[Oxidized fibrinogen and its relationship with hemostasis disturbances and endothelial dysfunction during coronary heart disease and myocardial infarction].

The highest oxidative modification of fibrinogen was found in acute myocardial infarction (MI) men and it was 1.26 and 1.56 times higher in comparison with coronary heart disease (CHD) men with anamnesis of MI and with men without CHD, respectively. Increased oxidized fibrinogen level correlated with increased levels of plasma lipid peroxidation products, Willebrand factor, fibrin degradation products, accelerated leukocyte-platelet aggregation and decreased level of plasma NO metabolites. Associations of oxidized fibrinogen with MI and typical parameters of thrombosis and hypercoagulatory hemostasis disturbances and endothelial function were revealed.

Automatic versus strategic effects of phonology and orthography on auditory lexical access in brain-damaged patients as a function of inter-stimulus interval.

The influence of both phonological and orthographic information on auditory lexical access was examined in left- and right-hemisphere-damaged individuals using a lexical decision paradigm. Subjects were presented with prime-target pairs that were either phonologically related (tooth-youth), orthographically related (touch-couch), both phonologically and orthographically related (blood-flood), or unrelated (bill-tent), at two inter-stimulus intervals (ISI)--100 ms and 750 ms--to tap more automatic versus more strategic processing. All groups demonstrated effects of orthography at both ISIs (facilitory at 100 ms ISI and inhibitory at 750 ms ISI), supporting the findings by Leonard and Baum (1997) that effects of orthography emerge independent of site of brain damage and suggesting that orthographic effects in auditory word recognition tend to be largely strategic. A facilitory effect of phonology was also found for all groups at both ISIs. The findings are discussed in relation to theories of lexical activation in brain-damaged individuals.

The effect of compressed speech on the ability of right-hemisphere-damaged patients to use context.

The ability of RHD patients to use context under conditions of increased processing demands was examined. Subjects monitored for words in auditorily presented sentences of three context types-normal, semantically anomalous, and random, at three rates of speech normal, 70% compressed (Experiment 1) and 60% compressed (Experiment 2). Effects of semantics and syntax were found for the RHD and normal groups under the normal rate of speech condition. Using compressed rates of speech, the effect of syntax disappeared, but the effect of semantics remained. Importantly, and contrary to expectations, the RHD group was similar to normals in continuing to demonstrate an effect of semantic context under conditions of increased processing demands. Results are discussed relative to contemporary theories of laterality, based on studies with normals, that suggest that the involvement of the left versus right hemisphere in context use may depend upon the type of contextual information being processed.

Lexical effects on the phonetic categorization of speech: the role of acoustic structure.

This study examines the extent to which acoustic parameters contribute to lexical effects on the phonetic categorization of speech. Experiment 1 was designed to replicate previous findings. Two test continua were created varying in voice onset time. Results of both identification and reaction time (RT) range data showed an effect of lexical status at the phonetic boundary, but only in the slowest RT ranges, suggesting that lexical effects on phonetic categorization are postperceptual. Experiment 2 explored whether the lexical effect would emerge when the stimulus continua more nearly approximated the parameter values of natural speech. Both identification and RT range data indicated that the lexical effect disappeared. These results suggest that without attention to the acoustic structure of the stimuli, the role of top-down processing in phonetic categorization may be overemphasized.

Phonological, semantic, and mediated priming in aphasia.

An auditory lexical decision task was conducted to examine rhyme, semantic, and mediated priming in nonfluent and fluent aphasic patients and normal controls. Overall, monosyllabic word targets were responded to faster when preceded by rhyming word and nonword primes than unrelated primes. Similarly, semantically related primes facilitated lexical decisions to word targets. No evidence of mediated priming emerged. Results for individual subjects suggest differences in patterns across the subject groups. Implications of the findings for the integrity of lexical access in aphasic patients are considered.

Contextual influences on phonetic identification in aphasia: the effects of speaking rate and semantic bias.

Two experiments examined the influence of context on stop-consonant voicing identification in fluent and nonfluent aphasic patients and normal controls. Listeners were required to label the initial stop in a target word varying along a voice onset time (VOT) continuum as either voiced or voiceless ([b]/[p] or [d]/[t]). Target stimuli were presented in sentence contexts in which the rate of speech of the sentence context (Experiment 1) or the semantic bias of the context (Experiment 2) was manipulated. The results revealed that all subject groups were sensitive to the contextual influences, although the extent of the context effects varied somewhat across groups and across experiments. In addition, a number of patients in both the fluent and nonfluent aphasic groups could not consistently identify even endpoint stimuli, confirming phonetic categorization impairments previously shown in such individuals. Results are discussed with respect to the potential reliance by aphasic patients on higher level context to compensate for phonetic perception deficits.

