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Biomedical subjects

J L Trimble

Publications and source records attributed to J L Trimble.

12 recordsLinked to original sources
PubMed1985

Text-scanning patterns of blind readers using Optacon and braille.

Tactual reading usually requires the coordinated use of the forearm/hand motor and tactile sensory systems. Therefore, in a series of studies of tactual reading behavior, we chose to record the text-scanning patterns of adult blind readers in an attempt to gain further insight into the nature of this process. Reading behavior for four modes of tactual reading was recorded (embossed braille one-hand, embossed braille two-hands, Optacon/letterprint, and Optacon/Inkbraille) by detecting and recording the instantaneous position of light-emitting diodes unobtrusively attached to the finger(s) or the Optacon camera. In addition to the comparative evaluation of the four sets of reading patterns, the salient features of the Optacon/letterprint patterns were quantitatively analyzed in an attempt to characterize this particular mode of reading. The text-scanning patterns of Optacon readers have not been previously reported. In general the text-scanning behavior for all modes of tactual reading seems to be similar; the only remarkable difference appears to be in the reading rates. Regarding Optacon/letterprint performance, reading rate was found to be significantly and negatively correlated with line-changing time and the number of regressions. No significant correlation was evident between rate and regression magnitude.

Adult↗
PubMed1985

Measuring gait-related blind mobility performance.

The gait characteristics of blind travelers can provide information about their mobility skills. Previous attempts at measuring these characteristics have suffered because they either do not provide continuous monitoring or allow usage outside a laboratory setting. A new instrument has been developed to overcome these problems. The instrument allows continuous monitoring of interankle distance during walking. Records of interankle distance were analyzed to determine maximum interankle distance/step, step time, and cadence. With this system, gait parameters revealed differences between two groups of travelers (blind and blindfolded) and changes over a series of four trials on turns, straightaways, and over the whole route. This suggests the system is useful as an assessment device both for research and for rehabilitation training.

Blindness↗
PubMed1984

Inkbraille as a potential new reading system for the blind.

Inkbraille, a reduced size ink-image version of the familiar braille code, was conceived in an attempt to sidestep the major disadvantages of embossed braille, while retaining the unsurpassed reading rates achieved by the blind using that code. Inkbraille would ultimately be translated by a specially designed hand-held electronic device with appropriate tactile output. Such a device is not yet available, so in this study we test the readability of Inkbraille when read by means of a commercially available electronic reading aid, the Optacon, which presents its output tactually on a field of vibrating pins which are sensed with a finger. Three modes of tactual reading were compared: conventional embossed braille, and the Opticon's vibrating-pinfield presentation of typed letters and its presentation of Inkbraille. All subjects were able to read Inkbraille upon initial exposure. Subjects who were tested in multiple sessions exhibited significant increases in Inkbraille reading rates after only limited exposure. Since Inkbraille and letterprint reading rates were the same in this study, the results led the authors to conclude that a rate limitation may have been imposed by the device (the Optacon) that was used to translate both the Inkbraille and the letterprint.

Blindness↗
PubMed1977

The effect of mannitol infusion on retinal function and oxygen tension.

Mannitol administered intravenously in rhesus monkeys resulted in a temporary recovery of the visual evoked response (VER) after its decrease due to elevation of the intraocular pressure. Mannitol infusion caused an immediate, albeit transitory, increase in retinal oxygen tension. These changes were independent of the ocular hypotensive effect of mannitol, and we conclude that the drug is a far better agent for the treatment of acute glaucoma than heretofore believed.

Animals↗
PubMed1977

Electro-oculography in infants.

To record the electro-oculogram in infants without using general anesthesia and passive globe rotation, we used the static vestibular reflex in which compensatory eye movements occur in response to angular rotation of the semicircular canal. To produce these eye movements, we placed the infant in a supine position in his mother's arms in a rocking chair and, while he nursed from a bottle, directed his attention to a distracting stimulus. We recorded the electro-oculogram during rocking under conditions of light and dark adaptation. We used the electro-oculograms to calculate the conventional light-to-dark amplitude ratio.

Electrooculography↗
PubMed1975

Ongoing occipital rhythms and the VER. I. Stimulation at peaks of the alpha-rhythm.

As a first step toward determining the source of variability in the visually evoked response (VER) between subjects, we have examined the relationships between the VER and the alpha-rhythm. This was done by comparing the VER's to photic stimuli delivered at positive and negative peaks of the alpha-rhythm (alpha-synchronized stimuli) with VER's to flashes delivered at a fixed interval, unsynchronized with the alpha-rhythm. Average VER's for the three classes of stimuli were calcuated for each of ten subjects. In addition, a grand average VER (GVVER) WAS CALCULATED FOR EACH STIMULUS CLASS BY AVERAGING THE INDIVIDUAL AVERAGE VER's. Quantitative comparisons between GVER's were made using cross- correlograms. Cross-correlograms were calculated between each of the GVER's, and between the GVER's to alpha-synchronized stimulation and their controls. These data show that the first 120 msec. poststimulus interval of the Gver's to alpha-synchronized stimulation are highly correlated with the prestimulus alpha- rhythm. The data also show a component occurring in al GVER's which is independent of the alpha-rhythm. This component begins 120 msec. After stimulation, reaches peak amplitude at 200 msec, and decays to baseline at 240 msec. Thses findings suggest that much of the variability in VER recordings may be due to alpha-activity which has been insufficiently attenuated by averaging.

Adult↗