Biomedical subjects

Pascal Belin

Publications and source records attributed to Pascal Belin.

At least 19 recordsLinked to original sources

PubMed2006

Voice processing in human and non-human primates.

Humans share with non-human primates a number of voice perception abilities of crucial importance in social interactions, such as the ability to identify a conspecific individual from its vocalizations. Speech perception is likely to have evolved in our ancestors on the basis of pre-existing neural mechanisms involved in extracting behaviourally relevant information from conspecific vocalizations (CVs). Studying the neural bases of voice perception in primates thus not only has the potential to shed light on cerebral mechanisms that may be--unlike those involved in speech perception--directly homologous between species, but also has direct implications for our understanding of how speech appeared in humans. In this comparative review, we focus on behavioural and neurobiological evidence relative to two issues central to voice perception in human and non-human primates: (i) are CVs 'special', i.e. are they analysed using dedicated cerebral mechanisms not used for other sound categories, and (ii) to what extent and using what neural mechanisms do primates identify conspecific individuals from their vocalizations?

Animals↗

PubMed2006

Superior voice timbre processing in musicians.

After several years of exposure to musical instrument practice, musicians acquire a great expertise in processing auditory features like tonal pitch or timbre. Here we compared the performance of musicians and non-musicians in two timbre discrimination tasks: one using instrumental timbres, the other using voices. Both accuracy (d-prime) and reaction time measures were obtained. The results indicate that the musicians performed better than the non-musicians at both tasks. The musicians also took more time to respond at both tasks. One interpretation of this result is that the expertise musicians acquired with instrumental timbres during their training transferred to timbres of voice. The musician participants may also have used different cognitive strategies during the experiment. Higher response times found in musicians can be explained by a longer verbal-auditory memory and the use of a strategy to further process auditory features.

Acoustic Stimulation↗

PubMed2006

Bilingual brain organization: a functional magnetic resonance adaptation study.

We used functional magnetic resonance adaptation (fMRA) to examine whether intra-voxel functional specificity may be present for first (L1)- and second (L2)-language processing. We examined within- and across-language adaptation for spoken words in English-French bilinguals who had acquired their L2 after the age of 4 years. Subjects listened to words presented binaurally through earphones. In two control conditions (one for each language), six identical words were presented to obtain maximal adaptation. The remaining six conditions each consisted of five words that were identical followed by a sixth word that differed. There were thus a total of eight experimental conditions: no-change (sixth word identical to first five); a change in meaning (different final word in L1); a change in language (final item translated into L2); a change in meaning and language (different final word in L2). The same four conditions were presented in L2. The study also included a silent baseline. At the neural level, within- and across-language word changes resulted in release from adaptation. This was true for separate analyses of L1 and L2. We saw no evidence for greater recovery from adaptation in across-language relative to within-language conditions. While many brain regions were common to L1 and L2, we did observe differences in adaptation for forward translation (L1 to L2) as compared to backward translation (L2 to L1). The results support the idea that, at the lexical level, the neural substrates for L1 and L2 in bilinguals are shared, but with some populations of neurons within these shared regions showing language-specific responses.

Adult↗

PubMed2006

Can spectro-temporal complexity explain the autistic pattern of performance on auditory tasks?

To test the hypothesis that level of neural complexity explain the relative level of performance and brain activity in autistic individuals, available behavioural, ERP and imaging findings related to the perception of increasingly complex auditory material under various processing tasks in autism were reviewed. Tasks involving simple material (pure tones) and/or low-level operations (detection, labelling, chord disembedding, detection of pitch changes) show a superior level of performance and shorter ERP latencies. In contrast, tasks involving spectrally- and temporally-dynamic material and/or complex operations (evaluation, attention) are poorly performed by autistics, or generate inferior ERP activity or brain activation. Neural complexity required to perform auditory tasks may therefore explain pattern of performance and activation of autistic individuals during auditory tasks.

Adolescent↗

PubMed2006

Cortical processing of complex auditory stimuli during alterations of consciousness with the general anesthetic propofol.

