Biomedical subjects

J C Ziegler

Publications and source records attributed to J C Ziegler.

At least 19 recordsLinked to original sources

PubMed2001

Identical words are read differently in different languages.

It is hypothesized that written languages differ in the preferred grain size of units that emerge during reading acquisition. Smaller units (graphemes, phonemes) are thought to play a dominant role in relatively consistent orthographies (e.g., German), whereas larger units (bodies, rhymes) are thought to be more important in relatively inconsistent orthographies (e.g., English). This hypothesis was tested by having native English and German speakers read identical words and nonwords in their respective languages (zoo-Zoo, sand-Sand, etc.). Although the English participants exhibited stronger body-rhyme effects, the German participants exhibited a stronger length effect for words and nonwords. Thus, identical items were processed differently in different orthographies. These results suggest that orthographic consistency determines not only the relative contribution of orthographic versus phonological codes within a given orthography; but also the preferred grain size of units that are likely to be functional during reading.

Adolescent↗

PubMed2001

Can orthographic rimes facilitate naming?

Although the orthographic rime (body) is thought to play an important role in reading English, previous priming experiments found little or no evidence for facilitatory body-priming effects in the naming task. That is, hose primes NOSE no better than does a completely unrelated prime. In the present study, the hypothesis that facilitatory body-priming effects are typically masked by strong inhibitory onset effects was investigated. It was shown that when the onset of a prime was removed, facilitatory body priming could be obtained with stimuli that previously had produced no evidence of facilitation. The present study thus reconciles conflicting patterns concerning facilitation versus inhibition in body priming.

Adult↗

PubMed2001

Pseudohomophone effects in lexical decision: still a challenge for current word recognition models.

Computational models that implement a serial mechanism of phonological assembly predict interactions between the size of the pseudohomophone (PsH) effect and stimulus length. Models with frequency-sensitive word representations predict baseword frequency effects. These predictions were tested in a lexical-decision task. The results showed constant PsH effects across different word lengths (in favor of parallel phonological activation) and baseword frequency effects (in favor of frequency-sensitive representations). However, the baseword frequency effect was opposite of what the models predicted. This result is most easily accommodated by models that assume an orthographic verification mechanism. The plausibility of such a mechanism was further supported by the results of 2 additional experiments investigating the effects of response speed and spelling probability (feedback consistency) on the size of the PsH effect.

Adult↗

PubMed2000

Graphemes are perceptual reading units.

Graphemes are commonly defined as the written representation of phonemes. For example, the word 'BREAD' is composed of the four phonemes /b/, /r/, /e/ and /d/, and consequently, of the four graphemes 'B', 'R', 'EA', and 'D'. Graphemes can thus be considered the minimal 'functional bridges' in the mapping between orthography and phonology. In the present study, we investigated the hypothesis that graphemes are processed as perceptual units by the reading system. If the reading system processes graphemes as units, then detecting a letter in a word should be harder when this letter is embedded in a multi-letter grapheme than when it corresponds to a single-letter grapheme. In Experiment 1A, done in English, participants were slower to detect a target letter in a word when the target letter was embedded in multi-letter grapheme (i.e. 'A' in 'BEACH') than when it corresponded to a single-letter grapheme (i.e. 'A' in 'PLACE'). In Experiment 1B, this effect was replicated in French. In Experiment 2, done in English, this grapheme effect remained when phonemic similarity between the target letter alone and the target letter inside the word was controlled. Together, the results are consistent with the assumption that graphemes are processed as perceptual reading units in alphabetic writing systems such as English or French.

Humans↗

PubMed2000

Visual and phonological codes in letter and word recognition: evidence from incremental priming.

Critical issues in letter and word priming were investigated using the novel incremental priming technique. This technique adds a parametric manipulation of prime duration (or prime intensity) to the traditional design of a fast masked priming study. By doing so, additional information on the time course and nature of priming effects can be obtained. In Experiment 1, cross-case letter priming (a-A) was investigated in both alphabetic decision (letter/non-letter classification) and letter naming. In Experiment 2, cross-case word priming was investigated in lexical decision and naming. Whereas letter priming in alphabetic decision was most strongly determined by visual overlap between prime and target, word priming in lexical decision was facilitated by both orthographic and phonological information. Orthographic activation was stronger and occurred earlier than phonological activation. In letter and word naming, in contrast, priming effects were most strongly determined by phonological/articulatory information. Differences and similarities between letter and word recognition are discussed in the light of the incremental priming data.

