In vivo functional near-infrared spectroscopy measures mood-modulated cerebral responses to a positive emotional stimulus in sheep
ABSTRACT The affective state of an animal, which is thought to reflect its welfare, consists of both short-term emotional reactions and long-term general mood. Because this state is generated and processed by the brain, we used non-invasive measurement of such brain activity as a novel indicator variable and investigated the interplay of mood and short-term emotional reactions in animals. We developed a wireless sensor for functional near-infrared spectroscopy (fNIRS), which assesses cortical perfusion changes, and consequently neuronal activity. Mood differences were induced by barren and enriched housing in a total of nine sheep and we observed their brain reaction in response to the positive situation of being groomed. We detected a decrease in cerebral oxyhaemoglobin concentration ([O(2)Hb]) which persisted during grooming. The localisation of the decrease in the brain did not depend on the site where the stimulus was applied. Also, the intensity of the response did not depend on the intensity of the grooming stimulus and a sham stimulus did not evoke an [O(2)Hb] response as seen with a grooming stimulus. Thus, we conclude that the observed haemodynamic brain response was unlikely to reflect pure somato-sensory information. We then found that the amplitude of the [O(2)Hb] response was larger if sheep were in a supposedly more negative mood. This contradicts the common assumption that negative mood generally taints reactions to emotional stimuli. Our results also demonstrate the potential of fNIRS for assessing affective states in freely moving animals.
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ABSTRACT: Using continuous wave near-infrared spectroscopy, we measured time-resolved concentration changes of oxy-hemoglobin and deoxy-hemoglobin from the primary motor cortex following finger tapping tasks. These data were processed using partial least squares-discriminant analysis (PLS-DA) to develop a prediction model for a brain-computer interface. The tasks were composed of a series of finger tapping for 15 sec and relaxation for 45 sec. The location of the motor cortex was confirmed by the anti-phasic behavior of the oxy- and deoxy-hemoglobin changes. The results were compared with those obtained using the hidden Markov model (HMM) which has been known to produce the best prediction model. Our data imply that PLS-DA makes better judgments in determining the onset of the events than HMM.Journal of the Optical Society of Korea 03/2012; 16(1). DOI:10.3807/JOSK.2012.16.1.057 · 0.96 Impact Factor
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ABSTRACT: This study was conducted as a pilot test case to investigate potential behavioral and neural indicators of positive emotional states in dogs. These states were induced by subjecting each dog to three types of human interactions (verbal contact only, physical contact only, or both). Each stimulus was repeated 10 times, at 1-min intervals, alternating with a baseline phase (no interaction) while behavior was observed and frontal cortical brain activation was recorded by functional near-infrared spectroscopy (fNIRS). Dogs reacted similarly to all 3 stimuli with a consistent hemodynamic pattern. Regarding behavior, dogs lay on their back, explored the handler and performed lip-licking more during exposure to the stimuli than during the baseline. There was only weak evidence that the dogs' behavioral reactions differed between the 3 stimuli, but their behavior changed markedly with repetition. For example, the proportion of time a dog spent lying with its head resting on the floor increased, whereas the probability of exploring the handler and the proportion of time spent lip-licking decreased over time. In contrast, the hemodynamic reaction did not change with repetition. The dogs' reactions are consistent with the stimuli being positive. The contrast between the changes in behavior with repetition and the consistency of the hemodynamic frontal cortical reaction would be in keeping with the assumption that there was a decrease in arousal as dogs habituated to the repetitions, reflected by their change in behavior, whereas because the valence of the stimuli remains constant, there was no change in the frontal hemodynamic reaction. Copyright © 2014. Published by Elsevier B.V.Behavioural Brain Research 12/2014; 281. DOI:10.1016/j.bbr.2014.11.044 · 3.39 Impact Factor
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ABSTRACT: Animal welfare concerns have raised an interest in animal affective states. These states also play an important role in the proximate control of behaviour. Due to their potential to modulate short-term emotional reactions, one specific focus is on long-term affective states, that is, mood. These states can be assessed by using non-verbal cognitive judgement bias paradigms. Here, we conducted a spatial variant of such a test on 24 focal animals that were kept under either unpredictable, stimulus-poor or predictable, stimulus-rich housing conditions to induce differential mood states. Based on functional near-infrared spectroscopy, we measured haemodynamic frontal brain reactions during 10s in which the sheep could observe the configuration of the cognitive judgement bias trial before indicating their assessment based on the go/no-go reaction. We used (generalised) mixed-effects models to evaluate the data. Sheep from the unpredictable, stimulus-poor housing conditions took longer and were less likely to reach the learning criterion and reacted slightly more optimistically in the cognitive judgement bias test than sheep from the predictable, stimulus-rich housing conditions. A frontal cortical increase in deoxy-haemoglobin [HHb] and a decrease in oxy-haemoglobin [O2Hb] were observed during the visual assessment of the test situation by the sheep, indicating a frontal cortical brain deactivation. This deactivation was more pronounced with the negativity of the test situation, which was reflected by the provenance of the sheep from the unpredictable, stimulus-poor housing conditions, the proximity of the cue to the negatively reinforced cue location, or the absence of a go reaction in the trial. It seems that (1) sheep from the unpredictable, stimulus-poor in comparison to sheep from the predictable, stimulus-rich housing conditions dealt less easily with the test conditions rich in stimuli, that (2) long-term housing conditions seemingly did not influence mood-which may be related to the difficulty of tracking a constant long-term state in the brain-and that (3) visual assessment of an emotional stimulus leads to frontal brain deactivation in sheep, specifically if that stimulus is negative. Copyright © 2014 Elsevier Inc. All rights reserved.Brain and Cognition 02/2015; 93:35-41. DOI:10.1016/j.bandc.2014.11.004 · 2.68 Impact Factor