On-line sensitivity to local and long-distance syntactic dependencies in Broca's aphasia.

Seven agrammatic Broca's aphasics and ten normal control subjects performed a word-monitoring task to determine the degree to which violations of syntax would affect word-monitoring performance. Both local and long-distance dependencies were explored, as well as the effects of additional interceding words. Results indicated that normal subjects' word-monitoring latencies were significantly slower to target words in ungrammatical contexts for both local and long-distance dependencies. Aphasic subjects showed a significant sensitivity to ungrammaticality in the local dependency condition; for the long-distance dependencies, however, no reaction time difference emerged between grammatical and ungrammatical stimuli. Results are discussed in relation to current theories of the nature of agrammatic deficits.

An acoustic analysis of rate of speech effects on vowel production in aphasia.

The present investigation examined the production of tense and lax vowel duration differences at two speaking rates in the speech of 10 nonfluent aphasics, 8 fluent aphasics, and 10 normal control subjects. Subjects produced four repetitions of each of the vowels [i e ae o u I epsilon upsilon --] at each speaking rate. Acoustic analyses revealed that subjects in all three groups were able to manipulate overall rate of speech. In addition, normal controls and fluent aphasic subjects produced vowels under the fast rate condition which were significantly shorter than those under the slow rate condition. Despite a change in overall speaking rate, the nonfluent aphasics did not exhibit a significant difference in vowel duration at the two rates of speech, suggesting a deficit in the implementation of this temporal parameter. Both normal controls and fluent aphasic patients produced nonoverlapping distributions of tense and lax vowels at both speaking rates. In contrast, the nonfluent aphasics demonstrated a great deal of overlap in the distribution of tense and lax vowel durations at the fast rate. Results are discussed in relation to the nature of the speech production deficits in nonfluent and fluent aphasic patients.

Anticipatory coarticulation in aphasia: effects of utterance complexity.

The magnitude and extent of anticipatory coarticulation were examined in groups of fluent and nonfluent aphasic patients and normal control subjects. One- and two-syllable target utterances were elicited at slow and fast rates of speech with or without a consonant intervening between the target consonant and vowel, and with or without a preceding schwa, to manipulate utterance complexity. Acoustic analyses (F2 and centroid frequencies) revealed that both groups of aphasic patients exhibited relatively normal patterns of anticipatory coarticulation. However, small but significant differences among the groups emerged in certain conditions. Surprisingly, increased utterance complexity was not found to reduce coarticulatory effects to a greater degree in the nonfluent relative to the fluent aphasic group. Perceptual tests largely confirmed the acoustic analyses.

Fricative production in aphasia: effects of speaking rate.

The present study investigated the effects of alterations in speaking rate on the production of the fricatives [f s v z] by 10 nonfluent aphasics, 7 fluent aphasics, and 10 normal control subjects. An examination of fricative consonants allowed us to address whether previous conflicting findings for vowels and stop consonants produced by nonfluent aphasic patients were due to basic differences in the treatment of major sound classes or to differences in the length of the segments under investigation. Acoustic analyses revealed that all subjects were able to manipulate rate of speech. Both groups of aphasic patients produced rate changes that were smaller in magnitude than those of the normal subjects. Further analyses demonstrated that both the fluent and the nonfluent aphasic patients were able to instantiate the rate changes in terms of fricative duration. However, both patient groups exhibited breakdowns in the ability to maintain contrastive differences between voiced and voiceless fricatives, particularly at fast rates of speech. Possible sources of these breakdowns are explored.

Production of stress retraction by left- and right-hemisphere-damaged patients.

An acoustic-perceptual investigation of a phonological phenomenon in which stress is retracted in double-stressed words (e.g., thirTEEN vs THIRteen MEN) was undertaken to identify the locus of functional impairments in speech prosody. Subjects included left-hemisphere-damaged (LHD) and right-hemisphere-damaged (RHD) patients and nonneurological controls. They were instructed to read sentences containing double-stressed target words in the presence of a clause boundary or its absence. Whereas all three groups of subjects were capable of manipulating the acoustic parameters that signal a shift in stress, there were some differences between the performance of the patient groups and that of the normal controls. Further, stress production deficits were more severe in LHD aphasic patients than in RHD patients. LHD speakers exhibited deficits in the control of both temporal and F0 cues. Their F0 disturbance appears to be secondary to a primary deficit in temporal control at the phase or sentence level, as an increased number of continuation rises found for the LHD patients seemed to arise from lengthy pauses within sentences. Findings are highlighted to address the nature of breakdown in speech prosody and the competing views of prosodic lateralization.

