The intelligibility of noise-vocoded speech: spectral information available from across-channel comparison of amplitude envelopes

Noise-vocoded (NV) speech is often regarded as conveying phonetic information primarily through temporal-envelope cues rather than spectral cues. However, listeners may infer the formant frequencies in the vocal-tract output-a key source of phonetic detail-from across-band differences in amplitude when speech is processed through a small number of channels. The potential utility of this spectral information was assessed for NV speech created by filtering sentences into six frequency bands, and using the amplitude envelope of each band (≤30 Hz) to modulate a matched noise-band carrier (N). Bands were paired, corresponding to F1 (≈N1 + N2), F2 (≈N3 + N4) and the higher formants (F3' ≈ N5 + N6), such that the frequency contour of each formant was implied by variations in relative amplitude between bands within the corresponding pair. Three-formant analogues (F0 = 150 Hz) of the NV stimuli were synthesized using frame-by-frame reconstruction of the frequency and amplitude of each formant. These analogues were less intelligible than the NV stimuli or analogues created using contours extracted from spectrograms of the original sentences, but more intelligible than when the frequency contours were replaced with constant (mean) values. Across-band comparisons of amplitude envelopes in NV speech can provide phonetically important information about the frequency contours of the underlying formants.     

Envejecer sin ver: evaluación del ajuste a la pérdida visual sobrevenida en la vejez

Introduction

The adjustment process to visual impairment can be approached by using theoretical models. The key variables in these models are usually measured by using psychometric instruments. The measurements can be taken from those already existing for the general population or be specifically designed for the visually impaired population. If the chosen measurements are reasonably valid and behave as the model predicts, they can be further used for designing programs that improve the process of adjusting.We describe the identification, adaptation and validation of some theses measurements.

Method

We selected the psychometrics instruments to be used in the research: the Age-Related Vision Loss Scale (AVL) by Horowitz and Reinhardt; the Nottingham Adjustment Scale (NAS) by Dodds, and the Geriatric Depression Scale (GDS) by Brink and Yesavage. The AVL and NAS were adapted for use in Spain. The referred measurements were applied to a sample of 335 respondents together with the Scale of Subjective Wellbeing (EBS), and their psychometric properties were assessed.

Results

The estimated reliabilities were: AVL (0.80), NASA2 (0.87), NASB (0.81), NASC (0.75), NASE (0.87), GDS (0.90). The relationships between the measurements were all in the expected direction, and the magnitude of the convergent-validity coefficients was considered as acceptable.

Conclusions

Our results suggests that the available measurements discussed above are appropriate for assessing the adjustment process, and are useful tools for individual assessment, as well as for designing intervention programs.All the measurements are available in computerized form in www.proyectotarragona.es.     

Effects of proximity and activity on visual and auditory monitoring in wild Japanese macaques

Group-living primates monitor group members to maintain the spatial cohesiveness of the group. We examined the possibility that visual scanning (turning the head for more than 3 sec) and contact calls (coo calls) function as visual and auditory monitoring behaviors to avoid separation from group members in wild Japanese macaques. The rate of visual scanning increased as proximity to group members decreased and as mobile activities (foraging and moving) increased, compared with immobile activities (resting and grooming). However, the rate of contact calls varied differently with proximity and activities. During resting and moving, the rate of contact calls increased as proximity decreased. In contrast, the rate increased with closer proximity during feeding. Visual scanning during all activities and contact calls during resting and moving increased when the group members were likely to spread over a larger area, suggesting that these behaviors functioned as monitoring of group members to avoid separation from the group. Contact calls also increased when the group members stayed in close proximity during foraging, suggesting that this behavior was also associated with competitive situations. Contact calls may also function to ease tension or maintain distance to avoid conflict in competitive situations.     

Environmentally driven shift between alternative female morphotypes in the mottled shore crab

Precocious maturity is an important life history trait and might be advantageous if the juvenile habitat is risky. Larvae of the mottled shore crab Pachygrapsus transversus settle to the benthic habitat at a very large size, undergo a brief juvenile development and mature within a few months at a size about a fourth of the asymptotic maximum size for this species. This strategy may rely on the capacity of this species to molt to a juvenile-like morphotype (mI) in which reproduction is suppressed. In the laboratory, winter temperature triggered the puberty molt for a large proportion of juveniles, and still allowed high growth rates if combined with long photoperiod. This would result in a large number of juvenile crabs to join the adult reproductive stock in spring, at the beginning of the breeding season. Adult morphs (mII) grow faster under winter conditions, and therefore might be able to direct resources to reproduction during summer. Yet, females held in captivity without any interaction with conspecifics failed to maintain their reproductive status and often reversed to mI stages. In contrast, when a potential mate was presented, all crabs held their mII status, regardless of whether interaction involved visual, visual + chemical, or visual + chemical + tactile cues. Males discriminate female morphs, and physical interactions, including the inspection of mate receptivity and copulation, took longer when they were interacting with mII females. More than a trade-off between growth and reproduction, sustaining a breeding condition in P. transversus females is apparently a bet for successful mating in the presence of a suitable male conspecific.     

