Non-invasive method to study cortex activity in free moving animals

Animals have been recognised as sentient beings and capable of affective experiences, such as negative or positive ones [1]. The quality of these affective experiences plays an essential role for their welfare. In addition, animal models - particularly mammal ones - might provide a guide to decoding brain affective mechanisms in humans, due to a strict cross-species homol-ogies in primary-process of emotional systems [2]. Emotions are strictly linked to cognitive processes defined as acquire, pro-cess, store and act on information from the environment and without an understanding of the interrelationship between brain, behaviour and the periphery it will not be possible to fully understand the neural basis of emotions [3]. Studying the association between brain regions and cognitive functions often involves invasive methods. Nowadays functional magnetic resonance im-aging (fMRI) is considered as the gold standard technique for non-invasive functional mapping of the human brain [4]. Never-theless, the use of fMRI in animals is an extremely demanding task. It can be applied only in anesthetized animals or, in few cases, in unsedated animals after lengthy training periods. This entails several limitations in the experimental scenarios. In contrast, functional near infrared spectroscopy (fNIRS) represents a new non-invasive method to assess cortex activity in ani-mals. Previous studies employing fNIRS on animals have shown different advantages: higher tolerance of movement arte-facts, mobile equipment that allows subjects to move freely, measurements that can be conducted in a familiar environment, therefore allowing the application of more complex emotionally challenging tasks than fMRI [5]. A similar wearable, wireless, multi-distance fNIRS sensor was used in this study to conduct several trials designed to study free-moving sheep cerebral cor-tex’s functional organization. Here we present the fNIRS results of the pilot phase that was conducted on three adult sheep undergoing a series of stimuli for 20s, each followed by a 20s interval. In order to explore different kinds of cortex activity, dif-ferent types of stimuli were applied. Among these, a neutral sound repeated 8 times; a visual stimulus, flashing a light intermit-tently on the pupil, repeated 4 times per eye; and the application of a pressure of 250 mmHg with a tourniquet on the forelimb, 4 times per limb. A following part of the study addressed the cortex activity in sheep trained to anticipate two events with a supposed different emotional value via classical conditioning. We intended to record the oxygen consumption of selected areas of the brain involved in the performance of behavioural mo-tor and associative tasks and to assess the brain activity in sheep. fNIRS allows to refine the studies on animals’ cortex activity and the development of this project aims to promote the use of large herbivores’ brains as suitable scientific models in neuro-science. References: 1. Boissy, A. and C. Lee, How assessing relationships between emotions and cognition can improve farm animal welfare. Revue Scientifique Et Technique-Office International Des Epizooties, 2014. 33(1): p. 103-110. 2. Panksepp, J., Affective neuroscience of the emotional BrainMind: evolutionary perspectives and implications for understanding depression. Dialogues Clin Neurosci, 2010. 12(4): p. 533-45. 3. Braesicke, K., et al., Autonomic arousal in an appetitive context in primates: a behavioural and neural analysis. Eur J Neurosci, 2005. 21(6): p. 1733-40. 4. Cutini, S., S.B. Moro, and S. Bisconti, Functional near infrared optical imaging in cognitive neuroscience: an introductory review. Journal of near Infrared Spectroscopy, 2012. 20(1): p. 75-92. 5. Gygax, L., et al., Prefrontal cortex activity, sympatho-vagal reaction and behaviour distinguish between situations of feed reward and frustration in dwarf goats. Behavioural Brain Research, 2013. 239: p. 104-114.