Facial temperature and pupil size as indicators of internal state in primates.

Studies in human subjects have revealed that autonomic responses provide objective and biologically relevant information about cognitive and affective states. Measures of autonomic responses can also be applied to studies of non-human primates, which are neuro-anatomically and physically similar to humans. Facial temperature and pupil size are measured remotely and can be applied to physiological experiments in primates, preferably in a head-fixed condition. However, detailed guidelines for the use of these measures in non-human primates are lacking. Here, we review the neuronal circuits and methodological considerations necessary for measuring and analyzing facial temperature and pupil size in non-human primates. Previous studies have shown that the modulation of these measures primarily reflects sympathetic reactions to cognitive and emotional processes, including alertness, attention, and mental effort, over different time scales. Integrated analyses of autonomic, behavioral, and neurophysiological data in primates are promising methods that reflect multiple dimensions of emotion and could provide tools for understanding the mechanisms underlying neuropsychiatric disorders and vulnerabilities characterized by cognitive and affective disturbances.

Properties of modified surface for biosensing interface.

Properties of modified surface, behavior against salting-out effect, suppressive effect for protein nonspecific adsorption, and wettability were examined using various mercapto compounds bearing methyloligoethylene glycol, oligoethylene glycol, alkyl oligoethylene glycol, alkyl phosphoryl choline, alkyl inverse phosphoryl choline, and alkyl sulfobetaine moieties. The behavior against salting-out effect was examined using gold nanoparticle with PBS and NaCl aqueous solution. The suppressive effect for protein nonspecific adsorption was evaluated by SPR, and the wettability was measured on the SPR chip. The gold nanoparticle modified with 8C3EG, 12C4EG, 12CPC, 6CCP, and 12CCP showed excellent behavior against salting-out effect. The suppression of protein nonspecific adsorption was effective with 6EG, 12C4EG, 12CPC, and 12CS. On the other hand, the modified surface possessed high wettability except for the surface modified with M6EG. The results indicate that incorporation of alkyl group into surface modification materials is effective for the enhancement of behavior against salting-out effect and suppressive effect for protein nonspecific adsorption regardless of wettability. Among the zwitter ionic derivatives, inverse phosphoryl choline derivatives showed intriguing properties, high behavior against salting-out effect with high wettability but low suppressive effect for protein nonspecific adsorption.

Rhythm information represented in the fronto-parieto-cerebellar motor system.

Rhythm is an essential element of human culture, particularly in language and music. To acquire language or music, we have to perceive the sensory inputs, organize them into structured sequences as rhythms, actively hold the rhythm information in mind, and use the information when we reproduce or mimic the same rhythm. Previous brain imaging studies have elucidated brain regions related to the perception and production of rhythms. However, the neural substrates involved in the working memory of rhythm remain unclear. In addition, little is known about the processing of rhythm information from non-auditory inputs (visual or tactile). Therefore, we measured brain activity by functional magnetic resonance imaging while healthy subjects memorized and reproduced auditory and visual rhythmic information. The inferior parietal lobule, inferior frontal gyrus, supplementary motor area, and cerebellum exhibited significant activations during both encoding and retrieving rhythm information. In addition, most of these areas exhibited significant activation also during the maintenance of rhythm information. All of these regions functioned in the processing of auditory and visual rhythms. The bilateral inferior parietal lobule, inferior frontal gyrus, supplementary motor area, and cerebellum are thought to be essential for motor control. When we listen to a certain rhythm, we are often stimulated to move our body, which suggests the existence of a strong interaction between rhythm processing and the motor system. Here, we propose that rhythm information may be represented and retained as information about bodily movements in the supra-modal motor brain system.

Categorical representation of objects in the central nucleus of the monkey amygdala.

The primate amygdala consists of several subnuclei. Neurons in this brain area have been known to respond to stimuli belonging to specific categories of objects, such as faces, animals, and artifacts. However, little is known about the functional differences among the nuclei of the primate amygdala. To clarify functional differences among these subnuclei in object categorization, we compared the responsiveness of neuronal populations among the lateral, basal and central nuclei of the monkey amygdala. The activity of 203 neurons was recorded while video clips of 13 stimuli belonging to three categories (monkey, human, and artifact) were presented. Of these neurons, 37, 39 and 37 neurons in the lateral, basal and central nuclei, respectively, responded to at least one of the stimuli. We applied a cluster analysis to the neuronal population responses from these nuclei, and also calculated information about the three categories and monkey identity from each neuronal population. We found that the three categories and monkey identity could be more properly classified by neuronal responsiveness in the central nucleus, which is an output gate of the amygdala, than by that in the lateral and basal nuclei. These results suggest that the information about objects suitable for the generation of appropriate emotional response is built up within the primate amygdala via an intra-amygdala network from the lateral nucleus to the central nucleus.

