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Florian Hutzler

Publications and source records attributed to Florian Hutzler.

13 recordsLinked to original sources

Evidence for a dysfunction of left posterior reading areas in German dyslexic readers.

The brain activity during a sentence reading task and a visual control task was examined with fMRI in 13 German dyslexic readers and 15 age-matched fluent readers (age: 14-16 years). These participants came from a longitudinal study and the dyslexic readers exhibited a persistent reading fluency deficit from early on. For the first time with German dyslexic readers, and in correspondence with the majority of functional imaging studies, we found reduced dyslexic activation in the left occipitotemporal cortex and in a small region of the left supramarginal gyrus. Enhanced activation was found in left inferior frontal and subcortical regions.

Adolescent↗

Does the frequency of the antecedent noun affect the resolution of pronominal anaphors? An ERP study.

Behavioral studies investigating the influence of the relative word frequency of antecedent nouns on the processing of anaphoric pronouns have yielded contradictory results. While some researchers found no effect of an antecedent's frequency of occurrence on coreference resolution [J. Simner, R. Smyth, Phonological activation in anaphoric lexical access (ALA), Brain Lang. 68 (1999) 40-45], others report shorter reading times for pronouns referring to low compared to high frequency nouns [R.G.P. van Gompel, A. Majid, Antecedent frequency effects during the processing of pronouns, Cognition 90 (2004) 255-264]. Using event-related potentials, our study aimed to further investigate the issue. Participants were presented with sentence pairs, of which the first contained either a high frequency, a middle frequency or a low frequency noun. The second sentence contained a pronoun which referred back to the noun in the first sentence. ERP waves were determined, time-locked to both the nouns and the anaphoric pronouns. We observed a graded N400 effect for antecedents of the three frequency classes with amplitudes reversely related to the word's lexical frequency. Coreferential pronouns elicited a P300, with amplitudes dependent on the noun's relative frequency of occurrence, i.e. the lower the antecedent's word frequency, the higher was the amplitude of the P300. This amplitude effect at the pronoun is interpreted in terms of the allocation of attentional resources to salient discourse entities.

Adult↗

Model-generated lexical activity predicts graded ERP amplitudes in lexical decision.

Recent neurocognitive studies of visual word recognition provide information about neuronal networks correlated with processes involved in lexical access and their time course (e.g., [Holcomb, Ph.J., Grainger J. and O'Rourke, T. (2002). An Electrophysiological Study of the Effects of Orthographic Neighborhood Size on Printed Word Perception, J. of Cogn. Neurosci. 14 938-950; Binder, J.R., McKiernan, K.A., Parsons, M.E., Westbury, C.F., Possing, E.T., Kaufman, J.N. and Buchanan, L. (2003). Neural Correlates of Lexical Access during Visual Word Recognition, J. Cogn. Neurosci. 15 372-393.]). These studies relate the orthographic neighborhood density of letter strings to the amount of global lexical activity in the brain, generated by a hypothetical mental lexicon as speculated in an early paper by [Jacobs, A.M. and Carr, T.H. (1995). Mind mappers and cognitive modelers: Toward cross-fertilization, Behav. Brain. Sci. 18 362-363]. The present study uses model-generated stimuli theoretically eliciting graded global lexical activity and relates this activity to activation of lexical processing networks using event-related potentials (ERPs). The results from a lexical decision task provide evidence for an effect of lexicality around 350 ms post-stimulus and also a graded effect of global lexical activity for nonwords around 500 ms post-stimulus. The data are interpreted as reflecting two different decision processes: an identification process based on local lexical activity underlying the 'yes' response to words and a temporal deadline process underlying the 'no' response to nonwords based on global lexical activity.

Adult↗

Perhaps correlational but not causal: no effect of dyslexic readers' magnocellular system on their eye movements during reading.

During reading, dyslexic readers exhibit more and longer fixations and a higher percentage of regressions than normal readers. It is still a matter of debate, whether these divergent eye movement patterns of dyslexic readers reflect an underlying problem in word processing or whether they are - as the proponents of the magnocellular deficit hypothesis claim - associated with deficient visual perception that is causal for dyslexia. To overcome problems in the empirical linkage of the magnocellular theory with reading, a string processing task is presented that poses similar demands on visual perception (in terms of letter identification) and oculomotor control as reading does. Two experiments revealed no differences in the eye movement patterns of dyslexic and control readers performing this task. Furthermore, no relationship between the functionality of the participants' magnocellular system assessed by the coherent motion task and string processing were found. The perceptual and oculomotor demands required during string processing were functionally equivalent to those during reading and the presented consonant strings had similar visual characteristics as reading material. Thus, a strong inference can be drawn: Dyslexic readers do not seem to have difficulties with the accurate perception of letters and the control of their eye movements during reading - their reading difficulties therefore cannot be explained in terms of oculomotor and visuo-perceptual problems.

