Prosodic realization of tonal target and F0 peak alignment in Mandarin neutral tone

Neutral tone in Mandarin is generally believed to lack tonal identity and exhibit more variability in its phonetic realization. We examined the tonal target of neutral tone in a prosodic word consisting of a full syllable (S) and one, two, or three neutral-tone syllables. In the experiment, the test words, presented in isolation and embedded in a carrier sentence, were read in two intonation patterns: declarative and interrogative. The results showed: (1) the tonal target of neutral tone is L(ow) at the end of the intonation phrase in declarative intonation and M(id) in question intonation; (2) its phonetic realization is influenced by intonation patterns, the tone of S and the number of neutral-tone syllables in the prosodic word; (3) the influence of the tone of S is more robust in shorter sequences than in longer ones with three neutral-tone syllables; (4) placement of the F0 peak in T2 (LH) and the neutral tone immediately following T3 (L) is susceptible to the number of neutral-tone syllables. It seems clear from our study that while the tonal target of neutral tone is related to prosodic structure, its actual F0 scaling is sensitive to prosodic manipulations such as intonation patterns and prosodic word length. In addition, tonelessness of neutral tone allows for more freedom in the alignment of the F0 peak, whose temporal coordination with its segmental host is, nevertheless, subject to both phonological and phonetic constraints.

Cortical microtubule pulling forces contribute to the union of the parental genomes in the C. elegans zygote

Previously, we reported that the Polo-like kinase PLK-1 phosphorylates the single C. elegans lamin (LMN-1) to trigger lamina depolymerization during mitosis. We showed that this event is required for the formation of a pronuclear envelopes scission event that removes membranes on the juxtaposed oocyte and sperm pronuclear envelopes in the zygote, allowing the parental chromosomes to merge in a single nucleus after segregation (Velez-Aguilera, 2020). Here we show that cortical microtubule pulling forces contribute to pronuclear envelopes scission by promoting mitotic spindle elongation. We also demonstrate that weakening of the pronuclear envelopes, via PLK-1-mediated lamina depolymerization, is a prerequisite for the astral microtubule pulling forces to trigger pronuclear membranes scission. Finally, we provide evidence that PLK-1 mainly acts via lamina depolymerization in this process. These observations thus indicate that temporal coordination between lamina depolymerization and mitotic spindle elongation facilitates pronuclear envelopes scission and parental genomes unification.

Behavioral and Neural Dynamics of Interpersonal Synchrony Between Performing Musicians: A Wireless EEG Hyperscanning Study

Interpersonal synchrony refers to the temporal coordination of actions between individuals and is a common feature of social behaviors, from team sport to ensemble music performance. Interpersonal synchrony of many rhythmic (periodic) behaviors displays dynamics of coupled biological oscillators. The current study addresses oscillatory dynamics on the levels of brain and behavior between music duet partners performing at spontaneous (uncued) rates. Wireless EEG was measured from N = 20 pairs of pianists as they performed a melody first in Solo performance (at their spontaneous rate of performance), and then in Duet performances at each partner’s spontaneous rate. Influences of partners’ spontaneous rates on interpersonal synchrony were assessed by correlating differences in partners’ spontaneous rates of Solo performance with Duet tone onset asynchronies. Coupling between partners’ neural oscillations was assessed by correlating amplitude envelope fluctuations of cortical oscillations at the Duet performance frequency between observed partners and between surrogate (re-paired) partners, who performed the same melody but at different times. Duet synchronization was influenced by partners’ spontaneous rates in Solo performance. The size and direction of the difference in partners’ spontaneous rates were mirrored in the size and direction of the Duet asynchronies. Moreover, observed Duet partners showed greater inter-brain correlations of oscillatory amplitude fluctuations than did surrogate partners, suggesting that performing in synchrony with a musical partner is reflected in coupled cortical dynamics at the performance frequency. The current study provides evidence that dynamics of oscillator coupling are reflected in both behavioral and neural measures of temporal coordination during musical joint action.

Sigma Oscillations Protect or Reinstate Motor Memory Depending on their Temporal Coordination with Slow Waves

Targeted memory reactivation (TMR) during post-learning sleep is known to enhance motor memory consolidation but the underlying neurophysiological processes remain unclear. Here, we confirm the beneficial effect of auditory TMR on motor performance. At the neural level, TMR enhanced slow waves (SW) characteristics. Additionally, greater TMR-related phase-amplitude coupling between slow (0.3-2 Hz) and sigma (12-16 Hz) oscillations after the SW peak was related to higher TMR effect on performance. Importantly, sounds that were not associated to learning strengthened SW-sigma coupling at the SW trough and the increase in sigma power nested in the trough of the potential evoked by these unassociated sounds was related to the TMR benefit. Altogether, our data suggest that, depending on their precise temporal coordination during post learning sleep, slow and sigma oscillations play a crucial role in either memory reinstatement or protection against irrelevant information; two processes that critically contribute to motor memory consolidation.

Cerebellar Control of a Unitary Head Direction Sense

Head direction (HD) cells, key neuronal elements in the mammalian's navigation system, are hypothesized to act as a continuous attractor network, in which temporal coordination between cell members is maintained under different brain states or external sensory conditions, resembling a unitary neural representation of direction. Whether and how multiple identified HD signals in anatomically separate HD cell structures are part of a single and unique attractor network is currently unknown. By manipulating the cerebellum, we identified pairs of thalamic and retrosplenial HD cells that lose their temporal coordination in the absence of external sensory drive, while the neuronal coordination within each of these brain regions remained intact. Further, we show that distinct cerebellar mechanisms are involved in the stability of direction representation depending on external sensory conditions. These results put forward a new role for the cerebellum in mediating stable and coordinated HD neuronal activity toward a unitary thalamocortical representation of direction.

Process-based temporal coordination in multiparty collaboration for societal challenges

Solving complex societal challenges requires innovation processes that involve heterogeneous organizations collaborating for sustained periods of time. These multiparty collaborations are confronted with incongruent temporal structures, creating temporal complexities that hamper joint action. We draw on an in-depth longitudinal field study of a multiparty collaboration in a “living lab” initiative that aimed to develop innovative solutions to enhance a city’s nightlife area’s safety and economic viability. We unpack the process of temporal coordination by identifying three temporal coordination mechanisms that enabled parties to address temporal complexities: leveraging serendipitous alignment, temporary exclusion, and aligning on the future. Whereas, prior research has stressed synchronization as a dominant approach to coordination, rooted in a clock-time orientation, these three mechanisms for temporal coordination are rooted in process-time. With a process-time orientation, temporal coordination becomes inherently partial and transient, meaning that temporal complexities may resurface over time and require re-initiation of joint action, building upon emerging outcomes of previous episodes. We discuss implications for the literature on interorganizational collaboration and temporal coordination.