Biomedical subjects

Zvia Breznitz

Publications and source records attributed to Zvia Breznitz.

9 recordsLinked to original sources

PubMed2005

Visual, auditory and cross-modal processing of linguistic and nonlinguistic temporal patterns among adult dyslexic readers.

This study examined visual, auditory, and cross-modal temporal pattern processing at the nonlinguistic and sublexical linguistic levels, and the relationships between these abilities and decoding skill. The central question addressed whether dyslexic readers are impaired in their perception of timing, as assessed by sensitivity to rhythm. Participants were college-level adult dyslexic and normal readers. The dyslexic adults evidenced generalized impairment in temporal processing: they were less accurate and slower than normal readers when required to detect the temporal gap that differentiated pairs of patterns. Impairment was greatest when processing visual syllables. Temporal pattern processing correlated to decoding ability only among normal readers. It is suggested that high-functioning dyslexics may cope with temporal processing problems by adopting a predominantly holistic, orthographic strategy when decoding. It is proposed that there may be cumulative effects of processing demands from different sources including modality, stimulus complexity, and linguistic demands, and that combinations of these may interact to impact temporal processing ability. Moreover, there may be fundamentally distinct and dissociable temporal processing abilities, each of which may be differently linked developmental dyslexia.

Adult↗

PubMed2005

Impaired phonological and orthographic word representations among adult dyslexic readers: evidence from event-related potentials.

The authors examined the processing of phonological and orthographic word representations among 17 dyslexic and 16 normal college-level readers using Event-Related Potential measures. They focused on 2 early components--the P200 and the P300. The results revealed P200 and P300 components of lower amplitude and later latency among dyslexic readers than among normal readers for both types of word representation. Group differences were greatest for phonological representations. In addition, the authors observed greater time gaps among dyslexic readers than among normal readers between different processing stages (i.e., between P2 and P3 peaks, between P3 and reaction time). Combined, the data suggest a consistent speed-of-processing deficit among dyslexic readers that is evident within and between stages of cognitive processing. The results are discussed in the context of deficits in stimulus encoding and working memory. In addition, the authors discuss the need for accurate timing and synchronization of phonological and orthographic codes for efficient word recognition.

Adult↗

PubMed2004

Electrocortical measures during a lexical decision task: a comparison between elementary school-aged normal and dyslexic readers and adult normal and dyslexic readers.

The authors examined the differences in performance between 30 dyslexic readers in 4th grade, 30 dyslexic readers attending university, and age-matched normal readers for both groups on a lexical decision task to evaluate the underlying factors of dyslexia that persist into adulthood. In both age groups, the dyslexic readers were significantly less accurate and slower than were the normal readers when reading word lists and in connected text. Electrophysiological data showed 2 main distinguishing components. Results supported the hypothesis that the dyslexia phenomenon is characterized by inaccurate and slow word-recognition skills. In addition, the authors found slow performance speed among all dyslexic readers in all stages of processing.

Adolescent↗

PubMed2003

Speed of lower-level auditory and visual processing as a basic factor in dyslexia: electrophysiological evidence.

This study investigated speed of processing (SOP) among college-level adult dyslexic and normal readers in nonlinguistic and sublexical linguistic auditory and visual oddball tasks, and a nonlinguistic cross-modal choice reaction task. Behavioral and electrophysiological (ERP) measures were obtained. The results revealed that between both groups, reaction times (RT) were longer and the latencies of P2 and P3 components occurred later in the visual as compared to auditory oddball tasks. RT and ERP latencies were longest in the cross-modal task. RT and ERP latencies were delayed among dyslexic as compared to normal readers across tasks. On the oddball tasks, group differences in brain activity were observed only when responding to low-probability targets. These differences were largest for the P3 component, and most pronounced in the case of phonemes. The gap between ERP latencies in the visual versus the auditory modalities for each component was larger among dyslexic as compared to normal readers, and was particularly evident at the linguistic level. A hypothesis is proposed that suggests an amodal, basic SOP deficit among dyslexic readers. The slower cross-modal SOP is attributed to slower information processing in general and to disproportionate "asynchrony" between SOP in the visual versus the auditory system. It is suggested that excessive asynchrony in the SOP of the two systems may be one of the underlying causes of dyslexics' impaired reading skills.

Adult↗

PubMed2003

Speed of processing of the visual-orthographic and auditory-phonological systems in adult dyslexics: the contribution of "asynchrony" to word recognition deficits.

