Abstract
BackgroundFunctional magnetic resonance imaging (fMRI) is a technique able to localize neural activity in the brain by detecting associated changes in blood flow. It is an essential tool for studying human functional neuroanatomy including the auditory system. There are only a few studies, however, using fMRI to study canine brain functions. In the current study ten anesthetized dogs were scanned during auditory stimulation. Two functional sequences, each in combination with a suitable stimulation paradigm, were used in each subject. Sequence 1 provided periods of silence during which acoustic stimuli could be presented unmasked by scanner noise (sparse temporal sampling) whereas in sequence 2 the scanner noise was present throughout the entire session (continuous imaging). The results obtained with the two different functional sequences were compared.ResultsThis study shows that with the proper experimental setup it is possible to detect neural activity in the auditory system of dogs. In contrast to human fMRI studies the strongest activity was found in the subcortical parts of the auditory pathways. Especially sequence 1 showed a high reliability in detecting activated voxels in brain regions associated with the auditory system.ConclusionThese results indicate that fMRI is applicable for studying the canine auditory system and could become an additional method for the clinical evaluation of the auditory function of dogs. Additionally, fMRI is an interesting technique for future studies concerned with canine functional neuroanatomy.
Highlights
Functional magnetic resonance imaging is a technique able to localize neural activity in the brain by detecting associated changes in blood flow
Concerning the activation found in the temporal cortex (TC) regions of interest (ROIs) it has to be noted that not all of the active voxels found in this ROI were located in areas commonly associated with an auditory function
The mean percentage signal change and the t-values calculated for the subcortical parts of the auditory pathways (CC and medial geniculate nucleus (MGN) ROI) were positive in all eight dogs, indicating a positive blood oxygenation level-dependent (BOLD) response of these areas following acoustic stimulation
Summary
Functional magnetic resonance imaging (fMRI) is a technique able to localize neural activity in the brain by detecting associated changes in blood flow. Functional magnetic resonance imaging (fMRI) is a technique able to localize neural activity in the brain including the auditory system by detecting associated changes in blood flow [5,6,7]. The resulting rise in oxygen supply exceeds the augmented demand for oxygen, leading to an increased ratio of oxygenated hemoglobin to deoxygenated hemoglobin This increase in oxygen saturation results in a signal rise in the regions of neural activity in special MRI sequences [8,9]. The combination of structural MRI and fMRI provides the possibility to gain morphologic information on the auditory system along with functional information on patients’ ability to hear
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