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Biomedical subjects

H J Neville

Publications and source records attributed to H J Neville.

At least 19 recordsLinked to original sources
PubMed2001

Phonological processing in visual rhyming: a developmental erp study.

We employed a visual rhyming priming paradigm to characterize the development of brain systems important for phonological processing in reading. We studied 109 righthanded, native English speakers within eight age groups: 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20, and 21-23. Participants decided whether two written words (prime-target) rhymed (JUICE-MOOSE) or not (CHAIR-MOOSE). In similar studies of adults, two main event-related potential (ERP) effects have been described: a negative slow wave to primes, larger over anterior regions of the left hemisphere and hypothesized to index rehearsal of the primes, and a negative deflection to targets, peaking at 400-450 msec, maximal over right temporal-parietal regions, larger for nonrhyming than rhyming targets, and hypothesized index phonological matching. In this study, these two ERP effects were observed in all age groups; however, the two effects showed different developmental timecourses. On the one hand, the frontal asymmetry to primes increased with age; moreover, this asymmetry was correlated with reading and spelling scores, even after controlling for age. On the other hand, the distribution and onset of the more posterior rhyming effect (RE) were stable across age groups, suggesting that phonological matching relied on similar neural systems across these ages. Behaviorally, both reaction times and accuracy improved with age. These results suggest that different aspects of phonological processing rely on different neural systems that have different to developmental timecourses.

Evoked Potentials↗
PubMed2001

Auditory memory in congenitally blind adults: a behavioral-electrophysiological investigation.

Blind people must rely more than sighted people on auditory input in order to acquire information about the world. The present study was designed to test the hypothesis that blind people have better memory than sighted individuals for auditory verbal material and specifically to determine whether memory encoding and/or retrieval are improved in blind adults. An incidental memory paradigm was employed in which 11 congenitally blind people and 11 matched sighted controls first listened to 80 sentences which ended either with a semantically appropriate or inappropriate word. Immediately following, the recognition phase occurred, in which all sentence terminal words were presented again randomly intermixed with the same number of new words. Participants indicated whether or not they had heard the word in the initial study phase. Event-related brain potentials (ERPs) were recorded from 28 electrode positions during both the encoding and the retrieval phase. Blind participants' memory performance was superior to that of sighted controls. In addition, during the recognition phase, previously presented words elicited ERPs with larger positive amplitudes than new words, particularly over the right hemisphere. During the study phase, words that would subsequently be recognized elicited a more pronounced late positive potential than words that were not subsequently recognized. These effects were reliable in the congenitally blind participants but could only be obtained in the subgroup of sighted participants who had the highest memory performance. These results imply that blind people encode auditory verbal material more efficiently than matched sighted controls and that this in turn allows them to recognize these items with a higher probability.

Adult↗
PubMed2001

An event-related fMRI study of syntactic and semantic violations.

We used event-related functional magnetic resonance imaging to identify brain regions involved in syntactic and semantic processing. Healthy adult males read well-formed sentences randomly intermixed with sentences which either contained violations of syntactic structure or were semantically implausible. Reading anomalous sentences, as compared to well-formed sentences, yielded distinct patterns of activation for the two violation types. Syntactic violations elicited significantly greater activation than semantic violations primarily in superior frontal cortex. Semantically incongruent sentences elicited greater activation than syntactic violations in the left hippocampal and parahippocampal gyri, the angular gyri bilaterally, the right middle temporal gyrus, and the left inferior frontal sulcus. These results demonstrate that syntactic and semantic processing result in nonidentical patterns of activation, including greater frontal engagement during syntactic processing and larger increases in temporal and temporo-parietal regions during semantic analyses.

Brain↗
PubMed2001

Sensitive periods differentiate processing of open- and closed-class words: an ERP study of bilinguals.

The goal of this study was to test the hypothesis that neural processes for language are heterogeneous in their adaptations to maturation and experience. This study examined whether the neural processes for open- and closed-class words are differentially affected by delays in second-language immersion. In English, open-class words primarily convey referential meaning, whereas closed-class words are primarily related to grammatical information in sentence processing. Previous studies indicate that event-related brain potentials (ERPs) elicited by these word classes display nonidentical distributions and latencies, show different developmental time courses, and are differentially affected by early language experience in Deaf individuals. In this study, ERPs were recorded from 10 monolingual English speakers and 53 Chinese-English bilingual speakers who were grouped according to their age of immersion in English: 1-3, 4-6, 7-10, 11-13, and >15 years of age. Closed-class words elicited an N280 that was largest over left anterior electrode sites for all groups. However, the peak latency was later (>35 ms) in bilingual speakers immersed in English after 7 years of age. In contrast, the latencies and distributions of the N350 elicited by open-class words were similar in all groups. In addition, the N400, elicited by semantic anomalies (open-class words that violated semantic expectation), displayed increased peak latencies for only the later-learning bilingual speakers (>11 years). These results are consistent with the hypothesis that language subprocesses are differentially sensitive to the timing of second-language experience.

