Speech comprehension necessitates the ability to divide the acoustic input into time-based segments for higher-level linguistic analysis and understanding. Oscillation-based frameworks propose that syllable-sized acoustic cues are tracked by low-frequency auditory cortex oscillations, consequently emphasizing syllabic-level acoustic processing's relevance for speech segmentation. The interplay between syllabic processing and higher-level speech processing, encompassing stages beyond segmentation, along with the anatomical and neurophysiological underpinnings of the involved neural networks, remains a subject of ongoing discussion. A frequency-tagging paradigm is used in two MEG experiments to investigate the interplay of lexical and sublexical word-level processing with (acoustic) syllable processing. Disyllabic words were presented to participants at a rate of 4 syllables each second. Displayed were lexical elements of the native language, sub-syllabic transitions from a foreign tongue, or simply the arrangement of syllables in pseudo-words. A study of two hypotheses concerned (i) the part that syllable-to-syllable transitions play in word-level processing; and (ii) the activation of brain areas during word processing that connect with acoustic syllable processing. The bilateral engagement of superior, middle, and inferior temporal and frontal brain regions was more pronounced when considering syllable-to-syllable transition information than when examining simply syllable information. An elevation in neural activity was, moreover, a result of the lexical content. The evidence regarding the interplay between word- and acoustic syllable-level processing proved to be inconclusive. Molecular Biology Lexical content presence correlated with a decrease in syllable tracking (cerebroacoustic coherence) within auditory cortex, and an increase in cross-frequency coupling in the right superior and middle temporal and frontal areas, differentiating it from other conditions. However, separate comparisons of conditions did not reveal this pattern. Experimental data demonstrate the subtle and sensitive role syllable-to-syllable transitions play in word-level processing.

Naturalistic speech situations generally show little incidence of overt speech errors, despite the complex systems involved in speech production. A functional magnetic resonance imaging study investigated neural evidence for internal error detection and correction via a tongue-twister paradigm, manipulating the potential for speech errors while specifically excluding any overt errors from data analysis. Previous investigations, employing the same methodology in the context of silently produced and imagined speech, revealed anticipatory activity in auditory cortex during spoken utterances, and hinted at error-correction processes in the left posterior middle temporal gyrus (pMTG). This region showed stronger activation when potential speech mistakes were anticipated to be non-words instead of words, according to findings by Okada et al. (2018). Leveraging the groundwork laid by previous work, this study aimed to reproduce the forward prediction and lexicality effects. Recruiting nearly twice the number of participants, novel stimuli were developed to more rigorously challenge internal error correction and detection mechanisms, and to encourage speech errors towards taboo vocabulary. The earlier findings regarding forward prediction were replicated. No evidence of a significant change in brain response was observed depending on the lexical class of potential speech errors; however, directing errors towards taboo words generated substantially more activity in the left pMTG region than directing errors toward (neutral) words. Other brain areas exhibited a heightened response to taboo words, but this response fell below expected levels, signifying less pronounced involvement in language processing based on decoding analysis, which suggests a significant role for the left pMTG in internal error correction.

The right hemisphere, although recognized for its role in processing how people speak, is understood to contribute less to the identification of phonetics than the left hemisphere, at least in relative terms. bioartificial organs Emerging data indicates that the right posterior temporal cortex might play a crucial role in acquiring phonetic variations specific to a particular speaker. The current study employed male and female speakers; one articulated an ambiguous fricative within lexical environments strongly associated with /s/ (for example, 'epi?ode'), and the other speaker produced this sound in contexts skewed towards /θ/ (such as 'friend?ip'). Listeners participating in the behavioral experiment (Experiment 1) exhibited perceptual learning that was lexically influenced, enabling them to categorize ambiguous fricatives based on their prior experience. An fMRI experiment (Experiment 2) revealed differential phonetic categorization based on the speaker, opening a window into the neural mechanisms behind talker-specific phonetic processing. Despite this, no evidence of perceptual learning was found, likely a consequence of our in-scanner headphones. Searchlight analysis elucidated that the activation patterns in the right superior temporal sulcus (STS) included information concerning the speaker and the specific phoneme they produced. The data illustrates the merging of speaker-specific cues and phonetic features occurring within the right STS. Functional connectivity analyses highlighted that the connection between phonetic identity and speaker information relies on the simultaneous activity within a left-lateralized phonetic processing center and a right-lateralized speaker processing center. These results collectively demonstrate the procedures through which the right hemisphere enables the processing of speaker-distinct phonetic information.

