The cognitive profile of essential tremor on the Repeatable Battery for the Assessment of Neuropsychological Status

Objective: Essential tremor (ET), while defined by progressive motor symptoms, is increasingly associated with cognitive impairments (e.g. attention, memory, and executive functions). This study characterizes the cognitive profile of individuals with ET on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), a commonly-used neuropsychological screening measure. Method: Seventy-seven individuals (mean age: 70.6, 34% female) diagnosed with ET and being considered for surgical/procedural intervention were recruited from a Movement Disorders Clinic. All participants completed the RBANS, Grooved Pegboard Test (GPB), and Fahn, Tolosa, Marin Tremor Scale (FTMTS) in the clinical evaluation of their tremor. Results: One-sample t-tests found Immediate Memory, Language, Attention, and Total Scale Index scores to be significantly lower than the expected population mean (p < .05). List Learning, Semantic Fluency, Coding, and List Recall subtests were significantly lower and Picture Naming was significantly higher than the expected population mean (p < .05). GPB scores were correlated with the Attention Index as well as List Learning and Coding subtests. FTMTS Severity was correlated with the Coding subtest and FTMTS Disability was correlated with the Figure Recall subtest. Conclusions: Results support prior literature indicating cognitive weaknesses in those with ET. Individuals with ET had poorer global cognitive abilities, with specific decrements in Immediate Memory, Attention, and Language. Notably, the Attention Index and Coding subtest were most affected by motor functioning. Cognitive screening measures, like the RBANS, can efficiently identify strengths and weaknesses in individuals with ET seeking surgical/procedural interventions.

Recognition subtests of the Repeatable Battery for the Assessment of Neuropsychological Status: evidence for a cortical vs. subcortical distinction

INTRODUCTION

Within clinical neuropsychology, a classic diagnostic distinction is made between cortical and subcortical disorders, especially based on their memory profiles. Typically, this is based on the comparison of recall and recognition trials, where individuals with cortical conditions do not tend to benefit (i.e., score well) on recognition trials and individuals with subcortical conditions do. Although the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a widely used brief cognitive battery, there is a lack of evidence to support this measure's utility in distinguishing between the memory profiles of these conditions.

METHOD

Thirty-six mild Alzheimer's disease (AD), 55 Parkinson's disease (PD), and 105 essential tremor (ET) participants (N = 196) were administered the RBANS with additional Story and Figure Recognition subtests. Group differences on recall and recognition scores (Total Correct, Hits or True Positives, False Positive Errors, and discriminability index) were examined across the three groups, while controlling for the influence of age and gender.

RESULTS

As expected, individuals with AD had poorer recognition scores compared to the other clinical groups across tasks (all p-values < .05), while the ET sample largely performed comparably to the PD sample. With the exception of comparable Figure Recognition and Recall in the PD sample, all groups exhibited significantly greater recognition Hit performance compared to Recall (all p-values < .05).

CONCLUSIONS

The group differences in performance across RBANS recognition subtests suggest support for traditional "cortical" and "subcortical" profiles. However, all groups, including the mild AD sample, demonstrated a benefit from recognition cues compared to free recall. Overall, these findings support the inclusion of the newly developed Story and Figure Recognition subtests in future clinical practice and research endeavors.

An Optrode Array for Spatiotemporally Precise Large-Scale Optogenetic Stimulation of Deep Cortical Layers in Non-human Primates

Optogenetics has transformed studies of neural circuit function, but remains challenging to apply in non-human primates (NHPs). A major challenge is delivering intense and spatially precise patterned photostimulation across large volumes in deep tissue. Here, we have developed and validated the Utah Optrode Array (UOA) to meet this critical need. The UOA is a 10×10 glass waveguide array bonded to an electrically-addressable μLED array. In vivo electrophysiology and immediate early gene (c-fos) immunohistochemistry demonstrated the UOA allows for large-scale spatiotemporally precise neuromodulation of deep tissue in macaque primary visual cortex. Specifically, the UOA permits both focal (single layers or columns), and large-scale (across multiple layers or columns) photostimulation of deep cortical layers, simply by varying the number of simultaneously activated μLEDs and/or the light irradiance. These results establish the UOA as a powerful tool for studying targeted neural populations within single or across multiple deep layers in complex NHP circuits.

Radiosurgery for epilepsy: clinical experience and potential antiepileptic mechanisms

Stereotactic radiosurgery, well established in the noninvasive treatment of focal lesions that are otherwise difficult to access through open surgery, is an emerging technology in the treatment of focal epileptic lesions. Recent studies suggest that seizures from hypothalamic hamartomas and mesial temporal lobe epilepsy remit at clinically significant rates with radiosurgery, but large variations among different studies have raised questions about appropriate treatment protocols and mechanisms. Proposed anticonvulsant mechanisms include neuromodulatory effects or ischemic necrosis of epileptic tissue. An ongoing trial that directly compares efficacy, morbidities, and cost of radiosurgery versus open surgery for mesial temporal lobe epilepsy is underway.