Cortex最新文献

Aging is associated with cognitive decline and memory impairment, but the underlying neural mechanisms remain unclear. Phase-amplitude coupling (PAC) between mid-frontal theta and occipital gamma is a proposed marker for the parallel storage of multiple items in working memory. However, prior research has mainly focused on young adults, with only a few studies in aging populations. Moreover, these studies typically used univariate PAC methods, which are susceptible to spurious estimates due to EEG nonstationarities and often assess PAC at individual electrodes, potentially overlooking the broader functional significance of PAC in coordinating neural activity across distant brain regions. To address these limitations, we applied multivariate PAC (mPAC) using generalized eigendecomposition (GED), which avoids confounds from non-sinusoidal waveforms and captures coupling across distributed brain regions. EEG was recorded from 113 younger and 117 older healthy adults during a sequence learning paradigm (6423 repetitions, 55,944 stimuli), where participants learned a fixed visual sequence over repeated observations, allowing us to track mPAC throughout incremental learning. Younger adults learned significantly faster than older adults. In both groups, mPAC increased with learning and distinguished fast from slow learners. However, older participants showed overall reduced mPAC, suggesting compromised parallel storage in working memory. Crucially, stratification analysis revealed that mPAC effects persisted across performance groups matched for mid-frontal theta power, indicating that theta amplitude alone does not explain the observed effects. These findings shed light on the age-related differences in memory formation processes and may guide interventions to enhance memory performance in older adults and slow learners.

Most people report that they can imagine seeing things in their mind's eye. But there are large individual differences. A small proportion of people report that they can never visualise (aphantasics), and a similarly small proportion of people report that their imagined experiences are as realistic as seeing (hyperphantasics). The majority of people describe their visualisations as being moderately vivid. The ratings that inform imagery vividness analyses are subjective self-reports, but it has been suggested that imagery modulations of the pupillary response could be used as a physiological index of individual differences in imagery vividness. When we assessed this inter-relationship, we found that imagery can indeed modulate the pupillary response, with pupils becoming relatively more dilated if people imagine seeing dark, as opposed to bright scenes. However, imagery modulation of the pupillary response was not associated with individual differences in imagery vividness ratings. Overall, our data suggest that while imagery can modulate the pupillary response, this effect does not provide a reliable index of individual differences in imagery vividness ratings.

Distractor-response binding (DRB) has been widely studied to understand the interplay between perception and motor processes, with DRB effects referring to performance costs or benefits that arise when previously co-occurring distractors and responses are retrieved together. We hypothesize that musical training and musical perception skills modulate flexibility in reconfiguring auditory perception-action associations; this has not yet been investigated in the context of DRB. Here, we use an auditory DRB paradigm with concomitant EEG recordings to investigate how auditory-motor bindings are established, retrieved, and how they might differ between harmonic versus inharmonic sounds. Using a healthy sample of participants (N = 42) with a wide range of musical training, we also investigated whether these processes are modulated by musical perception skills, assessed using the well-established Micro-PROMS (Profile of Music Perception Skills). Behavioral and EEG results indicated significant DRB effects for both harmonic and inharmonic distractor sound combinations. These effects were modulated by harmonicity: stronger behavioral DRB effects and weaker DRB effects in theta band activity were found when inharmonic as compared to harmonic distractor stimuli were presented. Beamformer analysis localized the theta band effect to the right superior temporal cortex, highlighting the role of this brain area in auditory-motor integration. Further, this study provides evidence that participants with better musical perception skills and higher cumulative practice time show increased flexibility in handling perception-action associations. Together, these findings enhance the understanding of how auditory stimuli interact with motor actions, particularly in relation to individual differences in musical perception skills.

Congenital amusia is a disorder characterized by abnormal pitch processing, including pitch encoding and pitch memory. Individuals with amusia were impaired in speech perception, but they showed comparable speech production as those without (mainly investigated in tonal languages). Nonetheless, most previous studies collected amusics' recordings based on real words, and little is known about how amusics produce nonwords that incorporate phonological components of syllables and lexical tones. In this study, two participant groups of amusics and typical, musically intact controls (18 participants per group) attended a nonword repetition task. All nonwords were syllable-tone combinations created following the Chinese word structure. The length of the nonwords gradually increased from one to seven syllables. Repetition accuracy and error patterns were analyzed using linear mixed-effects models. Results showed that amusics had fewer correct responses to syllables and tones within a nonword, especially for longer nonwords. Besides, amusics' error rates for the double-type error, meaning the simultaneous mistakes on both syllables and tones, were also larger than controls in the longer lengths. It was revealed that amusics repeated the nonwords less accurately than controls, and they were struggling with concurrent processing of different phonological components within a nonword. This study provides novel evidence that amusics exhibit degraded nonword repetition involving both syllables and tones, which supports the perception-production link and sheds light on designing intervention programs to soften the disorder of amusia.