The ability to perceive and comprehend intonation in linguistic and affective contexts by brain-damaged adults.

Receptive tasks of linguistic and affective prosody were administered to 9 right-hemisphere-damaged (RHD), 10 left-hemisphere-damaged (LHD), and 10 age-matched control (NC) subjects. Two tasks measured subjects' ability to discriminate utterances based solely on prosodic cues, and six tasks required subjects to identify linguistic or affective intonational meanings. Identification tasks manipulated the degree to which the auditory stimuli were structured linguistically, presenting speech-filtered, nonsensical, and semantically well-formed utterances in different tasks. Neither patient group was impaired relative to normals in discriminating prosodic patterns or recognizing affective tone conveyed suprasegmentally, suggesting that neither the LHD nor the RHD patients displayed a receptive disturbance for emotional prosody. The LHD group, however, was differentially impaired on linguistic rather than emotional tasks and performed significantly worse than the NC group on linguistic tasks even when semantic information biased the target response.

Unilateral brain damage, prosodic comprehension deficits, and the acoustic cues to prosody.

Stimuli from two previously presented comprehension tasks of affective and linguistic prosody (Pell & Baum, 1997) were analyzed acoustically and subjected to several discriminant function analyses, following Van Lancker and Sidtis (1992). An analysis of the errors made on these tasks by left-hemisphere-damaged (LHD) and right-hemisphere-damaged (RHD) subjects examined whether each clinical group relied on specific (and potentially different) acoustic features in comprehending prosodic stimuli (Van Lancker & Sidtis, 1992). Analyses also indicated whether the brain-damaged patients tested in Pell and Baum (1997) exhibited perceptual impairments in the processing of intonation. Acoustic analyses of the utterances reaffirmed the importance of F0 cues in signaling affective and linguistic prosody. Analyses of subjects' affective misclassifications did not suggest that LHD and RHD patients were biased by different sets of the acoustic features to prosody in judging their meaning, in contrast to Van Lancker and Sidtis (1992). However, qualitative differences were noted in the ability of LHD and RHD patients to identify linguistic prosody, indicating that LHD subjects may be specifically impaired in decoding linguistically defined categorical features of prosodic patterns.

Rhyme priming in aphasia: the role of phonology in lexical access.

The present experiment was conducted to explore the facilitory effects of rhyme in lexical processing in brain-damaged individuals. Normal subjects and non-fluent and fluent aphasic subjects performed auditory lexical decision and rhyme judgement tasks, in which prime-target pairs were phonologically related (either identical or rhyming) or unrelated. Results revealed rhyme facilitation of lexical decisions to real-word targets for normal and non-fluent aphasic subjects; for fluent aphasic subjects, results were equivocal. In the rhyme judgement task, facilitory effects of rhyme were found for all three groups with real-word targets. None of the groups showed clear rhyme facilitation effects with non-word targets in either task. Findings are discussed with reference to the role of phonology in lexical processing in normal and aphasic populations.

Rate of speech effects in aphasia: voice onset time.

This study investigated the ability to produce appropriate voice onset time (VOT) contrasts under conditions of rate modulation in groups of nonfluent aphasic subjects, fluent aphasic subjects, and nonneurological controls. Acoustic analyses of the consonants [b d g p t k] produced in the context of the vowels [i e a o u] at two different rates of speech revealed that normal subjects' VOTs were significantly shorter at the fast rate of speech relative to the slow/normal rate, as expected. In addition, the rate change had a significantly greater effect on voiceless stops as compared to voiced and on velar consonants as compared to labials and alveolars. The nonfluent aphasic patients exhibited a similar pattern except that no differences in magnitude of rate-related changes were found across place of articulation. Further, similar to previous studies, the nonfluent aphasic patients produced voice and voiceless consonants with somewhat overlapping VOT distributions, indicating an impairment in temporal integration in these subjects. Finally, the fluent aphasic patients demonstrated a surprisingly aberrant pattern of results, with VOTs under th fast condition shorter than under the slow, but no differences in magnitude of change across place of articulation or voicing categories. The results are discussed in relation to the nature of speech production deficits in both nonfluent and fluent aphasic patients. Implications for remediation are considered.

Speech timing subsequent to brain damage: effects of utterance length and complexity.

