Transition between encoding and consolidation/replay dynamics via cholinergic modulation of CAN current: A modeling study.

Hippocampal place cells that are activated sequentially during active waking get reactivated in a temporally compressed (5-20 times) manner during slow-wave-sleep and quiet waking. The two-stage model of the hippocampus suggests that neural activity during awaking supports encoding function while temporally compressed reactivation (replay) supports consolidation. However, the mechanisms supporting different neural activity with different temporal scales during encoding and consolidation remain unclear. Based on the idea that acetylcholine modulates functional transition between encoding and consolidation, we tested whether the cholinergic modulation may adjust intrinsic network dynamics to support different temporal scales for these two modes of operation. Simulations demonstrate that cholinergic modulation of the calcium activated non-specific cationic (CAN) current and the synaptic transmission may be sufficient to switch the network dynamics between encoding and consolidation modes. When the CAN current is active and the synaptic transmission is suppressed, mimicking the high acetylcholine condition during active waking, a slow propagation of multiple spikes is evident. This activity resembles the firing pattern of place cells and time cells during active waking. On the other hand, when CAN current is suppressed and the synaptic transmission is intact, mimicking the low acetylcholine condition during slow-wave-sleep, a time compressed fast (∼10 times) activity propagation of the same set of cells is evident. This activity resembles the time compressed firing pattern of place cells during replay and pre-play, achieving a temporal compression factor in the range observed in vivo (5-20 times). These observations suggest that cholinergic system could adjust intrinsic network dynamics suitable for encoding and consolidation through the modulation of the CAN current and synaptic conductance in the hippocampus.

Familiarity and preference for pitch probability profiles.

We investigated familiarity and preference judgments of participants toward a novel musical system. We exposed participants to tone sequences generated from a novel pitch probability profile. Afterward, we either asked participants to identify more familiar or we asked participants to identify preferred tone sequences in a two-alternative forced-choice task. The task paired a tone sequence generated from the pitch probability profile they had been exposed to and a tone sequence generated from another pitch probability profile at three levels of distinctiveness. We found that participants identified tone sequences as more familiar if they were generated from the same pitch probability profile which they had been exposed to. However, participants did not prefer these tone sequences. We interpret this relationship between familiarity and preference to be consistent with an inverted U-shaped relationship between knowledge and affect. The fact that participants identified tone sequences as even more familiar if they were generated from the more distinctive (caricatured) version of the pitch probability profile which they had been exposed to suggests that the statistical learning of the pitch probability profile is involved in gaining of musical knowledge.

Opera trainees' cognitive functioning is associated with physiological stress during performance.

In an opera performance, singers must perform difficult musical repertoire at a high level while dealing with the stress of standing before a large audience. Previous literature suggests that individuals with better cognitive functions experience less stress. During a music performance such functions, especially attention, memory, and executive function, are in high demand, suggesting that cognitive functions may play a role in music performance. This study used physiological and cognitive measures to examine this phenomenon in opera performance. Cardiac activity data were collected from 24 opera trainees during a resting-state period before and during a real-life performance. Heart-rate variability (HRV) was used as an indicator of physiological stress, such that higher HRV indicates lower stress. Standardized neuropsychological tests were used to measure attention (IVA-2), memory (CVLT-3, WMS-IV), and executive function (Trail Making Test). Results showed cognitive function- and state-specific relationships between HRV and cognitive function: HRV during the resting state had a positive correlation with attention, while HRV during a performance had a positive correlation with executive function. These results suggest that greater cognitive function is related to lower stress during opera performance. The findings of this study provide initial evidence for a relationship between cognitive functions and music performance stress in opera trainees.

Resting-state brain connectivity correlates of musical sophistication.