Adolescent↗

Effects of syllable-frequency in lexical decision and naming: an eye-movement study.

In three experiments we explored task-specific effects of syllable-frequency, following Perea and Carreiras' (1998) findings of a facilitative effect during naming and an inhibitory effect during lexical decision. In Experiment 1, an inhibitory effect of first syllable-frequency on articulation duration suggested a process-specific effect during naming: a facilitative effect on construction of phonological output, but an inhibitory effect on lexical access. Eye-movement recording was used in Experiment 2 to disentangle these two processes. An inhibitory effect on eye-movement parameters during both lexical decision and naming supported the assumption that higher first syllable-frequency inhibits lexical access. Implications of a general inhibitory effect of syllable-frequency for computational models of word recognition, specifically for the multiple-trace memory (MTM) model of polysyllabic word naming (Ans, Carbonnel, & Valdois, 1998), are discussed.

Adult↗

Developmental dyslexia in a regular orthography: a single case study.

This study of an adult case examined in detail with eye movement measures the reading speed problem which is characteristic for developmental dyslexia in regular orthographies. A dramatic length effect was found for low frequency words and for pseudowords, but not for high frequency words. However, even for high frequency words it was found that reading times were substantially prolonged although number of fixations did not differ. A neurocognitive assessment revealed no visual deficits (parallel processing, precedence detection, coherent motion detection) but speed impairments for certain verbal and phonological processes. We propose that the reading difficulties are phonological in nature, but these difficulties become manifest as inefficiency and not as inability.

Adult↗

Frequency effects with visual words and syllables in a dyslexic reader.

The present study investigated the nature of the inhibitory syllable frequency effect, recently reported for normal readers, in a German-speaking dyslexic patient. The reading impairment was characterized as a severe deficit in naming single letters or words in the presence of spared lexical processing of visual word forms. Three visual lexical decision experiments were conducted with the dyslexic patient, an unimpaired control person matched to the patient and a control group: Experiment 1 manipulated the frequency of words and word-initial syllables and demonstrated systematic effects of both factors in normal readers and in the dyslexic patient. The syllable frequency effect was replicated in a second experiment with a more strictly controlled stimulus set. Experiment 3 confirmed the patient's deficit in activating phonological forms from written words by demonstrating that a pseudohomophone effect as observed in the unimpaired control participants was absent in the dyslexic patient.

Aged↗

Inhibitory effects of first syllable-frequency in lexical decision: an event-related potential study.

Electrophysiological correlates of the behaviorally well-documented inhibitory effect of first syllable-frequency during lexical access are presented. In a lexical decision task, response times to words with high-frequency first syllables were longer than those to words with low-frequency first syllables and resulted in more negative event-related potentials (ERPs) in an early time window from 190 ms to 280 ms and in the N400 component. The onset of the observed first syllable-frequency effect was prior to the onset of the effect of lexicality (i.e., the first reliable differentiation in ERP waveforms in response to words and pseudowords, a potential marker of lexical access). The present study's results support Barber et al.'s [Neuroreport 15 (2004) 545] notion of the prelexical nature of the first syllable-frequency effect by (A) providing evidence for electrophysiological correlates of first syllable-frequency in another, non-Romance orthography (i.e., German), (B) relating the onset of the first syllable-frequency effect to the onset of the lexicality effect and (C) strengthening this pattern of results by means of a novel item-based analysis of ERP data. Implications of the prelexical nature of the inhibitory first syllable-frequency effect for computational models of reading, specifically for Ans et al.'s [Psychol. Rev. 105 (1998) 678] multiple-trace memory (MTM) model of reading are discussed.

Adult↗

Do current connectionist learning models account for reading development in different languages?

