The effects of background noise on dichotic listening to consonant-vowel syllables: An fMRI study

The present fMRI study attempts to identify brain areas that may underlie the effect of different background noises on functional brain asymmetry in a dichotic listening task. Previous studies have shown that the prominent right ear advantage in dichotic listening to consonant-vowel syllables is affected by background noise. To explore the underlying neuronal processes, haemodynamic brain responses using fMRI were recorded while participants performed the dichotic listening task in two different noisy backgrounds (conversational “babble” and traffic noise). The behavioural results showed a reduction of the right ear advantage in the background noise conditions, especially in the traffic noise condition. The behavioural results are discussed in terms of alertness-attentional mechanisms. The effects of background noise on brain activation involved significant activations in a speech-processing network. Specifically the changes in activations in the peri-Sylvian region of the superior temporal gyrus and in the temporo-parietal junction part in the left hemisphere, as well as in the superior temporal gyrus/sulcus area in the right hemisphere may mirror the effects of noise on behavioural performance. The effects of noise on brain activation are discussed with regard to pre-activation mechanisms.     

Assessing fetal response to maternal speech using a noninvasive functional brain imaging technique

Evidence for cortical sensory activation in the human fetus at the beginning of the third trimester of pregnancy was provided in a recent imaging study. Although hearing is functional before birth, it is not clear whether recognition of the mother's voice is learned in utero or rapidly following delivery. We developed an original fMRI procedure that allows for the specific exploration of fetal brain response to auditory stimuli. This procedure provides the first in vivo evidence for the development of maternal voice recognition in utero between 33 and 34 weeks of gestation. This methodology could have crucial implications in the study of fetal cognition.     

An event-related brain potential study of receptive speech comprehension using a modified Token Test

There is a long and distinguished history of evaluating sensory functions with evoked potentials (EPs). However, the clinical utility of event-related brain potentials (ERPs) in the assessment of cognitive functions remains to be established. We present evidence for the efficacy of ERPs in the assessment of speech comprehension. In this normative study, a version of the Token Test (Boller and Vignolo, 1966, Brain, 89, 815–831; De Renzi and Vignolo, 1962, Brain, 85, 665–678) was modified for computer presentation with simultaneous ERP recordings and then administered to a group of healthy individuals (n=27). A differential neural response pattern to incorrect and correct test items was obtained for the group and, more importantly, this result was also observed reliably at the individual subject level. This research complements on-going efforts in our laboratory to develop innovative measures for patients that are difficult or impossible to assess due to motoric and/or communicative limitations.     

Enhanced speech perception capabilities in a blind listener are associated with activation of fusiform gyrus and primary visual cortex

Blind individuals may learn to understand ultra-fast synthetic speech at a rate of up to about 25 syllables per second (syl)/s, an accomplishment by far exceeding the maximum performance level of normal-sighted listeners (8–10 syl/s). The present study indicates that this exceptional skill engages distinct regions of the central-visual system. Hemodynamic brain activation during listening to moderately- (8 syl/s) and ultra-fast speech (16 syl/s) was measured in a blind individual and six normal-sighted controls. Moderately-fast speech activated posterior and anterior ‘language zones’ in all subjects. Regarding ultra-fast tokens, the controls showed exclusive activation of supratemporal regions whereas the blind participant exhibited enhanced left inferior frontal and temporoparietal responses as well as significant hemodynamic activation of left fusiform gyrus (FG) and right primary visual cortex. Since left FG is known to be involved in phonological processing, this structure, presumably, provides the functional link betweeen the central-auditory and -visual systems.     

Imaging brain activity during natural vision using CASL perfusion fMRI

Functional MRI (fMRI) has begun to be used to explore human brain activity during ecological and natural conditions. Arterial spin labeling (ASL) perfusion fMRI provides an appealing approach for imaging sustained brain activity during natural conditions because of its long-term temporal stability and ability to noninvasively quantify absolute cerebral blood flow (CBF). The present study used ASL perfusion fMRI to measure brain activation patterns associated with natural vision by concurrently recording CBF and blood oxygen level-dependent (BOLD) contrasts while subjects were freely viewing a cartoon movie. Reliable quantitative whole-brain CBF values ( approximately 60 mL/100g/min) as well as regional CBF values (45 approximately 80 mL/100g/min) were measured during movie viewing and resting states. The perfusion contrast revealed CBF increases in multiple visual pathway areas and frontal areas, and CBF decreases in ventromedial frontal cortex and superior temporal cortex during movie viewing compared to resting states. Concurrent BOLD contrast revealed similar but weaker activation and deactivation patterns. Regression analyses of both CBF data and BOLD data showed significant associations between activation in the middle temporal (MT) region and subjects' perception of motion. Region of interest analysis based on a priori literature-defined MT demonstrated significant monotonic stepwise associations between the intensity of motion perception and the CBF and BOLD signal changes. These results demonstrate the feasibility of using ASL perfusion fMRI for imaging both sustained and dynamic effects in neural activation during natural and ecologically valid situations, and support the notion of maintained functional segregation and specialization during natural vision.     