Adolescent↗
PubMed2000

Event-related potentials during auditory language processing in congenitally blind and sighted people.

While behavioral studies have documented delayed language acquisition in blind children, other studies have revealed better speech discrimination abilities for blind than sighted adults. Several brain imaging studies have provided evidence for cortical reorganization due to visual deprivation but the cerebral organization of language in blind humans is not known yet. We hypothesized that the increasing specialization of language systems normally observed during development may not take place to the same degree in blind individuals since posterior visual areas do not receive their adequate input. On the other hand, we hypothesized that blind people, due to their greater reliance upon the auditory language signal, may process speech faster than sighted people. To test these assumptions, event-related potentials were recorded while 11 congenitally blind and 11 sighted adults matched in age, gender, handedness and education were engaged in a language task. Participants listened to sentences in order to decide after each sentence if it was meaningful or not. Incongruous sentence-final words elicited an N400 effect in both groups. The N400 effect had a left-lateralized fronto-central scalp distribution in the sighted but a symmetric and broad topography in the blind. Furthermore, the N400 effect started earlier in the blind than in the sighted. Closed class compared to open class sentence middle words elicited a more pronounced late negativity in the blind than in the sighted. These results suggest that blind people process auditory language stimuli faster than sighted people and that some language functions may be reorganized in the blind.

Adult↗
PubMed2000

Lexical, syntactic, and stress-pattern cues for speech segmentation.

Many sources of segmentation information are available in speech. Previous research has shown that one or another segmentation cue is used by listeners under certain circumstances. However, it has also been shown that none of the cues are absolutely reliable. Therefore, it is likely that people use a combination of segmentation cues when listening to normal speech. This study addresses the issue of how young adults use multiple segmentation cues (lexical, syntactic, and stress-pattern) in combination to break up continuous speech. Evidence that people use more than one cue at a time was found. Furthermore, the results suggest that people can use segmentation cues flexibly such that remaining cues are relied upon more heavily when other information is missing.

Adult↗
PubMed1999

Spatial attention to central and peripheral auditory stimuli as indexed by event-related potentials.

Young adult subjects attended selectively to brief noise bursts delivered in free-field via central and peripheral arrays of four loudspeakers each that were arranged along a semi-circle extending from the midline to 90 degrees right of center. Frequent "standard" stimuli (90%) and infrequent "target/deviant" stimuli (10%) of increased bandwidth were delivered at a fast rate in random order and equiprobably from all eight speakers. In separate runs, the subject's task was to selectively attend to the center or rightmost speaker, and to press a button to the infrequent "target" stimuli occurring at the designated (spatial) location. Behavioral detection rates and concurrently recorded event-related potentials (ERPs) indicated that auditory attention was deployed as a finely tuned gradient around the attended source. The attentional gradients were steeper for the central than the peripheral array, indicating that attention can be more sharply focused upon sound sources directly in front of the listener. The ERP data suggested that selection for location is accomplished in two distinct stages, with an initial broadly tuned filtering, followed by a more narrowly focused selection of attended-location deviants.

Acoustic Stimulation↗
PubMed1999

Improved auditory spatial tuning in blind humans.

Despite reports of improved auditory discrimination capabilities in blind humans and visually deprived animals, there is no general agreement as to the nature or pervasiveness of such compensatory sensory enhancements. Neuroimaging studies have pointed out differences in cerebral organization between blind and sighted humans, but the relationship between these altered cortical activation patterns and auditory sensory acuity remains unclear. Here we compare behavioural and electrophysiological indices of spatial tuning within central and peripheral auditory space in congenitally blind and normally sighted but blindfolded adults to test the hypothesis (raised by earlier studies of the effects of auditory deprivation on visual processing) that the effects of visual deprivation might be more pronounced for processing peripheral sounds. We find that blind participants displayed localization abilities that were superior to those of sighted controls, but only when attending to sounds in peripheral auditory space. Electrophysiological recordings obtained at the same time revealed sharper tuning of early spatial attention mechanisms in the blind subjects. Differences in the scalp distribution of brain electrical activity between the two groups suggest a compensatory reorganization of brain areas in the blind that may contribute to the improved spatial resolution for peripheral sound sources.

Adult↗
PubMed1999

Effects of interstimulus interval on auditory event-related potentials in congenitally blind and normally sighted humans.