Acoustic analyses of syllable durations were conducted in order to address several hypotheses concerning deficits in the control of speech timing subsequent to focal brain damage. Groups of nonfluent and fluent aphasics, right-hemisphere-damaged patients, and normal controls produced monosyllabic root syllables in medial and final position in the context of short and long sentences and syntactically simple and complex sentences. Durations of the target syllable as a proportion of the utterance were compared across contexts and groups. Somewhat surprisingly, the results revealed relatively normal temporal patterns in all subject groups, with the main exception emerging for the nonfluent aphasic patients who failed to demonstrate normal phrase-final lengthening effects. Implications of the findings for theories of temporal control in brain-damaged patients are considered.

The influence of neighborhood density on phonetic categorization in aphasia.

The present study examined the contribution of lexically based sources of information to acoustic-phonetic processing in fluent and nonfluent aphasic subjects and age-matched normals. To this end, two phonetic identification experiments were conducted which required subjects to label syllable-initial bilabial stop consonants varying along a VOT continuum as either /b/ or /p/. Factors that were controlled included the lexical status (word/nonword) and neighborhood density values corresponding to the two possible syllable interpretations in each set of stimuli. Findings indicated that all subject groups were influenced by both lexical status and neighborhood density in making phonetic categorizations. Results are discussed with respect to theories of acoustic-phonetic perception and lexical access in normal and aphasic populations.

Compensation for jaw fixation by aphasic patients.

The ability to compensate for fixation of the jaw by a bite block was investigated in 6 nonfluent aphasics, 6 fluent aphasics, and 10 normal control subjects. Acoustic analyses of the vowels [i u a ae] and fricatives [s s] revealed substantial but incomplete compensation for the perturbation in all three subject groups. Perceptual identification scores and quality ratings by naive and phonetically trained listeners indicated poorer identification of the high vowels [i u] under compensatory conditions relative to normal production. Of particular interest was the fact that all three groups of subjects exhibited similar patterns of results. The findings suggest that any deficit in speech motor programming demonstrated by the nonfluent aphasic patients did not affect compensatory abilities. Results are discussed with respect to normal speech adaptation skills and the nature of articulatory breakdown in nonfluent aphasia.

Temporal dimensions of consonant and vowel production: an acoustic and CT scan analysis of aphasic speech.

This study explored a number of temporal (durational) parameters of consonant and vowel production in order to determine whether the speech production impairments of aphasics are the result of the same or different underlying mechanisms and in particular whether they implicate deficits that are primarily phonetic or phonological in nature. Detailed analyses of CT scan lesion data were also conducted to explore whether more specific neuroanatomical correlations could be made with speech production deficits. A series of acoustic analyses were conducted including voice-onset time, intrinsic and contrastive fricative duration, and intrinsic and contrastive vowel duration as produced by Broca's aphasics with anterior lesions (A patients), nonfluent aphasics with anterior and posterior lesions (AP patients), and fluent aphasics with posterior lesions (P patients). The constellation of impairments for the anterior aphasics including both the A and AP patients suggests that their disorder primarily reflects an inability to implement particular types of articulatory gestures or articulatory parameters rather than an inability to implement particular phonetic features. They display impairments in the implementation of laryngeal gestures for both consonant and vowel production. These patterns seem to relate to particular anatomical sites involving Broca's area, the anterior limb of the internal capsule, and the lowest motor cortex areas for larynx and tongue. The posterior patients also show evidence of subtle phonetic impairments suggesting that the neural instantiation of speech may require more extensive involvement, including the perisylvian area, than previously suggested.

The role of fundamental frequency and duration in the perception of linguistic stress by individuals with brain damage.

Two tests of the ability of individuals with left-hemisphere damage (LHD) and right-hemisphere damage (RHD) and non-brain-damaged participants to identify phonemic and emphatic stress contrasts were undertaken. From a set of naturally produced base stimuli, two additional stimulus sets were derived. In one, fundamental frequency (F0) cues to stress were neutralized, whereas in the other duration cues were effectively neutralized. Results demonstrated that individuals with LHD were unable to identify phonemic stress contrasts with better-than-chance accuracy; individuals with RHD performed worse than normal participants but significantly better than the patients with LHD--particularly with the original full-cue stimuli. All groups performed better on the emphatic stress subtest, with the scores of only the patients with LHD at chance level for the F0-neutralized stimuli. The findings are considered in relation to hypotheses concerning the hemispheric lateralization of prosodic processing, particularly with respect to a hypothesis that posits differential lateralization for specific acoustic parameters.