The origins and development of speech envelope tracking during the first months of life

When humans listen to speech, their neural activity tracks the slow amplitude fluctuations of the speech signal over time, known as the speech envelope. Studies suggest that the quality of this tracking is related to the quality of speech comprehension. However, a critical unanswered question is how envelope tracking arises and what role it plays in language development. Relatedly, its causal role in comprehension remains unclear, as some studies have found it to be present even for unintelligible speech. Using electroencephalography, we investigated whether the neural activity of newborns and 6-month-olds is able to track the speech envelope of familiar and unfamiliar languages in order to explore the developmental origins and functional role of envelope tracking. Our results show that amplitude and phase tracking take place at birth for familiar and unfamiliar languages alike, i.e. independently of prenatal experience. However, by 6 months language familiarity modulates the ability to track the amplitude of the speech envelope, while phase tracking continues to be universal. Our findings support the hypothesis that amplitude and phase tracking could represent two different neural mechanisms of oscillatory synchronisation and may thus play different roles in speech perception.     

Naltrexone alters the processing of social and emotional stimuli in healthy adults

Endogenous opioids have complex social effects that may depend on specific receptor actions and vary depending on the “stage” of social behavior (e.g., seeking vs. responding to social stimuli). We tested the effects of a nonspecific opioid antagonist, naltrexone (NTX), on social processing in humans. NTX is used to treat alcohol and opiate dependence, and may affect both mu and kappa-opioid systems. We assessed attention (“seeking”), and subjective and psychophysiological responses (“responding”) to positive and negative social stimuli. Based on literature suggesting mu-opioid blockade impairs positive social responses, we hypothesized that NTX would decrease responses to positive social stimuli. We also tested responses to negative stimuli, which might be either increased by NTX’s mu-opioid effects or decreased by its kappa-opioid effects. Thirty-four healthy volunteers received placebo, 25 mg, or 50 mg NTX across three sessions under double-blind conditions. At each session, participants completed measures of attention, identification, and emotional responses for emotional faces and scenes. NTX increased attention to emotional expressions, slowed identification of sadness and fear, and decreased ratings of arousal for social and nonsocial emotional scenes. These findings are more consistent with anxiolytic kappa-antagonist than mu-blocking effects, suggesting effects on kappa receptors may contribute to the clinical effects of NTX.     

Role of inter-trial phase coherence in atypical auditory evoked potentials to speech and nonspeech stimuli in children with autism

Objective

This autism study investigated how inter-trial phase coherence (ITPC) drives abnormalities in auditory evoked potential (AEP) responses for speech and nonspeech stimuli.

The effects of stress and statistical cues on continuous speech segmentation: an event-related brain potential study

The study of the processes involved in speech segmentation has gained special relevance in recent years by trying to establish what type of information listeners use to segment the speech signal into words. An event-related brain potential experiment was conducted in order to understand how two of these cues (statistical and stress cues) interact. The experiment consisted of the presentation of artificial speech streams in which words were marked either by statistical cues alone, or by a combination of statistical and stress cues. As a baseline, comparison streams were also created with the same syllables but organized in random order. Results showed an N400 component that marks the on-line segmentation of speech into words, and an increased positivity (P2 component) for languages that include both types of cues. Possible implications of these results for the process of speech segmentation are discussed.     

早期启动言语记忆痕迹对脑卒中表达性和接受性失语患者疗效的影响

目的探讨早期启动言语记忆痕迹对脑卒中表达性和接受性失语患者语言康复效果的影响。方法100例脑卒中失语患者随机分为观察组和对照组,每组50例。对照组患者进行传统的语言康复训练。观察组在传统语言康复训练基础上,医护人员对每个患者的不同语言痕迹进行加强语言启动训练。结果60d内,观察组显效30例,有效13例,无效7例,总有效率86%;对照组显效22例,有效7例,无效21例,总有效率58%。2组比较有显著差异(P<0.01)。结论早期启动言语记忆痕迹在脑卒中失语患者康复训练中作用肯定,值得推广。     

Speech perception in noise deficits in Japanese children with reading difficulties: effects of presentation rate