BACKGROUND: The extent to which complex auditory stimuli are processed and differentiated during general anesthesia is unknown. The authors used blood oxygenation level-dependent functional magnetic resonance imaging to examine the processing words (10 per period; compared with scrambled words) and nonspeech human vocal sounds (10 per period; compared with environmental sounds) during propofol anesthesia. METHODS: Seven healthy subjects were tested. Propofol was given by a computer-controlled pump to obtain stable plasma concentrations. Data were acquired during awake baseline, sedation (propofol concentration in arterial plasma: 0.64 +/- 0.13 microg/ml; mean +/- SD), general anesthesia (4.62 +/- 0.57 microg/ml), and recovery. Subjects were asked to memorize the words. RESULTS: During all periods including anesthesia, the sounds conditions combined elicited significantly greater activations than silence bilaterally in primary auditory cortices (Heschl gyrus) and adjacent regions within the planum temporale. During sedation and anesthesia, however, the magnitude of the activations was reduced by 40-50% (P < 0.05). Furthermore, anesthesia abolished voice-specific activations seen bilaterally in the superior temporal sulcus during the other periods as well as word-specific activations bilaterally in the Heschl gyrus, planum temporale, and superior temporal gyrus. However, scrambled words paradoxically elicited significantly more activation than normal words bilaterally in planum temporale during anesthesia. Recognition the next day occurred only for words presented during baseline plus recovery and was correlated (P < 0.01) with activity in right and left planum temporale. CONCLUSIONS: The authors conclude that during anesthesia, the primary and association auditory cortices remain responsive to complex auditory stimuli, but in a nonspecific way such that the ability for higher-level analysis is lost.

Acoustic Stimulation↗

PubMed2006

Electrophysiological markers of voice familiarity.

Our ability to discriminate and recognize human voices is amongst the most important functions of the human auditory system. The current study sought to determine whether electrophysiological markers could be used as objective measures of voice familiarity, by looking at the electrophysiological responses [mismatch negativity (MMN) and P3a] when the infrequent stimulus presented is a familiar voice as opposed to an unfamiliar voice. Results indicate that the MMN elicited by a familiar voice is greater than that elicited by an unfamiliar voice at FCz. The familiar voice also produced a greater P3a wave than that triggered by the unfamiliar voice at Fz. As both the MMN and the P3a were elicited as participants were instructed not to pay attention to incoming stimulation, these findings suggest that voice recognition is a particularly potent preattentive process whose neural representations can be objectively described through electrophysiological assessments.

Acoustic Stimulation↗

PubMed2005

Sensitivity to voice in human prefrontal cortex.

We report two functional MRI (fMRI) experiments showing sensitivity to human voice in a region of human left inferior prefrontal cortex, pars orbitalis. The voice-enhanced response was observed for speech as well as non-linguistic vocalizations and was stronger for emotional than neutral vocalizations. This region could constitute a human prefrontal auditory domain similar to the one recently identified in the macaque brain.

Acoustic Stimulation↗

PubMed2005

Judgment of emotional nonlinguistic vocalizations: age-related differences.

Humans make extensive use of vocal information to attribute emotional states to other individuals. To date, most studies exploring perception of vocal emotions have done so in the context of speech prosody, although nonlinguistic emotional vocalizations represent an important, perhaps more universal, means to express emotions. Here, we explored the perception of emotional nonlinguistic vocalizations in healthy individuals, with an emphasis on potential age- and sex-related differences. Sixty participants rated 563 positive (e.g., laughs, sexual vocalizations), negative (e.g., cries, screams of fear), and neutral vocalizations (e.g., coughs), according to the valence, intensity, and authenticity of the emotion expressed. Ratings were consistent among individuals, suggesting that valence is an adequate measure of emotional categorization. An important effect of age emerged: (a) age by vocalization category interactions were observed for both valence and intensity ratings, and (b) younger participants rated stimuli as more emotional than older individuals (i.e., higher valence for positive, lower for negative, and more intense for both positive and negative). We also found a sex effect in the authenticity ratings: older women rated the vocalizations as less authentic than younger women whereas authenticity judgments did not differ between the two age groups in men. Taken together, these findings suggest that, as previously observed for facial expressions and prosody, the judgments of emotional vocalizations may vary with age.

Adult↗

PubMed2004

Abnormal cortical voice processing in autism.