The use of nasal skin temperature measurements in studying emotion in macaque monkeys.

Using an infrared thermographic system, we have demonstrated, as previously reported, that temperatures in the nasal region of macaque monkeys decrease during negative emotional states, such as when facing a threatening person. In this study, we explored the usefulness of measuring nasal skin temperatures in studies of monkey emotions as manifested by conspecific emotional behaviors and expressions. We measured nasal skin temperatures of rhesus monkeys (Macaca mulatta) in response to video clips, all showing monkeys: a raging individual (Experiment 1), three distinct emotional expressions (Experiment 2), and only faces or voices representing a threat (Experiment 3). We found that nasal skin temperatures significantly decreased in response to a threatening stimulus, even when the stimulus was a 2D image with digitized sound, similar to those used in many psychological or neurophysiological studies on animal emotion. Moreover, species-specific aggressive threats invariably elicited a decrease in nasal skin temperatures and skin conductance responses; however, screams or coos did not elicit this response. Simultaneous perception of both facial expressions and vocalizations induced a more prominent decrease in nasal skin temperatures than did the perception of facial expressions or vocalizations alone. Taken together, these data suggest that decreased nasal skin temperatures should be added to the list of indicators of emotional states in animals.

Responses of single neurons in monkey amygdala to facial and vocal emotions.

The face and voice can independently convey the same information about emotion. When we see an angry face or hear an angry voice, we can perceive a person's anger. These two different sensory cues are interchangeable in this sense. However, it is still unclear whether the same group of neurons process signals for facial and vocal emotions. We recorded neuronal activity in the amygdala of monkeys while watching nine video clips of species-specific emotional expressions: three monkeys showing three emotional expressions (aggressive threat, scream, and coo). Of the 227 amygdala neurons tested, 116 neurons (51%) responded to at least one of the emotional expressions. These "monkey-responsive" neurons-that is, neurons that responded to monkey-specific emotional expression-preferred the scream to other emotional expressions irrespective of identity. To determine the element crucial to neuronal responses, the activity of 79 monkey-responsive neurons was recorded while a facial or vocal element of a stimulus was presented alone. Although most neurons (61/79, 77%) strongly responded to the visual but not to the auditory element, about one fifth (16/79, 20%) maintained a good response when either the facial or vocal element was presented. Moreover, these neurons maintained their stimulus-preference profiles under facial and vocal conditions. These neurons were found in the central nucleus of the amygdala, the nucleus that receives inputs from other amygdala nuclei and in turn sends outputs to other emotion-related brain areas. These supramodal responses to emotion would be of use in generating appropriate responses to information regarding either facial or vocal emotion.

Impacts of facial identity and type of emotion on responses of amygdala neurons.

The amygdala has been implicated in the processing of emotional expressions. Who makes the emotion and the type of emotion are important in producing appropriate responses. How amygdala neurons are affected by facial identity and type of emotion, however, has not yet been systematically examined. We examined the activity of amygdala neurons using nine monkey stimuli: 3 monkeys x 3 types of emotion. Of the 227 neurons tested, 77 responded to the monkey stimuli. The effects of facial identity and type of emotion on the response magnitude were significant in 48 and 57 neurons, respectively. Both effects were significant in 38 neurons. These results indicate that both facial identity and type of emotion have strong impacts on amygdala functions.

Decrease in nasal temperature of rhesus monkeys (Macaca mulatta) in negative emotional state.

We established an infrared thermographic system for the detection of emotion-related temperature changes in rhesus monkeys (Macaca mulatta). We continuously measured temperatures of various facial regions of four rhesus monkeys during the presentation of a potentially 'threatening' person, i.e., a person in a laboratory coat with a catching net, who entered the experimental room and approached the monkeys. The temperatures were also measured before and after the presentation of the 'stimulation period.' The temperature of the nasal region decreased significantly within 10-30 s, and continued to decrease throughout the stimulation period. During this period, the monkeys frequently expressed silent bared-teeth face, staring open-mouth face, and lip-smacking, all of which were expressions of a negative emotion. Assuming that the monkeys experience the negative emotion when viewing the potentially threatening stimulus, we conclude that the decrease in nasal skin temperature is relevant to the alteration of the emotional state. The present findings suggest that nasal temperature can be a reliable and accurate indicator of a change from neutral to negative in emotional state of non-human primates.

High-selectivity, high-flexibility glass hollow-fiber membrane for gas separation.

A high gas selectivity, high flexibility glass hollow-fiber membrane based on spinodal phase separation has been prepared by direct winding from glass melt, followed by acid leaching processing.