Analysis of the neural correlates of minutes-scale memorability using intracranial EEG recordings from nine patients with epilepsy performing a musical memory task reveals complementary neural mechanisms through which statistical structure shapes musical sequence memory, clarifying how the brain encodes complex, ecologically valid stimuli.
Abstract
Music is a uniquely memorable human creation that, when skillfully composed, can persist in individual memory (as in e.g., earworms) and cultural transmission (e.g. global hits or anthems). While both acoustic and statistical properties are known to influence a song’s memorability, the neural mechanisms that facilitate the engramming of certain musical sequences remain unclear. Current theories suggest that memory systems function as predictive internal models, enhancing learning when expectations are violated. Yet expected stimuli, by aligning with and reinforcing prior knowledge, also enhance memorability. How these two opposing processes arise from the brain’s sensitivity to statistical regularities, especially in naturalistic sequences, is not well understood. Here, we leveraged music’s intrinsic balance between expectancy and surprise, and examined the neural correlates of minutes-scale memorability using intracranial EEG recordings from nine patients with epilepsy performing a musical memory task. Quantifying the statistical surprise of each musical excerpt with PolyRNN, a polyphonic model of musical expectations, we uncovered a U-shaped relationship between musical surprise and memory performance: both highly expected and highly surprising melodies led to greater memorability. While neural pattern similarity between song repetitions was enhanced for low-surprise stimuli, high-surprise stimuli enhanced neural pattern separability in medial temporal regions, each mediating memorability in distinguishable ways. These findings reveal complementary neural mechanisms through which statistical structure shapes musical sequence memory, clarifying how the brain encodes complex, ecologically valid stimuli.
Music, which is organized hierarchically (notes, phrases, sections), provides an ideal model for studying fine-grained motor sequence production. However, it is unknown how musicians’ brains integrate tonal structure over multiple timescales during real-life performance. Here, we scrambled an unfamiliar Tchaikovsky piano suite at four timescales—every 1/2/8 measures, or fully intact—and asked expert pianists to play (sightread) all four versions in the fMRI scanner. Responses in the motor network, default mode network, and hippocampus were strongly impacted by scrambling, indicating that they integrate tonal structure over relatively long timescales. Additionally, the emergence of functionally connected sub-networks between auditory, visual, motor, and default mode network regions across scramble levels supported this hierarchical integration process. Our results cannot be explained by lower-level cues (tempo, timbre, dynamics; local pitch height or rhythmic density) and instead reflect processing of high-level tonal structure. Our study highlights novel mechanisms of complex auditory-motor action planning during live music performance.
Jamal A. Williams, Coraline Rinn Iordan, Riesa Y. Cassano-Coleman et al.· bioRxiv· 0 citations
Rhythm emerges from the temporal patterning of sounds and the expectations that shape how we hear them. Rather than passively listening to incoming events, listeners organize timing information through internal predictions and external acoustic cues. In speech, louder sounds tend to mark the start of a group, whereas longer sounds mark its end, a pattern described by the Iambic–Trochaic Law (ITL) that supports segmentation and word learning. We asked whether this perceptual grouping principle in speech could also facilitate synchronization to musical rhythms. Thirty-six adults with minimal musical training tapped along to tone sequences in simple (4/4) or complex (7/8) meters, each presented with neutral, ITL-aligned, or reverse (ITL-reversed) contours. Synchronization accuracy showed no contour effects for simple meter, but contour effects emerged in complex meter, where reverse contours produced the most accurate tapping. Error analyses indicated that prosodic contours encouraged cautious timing relative to reverse, whereas reverse contours yielded more consistent beat tracking with fewer missed taps and fewer extra taps. These findings suggest that a long initial note provided an attentional anchor that stabilized timing, and that under the conditions tested here, duration cues yielded larger and more reliable synchronization benefits than intensity cues. Thus, intensity and duration cues may guide musical timing through distinct, attention-based mechanisms.
Andrea Cecilia Chavez, J. M. Toro· Attention, Perception, & Psy...· 0 citations
In nature, animals learn to replace predisposed behaviors with new strategies, yet the neural constraints on these transitions are unclear. Using an ethological search task in mice, we reveal medial prefrontal cortical (mPFC) neural correlates of a predisposed win-stay strategy that decays as animals learn to follow a more reliable auditory cue. Auditory cortex (ACx) activity predicts correct trial-by-trial sound-guided search, even on day one of training. This prognostic coding strengthens with learning and emerges from suppressed spiking, most pronounced in neurons tuned laterally to the cue’s spectrum. Chemogenetic disruption reveals ACx contributions to improving performance. Unexpectedly, the global silencing of mPFC accelerates successful usage of sound-tracking, contrary to its canonical role in flexible or stimulus-dependent behavior. Instead, a decentralized multiexpert competition model best predicts behavior and causal perturbations. These findings suggest that mPFC implements a default strategy based on prior knowledge, which actively hinders the expression of more efficient strategies.
Kai Lu, K. Wong, Cheng Yang et al.· Science Advances· 0 citations