Double dissociation of dopamine and subthalamic nucleus stimulation on effortful cost/benefit decision making.

Deep brain stimulation (DBS) and dopaminergic therapy (DA) are common interventions for Parkinson's disease (PD). Both treatments typically improve patient outcomes, and both can have adverse side effects on decision making (e.g., impulsivity).1,2 Nevertheless, they are thought to act via different mechanisms within basal ganglia circuits.3 Here, we developed and formally evaluated their dissociable predictions within a single cost/benefit effort-based decision-making task. In the same patients, we manipulated DA medication status and subthalamic nucleus (STN) DBS status within and across sessions. Using a series of descriptive and computational modeling analyses of participant choices and their dynamics, we confirm a double dissociation: DA medication asymmetrically altered participants' sensitivities to benefits vs. effort costs of alternative choices (boosting the sensitivity to benefits while simultaneously lowering sensitivity to costs); whereas STN DBS lowered the decision threshold of such choices. To our knowledge, this is the first study to show, using a common modeling framework, a dissociation of DA and DBS within the same participants. As such, this work offers a comprehensive account for how different mechanisms impact decision making, and how impulsive behavior (present in DA-treated patients with PD and DBS patients) may emerge from separate physiological mechanisms.

The temporal cost of deploying attention limits accurate target identification in rapid serial visual presentation.

Lag-1 sparing is a common exception to the attentional blink, where a target presented directly after T1 can be identified and reported accurately. Prior work has proposed potential mechanisms for lag 1 sparing, including the boost and bounce model and the attentional gating model. Here, we apply a rapid serial visual presentation task to investigate the temporal limitations of lag 1 sparing by testing three distinct hypotheses. We found that endogenous engagement of attention to T2 requires between 50 and 100 ms. Critically, faster presentation rates yielded lower T2 performance, whereas decreased image duration did not impair T2 detection and report. These observations were reinforced by subsequent experiments controlling for short-term learning and capacity-dependent visual processing effects. Thus, lag-1 sparing was limited by the intrinsic dynamics of attentional boost engagement rather than by earlier perceptual bottlenecks such as insufficient exposure to images in the stimulus stream or visual processing capacity limitations. Taken together, these findings support the boost and bounce theory over earlier models that focus only on attentional gating or visual short-term memory storage, informing our understanding of how the human visual system deploys attention under challenging temporal constraints.

Demand for Essential Nonambulatory Neurosurgical Care Decreased While Acuity of Care Increased During the Coronavirus Disease 2019 (COVID-19) Surge.

BACKGROUND: In times of health resource reallocation, capacities must remain able to meet a continued demand for essential, nonambulatory neurosurgical acute care. This study sought to characterize the demand for and provision of neurosurgical acute care during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: This single-center cross-sectional observational analysis compared nonambulatory neurosurgical consult encounters during the peri-surge period (March 9 to May 31, 2020) with those during an analogous period in 2019. Outcomes included consult volume, distribution of problem types, disease severity, and rate of acute operative intervention. RESULTS: A total of 1494 neurosurgical consults were analyzed. Amidst the pandemic surge, 583 consults were seen, which was 6.4 standard deviations below the mean among analogous 2016-2019 periods (mean 873; standard deviation 45, P = 0.001). Between 2019 and 2020, the proportion of degenerative spine consults decreased in favor of spinal trauma (25.6% vs. 34% and 51.9% vs. 41.4%, P = 0.088). Among aneurysmal subarachnoid hemorrhage cases, poor-grade (Hunt and Hess grades 4-5) presentations were more common (30% vs. 14.8%, P = 0.086). A greater proportion of pandemic era consults resulted in acute operative management, with an unchanged absolute frequency of acutely operative consults (123/583 [21.1%] vs. 120/911 [13.2%], P < 0.001). CONCLUSIONS: Neurosurgical consult volume during the pandemic surge hit a 5-year institutional low. Amidst vast reallocation of health care resources, demand for high-acuity nonambulatory neurosurgical care continued and proportionally increased for greater-acuity pathologies. In our continued current pandemic as well as any future situations of mass health resource reallocation, neurosurgical acute care capacities must be preserved.

