The Control of Movements via Motor Gamma Oscillations

The ability to perform movements is vital for our daily life. Our actions are embedded in a complex environment where we need to deal efficiently in the face of unforeseen events. Neural oscillations play an important role in basic sensorimotor processes related to the execution and preparation of movements. In this review, I will describe the state of the art regarding the role of motor gamma oscillations in the control of movements. Experimental evidence from electrophysiological studies has shown that motor gamma oscillations accomplish a range of functions in motor control beyond merely signaling the execution of movements. However, these additional aspects associated with motor gamma oscillation remain to be fully clarified. Future work on different spatial, temporal and spectral scales is required to further understand the implications of gamma oscillations in motor control.

Neural Oscillations and Networks in Processes Specific to Auditory Imagery

Auditory imagery is a cognitive process for generating sound in our mind. Despite the absence of external stimuli, neuroimaging studies have found overlapping neural activities within perception and imagery. While neuroimaging studies have revealed activities unique to auditory imagery, namely memory retrieval and mental manipulation, little is known about the functional oscillatory networks associated with these processes. Therefore, in this study, we aimed to distinguish between neural oscillations for memory retrieval and mental manipulation processes by building a novel experimental paradigm containing multiple imagery conditions with the goal of enabling the effective investigation of different oscillatory processes. We found that frontal and temporal gamma power was associated with mental manipulation, while frontotemporal delta phase coupling and delta-gamma phase-amplitude coupling were each associated with memory retrieval during auditory imagery. Moreover, we found that oscillations reflecting auditory-motor communication were associated with memory retrieval. Our results suggest the critical role of neural oscillations associated with imagery-specific processes and present evidence supporting the long-debated role of motor functions in auditory imagery. Our work thus adds dimension to the state of knowledge regarding functional networks within auditory imagery.

Why am I always late? Modeling the cognitive mechanisms underlying anticipatory timing under uncertainty

Responding to stimuli in a timely manner and anticipating the timing of future events both require us to internally track the passage of time. Models of timing on these tasks suggest that the subjective passage of time can be described as a noisy accumulation process driven by neural oscillations. In this paper, we show that the accuracy of these accumulators can be manipulated by occluding visual cues to the passage of time. Using a simple perceptual paradigm, we manipulate the total length of time that a stimulus must be tracked, the rate at which it moves, and the uncertainty that participants have about its position (length of occlusion). Participants consistently under-estimated the movement of the stimulus when it was occluded, corresponding to a drift rate in an accumulator model that was approximately half of what would be required to accurately track the passage of time. This results in consistently tardy anticipatory response times under uncertainty (Study 1) and an under-estimation of stimulus movement as it passes behind an occlusion (Study 2). Using a novel timing problems scale, we show that individual differences in model parameters representing subjective tracking of time under uncertainty predicted real-world difficulties managing time, tardiness, and procrastination.

Neurodevelopmental Preparedness for Language in the Neonatal Brain

Neonates show broad-based, universal speech perception abilities, allowing them to acquire any language. Moreover, an increasing body of research shows that prenatal experience with speech, which is a low-pass signal mainly preserving prosody, already shapes those abilities. In this review, we first provide a summary of the empirical evidence available today on newborns’ universal and experience-modulated speech perception abilities. We then interpret these findings in a new framework, focusing on the role of the prenatal prosodic experience in speech perception development. We argue that the chronological sequence of infants’ experience with speech, starting before birth with a low-pass filtered signal and continuing with the full-band signal after birth, sets up the prosodic hierarchy and a cascade of embedded neural oscillations as its brain correlate, laying the foundations for language acquisition. Prosody, constituting infants’ very first experience with language, may thus play a fundamental role in speech perception and language development.

Early Versus Late Mild Cognitive Impairment: Neural Event-Related Oscillations During a Go/No Go Task

Amnestic mild cognitive impairment (aMCI) is marked by episodic memory deficits, which is used to classify individuals into early MCI (EMCI) and late MCI (LMCI). Growing evidence suggests that individuals with EMCI and LMCI differ in other cognitive functions including cognitive control, but these are less frequently studied. Using a semantic Go/NoGo task, we examined differences in cognitive control between EMCI and LMCI on behavioral (accuracy and reaction time) and neural (scalp-recorded event-related oscillations in theta and alpha band) measures. Although no behavioral differences were observed between the groups, EMCI and LMCI groups differed in patterns of neural oscillations for Go compared to NoGo trials. The EMCI group showed differences in theta power at central electrodes and alpha power at central and centro-parietal electrodes between Go and NoGo trials, while the LMCI group did not exhibit such differences. Furthermore, the LMCI group had higher theta synchronization on Go trials at central electrodes compared to the EMCI group. These findings suggest that while behavioral differences may not be observable, neural changes underlying cognitive control processes may differentiate EMCI and LMCI stages and may be useful to understand the trajectory of aMCI.

Functional alterations in cortical processing of speech in glioma-infiltrated cortex

Recent developments in the biology of malignant gliomas have demonstrated that glioma cells interact with neurons through both paracrine signaling and electrochemical synapses. Glioma–neuron interactions consequently modulate the excitability of local neuronal circuits, and it is unclear the extent to which glioma-infiltrated cortex can meaningfully participate in neural computations. For example, gliomas may result in a local disorganization of activity that impedes the transient synchronization of neural oscillations. Alternatively, glioma-infiltrated cortex may retain the ability to engage in synchronized activity in a manner similar to normal-appearing cortex but exhibit other altered spatiotemporal patterns of activity with subsequent impact on cognitive processing. Here, we use subdural electrocorticography to sample both normal-appearing and glioma-infiltrated cortex during speech. We find that glioma-infiltrated cortex engages in synchronous activity during task performance in a manner similar to normal-appearing cortex but recruits a diffuse spatial network. On a temporal scale, we show that signals from glioma-infiltrated cortex have decreased entropy, which may affect its ability to encode information during nuanced tasks such as production of monosyllabic versus polysyllabic words. Furthermore, we show that temporal decoding strategies for distinguishing monosyllabic from polysyllabic words were feasible for signals arising from normal-appearing cortex but not from glioma-infiltrated cortex. These findings inform our understanding of cognitive processing in chronic disease states and have implications for neuromodulation and prosthetics in patients with malignant gliomas.