Biomedical subjects

Susanne Trauzettel-Klosinski

Publications and source records attributed to Susanne Trauzettel-Klosinski.

7 recordsLinked to original sources

PubMed2006

Cortical activation during word reading and picture naming in dyslexic and non-reading-impaired children.

OBJECTIVE: In a recent study on picture naming and word reading in dyslexics and control children we found a combination of normal picture retrieval times and severe reading impairments in dyslexics. Therefore, we hypothesize that brain response patterns differ between patients and controls during word reading, but are similar in picture naming as a non-letter mediated task. METHODS: Time course of brain activation was investigated by magnetoencephalography during word reading and picture naming in 9 dyslexic children and 13 age-matched controls (aged 9-10 years). RESULTS: We found 5 consecutive activations spreading from occipito-parietal to temporo-frontal sites. Group differences occurred only during reading: a delayed response in temporal superior and angular gyri at 235-285 ms and absence of activation in anterior temporal and inferior frontal regions at 430-530 ms for dyslexics. CONCLUSIONS: Problems in phonological processing are reflected in delay of early activity and absence of late activity in language related brain regions. From the lack of group differences during picture naming, we conclude the presence of two pathways: a phonological/orthographic one for word reading, which is disturbed in dyslexics, and a visual one for picture naming, which can be unaffected in dyslexics. SIGNIFICANCE: Evidence is provided for different pathways for the processing of letter-mediated and visual-eidetic information. This knowledge may be important for dyslexics in the context of coping with everyday demands and for training of relevant skills.

Auditory Perception↗

PubMed2006

Modulation of visual stimulus discrimination by sustained focal attention: an MEG study.

PURPOSE: Visual attention, normally focused on the center of the visual field, can be shifted to a location in the periphery. This process facilitates the recognition of objects in the attended region. The present experiment was designed to investigate the time course of sustained attention that is known to augment stimulus perception in normal subjects. METHODS: Cortical activity of the human brain related to shifts of the attentional focus was examined with magnetoencephalography. Subjects had to identify a stimulus presented on a screen at one of two locations in the periphery of their visual fields. Sustained attention was either deployed toward the target by a preceding cue or not. RESULTS: Results confirmed a reaction time advantage on recognizing objects in the part of the visual field where attention had been deployed. A stronger magnetic brain response was detected for noncued targets at a latency of 260 to 380 ms after target onset. Source localization revealed a neuronal generator of the attention-related component in the parietal cortex. CONCLUSIONS: Sustained attention facilitates target detection. The component that is localized in the parieto-occipital cortex in the noncued condition is thought to reflect a transient shift of attention toward the target location.

Adult↗

PubMed2004

Eye movement control during single-word reading in dyslexics.

We investigated whether dyslexics make instantaneous automatic adjustments of reading saccades depending on word length. We used a single-word reading paradigm on 10 dyslexic and 12 normally reading children aged 11-15 years. Eye movements were recorded by scanning laser ophthalmoscope (SLO) while subjects read single words of different length aloud. All subjects passed standardized prescreening tests, which included a reading test, to exclude those with discernible deficits of eyesight, oculomotor skill, or intellectual development. We measured number, direction, frequency, and amplitude of saccades, as well as the durations of inter-saccadic intervals, as functions of word length. The results show that word length influences the number and amplitude of reading saccades in both subject groups, but this relationship showed quantitatively significant group-specific differences: Both groups showed a gradual increase of the saccade amplitudes in either direction dependent on word length, but the gain of this function was significantly lower in the dyslexics. The durations of holding phases between saccades were significantly longer in the dyslexics, and accordingly, we found a lower rate of occurrence of saccades per unit time in the dyslexics. Forward saccade amplitudes showed no correlation with the duration of the preceding or following holding phases in either group. The data show that the mechanisms enabling dyslexics to make instantaneous adjustments of reading saccades depending on word length are present but quantitatively impaired. This supports the view that these adjustments may help dyslexics to increase reading speed, but that they cannot utilize them to the same extent as normal readers.

Adolescent↗

PubMed2003

Assessment of parafoveal function in maculopathy: a comparison between the Macular Mapping Test and kinetic Manual Perimetry.

