Experience with spoken language starts prenatally, as hearing becomes operational during the second half of gestation. While maternal tissues filter out many aspects of speech, they readily transmit speech prosody and rhythm. These properties of the speech signal then play a central role in early language acquisition. In this study, we ask how the newborn brain uses variation in duration, pitch and intensity (the three acoustic cues that carry prosodic information in speech) to group sounds. In four near-infrared spectroscopy studies (NIRS), we demonstrate that perceptual biases governing how sound sequences are perceived and organized are present in newborns from monolingual and bilingual language backgrounds. Importantly, however, these prosodic biases are present only for acoustic patterns found in the prosody of their native languages. These findings advance our understanding of how prenatal language experience lays the foundations for language development.

Because Broca's area is known to be involved in many cognitive functions, including language, music, and action processing, several attempts have been made to propose a unifying theory of its role that emphasizes a possible contribution to syntactic processing. Recently, we have postulated that Broca's area might be involved in higher-order chunk processing during implicit learning of a motor sequence. Chunking is an information-processing mechanism that consists of grouping consecutive items in a sequence and is likely to be involved in all of the aforementioned cognitive processes. Demonstrating a contribution of Broca's area to chunking during the learning of a nonmotor sequence that does not involve language could shed new light on its function. To address this issue, we used offline MRI-guided TMS in healthy volunteers to disrupt the activity of either the posterior part of Broca's area (left Brodmann's area [BA] 44) or a control site just before participants learned a perceptual sequence structured in distinct hierarchical levels. We found that disruption of the left BA 44 increased the processing time of stimuli representing the boundaries of higher-order chunks and modified the chunking strategy. The current results highlight the possible role of the left BA 44 in building up effector-independent representations of higher-order events in structured sequences. This might clarify the contribution of Broca's area in processing hierarchical structures, a key mechanism in many cognitive functions, such as language and composite actions.

Many applications have been found for carbon nanotubes, and we can now add a role as a 'nanothermometer' to this list. We describe how the height of a continuous, unidimensional column of liquid gallium inside a carbon nanotube (up to about 10 micrometres long and about 75 nanometres in diameter) varies linearly and reproducibly in the temperature range 50-500 degrees C, with an expansion coefficient that is the same as for gallium in the macroscopic state. We chose gallium as our thermal indicator because it has one of the greatest liquid ranges of any metal (29.78-2,403 degrees C) and a low vapour pressure even at high temperatures. This nanothermometer should be suitable for use in a wide variety of microenvironments.

This review is aimed at celebrating the upcoming 20th anniversary of the birth of human functional near-infrared spectroscopy (fNIRS). After the discovery in 1992 that the functional activation of the human cerebral cortex (due to oxygenation and hemodynamic changes) can be explored by NIRS, human functional brain mapping research has gained a new dimension. fNIRS or optical topography, or near-infrared imaging or diffuse optical imaging is used mainly to detect simultaneous changes in optical properties of the human cortex from multiple measurement sites and displays the results in the form of a map or image over a specific area. In order to place current fNIRS research in its proper context, this paper presents a brief historical overview of the events that have shaped the present status of fNIRS. In particular, technological progresses of fNIRS are highlighted (i.e., from single-site to multi-site functional cortical measurements (images)), introduction of the commercial multi-channel systems, recent commercial wireless instrumentation and more advanced prototypes.

Considerable knowledge on neural development related to speech perception has been obtained by functional imaging studies using near-infrared spectroscopy (optical topography). In particular, a pioneering study showed stronger left-dominant activation in the temporal lobe for (normal) forward speech (FW) than for (reversed) backward speech (BW) in neonates. However, it is unclear whether this stronger left-dominant activation for FW is equally observed for any language or is clearer for the mother tongue. We hypothesized that the maternal language elicits clearer activation than a foreign language in newborns because of their prenatal and/or few-day postnatal exposure to the maternal language. To test this hypothesis, we developed a whole-head optode cap for 72-channel optical topography and visualized the spatiotemporal hemodynamics in the brains of 17 Japanese newborns when they were exposed to FW and BW in their maternal language (Japanese) and in a foreign language (English). Statistical analysis showed that all sound stimuli together induced significant activation in the bilateral temporal regions and the frontal region. They also showed that the left temporal-parietal region was significantly more active for Japanese FW than Japanese BW or English FW, while no significant difference between FW and BW was shown for English. This supports our hypothesis and suggests that the few-day-old brain begins to become attuned to the maternal language. Together with a finding of equivalent activation for all sound stimuli in the adjacent measurement positions in the temporal region, these findings further clarify the functional organization of the neonatal brain.

Although ageing is known to affect memory, the precise nature of its effect on retrieval and encoding processes is not well understood. Here, we examine the effect of ageing on the free recall of word lists, in which the semantic structure of word sequences was manipulated from unrelated words to pairs of associated words with various separations (between pair members) within the sequence. We find that ageing is associated with reduced total recall, especially for sequences with associated words. Furthermore, we find that the degree of semantic clustering (controlled for chance clustering) shows an age effect and that it interacts with the distance between the words within a pair. The results are consistent with the view that age effects in memory are mediated both by retrieval and by encoding processes associated with frontal control and working memory.

