Biomedical subjects

S I Tillery

Publications and source records attributed to S I Tillery.

5 recordsLinked to original sources

PubMed1995

Task dependence of primate arm postures.

We studied the relations between arm posture and hand location as monkeys performed tasks involving three-dimensional arm movements. Two specific questions were addressed: how reliable are these relations from trial to trial and from day to day, and are the arm postures dictated only by the location of the hand or are the postures also dependent on the task being performed? Based on the variable errors in linear regressions, we found that monkeys performed the tasks in a very stereotypic fashion from trial-to-trial: for a given monkey and task, knowing the position of the hand was sufficient to determine the posture of the arm. These relations did not change from day to day; the relation between hand location and posture was stable over the course of the experiments. In some of the tasks, the postures employed by the monkeys were strikingly similar to those observed in human psychophysical studies. The relations between hand location and arm posture exhibited a large degree of task dependence. Changing the required orientation of the hand resulted in changes in the arm posture.

Animals↗

PubMed1994

Errors in kinesthetic transformations for hand apposition.

We investigated the ability of human subjects to duplicate with the left hand the spatial location of the right hand, using only kinesthetic cues. Under this experimental condition, subjects produced large and idiosyncratic errors which varied with the spatial location of the hand. Tactile cues originating from contact of the hand with a rigid surface generally led to a decrease in the variable error. However, even without tactile cues, the variable error was small compared with other tasks in which subjects are required to estimate the spatial location of the hand on the basis of kinesthetic cues. The results suggest that subjects did not derive an estimate of the location of the right hand in extrapersonal space, but rather that they performed the task within intrapersonal space.

Cues↗

PubMed1991

A coordinate system for the synthesis of visual and kinesthetic information.

The results of this study suggest that information derived from kinesthetic inputs alone is not normally used to generate an estimate of the location of the hand in extrapersonal space. This finding provides support for the interpretation of previous results suggesting that a representation of a visual target in extrapersonal space must be transformed into a kinesthetic reference frame before the parameters of a targeted arm movement can be computed (Soechting and Flanders, 1989b). We asked subjects to use a pointer to indicate the spatial location of their hand following an unseen passive displacement. We found that subjects had large errors in the locations that they chose and that there was a large degree of variability for repeated trials with the same hand location. The errors were a result neither of using the pointer to indicate a spatial locus nor of an inability to make use of kinesthetic information. Instead, the errors resulted from an inability of subjects to synthesize an estimate of the hand's spatial location from only kinesthetic cues. We also asked subjects to use the pointer to indicate the location of their hand following a passive displacement when they had visual information about the passive displacement. In this case, we found that subjects performed better than when they had only kinesthetic information, but not as well as when they had only visual information about target location. This finding suggests that kinesthetic information about target location affects the processing of visual information.

Arm↗

PubMed1986

Age-bodyweight relationships to lung growth in the F344 rat as indexed by lung weight measurements.

Measurements of the total lung weights and the individual weights of the lung lobes of male F344 rats ranging in age from about 30 days to 140 days or more were made in order to determine how lung growth and the growths of the individual lung lobes relate to bodyweight over the course of maturation of this species. Additionally, in this study we also compared how each lung lobe grows relative to total lung growth, evaluated the ratios of lung dry weight to wet weight and obtained information on the weights of the trachea and extra-hilar main-stem bronchi as the F344 rat matures. The wet weights WLT of the trachea-lung preparations and the pooled lobe weights WPL as functions of rat bodyweight WB could be readily described by the following logarithmic expressions: WLT = 0.596 ln WB - 1.923, r = 0.95; WPL = 0.464 ln WB - 1.566, r = 0.96. Expressed as percentages of the pooled lobe weights, the individual lobes remained at constant values as the animals grew with the exception of the right caudal lobe which decreased between bodyweights of 72 and 96 g; absolute wet weight measurements of the individual lobes indicated that the right cranial, right middle and right intermediate lobes actually decreased in weight between bodyweights of 300 and 385 g. The dry weights of the lobes consistently represented approximately 22% of the wet weights regardless of animal age or bodyweight, and on average the airways represented about 20% of the weights of the intact airway-lung preparations over the course of animal maturation.

Aging↗

PubMed1986

Immunohistologic identification of factor VIII related antigen in frozen sections of rat lung.

Factor VIII related antigen (F VIII RAg) is localized in the cytoplasm of vascular endothelial cells. In this study, endothelial cells in frozen lung sections of Fischer-344 rat lungs were surveyed for F VIII RAg using a commercially available primary antibody against human F VIII RAg and an immunofluorescence assay. Rat pulmonary endothelial cells were positively labeled for F VIII RAg, whereas other lung cell types were not. Immunohistologic staining of F VIII RAg is useful in the rat model for identifying pulmonary endothelial cells in lung sections, and may be of use for detecting changes in lung endothelial cells due to environmental insults.

Animals↗