Biomedical subjects

Katsuki Nakamura

Publications and source records attributed to Katsuki Nakamura.

4 recordsLinked to original sources

PubMed2005

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.

Animals↗

PubMed2005

Comparison between monkey and human visual fields using a personal computer system.

To use monkeys as models for eye diseases that may lead to blindness, we need to develop a method to precisely measure its visual field and to understand similarities and differences in visual field properties between monkeys and humans. The visual field of monkey was not measured precisely although the necessity. We established a new system with personal computers for precise measurement of the monkey visual field. Four monkeys and three humans served as subjects. The luminance-contrast sensitivity of the central 24 degrees field was measured while the subject was fixating a small spot. During the measurement, we continuously recorded the eye position, and discarded the data when fixation was broken. Reliability indices demonstrated high and stable behavioral performance by both monkeys and humans. The luminance-contrast sensitivity was highest around the fovea, and declined as eccentricity increased. The blind spot was clearly detected 15 degrees temporally. The overall sensitivity was higher in humans than in monkeys and the sensitivity dropped more sharply in the periphery in monkeys than in humans. We recommend this system as a convenient and reliable way to measure visual functions in monkeys in basic ophthalmologic research or in assessment of the drug effects on the visual field.

Adult↗

PubMed2003

Visual response properties of neurons in the parahippocampal cortex of monkeys.

We examined visual response properties of single neurons in the parahippocampal (PH) cortex of alert monkeys using various visual stimuli (bars, geometrical shapes such as a circle, and images such as a human face) while the monkey fixated a spot for a juice reward. Of the investigated PH neurons 104 of 359 (29%) were found to be visually responsive. The investigation was focused on spatial and object aspects of visual processing. We investigated a visual receptive field (RF) property and a direction selectivity for a moving bar with respect to spatial processing. For half of these PH neurons (53%), the optimal stimulus position, where a visual stimulus elicited the maximal response, located peripherally, that is, with an eccentricity of more than 10 deg. More than 20% of these PH neurons had an RF that does not include the center of gaze. There were neurons in the PH cortex that appeared to convey motion signals. In addition, some PH neurons showed eye-position-dependent activity. With respect to object processing, we investigated selectivities for images, geographical shapes, orientations of a bar, and colors. For comparison purposes, we also examined responses of perirhinal (PR) neurons. PH neurons showed selective responses to these stimuli, but PR neurons were found to be more selective for images than PH neurons. These results suggest that the PH cortex is involved in both spatial and object processing, but less involved than the PR cortex in processing of complex images.

Animals↗

PubMed2002

Recognition of emotion from facial, prosodic and written verbal stimuli in Parkinson's disease.

Although the basal ganglia are thought to be important in recognizing emotion, there is contradictory evidence as to whether patients with Parkinson's disease (PD) have deficits in recognizing facial expressions. In addition, few studies have examined their ability to recognize emotion from non-visual stimuli, such as voices. We examined the ability of PD patients and age-matched controls to recognize emotion in three different modalities: facial, prosodic, and written verbal stimuli. Compared to controls, PD patients showed deficits in recognizing fear and disgust in facial expressions. These impairments were not seen in their recognition of prosodic or written verbal stimuli. This modality-specific deficit suggests that the neural substrates for recognizing emotion from different modalities are not fully identical.

Aged↗