To test the hypothesis of auditory compensation after early visual deprivation, congenitally blind and sighted adults performed an auditory discrimination task. They had to detect a rare target tone among frequent standard tones. Stimuli were presented with different interstimulus intervals (ISIs) (200, 1000, 2000 ms) and the auditory-event related potentials to all tones and reaction times to targets were recorded. Increasing ISIs resulted in an increasing amplitude of the vertex response (N1-P2) in both groups, but this amplitude recovery was more pronounced in the blind. Furthermore, targets elicited larger and more posteriorly distributed N2 responses in the blind than in the sighted. Since target detection times were shorter in the blind as well, these findings imply compensatory adaptations within the auditory modality in humans blind from birth.

Acoustic Stimulation↗
PubMed1998

Hemispheric specialization for English and ASL: left invariance-right variability.

Functional magnetic resonance imaging (fMRI) was used to compare the cerebral organization during sentence processing in English and in American sign language (ASL). Classical language areas within the left hemisphere were recruited by both English in native speakers and ASL in native signers. This suggests a bias of the left hemisphere to process natural languages independently of the modality through which language is perceived. Furthermore, in contrast to English, ASL strongly recruited right hemisphere structures. This was true irrespective of whether the native signers were deaf or hearing. Thus, the specific processing requirements of the language also in part determine the organization of the language systems of the brain.

Adult↗
PubMed1998

Cerebral organization for language in deaf and hearing subjects: biological constraints and effects of experience.

Cerebral organization during sentence processing in English and in American Sign Language (ASL) was characterized by employing functional magnetic resonance imaging (fMRI) at 4 T. Effects of deafness, age of language acquisition, and bilingualism were assessed by comparing results from (i) normally hearing, monolingual, native speakers of English, (ii) congenitally, genetically deaf, native signers of ASL who learned English late and through the visual modality, and (iii) normally hearing bilinguals who were native signers of ASL and speakers of English. All groups, hearing and deaf, processing their native language, English or ASL, displayed strong and repeated activation within classical language areas of the left hemisphere. Deaf subjects reading English did not display activation in these regions. These results suggest that the early acquisition of a natural language is important in the expression of the strong bias for these areas to mediate language, independently of the form of the language. In addition, native signers, hearing and deaf, displayed extensive activation of homologous areas within the right hemisphere, indicating that the specific processing requirements of the language also in part determine the organization of the language systems of the brain.

Adult↗
PubMed1998

Neural organization and plasticity of language.

Powerful advances in neuroimaging techniques have added to and refined classical descriptions of the neurobiology of language in adults. Recent studies have employed these methodologies to study the nature and extent of plasticity of language-relevant aspects of cerebral organization in adults, in early and late bilinguals and in people who have acquired language through different modalities. Studies of children have documented dynamic shifts in cerebral organization over the course of language acquisition. Each of these different approaches has revealed constraints on the identity of the neural systems that mediate language; these studies have also described the marked and specific effects of language experience on the organization of these systems.

Adult↗
PubMed1997

Neural systems mediating American sign language: effects of sensory experience and age of acquisition.

ERPs were recorded from deaf and hearing native signers and from hearing subjects who acquired ASL late or not at all as they viewed ASL signs that formed sentences. The results were compared across these groups and with those from hearing subjects reading English sentences. The results suggest that there are constraints on the organization of the neural systems that mediate formal languages and that these are independent of the modality through which language is acquired. These include different specializations of anterior and posterior cortical regions in aspects of grammatical and semantic processing and a bias for the left hemisphere to mediate aspects of mnemonic functions in language. Additionally, the results suggest that the nature and timing of sensory and language experience significantly impact the development of the language systems of the brain. Effects of the early acquisition of ASL include an increased role for the right hemisphere and for parietal cortex and this occurs in both hearing and deaf native signers. An increased role of posterior temporal and occipital areas occurs in deaf native signers only and thus may be attributable to auditory deprivation.

Adult↗
PubMed1997

Electrophysiological studies of language and language impairment.

The organization of language-relevant brain systems was examined in normally developing and language-impaired children. Atypical patterns of brain activity were observed in subsets of children with specific language impairment (SLI) for both sensory (auditory and visual) and language processing. However, it was not the same groups of children who displayed abnormalities across the different tasks. The results supported a multiple-factors and multiple-subtypes framework for interpreting the neurobiology of SLI. The roots of SLI were also considered in normal infants and late talkers in studies of primary language acquisition. These studies suggest that the organization of neural systems important in language acquisition display dramatic changes during this time. Some of these are linked to the attainment of language milestones and appear to be independent of chronological age. Moreover, abnormalities in the lateral organization of electrophysiological activity may help predict which late talkers will catch up and who will later display SLI. More generally, the event-related potential technique is a powerful tool in studying the neurobiology of language and language impairment.