Partial speech input is frequently correlated with the swift and automatic activation of progressively higher-level representations of words, beginning with sound and advancing to meaning. Our magnetoencephalography findings reveal that incremental processing of words is less effective when presented in isolation than within the context of continuous speech. This implies a less unified and automated word-recognition procedure than is typically posited. Neural effects of phoneme probability, determined by phoneme surprisal, are demonstrated, based on isolated word data, to be significantly stronger than the statistically insignificant effects of phoneme-by-phoneme lexical uncertainty, quantified by cohort entropy. The perception of connected speech reveals robust effects from both cohort entropy and phoneme surprisal, with a significant interaction between the contexts. This dissociation challenges the validity of word recognition models in which phoneme surprisal and cohort entropy function as uniform process indicators; these closely related information-theoretic measures both stem from the probability distribution of potential word forms consistent with the input. We propose that phoneme surprisal effects reflect the automatic retrieval of lower levels of auditory input representation (e.g., word forms), whereas cohort entropy effects are contingent upon the task, potentially driven by a competition process or a higher-level representation engaged later in (or not at all during) the word-processing stage.

The process of speech production, achieving its desired acoustic output, hinges on the successful information transmission within cortical-basal ganglia loop circuits. Consequently, speech articulation problems are prevalent in as many as ninety percent of Parkinson's disease patients. Deep brain stimulation (DBS), a highly effective treatment for Parkinson's disease, sometimes aiding in speech improvement, is, however, sometimes counterbalanced by subthalamic nucleus (STN) DBS, potentially resulting in diminished semantic and phonological fluency. A deeper comprehension of the cortical speech network's interplay with the STN is crucial to resolving this paradox, a study facilitated by intracranial EEG recordings during deep brain stimulation surgery. Our analysis of the propagation of high-gamma activity between the STN, STG, and ventral sensorimotor cortices during oral reading was carried out using event-related causality, which estimates the power and direction of neural activity flow. We implemented a novel bivariate smoothing model, built on a two-dimensional moving average, to achieve precise embedding of statistical significance in the time-frequency space. This model effectively reduces random noise while retaining a sharp step response. The ventral sensorimotor cortex and the subthalamic nucleus displayed sustained and reciprocal neural interactions. Additionally, the superior temporal gyrus exhibited propagation of high-gamma activity to the subthalamic nucleus, preceding the initiation of speech. The utterance's lexical standing affected the intensity of this influence, highlighting more significant activity propagation in the case of word reading in contrast to pseudoword reading. The unusual characteristics within these data suggest a possible role for the STN in the forward-directed management of vocal output.

A critical aspect of seed germination timing is its impact on both animal food-caching practices and the subsequent growth of new plant seedlings. RXC004 cost However, the behavioral modifications of rodents in reaction to the fast germination of acorns are not fully understood. This study explored how seed-caching rodents react to the germination of Quercus variabilis acorns, using them as a food source. Our findings indicate that Apodemus peninsulae demonstrates embryo excision as a strategy to impede seed germination, the first instance of this behavior in non-squirrel rodents. We proposed that this species might be in an early phase of the evolutionary process of adapting to seed perishability in rodents, considering the low rate of embryo excision. Alternatively, every rodent species preferred to prune the radicles of germinating acorns prior to their storage, implying that radicle pruning is a constant and more widespread foraging strategy among food-caching rodents.