Biology subjects

Pagnotta, M. F.

Publications and source records attributed to Pagnotta, M. F..

5 recordsLinked to original sources

bioRxiv2026

Enhancing working memories using repetitive TMS

Working memory, the ability to retain and manipulate information no longer present in the environment, is fundamental for goal-directed behavior (Baddeley, 2012; Baddeley & Hitch, 1974; D'Esposito, 2007; D'Esposito & Postle, 2015). Alpha oscillations (~8-12 Hz) have two apparently contradictory roles in working memory. Alpha activity gates irrelevant information through inhibition, a role causally supported by rhythmic transcranial magnetic stimulation (TMS) of parietal cortex at alpha frequency when a retrospective cue renders a memory item irrelevant (Bonnefond & Jensen, 2012; Riddle et al., 2020). Yet alpha activity also tracks the content of memory and binds the features of memorized objects during maintenance (Foster et al., 2016; Pagnotta et al., 2026). Whether alpha oscillations causally support the fidelity of memory representations during maintenance is untested. Here, 24 participants received short trains of repetitive TMS (rTMS) at theta (6 Hz) or alpha frequency (10 Hz), or in an arrhythmic control pattern, during the second half of the delay of a color working memory task, over the left posterior inferior frontal sulcus or the left intraparietal sulcus. A mixture model separated memory precision from swap errors and guesses. Alpha stimulation of the intraparietal sulcus specifically increased memory precision, whereas rhythmic stimulation of either site reduced response error, guesses and swaps irrespective of frequency. These results provide causal evidence that alpha oscillations support the fidelity of working memory representations during maintenance, and show that rhythmic stimulation at the appropriate frequency, site and time can enhance human working memory.

neuroscience↗

bioRxiv2026

A single cortical circuit implements fast and slow visual search

How the brain produces different behaviors from a fixed anatomical substrate is a foundational question in neuroscience. The dominant account holds that behavioral flexibility requires distinct neural circuits: dedicated systems selectively recruited for different processing modes. An alternative proposes that flexibility arises not from switching between circuits, but from dynamically controlling the speed at which a shared circuit operates. Here, we test this account directly using intracranial EEG recordings from nineteen human patients performing two visual search tasks of markedly different difficulty: an easy color-singleton search and a difficult orientation search, a fast vs. slow dissociation attributed for four decades to distinct anatomical and oscillatory neural systems. We show that both search tasks recruit the same cortical regions, oscillatory frequencies, and processing hierarchy. Dynamic time warping reveals that the two neural trajectories are time-stretched versions of one another; the same temporal scaling appears within each condition between faster and slower trials, indexing response speed rather than the distinction between tasks. Alpha-band oscillations (~8-10 Hz) support this temporal scaling through two coordinated mechanisms: synchronizing activity across a posterior cortical network and phase-gating local high-frequency activity (70-150 Hz) within those regions at the same preferred phase in both conditions. These findings establish that, for the two tasks studied here, fast and slow visual search are not implemented by selecting between distinct dedicated circuits, but by adjusting the speed of a single alpha-coordinated architecture. The same principle may apply to other search tasks, and to other domains in which dual-process architectures have been invoked, a testable prediction for future studies.

neuroscience↗

bioRxiv2025

Sensorimotor dynamics differentiate singing and speaking

Singing and speaking often dissociate clinically--people who stutter can sing fluently, and individuals with aphasia and speech output problems from stroke may express sentences fluently in song--yet the neural mechanisms of this centuries-old clinical phenomenon remain unclear. We recorded intracranial EEG while neurosurgical patients produced matched sentences by singing or speaking, sampling millimeter- and millisecond-scale activity across both hemispheres. During articulation, high-frequency activity (70-150 Hz) lateralized oppositely across behaviors, with right-dominant sensorimotor cortex (SMC) activation for singing and left-dominant activation for speaking. Phase-amplitude coupling revealed that mu-band ([~]10 Hz) phase locally organized HFA in left SMC in a channel-specific, spatially interdigitated architecture preserved across both behaviors. Mu-band synchrony in speaking showed an early left-led pattern, whereas singing exhibited a ramping of synchrony within the left sensorimotor cortex and between the two motor cortices, supporting progressive interhemispheric recruitment. Frequency-domain Granger- Geweke causality revealed that the left primary somatosensory cortex drives both motor cortices at speech onset. In contrast in singing, control over motor cortices relied on both hemispheres. Singing and speaking engage a shared mu-coupled sensorimotor substrate through distinct recruitment dynamics.

neuroscience↗

bioRxiv2024

Alpha phase-coding supports feature binding during working memory maintenance

The ability to successfully retain and manipulate information in working memory (WM) requires that objects individual features are bound into cohesive representations; yet, the mechanisms supporting feature binding remain unclear. Binding (or swap) errors, where memorized features are erroneously associated with the wrong object, can provide a window into the intrinsic limits in capacity of WM that represent a key bottleneck in our cognitive ability. We tested the hypothesis that binding in WM is accomplished via neural phase synchrony and that swap errors result from perturbations in this synchrony. Using magnetoencephalography data collected from human subjects in a task designed to induce swap errors, we showed that swaps are characterized by reduced phase-locked oscillatory activity during memory retention, as predicted by an attractor model of spiking neural networks. Further, we found that this reduction arises from increased phase coding variability in the alpha-band over a distributed network of sensorimotor areas. Our findings demonstrate that feature binding in WM is accomplished through phase coding dynamics that emerge from the competition between different memories. SignificanceWe investigate the neural basis of working memory, focusing on how feature binding is accomplished and how binding or swap errors arise. Using magnetoencephalography, we found that stable phase-locking of alpha oscillations supports correct feature binding, while swap errors correlate with reduced alpha phase preservation, localized to specific brain areas. These findings align with a biologically-plausible computational model predicting that temporal synchrony in neuronal firing underpins feature binding. This work advances our understanding of the neural mechanisms of working memory, providing empirical support for theories of time-based binding and demonstrating the utility of biophysically-realistic models in human neuroimaging studies.

neuroscience↗

bioRxiv2020

Nested oscillations and brain connectivity during sequential stages of feature-based attention

Brain mechanisms of visual selective attention involve both local and network-level activity changes at specific oscillatory rhythms, but their interplay remains poorly explored. Here, we investigate anticipatory and reactive effects of feature-based attention using separate fMRI and EEG recordings, while participants attended to one of two spatially overlapping visual features (motion and orientation). We focused on EEG source analysis of local nested oscillations and on graph analysis of connectivity changes in a network of fMRI-defined regions of interest, and characterized a cascade of attentional effects and their interplay at multiple spatial scales. We discuss how the results may reconcile several theories of selective attention, by showing how {beta} rhythms support anticipatory information routing through increased network efficiency and {beta}-{gamma} coupling in functionally specialized regions (V1 for orientation, V5 for motion), while reactive -band desynchronization patterns and increased -{gamma} coupling in V1 and V5 mediate stimulus-evoked processing of task-relevant signals.

neuroscience↗