Learning to read a relatively irregular orthography, such as English, is harder and takes longer than learning to read a relatively regular orthography, such as German. At the end of grade 1, the difference in reading performance on a simple set of words and nonwords is quite dramatic. Whereas children using regular orthographies are already close to ceiling, English children read only about 40% of the words and nonwords correctly. It takes almost 4 years for English children to come close to the reading level of their German peers. In the present study, we investigated to what extent recent connectionist learning models are capable of simulating this cross-language learning rate effect as measured by nonword decoding accuracy. We implemented German and English versions of two major connectionist reading models, Plaut et al.'s (Plaut, D. C., McClelland, J. L., Seidenberg, M. S., & Patterson, K. (1996). Understanding normal and impaired word reading: computational principles in quasi-regular domains. Psychological Review, 103, 56-115) parallel distributed model and Zorzi et al.'s (Zorzi, M., Houghton, G., & Butterworth, B. (1998a). Two routes or one in reading aloud? A connectionist dual-process model. Journal of Experimental Psychology: Human Perception and Performance, 24, 1131-1161); two-layer associative network. While both models predicted an overall advantage for the more regular orthography (i.e. German over English), they failed to predict that the difference between children learning to read regular versus irregular orthographies is larger earlier on. Further investigations showed that the two-layer network could be brought to simulate the cross-language learning rate effect when cross-language differences in teaching methods (phonics versus whole-word approach) were taken into account. The present work thus shows that in order to adequately capture the pattern of reading acquisition displayed by children, current connectionist models must not only be sensitive to the statistical structure of spelling-to-sound relations but also to the way reading is taught in different countries.

Child↗

The visual word form area and the frequency with which words are encountered: evidence from a parametric fMRI study.

Cohen and Dehaene et al. proposed that the Visual Word Form Area (VWFA) in the left midfusiform gyrus, contrary to its name, is limited to the extraction of an abstract letter string and not involved in proper visual word recognition. We examined this prelexical function of the VWFA by a parametric block design with five levels of written word frequency. The lowest level was represented by pseudowords and the highest level by words of very high frequency. Contrary to the assumed prelexical function of the VWFA, increasing frequency was associated with decreasing brain activation in a large posterior cluster of the left hemisphere including middle and posterior fusiform regions. The same negative relation between frequency and activation was found in several left frontal clusters. The relation of increasing frequency and decreasing activation in occipitotemporal regions corresponds to a similar relation in the same brain regions found by studies which experimentally manipulated object or face familiarity. This convergence suggests that fusiform regions are specialized for extracting and storing abstract patterns when processing visual objects and these patterns serve as recognition units in subsequent encounters with the same objects.

Adolescent↗

Eye movements of dyslexic children when reading in a regular orthography.

Participants were German dyslexic readers (13-year-olds) who-compared to English dyslexic readers-suffer mainly from slow laborious reading and less from reading errors. The eye movements of eleven dyslexic boys and age-matched controls were recorded during reading of text passages and pseudoword lists. For both text and pseudoword reading, the dyslexic readers exhibited more and much longer fixations, but relatively few regressions. Increased length of words and pseudowords led to a greater increase in number of fixations for dyslexic than normal readers. Comparisons across studies suggest that the present German dyslexic eye movement findings differ from English-based findings by a lower frequency of regressions (presumably due to the higher regularity of German) and from Italian findings by longer fixation duration (presumably due to the greater syllabic complexity of German).

Child↗

Children with dyslexia and right parietal lobe dysfunction: event-related potentials in response to words and pseudowords.

Hari and Renvall (Trends Cogn. Sci., 5 (2001) 525) proposed that dyslexic children suffer from sluggish attention deployment due to a right parietal lobe dysfunction. To examine this hypothesis, good and poor readers (12, 11-year-old boys in each group) had to read familiar words (low attentional demand) and pseudowords (high attentional demand). The amplitude of the event-related potential at around 100 ms post-stimulus (N1) in response to words and pseudowords was used as measure of attention deployment. Consistent with the attention deficit/right parietal lobe dysfunction hypothesis, poor readers showed lower N1 amplitudes in response to pseudowords, but not in response to words at central sites of the right hemisphere. However, poor readers also showed lower N1 amplitudes to both words and pseudowords at left frontal sites suggestive of an early deficit in activating phonological codes.

Attention↗

Dyslexia: verbal impairments in the absence of magnocellular impairments.

Sensitivity to dynamic visual and auditory stimuli was assessed in dyslexic children (Grade 7) who at school entrance had suffered from the well-established double-deficit of impaired phonological sensitivity and deficient rapid naming performance. A visual magnocellular deficit was assessed by the coherent motion detection task of the Oxford group. An auditory magnocellular deficit was assessed by the illusory sound movement perception task of Hari and Kiesilä. On both tasks our dyslexic subjects' performance was similar or even better than the performance of normally reading controls. Differences in the inclusion of ADHD cases in dyslexic samples is discussed as a potential explanation of differences in results.

Acoustic Stimulation↗