Distinct population code for movement kinematics and changes of ongoing movements in human subthalamic nucleus.

The subthalamic nucleus (STN) is theorized to globally suppress movement through connections with downstream basal ganglia structures. Current theories are supported by increased STN activity when subjects withhold an uninitiated action plan, but a critical test of these theories requires studying STN responses when an ongoing action is replaced with an alternative. We perform this test in subjects with Parkinson's disease using an extended reaching task where the movement trajectory changes mid-action. We show that STN activity decreases during action switches, contrary to prevalent theories. Furthermore, beta oscillations in the STN local field potential, which are associated with movement inhibition, do not show increased power or spiking entrainment during switches. We report an inhomogeneous population neural code in STN, with one sub-population encoding movement kinematics and direction and another encoding unexpected action switches. We suggest an elaborate neural code in STN that contributes to planning actions and changing the plans.

Theta band network supporting human episodic memory is not activated in the seizure onset zone.

Episodic memory, everyday memory for events, is frequently impaired in patients with epilepsy. We tested patients undergoing intracranial electroencephalography (intracranial EEG) monitoring for the treatment of medically-refractory epilepsy on a well-characterized paradigm that requires episodic memory. We report that an anatomically diffuse network characterized by theta-band (4-7 Hz) coherence is activated at the time of target selection in a task that requires episodic memory. This distinct network of oscillatory activity is absent when episodic memory is not required. Further, the theta band synchronous network was absent in electrodes within the patient's seizure onset zone (SOZ). Our data provide novel empirical evidence for a set of brain areas that supports episodic memory in humans, and it provides a pathophysiologic mechanism for the memory deficits observed in patients with epilepsy.

Anatomy, Physiology, and Clinical Syndromes of the Basal Ganglia: A Brief Review.

Movement disorders typically arise from dysfunction of the basal ganglia (BG), cerebellum, or both. The BG-a group of deep, subcortical structures-form complex circuits that shape motor control and motor learning, as well as limbic and associative functions. In this article, we summarize the anatomy and physiology of the BG and cerebellum, and briefly highlight the clinical syndromes that may arise in the context of their injury or dysfunction.

Interdisciplinary Home Visits for Individuals with Advanced Parkinson's Disease and Related Disorders.

Parkinson's disease (PD) is a complex, multisymptom, neurodegenerative disease affecting primarily older adults. With progression, many individuals become homebound and removed from coordinated, expert care, resulting in excess morbidity, mortality, and healthcare expenditures in acute care settings and institutions. Home visit care models have achieved the triple aim of improving individual and population health while reducing costs in many frail, community-dwelling geriatric cohorts. This study details a novel, interdisciplinary home visit program specifically designed for individuals with PD and related disorders and their family caregivers built upon best practice principles in the care of multimorbid older adults. At each quarterly home visit, a movement disorders-trained neurologist, social worker, and nurse work in parallel with the individual and caregiver to complete a history, physical, detailed medication reconciliation, psychosocial needs assessment, and home safety assessment. A comprehensive, person-centered plan is agreed upon, referrals to community resources are made, standardized documentation is shared, and follow-up communication is instituted. In the first 2 years, 272 visits were conducted with 85 individuals who represent one of the oldest, most disabled PD populations reported. Satisfaction with and retention in the program were high. This study represents the first translation of the success of interdisciplinary and home-based geriatric care models to a population with a specific neurological disease. Preliminary evidence supports the need for such programs in vulnerable populations. Future studies will prospectively assess person-centered outcomes, the effect of using telemedicine on sustainability, and cost effectiveness.

View-invariant object category learning, recognition, and search: how spatial and object attention are coordinated using surface-based attentional shrouds.

How does the brain learn to recognize an object from multiple viewpoints while scanning a scene with eye movements? How does the brain avoid the problem of erroneously classifying parts of different objects together? How are attention and eye movements intelligently coordinated to facilitate object learning? A neural model provides a unified mechanistic explanation of how spatial and object attention work together to search a scene and learn what is in it. The ARTSCAN model predicts how an object's surface representation generates a form-fitting distribution of spatial attention, or "attentional shroud". All surface representations dynamically compete for spatial attention to form a shroud. The winning shroud persists during active scanning of the object. The shroud maintains sustained activity of an emerging view-invariant category representation while multiple view-specific category representations are learned and are linked through associative learning to the view-invariant object category. The shroud also helps to restrict scanning eye movements to salient features on the attended object. Object attention plays a role in controlling and stabilizing the learning of view-specific object categories. Spatial attention hereby coordinates the deployment of object attention during object category learning. Shroud collapse releases a reset signal that inhibits the active view-invariant category in the What cortical processing stream. Then a new shroud, corresponding to a different object, forms in the Where cortical processing stream, and search using attention shifts and eye movements continues to learn new objects throughout a scene. The model mechanistically clarifies basic properties of attention shifts (engage, move, disengage) and inhibition of return. It simulates human reaction time data about object-based spatial attention shifts, and learns with 98.1% accuracy and a compression of 430 on a letter database whose letters vary in size, position, and orientation. The model provides a powerful framework for unifying many data about spatial and object attention, and their interactions during perception, cognition, and action.

Munker-White-like illusions without T-junctions.

Some interpretations of the Munker-White illusion were evaluated by designing new versions of this illusion devoid of T-junctions (Munker-White-like images). The magnitudes of both Munker-White and Munker-White-like illusions were then quantified by using a brightness-matching technique. The results showed the effect to persist in all proposed versions. Since the illusion still remains despite the absence of explicit T-junctions and any explanation considering transparency, mechanisms other than those proposed by these interpretations must be responsible.