Understanding the rapidly developing building blocks of speech perception in infancy requires a close look at the auditory prerequisites for speech sound processing. Pioneering studies have demonstrated that hemispheric specializations for language processing are already present in early infancy. However, whether these computational asymmetries can be considered a function of linguistic attributes or a consequence of basic temporal signal properties is under debate. Several studies in adults link hemispheric specialization for certain aspects of speech perception to an asymmetry in cortical tuning and reveal that the auditory cortices are differentially sensitive to spectrotemporal features of speech. Applying concurrent electrophysiological (EEG) and hemodynamic (near-infrared spectroscopy) recording to newborn infants listening to temporally structured nonspeech signals, we provide evidence that newborns process nonlinguistic acoustic stimuli that share critical temporal features with language in a differential manner. The newborn brain preferentially processes temporal modulations especially relevant for phoneme perception. In line with multi-time-resolution conceptions, modulations on the time scale of phonemes elicit strong bilateral cortical responses. Our data furthermore suggest that responses to slow acoustic modulations are lateralized to the right hemisphere. That is, the newborn auditory cortex is sensitive to the temporal structure of the auditory input and shows an emerging tendency for functional asymmetry. Hence, our findings support the hypothesis that development of speech perception is linked to basic capacities in auditory processing. From birth, the brain is tuned to critical temporal properties of linguistic signals to facilitate one of the major needs of humans: to communicate.

Non-adjacent dependencies are challenging for the language learning machinery and are acquired later than adjacent dependencies. In this transcranial magnetic stimulation (TMS) study, we show that participants successfully discriminated between grammatical and non-grammatical sequences after having implicitly acquired an artificial language with crossed non-adjacent dependencies. Subsequent to transcranial magnetic stimulation of Broca's region, discrimination was impaired compared to when a language-irrelevant control region (vertex) was stimulated. These results support the view that Broca's region is engaged in structured sequence processing and extend previous functional neuroimaging results on artificial grammar learning (AGL) in two directions: first, the results establish that Broca's region is a causal component in the processing of non-adjacent dependencies, and second, they show that implicit processing of non-adjacent dependencies engages Broca's region. Since patients with lesions in Broca's region do not always show grammatical processing difficulties, the result that Broca's region is causally linked to processing of non-adjacent dependencies is a step towards clarification of the exact nature of syntactic deficits caused by lesions or perturbation to Broca's region. Our findings are consistent with previous results and support a role for Broca's region in general structured sequence processing, rather than a specific role for the processing of hierarchically organized sentence structure.

This study assessed whether the neonatal brain recruits different neural networks for native and non-native languages at birth. Twenty-seven one-day-old full-term infants underwent functional near-infrared spectroscopy (fNIRS) recording during linguistic and non-linguistic stimulation. Fourteen newborns listened to linguistic stimuli (native and non-native language stories) and 13 newborns were exposed to non-linguistic conditions (native and non-native stimuli played in reverse). Comparisons between left and right hemisphere oxyhemoglobin (HbO2) concentration changes over the temporal areas revealed clear left hemisphere dominance for native language, whereas non-native stimuli were associated with right hemisphere lateralization. In addition, bilateral cerebral activation was found for non-linguistic stimulus processing. Overall, our findings indicate that from the first day after birth, native language and prosodic features are processed in parallel by distinct neural networks.

BACKGROUND: Suprasegmental perception (perception of stress, intonation,

AIMS: Near-infrared spectroscopy has the potential for aiding the diagnosis of major depressive disorder. The purpose of this study was to systematically review the evidence from observational studies regarding the use of near-infrared spectroscopy in patients with major depressive disorder and to identify the characteristic pattern of prefrontal lobe activity in major depressive disorder. METHODS: medline, PubMed, Cochrane Library and Web of Science databases were searched in December 2013. All case-control studies were included. The quality of evidence was examined using the Newcastle-Ottawa Quality Assessment Scale. The primary outcome measures were the mean oxygenated and deoxygenated hemoglobin alterations of the cerebral cortex during cognitive activation periods. The standard mean difference for the overall pooled effects across the included studies was estimated using random or fixed effect models. The primary outcome measures were included in the meta-analysis. RESULTS: Fourteen studies met the inclusion criteria. Six studies (n = 692 participants) were included in the analysis of the mean oxygenated hemoglobin alterations; the pooled mean standardized difference was -0.74 (95% confidence interval, -0.97 to -0.52), indicating that patients with major depressive disorder were associated with attenuated increase in oxygenated hemoglobin during cognitive activation in the prefrontal regions compared to healthy controls. Five studies (n = 668 participants) were included in the analysis of mean deoxygenated-hemoglobin changes; the pooled standardized mean difference was 0.18 (95% confidence interval, -0.20 to 0.56). CONCLUSIONS: Using near-infrared spectroscopy measurements, we observed that compared to healthy subjects, patients with major depressive disorder had significantly lower prefrontal activation during cognitive tasks.