukuda, Mitsuhiro; Kim, Seong-Gi (2018) Inhibitory Neuron Activity Contributions to Hemodynamic Responses and Metabolic Load Examined Using an Inhibitory Optogenetic Mouse Model. Cereb Cortex 28:4105-4119
Michelson, Nicholas J; Vazquez, Alberto L; Eles, James R et al. (2018) Multi-scale, multi-modal analysis uncovers complex relationship at the brain tissue-implant neural interface: new emphasis on the biological interface. J Neural Eng 15:033001
Michelson, Nicholas J; Eles, James R; Vazquez, Alberto L et al. (2018) Calcium activation of cortical neurons by continuous electrical stimulation: Frequency dependence, temporal fidelity, and activation density. J Neurosci Res :
Murphy, Matthew C; Chan, Kevin C; Kim, Seong-Gi et al. (2018) Macroscale variation in resting-state neuronal activity and connectivity assessed by simultaneous calcium imaging, hemodynamic imaging and electrophysiology. Neuroimage 169:352-362
Iordanova, Bistra; Vazquez, Alberto; Kozai, Takashi Dy et al. (2018) Optogenetic investigation of the variable neurovascular coupling along the interhemispheric circuits. J Cereb Blood Flow Metab 38:627-640
Li, Lingjue; Poloyac, Samuel M; Watkins, Simon C et al. (2017) Cerebral microcirculatory alterations and the no-reflow phenomenon in vivo after experimental pediatric cardiac arrest. J Cereb Blood Flow Metab :271678X17744717