This study investigated whether "asynchrony" in speed of processing (SOP) between the visual-orthographic and auditory-phonological modalities contributes to word recognition deficits among adult dyslexics. Male university students with a history of diagnosed dyslexia were compared to age-matched normal readers on a variety of experimental measures while event-related potentials and reaction time data were collected. Measures were designed to evaluate auditory and visual processing for non-linguistic (tones and shapes) and linguistic (phonemes and graphemes) low-level stimuli as well as higher-level orthographic and phonological processing (in a lexical decision task). Data indicated that adult dyslexic readers had significantly slower reaction times and longer P300 latencies than control readers in most of the experimental tasks and delayed P200 latencies for the lexical decision task. Moreover, adult dyslexics revealed a systematic SOP gap in P300 latency between the auditory/phonological and visual/orthographic processing measures. Our data support and extend previous work that found SOP asynchrony to be an underlying factor of childhood dyslexia. The present data suggests, however, that among adult dyslexics the between modalities asynchrony occurs at later processing stages than in children.

Adult↗

PubMed2003

The speech and vocalization patterns of boys with ADHD compared with boys with dyslexia and boys without learning disabilities.

This research study dealt with an inquiry into the speech and vocalization patterns of boys with Attention Deficit Hyperactivity Disorder (ADHD) who were not under the influence of stimulating medication, compared with the speech and vocalization patterns of boys with reading disabilities and a control group of learners without learning disabilities. The voices of 105 participants were recorded during interviews and analyzed in the laboratory using equipment that examined the temporal speech patterns and physical features of vocalization. The speech patterns were examined with a frequency examination, speech unit length duration, and correlation between the vocalization and pauses in the speech unit. The physical features of vocalization were examined with volume and frequency scales. The research results indicated that the speech and vocalization patterns of boys with ADHD were significantly different from those of boys with reading disabilities and from the boys in the control group. The results support the assumption that speech and vocalization indicators can be used as objective indicators for the diagnosis of hyperactivity syndrome with attention and concentration difficulties.

Articulation Disorders↗

PubMed2003

Speed of phonological and orthographic processing as factors in dyslexia: electrophysiological evidence.

The author investigated the hypothesis that speed of processing in the phonological and orthographic systems is one of the underlying variables of word-reading effectiveness. Speed of processing was assessed using measures of behavioral reaction time and electrophysiological latencies during phonological and orthographic task performance. Participants were 20 dyslexic and 20 normal-reading, male college students. An electrophysiological component complex (N1-P2-N2), as well as 2 other components (P3 and N4), was identified in both groups on each of the experimental tasks. Significant group differences were obtained only on the phonological tasks. Speed of processing during phonological judgment tasks was significantly prolonged among the dyslexic readers compared with the controls as reflected by P2, P3, and N4 latencies and reaction time. Between-task comparisons revealed significantly prolonged P2, P3, and N4 latencies on phonological compared with orthographic tasks in both dyslexic and normal readers, indicating that phonological classification of words may demand more time than orthographic classification. However, the gap score between speed of processing on the phonological and orthographic tasks was larger among the dyslexic readers and was observed mainly in P3 latency and reaction time. The highest correlation between word-reading accuracy score and the experimental measures was obtained in the dyslexic group with P3 latency gap score and in the control group with P2 latency gap score. The author proposes that slow phonological processing may cause "asynchrony" between the processing speeds within and between phonological and orthographic systems and may lead to a lack of efficient integration among the various subprocesses activated in reading, may slow down reading rate, and may impair word-reading effectiveness.

Adult↗

PubMed2002

Automatic and controlled verbal-information processing in patients with frontal lobe lesions.

The selectivity of frontal lobe lesion effects in the domains of verbal-information processing has not been well established. The authors hypothesized that capacity-limited controlled processing would be more impaired than automatic processing in frontal lobe patients (FLPs). Fifteen FLPs were compared with 2 matched control groups: 14 posterior-lesion patients and 15 normal controls. Both behavioral and event-related brain potential (ERP) measures were collected. Results suggest that both automatic and controlled processing were affected by frontal lobe lesions. ERP results indicated that the main dificulty for the FLPs was in the perceptual stage of information processing. This rather unexpected result may be explained by a basic difficulty of FLPs in attending to a new stimulus in order to process it.

Adult↗

PubMed2002

Distractibility after frontal lobe lesions: behavioral and event-related brain potential evidence.

The authors used a semantic priming paradigm to investigate the distractibility phenomenon of patients with frontal lobe lesions (FLPs). They tested two distractibility categories: an inhibition category requiring inhibition of an automatic response and a distraction category caused by irrelevant, unexpected stimuli. Fifteen FLPs were compared with 2 matched control groups: 14 posterior-lesion patients and 15 normal controls. Both behavioral and event-related brain potential (ERP) measures were used. The results suggest that, although there were differences in performance between the FLP group and the control groups, there was no evidence that the FLPs had difficulty specifically with the inhibition category. The most consistent ERP result was that the FLP group had longer N100 latencies than either control group. On the basis of these results, the authors hypothesize that FLPs have difficulty focusing on and starting to process a new stimulus. The authors also discuss the unique contribution ERP evidence has made to cognitive studies.

Adult↗