We examined the effects of presentation rate on speech perception in noise and its relation to reading in 117 typically developing (TD) children and 10 children with reading difficulties (RD) in Japan. Responses in a speech perception task were measured for speed, accuracy, and stability in two conditions that varied stimulus presentation rate: high rate and same rate conditions. TD children exhibited significantly more stable responses in the high rate condition than they did in the same rate condition. Multiple regression analyses indicated that response stability in the high rate condition accounted for a unique amount of variance in reading and mora deletion. As a group, children with RD performed less accurately than did TD children in the high rate condition, but not in the same rate condition. Findings suggest that the dependence of speech perception on stimulus context relates to reading proficiency or difficulty in Japanese children. The influences of phonology and orthography of language on the relationships between speech perception and reading are discussed.     

The effect of stimulus structure on the auditory-visual perception of speech by Hebrew speaking adults with profound hearing loss

The present study evaluated the effect of speech features and context on the auditory-visual perception of speech by Hebrew speaking adults with profound hearing loss. All participants had profound, sensorineural hearing loss (95 dBHL+). They were presented with the following speech perception materials selected to evaluate the effect of the following variables: (1) /aCa/ nonsense syllables to evaluate the effect of voicing, place and manner of articulation on perception; (2) nonmeaningful and meaningful words to assess the effect of phoneme position; and (3) sentences to evaluate the effect of length, type and knowledge of the topic on perception. Speech material was introduced through the auditory-visual modality. Results indicated that all participants relied mainly on visual information; therefore perception of variables containing more pronounced visual cues was better than that of variables with poor visual information. Front place of articulation, fricatives, initial phonemes and short sentences, for example, were perceived better than back place of articulation, nasals, final phonemes and long sentences respectively. Further research, in which these kinds of speech materials are presented through the different sensory modalities using different sensory devices, is recommended.     

The effects of 40 hours of total sleep deprivation on inflammatory markers in healthy young adults

Inflammatory cytokines are released in response to stress, tissue damage, and infection. Acutely, this response is adaptive; however, chronic elevation of inflammatory proteins can contribute to health problems including cardiovascular, endocrine, mood, and sleep disorders. Few studies have examined how sleep deprivation acutely affects inflammatory markers, which was the aim of the current study. Nineteen healthy men and women aged 28.05+/-8.56 (mean+/-SD) were totally sleep deprived for 40 h under constant routine conditions. Pro-inflammatory markers: intracellular adhesion molecule-1 (ICAM-1), E-selectin, vascular adhesion molecule-1 (VCAM-1), c-reactive protein (CRP), interleukin-6 (IL-6), and interleukin-1beta (IL-1beta), and the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1ra) were assayed in plasma. Daytime levels during baseline (hours 1-15 of scheduled wakefulness) were compared to daytime levels during sleep deprivation (hours 25-39 of scheduled wakefulness), thus controlling for circadian phase within an individual. Repeated measures ANOVA with planned comparisons showed that 40 h of total sleep deprivation induced a significant increase in E-selectin, ICAM-1, IL-1beta, and IL-1ra, a significant decrease in CRP and IL-6, and no significant change in VCAM-1. Alterations in circulating levels of pro- and anti-inflammatory cytokines and cell adhesion molecules during sleep deprivation were consistent with both increased and decreased inflammation. These findings suggest that one night of sleep loss triggers a stress response that includes stimulation of both pro- and anti-inflammatory proteins in the healthy young subjects tested under our experimental conditions.     

Cerebral mechanisms of prosodic sensory integration using low-frequency bands of connected speech

Even if speech perception has been reported to involve both left and right hemispheres, converging data have posited the existence of a functional asymmetry at the level of secondary auditory cortices. Using fMRI in 12 right-handed French men listening passively to long connected speech stimuli, we addressed the question of neuronal networks involved in the integration of low frequency bands of speech by comparing 1) differences in brain activity in two listening conditions (FN, NF) differing in the integration of pitch modulations (in FN, low frequencies, obtained by a low-pass filter, are addressed to the left ear while the whole acoustic message is simultaneously addressed to the right ear, NF being the reverse position); 2) differences in brain activity induced by high and low degrees of prosodic expression (expressive vs. flat); and 3) effects of the same connected speech stimulus in the two listening conditions. Each stimulus induced a specific cerebral network, the flat one weakening activations which were mainly reduced to the bilateral STG for both listening conditions. In the expressive condition, the specific sensory integration FN results in an increase of the articulatory loop and new recruitments such as right BA6-44, left BA39-40, the left posterior insula and the bilateral BA30. This finding may be accounted for by the existence of temporal windows differing both in length and in acoustic cues decoding, strengthening the "asymmetric sampling in time" hypothesis posited by Poeppel (Speech Commun 2003; 41:245-255). Such an improvement of prosodic integration could find applications in the rehabilitation of some speech disturbances.     