Adult↗

PubMed2000

Phonology matters: the phonological frequency effect in written Chinese.

Does phonology play a role in silent reading? This issue was addressed in Chinese. Phonology effects are less expected in Chinese than in alphabetical languages like English because the basic units of written Chinese (the characters) map directly into units of meaning (morphemes). This linguistic property gave rise to the view that phonology could be bypassed altogether in Chinese. The present study, however, shows that this is not the case. We report two experiments that demonstrate pure phonological frequency effects in processing written Chinese. Characters with a high phonological frequency were processed faster than characters with a low phonological frequency, despite the fact that the characters were matched on orthographic (printed) frequency. The present research points to a universal phonological principle according to which phonological information is routinely activated as a part of word identification. The research further suggests that part of the classic word-frequency effect may be phonological.

Adult↗

PubMed2000

Linguistic difficulties in language and reading development constrain skilled adult reading.

This study investigated whether the quality and specification of phonological representations in early language development would predict later skilled reading. Two perceptual identification experiments were performed with skilled readers. In Experiment 1, spelling difficulties in Grade 1 were used as a proxy measure for poorly specified representations in early language development. In Experiment 2, difficulties in perceiving and representing liquid and nasalized phonemes in final consonant clusters were used for the same purpose. Both experiments showed that words that were more likely to develop underspecified lexical representations in early language development remained more difficult in skilled reading. This finding suggests that early linguistic difficulties in speech perception and structuring of lexical representations may constrain the long-term organization and dynamics of the skilled adult reading system. The present data thus challenge the assumption that skilled reading can be fully understood without taking into account linguistic constraints acting upon the beginning reader.

Adult↗

PubMed1999

SCRIPTKELL: a tool for measuring cognitive effort and time processing in writing and other complex cognitive activities.

We present SCRIPTKELL, a computer-assisted experimental tool that makes it possible to measure the time and cognitive effort allocated to the subprocesses of writing and other cognitive activities. SCRIPTKELL was designed to easily use and modulate Kellogg's (1986) triple-task procedure, which consists of a combination of three tasks: a writing task (or another task), a reaction time task (auditory signal detection), and a directed retrospection task (after each signal detection during writing). We demonstrate how this tool can be used to address several novel empirical and theoretical issues. In sum, SCRIPTKELL should facilitate the flexible realization of experimental designs and the investigation of critical issues concerning the functional characteristics of complex cognitive activities.

Cognition↗

PubMed1999

From print to meaning: an electrophysiological investigation of the role of phonology in accessing word meaning.

This study investigated the role and time-course of phonology in accessing meaning during silent reading. In Experiment 1, the homophone effect was replicated in a semantic categorization task in French. When deciding whether a stimulus belonged to a semantic category (FOOD), subjects made more errors to homophones (MEET) than to orthographic controls (MELT). In Experiment 2, event-related brain potentials (ERPs) were used to study the online development of this effect. If access to meaning was mediated by phonology, smaller N400 components should be obtained to homophones than to orthographic controls. The ERP data exhibited a full-blown N400 component to homophones that did not differ from the N400 to controls. No differences between homophones and controls were found before the N400. After the N400, however, homophones differed from controls, with ERPs to homophones being similar to those of correct category exemplars. The results suggest that the final selection of a word's meaning does not depend on its phonological form. This result is incompatible with a strong phonological view according to which the only way to meaning is via a word's phonology.

Adult↗

PubMed1998

Mechanism of inhibition of rat liver bilirubin UDP-glucuronosyltransferase by triphenylalkyl derivatives.

A series of potent and competitive inhibitors of UDP-glucuronosyltransferase derived from 7,7,7-triphenylheptanoic acid has been synthesized in order to probe the active site of the isozyme involved in the glucuronidation of the endogenous toxic compound, bilirubin IX alpha. Like triphenylalkylcarboxylic acids, triphenyl alcohols were found to be very effective competitive inhibitors of the reaction (Ki 12 to 180 microM). Superimposition of the best inhibitors with bilirubin by computer modeling showed a marked spatial similarity, which accounts for the observed competitive-type inhibition. The bulky triphenylmethyl moiety of the inhibitor superimposed well on the part of the bilirubin molecule containing three of the four pyrrole rings. In agreement, substitution of the triphenylmethyl moiety by planar structures such as fluorenyl or indenyl rings completely suppressed the inhibition. In addition, the weak inhibition exerted by the shortest carboxylic acids could be related to the higher acidity of these molecules. The inhibition potency depended on the acidity of the molecules; the more acidic, the less inhibitory, suggesting that the presence of a negative charge on the inhibitor molecule prevents bilirubin glucuronidation. Based on these results, a reaction mechanism for bilirubin glucuronidation is postulated.

