Abstract
The aim of this work was to critically assess if functional near infrared spectroscopy (fNIRS) can be profitably used as a tool for noninvasive recording of brain functions and emotions in sheep. We considered an experimental design including advances in instrumentation (customized wireless multi-distance fNIRS system), more accurate physical modelling (two-layer model for photon diffusion and 3D Monte Carlo simulations), support from neuroanatomical tools (positioning of the fNIRS probe by MRI and DTI data of the very same animals), and rigorous protocols (motor task, startling test) for testing the behavioral response of freely moving sheep. Almost no hemodynamic response was found in the extra-cerebral region in both the motor task and the startling test. In the motor task, as expected we found a canonical hemodynamic response in the cerebral region when sheep were walking. In the startling test, the measured hemodynamic response in the cerebral region was mainly from movement. Overall, these results indicate that with the current setup and probe positioning we are primarily measuring the motor area of the sheep brain, and not probing the too deeply located cortical areas related to processing of emotions.
Highlights
The aim of this work was to critically assess if functional near infrared spectroscopy can be profitably used as a tool for noninvasive recording of brain functions and emotions in sheep
Several methods successfully used in human brain mapping have been employed in functional imaging of the animal brain, including functional magnetic resonance imaging[7,8,9,10,11,12,13,14], electroencephalography and sensory evoked p otentials[15,16,17,18,19]
The aim of this work was to improve reliability and accuracy of functional near infrared spectroscopy (fNIRS) measurements in sheep and critically assess whether fNIRS can be profitably used as a tool for noninvasive recording of brain functions and emotions in this species. To this purpose we have considered an experimental design that encompasses advances in instrumentation, more accurate physical modelling, support from neuroanatomical tools, and rigorous protocols for testing the behavioral response of freely moving sheep
Summary
The aim of this work was to critically assess if functional near infrared spectroscopy (fNIRS) can be profitably used as a tool for noninvasive recording of brain functions and emotions in sheep. The measured hemodynamic response in the cerebral region was mainly from movement Overall, these results indicate that with the current setup and probe positioning we are primarily measuring the motor area of the sheep brain, and not probing the too deeply located cortical areas related to processing of emotions. As cognitive processes or emotional states can often be reflected in brain responses[6], a better understanding of affective states of sheep in various environments or as a response to different stimuli will benefit both neuroscience and animal welfare. goats23, dogs[24], and sheep[25,26,27,28,29] In these studies, fNIRS monitoring has been considered and used as an additional technique to measure emotional and cognitive responses in animals exposed to different stimuli or different environments. Results were sometimes inconsistent among studies[6,30], suggesting that measurement accuracy and reliability need to be improved
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