Longitudinal Functional Magnetic Resonance Imaging in Animal Models

Abstract

Functional magnetic resonance imaging (fMRI) has had an essential role in furthering our understanding of brain physiology and function. fMRI techniques are nowadays widely applied in neuroscience research, as well as in translational and clinical studies. The use of animal models in fMRI studies has been fundamental in helping elucidate the mechanisms of cerebral blood flow regulation, and in the exploration of basic neuroscience questions, such as the mechanisms of perception, behavior, and cognition. Because animals are inherently noncompliant, most fMRI performed to date have required the use of anesthesia, which interferes with brain function and compromises interpretability and applicability of results to our understanding of human brain function. An alternative approach that eliminates the need for anesthesia involves training the animal to tolerate physical restraint during the data acquisition. In the present work we review these two different approaches to obtaining fMRI data from animal models, with a specific focus on the acquisition of longitudinal data from the same subjects.

Two-photon imaging of cerebral hemodynamics and neural activity in awake and anesthetized marmosets

“…We found that 32% of measured penetrating arterioles reached a peak dilation of approximately 14% at 6 s following a short stimulation onset. In our previous studies, the spatiotemporal evolution of functional hyperemia was measured using BOLD fMRI in awake marmosets (Silva et al, 2011). The hemodynamic response signal reached its peak value 4–5 s following the stimulus onset (Silva et al, 2011).…”

“…Animals were gradually accustomed to body restraint in the prone, sphinx position starting with 15 min of restraint on the first day of training and increasing by 15-min intervals up to 2 h at 3 times per week, over the course of 2 weeks (Silva et al, 2011). The behavioral assessment scale (Fig.…”

Perivenular brain lesions in a primate multiple sclerosis model at 7-tesla magnetic resonance imaging

“…Data acquisition was performed in Transmit Only-Receive Only mode using a homemade linear birdcage coil (120mm inner diameter) as a radiofrequency transmitter and a homemade, 5-channel radiofrequency surface-array receiver coil assembly placed over the head of the animal. The receive coil assembly had one elliptical loop (18×36mm diameter) on top and two pairs of overlapped circular loops (22mm diameter) that were obliquely wrapped laterally around the head (14). …”

Chapter 7. Pharmacological fMRI in Drug Discovery and Development

“…Similar procedures have been published and adopted for non-human primates. 53 Some reports suggest that in the awake rat paradigm there is better concordance between phMRI endpoints and compound target-binding when compared to anesthetized animals. 54 Similarly, in awake rats, there seems to be better concordance between phMRI endpoints and behavioral outcome.…”