Animals↗

PubMed1998

No more problems in Coltheart's neighborhood: resolving neighborhood conflicts in the lexical decision task.

In the area of visual word recognition, there is considerable disagreement as to whether neighborhood effects for words in the lexical decision task are facilitatory or inhibitory: While they seem to be mostly facilitatory in English, they tend to be absent or inhibitory in French or Spanish. The present study investigated the possibility that the facilitatory neighborhood effect obtained in English is due to the fact that most neighbors in English are body neighbors (i.e. they share the same orthographic rime). Our results showed that when words were matched for orthographic neighborhood (N), the effects of body neighbors (BN) were facilitatory (i.e. shorter reaction times for words with many body neighbors than for words with few body neighbors). In contrast, when words are matched for BN, the effects of N are unreliable with a tendency towards inhibition. In conclusion, it appears that research conducted in English has always found neighborhood effects to be facilitatory because of the dominant role of body neighbors in English. In contrast, neighborhood effects in French and Spanish may have been more ambiguous because these languages either do not confound N and BN, or they do not require a greater sensitivity to the body/rime unit.

Humans↗

PubMed1998

A phoneme effect in visual word recognition.

In alphabetic writing systems like English or French, many words are composed of more letters than phonemes (e.g. BEACH is composed of five letters and three phonemes, i.e./biJ/). This is due to the presence of higher order graphemes, that is, groups of letters that map into a single phoneme (e.g. EA and CH in BEACH map into the single phonemes /i/ and /J/, respectively). The present study investigated the potential role of these subsyllabic components for the visual recognition of words in a perceptual identification task. In Experiment 1, we manipulated the number of phonemes in monosyllabic, low frequency, five-letter, English words, and found that identification times were longer for words with a small number of phonemes than for words with a large number of phonemes. In Experiment 2, this 'phoneme effect' was replicated in French for low frequency, but not for high frequency, monosyllabic words. These results suggest that subsyllabic components, also referred to as functional orthographic units, play a crucial role as elementary building blocks of visual word recognition.

Humans↗

PubMed1998

Simulating individual word identification thresholds and errors in the fragmentation task.

This article presents a large-scale study that collected word identification thresholds and errors in the fragmentation task for all four-letter French words. In the first part of this article, we identify some of the variables (e.g., word frequency, neighborhood size, letter confusability) that affect performance in the fragmentation task. In the second part, we analyze individual response performance and identify different response strategies. We demonstrate that the interactive activation model can account for individual response strategies by adapting two of its original parameters: word-letter feedback and letter-word inhibition. In the third part, we demonstrate that the adaptation of the interactive activation model to the fragmentation task makes it possible to successfully simulate a facilitatory frequency effect on identification thresholds, an inhibitory neighborhood size effect on error rates, and an inhibitory letter confusability effect on identification thresholds. When the task-specific processes of the fragmentation task are specified and individual response strategies are considered, the interactive activation model provides a parsimonious architecture for modeling the task-independent processes involved in word perception.

Attention↗

PubMed1997

Monometoxytrityl derivatives of uridine as inhibitors of a human recombinant UDP-glucuronosyltransferase: UGT1*6.

A series of inhibitors of the human liver recombinant UDP-glucuronosyltransferase 1*6 derived from uridine were synthetized as probes of the binding site of the cosubstrate, UDP-glucuronic acid. If triphenylmethanol or uridine alone failed to inhibit the glucuronidation of 4-methylumbelliferone, the trityl derivatives of uridine were found to be very effective inhibitors of the enzyme (Ki 4.4 to 73 microM). The type of inhibition (competitive or mixed) varied with the substitutions on the uracile or on the triphenylmethyl moiety by halogen atoms or methyl groups. Structural features for the binding of the cofactor are postulated.

Animals↗

PubMed1997

Phonology can help or hurt the perception of print.

