Biomedical subjects

R Sgolastra

Publications and source records attributed to R Sgolastra.

3 recordsLinked to original sources

PubMed2001

Gravitational cues contribute to accurate localisation of mentally represented cutaneous targets.

The purpose of this research was to ascertain whether gravitational cues contribute to localisation ability of mentally represented cutaneous targets. Eight right-handed male subjects were asked to use each hand to point accurately toward four points in the anterior trunk midline solely on the basis of the mental representation of their position along the trunk while standing upright and while lying supine. It was found that subjects were more accurate when performing in the upright posture. However, statistical analysis of the mean constant transverse errors of pointing showed that neither posture nor target factors had any significant effect on pointing accuracy. On the contrary, analysis of the mean constant longitudinal errors showed that both the posture and target factors were significant. Subjects pointed caudally to the target locations and made the largest errors, which were on the order of centimeters, when performing in the horizontal posture. These findings indicate that gravitational cues are critical in accurately localising mentally represented cutaneous targets.

Adult↗

PubMed1999

The head midline as a reliable reference frame for encoding head-on-body orientation.

Twelve right-handed male subjects were asked to use each hand to point accurately toward the center of their forehead, determining the correct position according to their mental representation, while the head was either aligned with the trunk or tilted 30 degrees to the right or left. Analysis of end-positions of pointing revealed that the right hand exhibited a slight leftward bias with respect to the putative head midline passing through the center of the glabella and the center of the fissure between the two upper central incisors, regardless of the head-on-body orientation, whereas the left hand proved very accurate when the head was aligned with the trunk but, when the head was tilted either way, it deviated to the opposite side. These results lead to the conclusion that the head midline appears to act as a reliable reference frame for encoding head-on-body orientation when pointing is carried out by the dominant hand.

Adult↗

PubMed1997

Psychophysical properties of the trunk midline.

This study was carry out to obtain direct evidence that the body midline actually is perceived and to assess some psychophysical properties of this line. Twelve normal, right-handed male subjects were asked to make accurate pointing movements toward the midline of the anterior trunk on the basis of their mental representation of this line. Each hand was used to point while the head was either aligned with the trunk or tilted 30 degrees to the right or left. Analysis of end-positions of pointing on trunk images acquired by an image analysis system indicated that the trunk midline indeed is perceived as a straight line. Three putative trunk midlines were taken into consideration on the basis of anatomic landmarks, and it was found that the mental representation of the trunk midline came nearest to the line orthogonal to the intermammary line crossing its midpoint. The performing hand and the position of the head relative to the trunk both had an effect on the mental representation of the trunk midline. These findings suggest that somatosensory signals from the trunk, as well as proprioceptive input from the neck, contribute to the elaboration of the subject's mental representation of the trunk midline.

Adult↗