A low-cost solution for quantification of movement during DBS surgery.

BACKGROUND: During the deep brain stimulation (DBS) electrode implantation operation with microelectrode recordings (MER) in awake patients, somatotopic testing and test stimulation are performed to improve electrode placement and provide the most beneficial symptom reduction possible, while minimizing side effects. As this procedure is commonly used to alleviate abnormal movements associated with Parkinson's disease (PD) and Essential Tremor (ET), intraoperative assessment of a patient's movements is critical to optimizing surgical benefit. However, despite its importance, movement assessment is typically subjective and qualitative. NEW METHOD: Here, we present a detailed description of a low-cost, open-source system as a solution. RESULTS: The described system measures movements intraoperatively and in synchrony with neurophysiological recordings for both online visualization and offline analysis. COMPARISON WITH EXISTING METHOD(S): Few movement quantification systems are designed to interface with intraoperative neurophysiological recordings; the widespread application of such systems may be limited by their cost and proprietary, closed-source nature. The system presented provides a low-cost, open-source alternative. CONCLUSIONS: The system outlined in this work may improve the DBS procedure by adding valuable objectivity in movement quantification.

Comprehensive assessment of isolated traumatic subarachnoid hemorrhage.

Recent studies have shown that isolated traumatic subarachnoid hemorrhage (tSAH) in the setting of a high Glasgow Coma Scale (GCS) score (13-15) is a relatively less severe finding not likely to require operative neurosurgical intervention. This study sought to provide a more comprehensive assessment of isolated tSAH among patients with any GCS score, and to expand the analysis to examine the potential need for aggressive medical, endovascular, or open surgical interventions in these patients. By undertaking a retrospective review of all patients admitted to our trauma center from 2003-2012, we identified 661 patients with isolated tSAH. Only four patients (0.61%) underwent any sort of aggressive neurosurgical, medical, or endovascular intervention, regardless of GCS score. Most tSAH patients without additional systemic injury were discharged home (68%), including 53% of patients with a GCS score of 3-8. However, older patients were more likely to be discharged to a rehabilitation facility (p<0.01). There were six (1.7%) in-hospital deaths, and five patients of these patients were older than 80 years old. We conclude that isolated tSAH, regardless of admission GCS score, is a less severe intracranial injury that is highly unlikely to require aggressive operative, medical, or endovascular intervention, and is unlikely to be associated with major neurologic morbidity or mortality, except perhaps in elderly patients. Based upon our findings, we argue that impaired consciousness in the setting of isolated tSAH should strongly compel a consideration of non-traumatic factors in the etiology of the altered neurological status.

Prospective assessment of stereotactic ablative surgery for intractable major depression.

BACKGROUND: Despite therapeutic advances for major depression, a subset of patients with this disorder does not respond to conventional treatment. Stereotactic ablative procedures such as anterior cingulotomy have been performed in severely affected, treatment-resistant patients, but the long-term results of such procedures are not fully understood. METHODS: Findings are reported for 33 patients with severe treatment-resistant major depression who underwent ablative stereotactic procedures (dorsal anterior cingulotomy followed if necessary by subcaudate tractotomy). Preoperative and long-term postoperative Beck Depression Inventory scores were obtained along with postoperative Clinical Global Improvement values. Both were analyzed to evaluate patients' responses to the surgical procedure(s). RESULTS: At mean follow-up of 30 months after one or more stereotactic ablative procedures, 11 patients (33.3%) were classified as responders, 14 (42.4%) were partial responders, and 8 (24.2%) did not respond to the surgical procedure(s). Among those (17) who underwent only one procedure, seven (41.2%) responded, whereas six (35.3%) and four (23.5%) showed partial or no response, respectively. Among patients who required multiple surgical procedures, four patients (25%) responded, whereas eight (50%) and four (25%) patients demonstrated partial or no responses, respectively, at long-term follow-up evaluations. CONCLUSIONS: Approximately 75% of depression patients previously resistant to antidepressant therapies received partial or substantial benefit from stereotactic ablative procedures. Those requiring only a single anterior cingulotomy tended to demonstrate more pronounced responses than patients who underwent multiple surgical procedures.