Phonological manipulations affect performance in a letter search task that requires only a shallow level of processing. In Experiment 1, phonology reduced accuracy in the letter search task when a pseudohomophone (GAIM) contained a target letter ("i") that was missing in the spelling of its (nonpresented) sound-alike base word (GAME). In Experiment 2, phonology increased accuracy in the letter search task when the target letter was present in both the spelling of the pseudohomophone and the spelling of its sound-alike base word ("m" in GAIM and GAME). In Experiment 3, we showed that the phonology-hurts effect of Experiment 1 is not peculiar to nonword letter strings but generalizes to familiar words. In Experiment 4, we obtained a phonology-hurts effect on correct response times when stimuli were visible until participants responded (stimuli were not masked).

Humans↗

PubMed1996

Management of the intraaortic balloon pump patient. Pharmacologic considerations.

This article reviews the common pharmacologic agents used in conjunction with the IABP for treatment of LV failure. The complex interaction between the IABP and pharmacologic agents must be carefully monitored to optimize outcome in this critically ill patient group. It is important that ICU nurses be aware of the treatment goals and their rationale, as well as monitored parameters which detect, trend and predict the direction of hemodynamic change. By using these early indicators of hemodynamics, early information can be given to the physician and intervention can be implemented on a timely basis. Early and appropriate intervention can improve outcome in many patients and may ultimately reduce costs.

Critical Care↗

PubMed1992

Selective and potent inhibition of different hepatic UDP-glucuronosyltransferase activities by omega,omega,omega-triphenylalcohols and UDP derivatives.

A homologous series of omega,omega,omega-triphenylalcohols and corresponding omega,omega,omega-triphenylalkyl-UDP derivatives was synthesized and tested as inhibitors of UDP-glucuronosyltransferase (UGT) activity in rat liver microsomes, with 1-naphthol, testosterone and bilirubin as substrates. Introduction of the UDP moiety in the triphenylalcohols increased their inhibition potency markedly toward the isoforms which glucuronidate 1-naphthol and testosterone, but strongly decreased that toward bilirubin. The inhibiting potency of the UDP-derivatives increased as a function of the length of the hydrocarbon chain. The best inhibitor 7,7,7-triphenylheptyl-UDP showed an I50 of 30 and 10 microM for 1-naphthol and testosterone glucuronidation, respectively; even a 1 mM concentration of the compound had little, if any, effect on bilirubin glucuronidation. The inhibition by 7,7,7-triphenylheptyl-UDP was mixed-type toward 1-naphthol, and non competitive toward testosterone (apparent K(i) 30 microM and 1.7 microM, respectively); on the other hand, the inhibition was competitive toward the common substrate UDP-glucuronic acid (apparent K(i) 1.9-1.2 microM). In addition, 7,7,7-triphenylheptyl-UDP (0.25-0.50 mM) almost inhibited glucuronidation of 1-naphthol and testosterone catalyzed by the recombinant rat liver UGT-2B1 and human liver UGT-1A1, whose cDNA has been expressed in V79 cells. In conclusion, the data indicate that 7,7,7-triphenyheptyl-UDP interacted competitively with the UDP binding site of UGT. The results also indicate that it is possible to design transition state analogue inhibitors with specificity for different UGT forms.

Alcohols↗

PubMed1992

Psychiatric disturbances in metachromatic leukodystrophy. Insights into the neurobiology of psychosis.

Metachromatic leukodystrophy is a rare inherited disorder of the nervous system. Symptoms initially can present during childhood, adolescence, or adulthood. Psychiatric symptoms, including complex auditory hallucinations and bizarre delusions, are a prominent feature of metachromatic leukodystrophy presenting when the patient is between 12 and 30 years. One hundred twenty-nine published case reports were reviewed, focusing on the presence of psychosis. Psychosis was present in 53% of the published case reports of adolescent and early adult-onset metachromatic leukodystrophy, a much higher prevalence than that seen with other primary neurological disorders. The pathological lesion of metachromatic leukodystrophy is demyelination of the central and peripheral nervous systems, particularly the subfrontal white matter, suggesting that psychosis may result from the disruption of corticocortical and corticosubcortical connections, especially involving the frontal lobes. While similar lesions appear in the infantile, juvenile, and late adult forms of metachromatic leukodystrophy, psychotic symptoms were reported only in those cases presenting in adolescence and young adulthood, suggesting that age is another important neurobiological factor in the development of psychosis.

Adolescent↗