BACKGROUND: Parafoveal function is crucial for patients with maculopathies, because they have to use the parafoveal retina for reading after foveal vision loss. Manual perimetry is a reliable but lengthy method for assessing macular function. The Macular Mapping Test (MMTest) was therefore designed as a quick and easy test. In this study both methods were compared in patients with central scotoma. METHODS: In 50 patients with maculopathy (22 Stargardt's, 20 age-related, 5 diabetic, 3 other macular dystrophies), 30 degrees Tuebingen Manual Perimetry was performed kinetically. The MMTest assesses local responses to brief displays of letters in the central visual field (8 degrees radius) on a computer screen. A "wagon-wheel" pattern is used to stabilize gaze in the center. Comparison of the methods was based on the correspondence of field defects in each sector. RESULTS: The overall correspondence was 87.5%. The results could be divided into three groups, depending on fixation behavior: group 1 ( n=27): central fixation in both methods, median correspondence 87.5%, best in Stargardt's disease (95.3%), lowest in diabetic maculopathy (71.8%); group 2 ( n=21): eccentric fixation in both methods (84.3%); group 3 ( n=2): eccentric in TMP, central in MMTest (65.6% and 81.2%). CONCLUSION: Provided that the fixation locus is known, the MMTest is a quick and easy screening method, which shows a high correspondence with the results of manual perimetry.

Adolescent↗

PubMed2003

Support for patients loosing sight.

This overview on support of patients loosing sight is based on a literature survey regarding reading disabilities and orientation and on results of experience trials performed at the University Eye Clinic Tübingen. In reading disorders, the main goal of rehabilitation is to regain or maintain the ability to read newspaper print. The fundament of rehabilitation is the use of optical and electronical devices and the application of specially designed training programs. The ability of a person with low vision to achieve successful orientation and mobility rehabilitation depends on residual vision, posture and balance, body image, auditory and tactile abilities, intelligence and personality. Rehabilitation efforts focus on the enhancement of residual vision applying magnifying contrast-enhancing and photomultiplying devices. The main pillar of orientation and mobility rehabilitation is a training especially designed for the patient's needs. Rehabilitation efforts must be tailored to the type of vision loss and to specific functional implications--the success rate is high. An optimal fitting of the required spectrum of low vision aids should be provided to the patient and importantly, professional teaching and training is recommended. Activities of daily living, orientation and mobility, and psychological concerns must be addressed. Close cooperation with other branches of rehabilitation is essential.

Humans↗

PubMed2003

Nasotemporal overlap of retinal ganglion cells in humans: a functional study.

PURPOSE: A zone of overlap along the vertical retinal meridian where ipsi- and contralaterally projecting ganglion cells intermingle has been demonstrated histologically in nonhuman primates. The widening of the zone of overlap in the foveal region was thought to produce a foveal sparing extending 1.5 degrees in the blind hemifield in human hemianopia. The functional relevance of the nasotemporal overlap is still unclear and cannot be shown definitely by conventional perimetry, because of insufficient spatial accuracy, light-scattering effects, and insufficient fixation control. Therefore, this study was undertaken to investigate the vertical field border by a perimetric method that does not have these shortcomings. METHODS: A scanning laser ophthalmoscope (SLO) was used to scan vertical triplets of dots along the vertical field border in 20 patients (36 eyes) with homonymous hemianopia without macular sparing. Stimuli and fundus were imaged simultaneously for fixation monitoring. RESULTS: None of the patients showed a field border that coincided exactly with the vertical midline. In 34 eyes, the seeing area extended from the vertical meridian into the blind hemifield and formed a vertical strip of perception. None of the patients showed additional foveal sparing. Twenty-two eyes showed a concave shape of the seeing area within the foveal region of the blind hemifield. CONCLUSIONS: Our results show that the nasotemporal overlap exists in humans. It consists of a strip of intact perception reaching into the blind hemifield. The concave shape can be explained by the size and distribution of the receptive fields of the retinal ganglion cells.

Adult↗

PubMed2002

Pictogram naming in dyslexic and normal children assessed by SLO.

We measured pictogram naming (PN) and text reading in dyslexic and normally reading young teenagers. Eye movements were monitored by scanning laser ophthalmoscope, revealing positions of fovea, stimuli on the retina, and speech simultaneously. While text reading speed showed the expected difference between groups, PN speeds overlapped widely. PN was mainly controlled by retrieval time in both groups and correlated with age in dyslexics. During PN, only backward saccades occurred more frequently in dyslexics. We conclude that PN activates visual/eidetic mechanisms that are distinct from the phonemic/analytic pathway necessary for reading. This dual organization leads to a wide range of combinations of performances in PN and text reading.

Child↗