Abstract
SummaryFunctional brain-imaging techniques used in humans and animals, such as functional MRI and intrinsic optical signal (IOS) imaging, are thought to largely rely on neurovascular coupling and hemodynamic responses. Here, taking advantage of the well-described micro-architecture of the mouse olfactory bulb, we dissected the nature of odor-evoked IOSs. Using in vivo pharmacology in transgenic mouse lines reporting activity in different cell types, we show that parenchymal IOSs are largely independent of neurotransmitter release and neurovascular coupling. Furthermore, our results suggest that odor-evoked parenchymal IOSs originate from changes in light scattering of olfactory sensory neuron axons, mostly due to water movement following action potential propagation. Our study sheds light on a direct correlate of neuronal activity, which may be used for large-scale functional brain imaging.
Highlights
In the last decades, imaging techniques have allowed us to watch the brain at work with extraordinary details and have provided an in-depth understanding of how neural networks function
Highlights d We studied the origin of intrinsic optical signals (IOSs) in the mouse olfactory bulb d IOSs are independent of neurovascular coupling and astrocyte function d IOSs are independent of neurotransmitter release and postsynaptic neuronal activity d IOSs arise from activity-dependent swelling of sensory neuron axons
Functional brain-imaging techniques used in humans and animals, such as functional MRI and intrinsic optical signal (IOS) imaging, are thought to largely rely on neurovascular coupling and hemodynamic responses
Summary
In the last decades, imaging techniques have allowed us to watch the brain at work with extraordinary details and have provided an in-depth understanding of how neural networks function. IOSs have been used as a surrogate of BOLD-fMRI to study neurovascular coupling (Berwick et al, 2002; Cardoso et al, 2012; Niessing et al, 2005; Schummers et al, 2008; Sirotin and Das, 2009) They have been extensively used for brain mapping in different species and several brain regions: visual, somatosensory, auditory, and gustatory cortices (Accolla et al, 2007; Accolla and Carleton, 2008; Frostig et al, 1990; Grinvald et al, 1986; Harrison et al, 1998), as well as the olfactory bulb (OB) (Abraham et al, 2004, 2014; Meister and Bonhoeffer, 2001; Rubin and Katz, 1999; Vincis et al, 2012). It has been proposed that, at shorter wavelengths (450–650 nm), IOSs originate from hemodynamics, following astrocyte-mediated neurovascular coupling (Gurden et al, 2006; Schummers et al, 2008)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