Differential processing of hierarchical visual stimuli in young and older healthy adults: implications for pathology

Hierarchical figures in which large (global) forms are constructed from smaller (local) forms (Navon, 1977) have proved valuable in studies of perceptual organisation and hemispheric specialisation in both healthy volunteers and a wide range of neurological and psychiatric patients. In studies using Navon figures, normal young adults typically identify global forms faster than local forms. When the global and local forms are incongruent (e.g., a large E made of smaller Rs), global forms often interfere with local form identification more than vice versa. In two conditions on the same subjects, we contrasted the performance of young (mean age 22 years) and older (mean age 58 years) healthy volunteers on global and local processing. In the directed attention task, subjects were instructed to detect a target letter that occurred at the prespecified local or global level. The young subjects showed, as expected, faster reaction times (RTs) to detect global targets. In contrast, the older subjects showed significantly faster RTs to the local targets. Likewise, in a divided attention task, in which subjects were instructed to detect a target letter that could occur at either the local or the global level, the young adults were slightly quicker to detect the global targets and the older subjects were significantly quicker to detect the local targets. Error rates were generally low and there was no significant speed/accuracy trade-off in either condition. The observed local precedence effects in healthy older subjects were unexpected and are discussed in reference to previous work on differential hemispheric aging. That work has suggested that the left hemisphere is preferentially biased toward local processing and ages relatively slowly while the right hemisphere is biased toward global processing and ages relatively quickly. The implications of such putative differential aging for the interpretation of pathological local/global processing in neurological and psychiatric diseases are also emphasised.     

The impact of STN deep brain stimulation on speech in individuals with Parkinson's disease: The patient's perspective

BackgroundSpeech disturbance is highly prevalent and disabling for individuals with Parkinson's disease (PD). Deep brain stimulation (DBS) has been found to adversely impact speech in a number of individuals with PD. This study investigated the differential speech profiles between individuals with PD with and without DBS from the patient's perspective.MethodsA cross sectional research design was used. A total of 758 individuals with PD participated in this study, including 287 individuals with DBS and 471 individuals without DBS. Participants completed the Voice Handicap Index (VHI) and additional questions regarding speech symptoms and the impact of speech on social interaction.ResultsIndependent of age and disease duration, there were statistically significant differences in perceived speech disturbance severity between the STN-DBS group and Non-DBS group, with the DBS group reporting more severe symptoms as well as more significant symptom interference with social interaction and with daily experiences encountered relating to functional, physical, and emotional issues of a voice disorder (VHI). Low volume was the “most common” speech symptom for all individuals with PD patients across both age (younger and older) and disease duration (6–10 years and 11+ years) cohorts. DBS had the greatest adverse impact on “slurred speech.”ConclusionDBS therapy's contribution to speech disturbance is gaining more attention, and the speech symptoms ensuing from and/or being exacerbated by DBS are in the incipient stages of being investigated. Implications for DBS therapy on perceived quality of life are discussed.     

The influence of encoding strategy on episodic memory and cortical activity in schizophrenia.

BACKGROUND: Recent work suggests that episodic memory deficits in schizophrenia may be related to disturbances of encoding or retrieval. Schizophrenia patients appear to benefit from instruction in episodic memory strategies. We tested the hypothesis that providing effective encoding strategies to schizophrenia patients enhances encoding-related brain activity and recognition performance. METHODS: Seventeen schizophrenia patients and 26 healthy comparison subjects underwent functional magnetic resonance imaging scans while performing incidental encoding tasks of words and faces. Subjects were required to make either deep (abstract/concrete) or shallow (alphabetization) judgments for words and deep (gender) judgments for faces, followed by subsequent recognition tests. RESULTS: Schizophrenia and comparison subjects recognized significantly more words encoded deeply than shallowly, activated regions in inferior frontal cortex (Brodmann area 45/47) typically associated with deep and successful encoding of words, and showed greater left frontal activation for the processing of words compared with faces. However, during deep encoding and material-specific processing (words vs. faces), participants with schizophrenia activated regions not activated by control subjects, including several in prefrontal cortex. CONCLUSIONS: Our findings suggest that a deficit in use of effective strategies influences episodic memory performance in schizophrenia and that abnormalities in functional brain activation persist even when such strategies are applied.