The Penn Electrophysiology of Encoding and Retrieval Study.

The Penn Electrophysiology of Encoding and Retrieval Study (PEERS) aimed to characterize the behavioral and electrophysiological (EEG) correlates of memory encoding and retrieval in highly practiced individuals. Across five PEERS experiments, 300+ subjects contributed more than 7,000 memory testing sessions with recorded EEG data. Here we tell the story of PEERS: its genesis, evolution, major findings, and the lessons it taught us about taking a big scientific approach in studying memory and the human brain. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

EEG decoders track memory dynamics.

Encoding- and retrieval-related neural activity jointly determine mnemonic success. We ask whether electroencephalographic activity can reliably predict encoding and retrieval success on individual trials. Each of 98 participants performed a delayed recall task on 576 lists across 24 experimental sessions. Logistic regression classifiers trained on spectral features measured immediately preceding spoken recall of individual words successfully predict whether or not those words belonged to the target list. Classifiers trained on features measured during word encoding also reliably predict whether those words will be subsequently recalled and further predict the temporal and semantic organization of the recalled items. These findings link neural variability predictive of successful memory with item-to-context binding, a key cognitive process thought to underlie episodic memory function.

Dynamic models for musical rhythm perception and coordination.

Rhythmicity permeates large parts of human experience. Humans generate various motor and brain rhythms spanning a range of frequencies. We also experience and synchronize to externally imposed rhythmicity, for example from music and song or from the 24-h light-dark cycles of the sun. In the context of music, humans have the ability to perceive, generate, and anticipate rhythmic structures, for example, "the beat." Experimental and behavioral studies offer clues about the biophysical and neural mechanisms that underlie our rhythmic abilities, and about different brain areas that are involved but many open questions remain. In this paper, we review several theoretical and computational approaches, each centered at different levels of description, that address specific aspects of musical rhythmic generation, perception, attention, perception-action coordination, and learning. We survey methods and results from applications of dynamical systems theory, neuro-mechanistic modeling, and Bayesian inference. Some frameworks rely on synchronization of intrinsic brain rhythms that span the relevant frequency range; some formulations involve real-time adaptation schemes for error-correction to align the phase and frequency of a dedicated circuit; others involve learning and dynamically adjusting expectations to make rhythm tracking predictions. Each of the approaches, while initially designed to answer specific questions, offers the possibility of being integrated into a larger framework that provides insights into our ability to perceive and generate rhythmic patterns.

Modality effects in free recall: A retrieved-context account.

The modality effect refers to the robust finding that memory performance differs for items presented aurally, as compared with visually. Whereas auditory presentation leads to stronger recency performance in immediate recall, visual presentation often produces better primacy performance (the inverse modality effect). To investigate and model these differences, we conducted two large-scale web-based immediate free recall experiments. In both experiments, participants studied visual and auditory word lists of varying lengths and rates of presentation. We observed typical modality and inverse modality effects, while also discovering that participants were more likely to initiate recall from recent items on auditory trials than on visual trials. However, modality effects persisted regardless of the first item recalled. Meanwhile, an analysis of intrusion errors revealed that participants were more likely on visual trials than on auditory trials to erroneously recall words from one list prior. Furthermore, words presented in the same modality as the present list intruded more often than those presented in a different modality. We next developed a retrieved-context account of the modality effect by fitting the Context Maintenance and Retrieval model to data across multiple list lengths. Through our simulations, we demonstrate that the modality effect can be explained by faster contextual drift and stronger context-to-item association formation during auditory presentation, relative to visual. Our modeling shows that modality effects can arise without hypothesizing distinct memory stores for recent and remote information. Finally, we propose that modality effects may derive primarily from the temporal dynamics of stimuli, rather than their modality. (PsycInfo Database Record (c) 2023 APA, all rights reserved).