Introduction: A growing body of research has investigated how performing arts training, and more specifically, music training, impacts the brain. Recent meta-analytic work has identified multiple brain areas where activity varies as a function of levels of musical expertise gained through music training. However, research has also shown that musical sophistication may be high even without music training. Thus, we aim to extend previous work by investigating whether the functional connectivity of these areas relates to interindividual differences in musical sophistication, and to characterize differences in connectivity attributed to performing arts training. Methods: We analyzed resting-state functional magnetic resonance imaging from n = 74 participants, of whom 37 received performing arts training, that is, including a musical instrument, singing, and/or acting, at university level. We used a validated, continuous measure of musical sophistication to further characterize our sample. Following standard pre-processing, fifteen brain areas were identified a priori based on meta-analytic work and used as seeds in separate seed-to-voxel analyses to examine the effect of musical sophistication across the sample, and between-group analyses to examine the effects of performing arts training. Results: Connectivity of bilateral superior temporal gyrus, bilateral precentral gyrus and cerebellum, and bilateral putamen, left insula, and left thalamus varied with different aspects of musical sophistication. By including these measures of these aspects as covariates in post hoc analyses, we found that connectivity of the right superior temporal gyrus and left precentral gyrus relate to effects of performing arts training beyond effects of individual musical sophistication. Discussion: Our results highlight the potential role of sensory areas in active engagement with music, the potential role of motor areas in emotion processing, and the potential role of connectivity between putamen and lingual gyrus in general musical sophistication.

Electrophysiological and behavioral indicators of musical knowledge about unfamiliar music.

Most listeners possess sophisticated knowledge about the music around them without being aware of it or its intricacies. Previous research shows that we develop such knowledge through exposure. This knowledge can then be assessed using behavioral and neurophysiological measures. It remains unknown however, which neurophysiological measures accompany the development of musical long-term knowledge. In this series of experiments, we first identified a potential ERP marker of musical long-term knowledge by comparing EEG activity following musically unexpected and expected tones within the context of known music (n = 30). We then validated the marker by showing that it does not differentiate between such tones within the context of unknown music (n = 34). In a third experiment, we exposed participants to unknown music (n = 40) and compared EEG data before and after exposure to explore effects of time. Although listeners' behavior indicated musical long-term knowledge, we did not find any effects of time on the ERP marker. Instead, the relationship between behavioral and EEG data suggests musical long-term knowledge may have formed before we could confirm its presence through behavioral measures. Listeners are thus not only knowledgeable about music but seem to also be incredibly fast music learners.

Modality of practice modulates resting state connectivity during motor learning.

When bookending skilled motor practice, changes in resting state functional magnetic resonance imaging (rs-fMRI; used to characterise synchronized patterns of activity when the brain is at rest) reflect functional reorganization that supports motor memory consolidation and learning. Despite its use in practice in numerous domains, the neural mechanisms underlying motor memory consolidation and learning that result from motor imagery practice (MIP) relative to physical practice are not well understood. The current study examined how rs-fMRI is modulated by skilled motor practice that results through either MIP or physical practice. Two groups of participants engaged in five days of MIP or physical practice of a dart throwing task. Performance and rs-fMRI were captured before and after training. Relative to physical practice, where focal changes in rs-fMRI within a cerebellar-cortical network were observed, MIP stimulated widespread changes in rs-fMRI within a frontoparietal network encompassing bilateral regions. Findings indicate functional reorganization that supports motor memory consolidation and learning is not equivalent across practice modalities. Ultimately, this work provides new information regarding the unique neural underpinnings MIP relies on to drive motor memory consolidation and learning.

The role of duration and frequency of occurrence in perceived pitch structure.

INTRODUCTION: To survive, organisms need to organize perceptual input into coherent, usable structures. Research has illuminated the potential role of frequency of occurrence and duration as cues to extract statistical regularities from our environment. Musical stimuli provide a unique opportunity to study how these cues are used to organize auditory input into higher level perceptual entities, i.e., pitch structure, and to assess the influence of cognitive schema. METHODS: To examine the relative importance of these two cues in pitch structure perception, we constructed novel tone sequences in which frequency of occurrence and duration cues were pitted against each other. We assessed perceived pitch structure in musically trained and untrained listeners using a probe tone paradigm. RESULTS: In all experiments, a 3-tiered hierarchy of pitch structure emerged, with highest ratings for tones of longer duration, next highest for shorter, more frequent tones and lowest for probe tones that did not occur in the sequence. The hierarchy did not reflect assimilation to Western tonal schema. DISCUSSION: Our results argue against theories positing the same mechanism for the processing of duration and frequency of occurrence, and that duration is weighted preferentially. We further suggest that the organization of perceptual information will proceed according to whatever information is relevant, available, and most easily acquired.