Impairments in social interaction are a key feature of autism and are associated with atypical social information processing. Here we report functional magnetic resonance imaging (fMRI) results showing that individuals with autism failed to activate superior temporal sulcus (STS) voice-selective regions in response to vocal sounds, whereas they showed a normal activation pattern in response to nonvocal sounds. These findings suggest abnormal cortical processing of socially relevant auditory information in autism.

Adult↗

PubMed2004

Neuropsychology: pitch discrimination in the early blind.

Do blind people develop superior abilities in auditory perception to compensate for their lack of vision? They are known to be better than sighted people at orientating themselves by sound, but it is not clear whether this enhanced awareness extends to other auditory domains, such as listening to music or to voices. Here we show that blind people are better than sighted controls at judging the direction of pitch change between sounds, even when the speed of change is ten times faster than that perceived by the controls--but only if they became blind at an early age. The younger the onset of blindness, the better is the performance, which is in line with cerebral plasticity being optimal during the early years.

Acoustic Stimulation↗

PubMed2004

Sensitivity to auditory object features in human temporal neocortex.

This positron emission tomography study examined the hemodynamic response of the human brain to auditory object feature processing. A continuum of object feature variation was created by combining different numbers of stimuli drawn from a diverse sample of 45 environmental sounds. In each 60 sec scan condition, subjects heard either a distinct individual sound on each trial or simultaneous combinations of sounds that varied systematically in their similarity or distinctiveness across conditions. As more stimuli are combined they become more similar and less distinct from one another; the limiting case is when all 45 are added together to form a noise that is repeated on each trial. Analysis of covariation of cerebral blood flow elicited by this parametric manipulation revealed a response in the upper bank of the right anterior superior temporal sulcus (STS): when sounds were identical across trials (i.e., a noise made up of 45 sounds), activity was at a minimum; when stimuli were different from one another, activity was maximal. A right inferior frontal area was also revealed. The results are interpreted as reflecting sensitivity of this region of temporal neocortex to auditory object features, as predicted by neurophysiological and anatomical models implicating an anteroventral functional stream in object processing. The findings also fit with evidence that voice processing may involve regions within the anterior STS. The data are discussed in light of these models and are related to the concept that this functional stream is sensitive to invariant sound features that characterize individual auditory objects.

Acoustic Stimulation↗

PubMed2004

A "voice inversion effect?".

Voice is the carrier of speech but is also an "auditory face" rich in information on the speaker's identity and affective state. Three experiments explored the possibility of a "voice inversion effect," by analogy to the classical "face inversion effect," which could support the hypothesis of a voice-specific module. Experiment 1 consisted of a gender identification task on two syllables pronounced by 90 speakers (boys, girls, men, and women). Experiment 2 consisted of a speaker discrimination task on pairs of syllables (8 men and 8 women). Experiment 3 consisted of an instrument discrimination task on pairs of melodies (8 string and 8 wind instruments). In all three experiments, stimuli were presented in 4 conditions: (1) no inversion; (2) temporal inversion (e.g., backwards speech); (3) frequency inversion centered around 4000 Hz; and (4) around 2500 Hz. Results indicated a significant decrease in performance caused by sound inversion, with a much stronger effect for frequency than for temporal inversion. Interestingly, although frequency inversion markedly affected timbre for both voices and instruments, subjects' performance was still above chance. However, performance at instrument discrimination was much higher than for voices, preventing comparison of inversion effects for voices vs. non-vocal stimuli. Additional experiments will be necessary to conclude on the existence of a possible "voice inversion effect."

Acoustic Stimulation↗

PubMed2004

Priming of non-speech vocalizations in male adults: the influence of the speaker's gender.

Previous research reported a priming effect for voices. However, the type of information primed is still largely unknown. In this study, we examined the influence of speaker's gender and emotional category of the stimulus on priming of non-speech vocalizations in 10 male participants, who performed a gender identification task. We found a significant priming effect, which was greater for female than male vocalizations. In contrast, the emotional category of the stimuli did not appear to modulate the magnitude of priming. These data suggest that different aspects of the information conveyed in non-speech vocalizations may contribute differently to behavioral priming, possibly influenced by task relevance.

