Washout of chronic therapeutic deep brain stimulation increases cortical phase-amplitude coupling.

Invasive human brain recordings have shown that acute therapeutic deep brain stimulation (DBS) reduces cortical synchronization, measured by coupling of beta phase to gamma amplitude. Here we show by noninvasive scalp electroencephalography that withdrawal of chronic DBS elevates phase-amplitude coupling, in proportion to the worsening of contralateral rigidity

Altered Prefrontal Theta and Gamma Activity during an Emotional Face Processing Task in Parkinson Disease.

Patients with Parkinson disease (PD) often experience nonmotor symptoms including cognitive deficits, depression, and anxiety. Cognitive and affective processes are thought to be mediated by prefrontal cortico-basal ganglia circuitry. However, the topography and neurophysiology of prefrontal cortical activity during complex tasks are not well characterized. We used high-resolution electrocorticography in pFC of patients with PD and essential tremor, during implantation of deep brain stimulator leads in the awake state, to understand disease-specific changes in prefrontal activity during an emotional face processing task. We found that patients with PD had less task-related theta-alpha power and greater task-related gamma power in the dorsolateral pFC, inferior frontal cortex, and lateral OFC. These findings support a model of prefrontal neurophysiological changes in the dopamine-depleted state, in which focal areas of hyperactivity in prefrontal cortical regions may compensate for impaired long-range interactions mediated by low-frequency rhythms. These distinct neurophysiological changes suggest that nonmotor circuits undergo characteristic changes in PD

Proceedings of the Third Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

The proceedings of the 3rd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, imaging, and computational work on DBS for the treatment of neurological and neuropsychiatric disease. Significant innovations of the past year are emphasized. The Think Tank\u27s contributors represent a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers, and members of industry. Presentations and discussions covered a broad range of topics, including policy and advocacy considerations for the future of DBS, connectomic approaches to DBS targeting, developments in electrophysiology and related strides toward responsive DBS systems, and recent developments in sensor and device technologies

Proceedings of the Eighth Annual Deep Brain Stimulation Think Tank: Advances in Optogenetics, Ethical Issues Affecting DBS Research, Neuromodulatory Approaches for Depression, Adaptive Neurostimulation, and Emerging DBS Technologies

We estimate that 208,000 deep brain stimulation (DBS) devices have been implanted to address neurological and neuropsychiatric disorders worldwide. DBS Think Tank presenters pooled data and determined that DBS expanded in its scope and has been applied to multiple brain disorders in an effort to modulate neural circuitry. The DBS Think Tank was founded in 2012 providing a space where clinicians, engineers, researchers from industry and academia discuss current and emerging DBS technologies and logistical and ethical issues facing the field. The emphasis is on cutting edge research and collaboration aimed to advance the DBS field. The Eighth Annual DBS Think Tank was held virtually on September 1 and 2, 2020 (Zoom Video Communications) due to restrictions related to the COVID-19 pandemic. The meeting focused on advances in: (1) optogenetics as a tool for comprehending neurobiology of diseases and on optogenetically-inspired DBS, (2) cutting edge of emerging DBS technologies, (3) ethical issues affecting DBS research and access to care, (4) neuromodulatory approaches for depression, (5) advancing novel hardware, software and imaging methodologies, (6) use of neurophysiological signals in adaptive neurostimulation, and (7) use of more advanced technologies to improve DBS clinical outcomes. There were 178 attendees who participated in a DBS Think Tank survey, which revealed the expansion of DBS into several indications such as obesity, post-traumatic stress disorder, addiction and Alzheimer’s disease. This proceedings summarizes the advances discussed at the Eighth Annual DBS Think Tank

When and where will a target go? A behavioural and electrophysiological study of expectation in primates

In a rapidly changing visual environment, the delay between perception and action might impair the probability of survival of a prey or the efficiency of a predator. In order to compensate for delays associated with sensory-motor processing, primates often make predictions about future events and initiate anticipatory movements. To prepare an anticipatory movement, an estimation of when and where to a target is likely to move is necessary. Such an internal representation is often termed 'expectation'. The aim of this thesis was to investigate the gradual changes of a subject's expectation at the behavioral and electrophysiological levels. Anticipatory smooth pursuit was used in order to study temporal and directional changes in expectation. We found that temporal uncertainty strongly modulated the latency and the velocity of anticipatory movements suggesting that monkeys could estimate the hazard rate of target motion onset in order to decide when to initiate an anticipatory movement. In addition, we have shown that monkeys could use prior directional information in order to voluntarily initiate anticipatory responses in the direction of expected target motion. This prior directional information significantly affected the latency and velocity of these movements. Finally, we have shown that the majority of recorded supplementary eye field (SEF) neurons encoded expected target motion direction. The presence of a directional cue induced an increase of activity in the preferred direction of the neuron. Moreover, a large sub-population of neurons encoded the direction of future anticipatory movement. These results suggest that the SEF could be involved in the cognitive control of anticipatory pursuit eye movements when prior temporal and directional information is provided.(SBIM 3) -- UCL, 200

Influence of cognitive expectation on the initiation of anticipatory and visual pursuit eye movements in the rhesus monkey.

A classic paradigm to study anticipatory pursuit consists in training monkeys to look at a target that appears in the center of a visual display, disappears during a short "gap" period, then reappears and immediately starts to move. To determine the role of prior directional information on anticipatory pursuit eye movements, we trained rhesus monkeys to associate the color of a centrally presented visual cue with the direction of an upcoming target motion. In a first experiment, a gap period occurred randomly in 50% of the trials. Consequently, two possible choices of timing of target motion onset were given to subjects to guide their anticipatory responses. In a second experiment, a gap period occurred during each trial and only a single choice of timing of target motion onset was given to subjects. We found that monkeys used the learned association between the color of the cue and the direction of future target motion to voluntarily initiate anticipatory pursuit movements in the appropriate direction. Anticipatory movements could be classified in two distinct populations: early and late movements. Early movements were most frequent when prior directional information was provided and when two choices of timing of target motion onset were given. The latency of visual pursuit was shortened and its velocity was larger when prior directional information was provided. We conclude that cognitive expectation of future target motion plays a dominant role in determining characteristics of anticipatory pursuit in the monkey

Neuronal bases of directional expectation and anticipatory pursuit

Expectation of upcoming events is an essential cognitive function on which anticipatory actions are based. The neuronal basis of this prospective representation is poorly understood. We trained rhesus monkeys in a smooth-pursuit task in which the direction of upcoming target motion was indicated using a color cue. Under these conditions, directional expectation frequently evoked anticipatory smooth movements. We found that the activity of a population of neurons in the supplementary eye fields encoded the expected future direction of the target. Neuronal activity increased after presentation of the cue, indicating future target motion in the preferred direction. Neuronal activity either remained unaltered or was reduced if the antipreferred direction was cued. In addition, approximately 30% of these neurons were more active during trials with anticipatory pursuit in the preferred direction than during trials when monkeys did not anticipate target motion onset. This subset of recorded neurons encoded the direction of the subsequent anticipatory pursuit. We hypothesize that the neural representation of directional expectation could be conceptualized as a competitive interaction between pools of neurons representing likely future events, with the winner of this competition determining the direction of the subsequent anticipatory movement. Similar mechanisms could drive prediction before movement initiation in other motor domains