Changes in Parkinsonian gait kinematics with self-generated and externally-generated cues: a comparison of responders and non-responders

Abstract

Purpose: Rhythmic auditory stimulation such as listening to music can alleviate gait bradykinesia in people with Parkinson disease (PD) by increasing spatiotemporal gait features. However, evidence about what specific kinematic alterations lead to these improvements is limited, and differences in responsiveness to cueing likely affect individual motor strategies. Self-generated cueing techniques, such as singing or mental singing, provide similar benefits but no evidence exists about how these techniques affect lower limb joint movement. In this study, we assessed immediate effects of external and self-generated cueing on lower limb movement trajectories during gait.

Methods: Using 3D motion capture, we assessed sagittal plane joint angles at the hip, knee, and ankle across 35 participants with PD, divided into responders (n?=?23) and non-responders (n?=?12) based on a clinically meaningful change in gait speed. Joint motion was assessed as overall range of motion as well as at two key time points during the gait cycle: initial contact and toe-off.

Results: Responders used both cue types to increase gait speed and induce increases in overall joint ROM at the hip while only self-generated cues also increased ROM at the ankle. Increased joint excursions for responders were also evident at initial contact and toe-off.

Conclusions: Our results indicate that self-generated rhythmic cues can induce similar increases in joint excursions as externally-generated cues and that some people may respond more positively than others. These results provide important insight into how self-generated cueing techniques may be tailored to meet the varied individual needs of people with PD.     

Estimated absorbance spectra of the visual pigments of the North Atlantic right whale (Eubalaena glacialis)

To assess the spectral sensitivities of the retinal visual pigments from the North Atlantic right whale (Eubalaena glacialis), we have cloned and sequenced two exons from the rod opsin gene and two exons from the middle‐wavelength sensitive (MWS) cone opsin gene in order to determine the amino acids at positions known to be key regulators of the spectral location of the absorbance maximum (λ_max). Based on previous mutagenesis models we estimate that the right whale possesses a rod visual pigment with a λ_max of 499 nm and a MWS cone visual pigment with a λ_max of 524 nm. Although the MWS cone visual pigment from the right whale is blue‐shifted in its spectral sensitivity like those from odontocetes, the spectral sensitivity of the right whale rod visual pigment is similar to those from terrestrial mammals.     

Theoretical analysis of reverse-time correlation for idealized orientation tuning dynamics

A theoretical analysis is presented of a reverse-time correlation method used in experimentally investigating orientation tuning dynamics of neurons in the primary visual cortex. An exact mathematical characterization of the method is developed, and its connection with the Volterra–Wiener nonlinear systems theory is described. Various mathematical consequences and possible physiological implications of this analysis are illustrated using exactly solvable idealized models of orientation tuning.     

2 Hz与100 Hz刺激在诱导大鼠视皮层长持续长时程增强中的不同作用

在哺乳动物的视皮层,多种不同参数的刺激可诱导出长时程增强(long-term potentiation,LTP)现象。但关于刺激参数与持续时间长于3h的长持续LTP(long lasting LTP,L-LTP)之间关系的研究较少。本研究用3周龄的大鼠视皮层脑片标本,在Ⅳ层刺激而在Ⅱ／Ⅲ层记录场电位,待场电位稳定后施加强直刺激诱导LTP,探讨2Hz与100Hz的强直刺激在诱发持续时间长于3h的L-LTP中的作用。结果表明,多于300个脉冲不同频率的刺激可稳定地诱导出L-LTP;2Hz与100Hz的刺激诱发的L-LTP有明显不同的表达形式,100Hz刺激可诱导出较大的L-LTP;频率相同而脉冲数不同的强直刺激诱发的L-LTP有相同的表达形式。以上结果提示,不同频率的强直刺激诱发的L-LTP机制可能不同;相同频率的刺激(脉冲数不同)诱发的L-LTP可能有相同的机制。     

Effects of chronic iTBS‐rTMS and enriched environment on visual cortex early critical period and visual pattern discrimination in dark‐reared rats

Early cortical critical period resembles a state of enhanced neuronal plasticity enabling the establishment of specific neuronal connections during first sensory experience. Visual performance with regard to pattern discrimination is impaired if the cortex is deprived from visual input during the critical period. We wondered how unspecific activation of the visual cortex before closure of the critical period using repetitive transcranial magnetic stimulation (rTMS) could affect the critical period and the visual performance of the experimental animals. Would it cause premature closure of the plastic state and thus worsen experience‐dependent visual performance, or would it be able to preserve plasticity? Effects of intermittent theta‐burst stimulation (iTBS) were compared with those of an enriched environment (EE) during dark‐rearing (DR) from birth. Rats dark‐reared in a standard cage showed poor improvement in a visual pattern discrimination task, while rats housed in EE or treated with iTBS showed a performance indistinguishable from rats reared in normal light/dark cycle. The behavioral effects were accompanied by correlated changes in the expression of brain‐derived neurotrophic factor (BDNF) and atypical PKC (PKCζ/PKMζ), two factors controlling stabilization of synaptic potentiation. It appears that not only nonvisual sensory activity and exercise but also cortical activation induced by rTMS has the potential to alleviate the effects of DR on cortical development, most likely due to stimulation of BDNF synthesis and release. As we showed previously, iTBS reduced the expression of parvalbumin in inhibitory cortical interneurons, indicating that modulation of the activity of fast‐spiking interneurons contributes to the observed effects of iTBS. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 19–33, 2016     

Synapse-Selective Control of Cortical Maturation and Plasticity by Parvalbumin-Autonomous Action of SynCAM 1

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