Adult↗

PubMed2004

Is voice processing species-specific in human auditory cortex? An fMRI study.

Recent studies suggested a sensitivity of regions of the human superior temporal sulcus (STS) to the sound of the human voice. However, the question of the species specificity of this response is still open. Healthy adult volunteers were scanned in an event-related fMRI design to compare responses in the STS to human and animal vocalizations, as well as to control nonvocal sounds (e.g., musical instruments). Bilateral activation of anterior STS was observed for human vocalizations, when contrasted with both nonvocal sounds and animal vocalizations. Animal vocalizations, compared to nonvocal sounds, elicited a more restricted left STS activation, although this region responded even more strongly to human vocalizations. This study provides the first evidence suggesting a species specificity in STS responses to vocalizations in humans.

Acoustic Stimulation↗

PubMed2004

BgK, a disulfide-containing sea anemone toxin blocking K+ channels, can be produced in Escherichia coli cytoplasm as a functional tagged protein.

BgK, a sea anemone peptide consisting of 37 amino acid residues and 3 disulfide bonds, blocks voltage-gated potassium (Kv1) channels. Here, we report a method for producing tagged BgK in Escherichia coli, as a soluble cytoplasmic protein. First, using peptidic synthesis, we show that addition of a 15 residue peptide (S.Tag) at the BgK C-terminus does not affect its biological activity. Then, a synthetic DNA sequence encoding BgK was constructed and cloned to produce a BgK-S.Tag hybrid in the cytoplasm of E. coli. The presence of S.Tag did not only facilitate detection, quantification, and purification of the recombinant protein, but also increased the production yield by more than two orders of magnitude. Moreover, use of an E. coli OrigamiB(DE3)pLacI strain also increased production; up to 5.8-7.5mg of BgK-S.Tag or mutated BgK(F6A)-S.Tag was produced per liter of culture and could be functionally characterized in crude extracts. Using a two-step purification procedure (affinity chromatography and RP-HPLC), we obtained 1.8-2.8mg of purified recombinant protein per liter of culture. The recombinant peptides displayed functional properties similar to those of native BgK or BgK(F6A).

Animals↗

PubMed2004

Thinking the voice: neural correlates of voice perception.

The human voice is the carrier of speech, but also an "auditory face" that conveys important affective and identity information. Little is known about the neural bases of our abilities to perceive such paralinguistic information in voice. Results from recent neuroimaging studies suggest that the different types of vocal information could be processed in partially dissociated functional pathways, and support a neurocognitive model of voice perception largely similar to that proposed for face perception.

Auditory Perception↗

PubMed2004

Perception of complex sounds in autism: abnormal auditory cortical processing in children.

OBJECTIVE: The authors have previously described less activation of left speech-related temporal areas in adults with autism when listening to speech-like sounds than in normal adults. Here, they investigated whether this abnormal cortical processing was also present in children with primary autism. METHOD: Regional cerebral blood flow was measured with positron emission tomography after premedication in 11 autistic children and six nonautistic mentally retarded children during rest and while they were listening to speech-like sounds. RESULTS: As with autistic adults, direct comparison between the two groups revealed significantly less activation in the autistic group localized in left speech-related areas. CONCLUSIONS: For the first time to their knowledge, an activation study was performed in children with autism and has confirmed previous results obtained in adults. The abnormal cortical auditory processing observed in both children and adults with autism could be involved in inadequate behavioral responses to sounds and in language impairments characteristic of autism.

Acoustic Stimulation↗

PubMed2003

Adaptation to speaker's voice in right anterior temporal lobe.

Little is known on how voices are represented in the brain. We used fMRI to investigate whether parts of auditory cortex would be sensitive to the repetition of a speaker's voice. Subjects were scanned while passively listening to spoken syllables, presented in blocs in which either syllable or speaker were repeated. Only one cortical region, located in the anterior part of the right superior temporal sulcus (STS), responded differently to the two conditions: activation relative to the silent baseline was significantly reduced when syllables were spoken by a single voice than when they were spoken by different voices. This result suggest that the right anterior STS plays an important role in the representation of individual voices.

Acoustic Stimulation↗