Functional Magnetic Resonance Imaging (fMRI) with Auditory Stimulation in Songbirds

Abstract

The neurobiology of birdsong, as a model for human speech, is a pronounced area of research in behavioral neuroscience. Whereas electrophysiology and molecular approaches allow the investigation of either different stimuli on few neurons, or one stimulus in large parts of the brain, blood oxygenation level dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) allows combining both advantages, i.e. compare the neural activation induced by different stimuli in the entire brain at once. fMRI in songbirds is challenging because of the small size of their brains and because their bones and especially their skull comprise numerous air cavities, inducing important susceptibility artifacts. Gradient-echo (GE) BOLD fMRI has been successfully applied to songbirds (1-5) (for a review, see (6)). These studies focused on the primary and secondary auditory brain areas, which are regions free of susceptibility artifacts. However, because processes of interest may occur beyond these regions, whole brain BOLD fMRI is required using an MRI sequence less susceptible to these artifacts. This can be achieved by using spin-echo (SE) BOLD fMRI (7,8) . In this article, we describe how to use this technique in zebra finches (Taeniopygia guttata), which are small songbirds with a bodyweight of 15-25 g extensively studied in behavioral neurosciences of birdsong. The main topic of fMRI studies on songbirds is song perception and song learning. The auditory nature of the stimuli combined with the weak BOLD sensitivity of SE (compared to GE) based fMRI sequences makes the implementation of this technique very challenging.

Song Processing in the Zebra Finch Auditory Forebrain Reflects Asymmetric Sensitivity to Temporal and Spectral Structure

“…These analyses were similar to those previously described (Van Ruijssevelt et al, 2013). In short, we realigned and co-registered the fMRI time series to their corresponding 3D RARE.…”

“…We performed both data preprocessing and statistical voxel-based analyses using the Statistical Parametric Mapping toolbox (SPM12, Wellcome Trust Centre for Neuroimaging, London, UK; http://www.fil.ion.ucl.ac.uk/spm ). These analyses were similar to those previously described (Van Ruijssevelt et al, 2013 ). In short, we realigned and co-registered the fMRI time series to their corresponding 3D RARE.…”

“…We acquired all of our MRI data on a horizontal 7 Tesla MR system (Pharmascan 70/16 US, Bruker Biospin, Germany) following established protocols (Van Ruijssevelt et al, 2013 ). In short, fMRI scans consisted of a time series of 298 T 2 -weighted rapid acquisition relaxation-enhanced (RARE) volumes of 15 slices covering the whole brain (slice thickness = 0.75 mm, interslice gap = 0.05 mm) with an in-plane resolution of (0.25 × 0.25) mm 2 .…”

fMRI Reveals a Novel Region for Evaluating Acoustic Information for Mate Choice in a Female Songbird

“…In contrast, functional magnetic resonance imaging (fMRI) can infer neural activity at the level of the whole brain and differential neural responses to a range of different stimuli can be investigated within a single individual. Therefore, we used blood-oxygen level dependent (BOLD) fMRI-which has previously been successfully implemented in songbirds [15][16][17][18] -to elucidate the neural substrates of the processing of FD songs at the level of the whole brain in female zebra finches. Our fMRI data, validated by immunocytochemistry (ICC), identified two regions selectively activated by FD versus UD songs.…”

A three-dimensional digital atlas of the starling brain

“…This approach is particularly useful in combination with other whole-brain imaging techniques such as functional MRI (Van Meir et al 2005;Voss et al 2007;Poirier et al 2009;De Groof et al 2013;Van Ruijssevelt et al 2013) and Diffusion Tensor Imaging (De Groof et al 2009). The atlas could be applied as a template for (future) studies of these types in starlings (De Groof et al 2013).…”