Child↗
PubMed1989

Effects of locus coeruleus lesions on auditory, long-latency, event-related potentials in monkey.

It has previously been demonstrated that monkeys exhibit certain event-related potential (ERP) components showing latency, polarity, and contingency similarities to those observed in humans. In the present study, monkey P300-like components were studied in order to evaluate the hypothesis that the noradrenergic locus coeruleus (LC) system participates in their generation or modulation. ERPs were recorded from untrained squirrel monkeys (Saimiri sciureus) twice a week for 4 weeks before and after bilateral LC lesions and interruption of dorsal bundle (DB) fibers. Stimuli consisted of 2 and 6 kHz tone pips (40 msec duration, 60 dB above nHL) presented once a second in random order. In most sessions, one tone constituted 90% of the stimuli and the other tone 10%, while in some sessions tones were made equiprobable to test the effects of manipulating stimulus probability. LC and DB lesions were made by first localizing the nucleus and creating an electrolytic lesion. Then, the electrode was placed at the anterior pole of the nucleus and a knife cut effected. The extent of damage to LC perikarya and ascending axons was assessed by reconstructing lesions from Nissl-stained sagittal sections through the brain stems. The effect of lesions on cortical noradrenergic axons was immunohistochemically verified utilizing antisera directed against dopamine-B-hydroxylase and tyrosine hydroxylase to label noradrenergic and dopaminergic axons, respectively. The prelesion ERP results replicated previous findings of P300-like components recorded in response to low-probability tones. The postlesion ERP data indicated that following damage to LC cell bodies, combined with interruption of histochemically detectable ascending noradrenergic axons, monkey P300-like potentials exhibited decreased areas, altered brain-surface distribution, and reduced sensitivity to stimulus probability. The correlation between the extent of cell body lesions and percentage reduction in the magnitude of P300-like responses was significant. However, interruption of DB fibers alone did not have similar effects. Neither type of lesion had any effect on amplitudes, latencies, or brain-surface distributions of P52, P172, or N250-900. There was, however, a significant effect on N106. Stimulus probability effects on the frontally distributed P52 and N106 were not altered by the lesions. These data support the hypothesis that the integrity of the LC nucleus and its ascending fibers is important in the generation and modulation of surface-recorded P300-like activity.

Animals↗
PubMed1988

Endogenous event-related potentials in monkey: the role of task relevance, stimulus probability, and behavioral response.

Monkeys were trained in auditory discrimination tasks resembling human paradigms in which long-latency endogenous components, such as P300, are typically recorded. Morphological, topographical, and functional properties of the monkey event-related potentials (ERPs) were analyzed to determine similarities and differences with human ERPs reported in the literature. ERPs were recorded from epidural electrodes in monkeys trained to produce operant responses. In a conditional discrimination (CD) task, tone pips (2 kHz or 6 kHz, 40 msec duration, and 60 dB above nHL) were presented every 4-8 sec. Target tones presented during 'time-in' (TI) were rewarded when followed by a response in the correct post-stimulus interval (400-3000 msec). In contrast, tones presented during 'time-out' (TO) were not rewarded. Under both conditions, tones elicited an initial frontally dominant triphasic complex (P56-N92-P157). Additionally, TI target tones followed by a response elicited a large negativity (N358) having maximal amplitude over mid-frontal regions and followed by a parietally distributed positivity (P658). The scalp distribution and covariation with task requirements of N358 resemble those reported for the human 'O' wave. ERPs were also recorded in an auditory oddball paradigm in which tone pips (2 kHz and 6 kHz, 40 msec duration, and 60 dB above nHL) were presented in random order every second. Monkeys trained in the CD paradigm, along with additional subjects, were trained to make delayed responses following target tones embedded in a background of different-pitch tones. Tone probabilities were varied in different sessions from 90-10, 70-30, to 50-50 to assess the effects of probability. Background and target tones elicited a triphasic complex (P52-N110-P159) similar in latency and distribution to that recorded in the CD task. Additionally, target tones in this paradigm elicited a long-latency positive component (LPC) that exhibited an inverse relationship with stimulus probability. LPC had an onset latency of approximately 150-200 msec, a duration of approximately 300 msec, and multiple peaks (P244 and P376). These data indicate the importance of stimulus context in eliciting long-latency endogenous activity. It further suggests that strong analogies exist between monkey and human potentials recorded under similar paradigms. The effects of task relevance, stimulus probability, and the act of producing behavioral responses are similar to the effects of these variables on analogous human potentials.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