Wael F. Asaad

Electrical stimulation of different nodes within the Circuit of Papez has been assessed in a variety of human studies with conflicting or indeterminate results. Our goal was to combine a precise psychophysical paradigm with varying stimulation protocols across two experimental settings (intra-op, post-op) to more robustly identify and characterize the interaction between fornix stimulation and memory and to isolate whether those effects are specific to memory encoding, rather than related to distinct, supporting cognitive functions.

Attentional capture by emotionally salient stimuli is adaptive, permitting identification of possible threats; however, an excessive bias towards emotional stimuli can interrupt goal-directed behavior. This is especially relevant in psychiatric disease, where severe emotional distress can interfere with daily function. As such, understanding the mechanisms by which emotional stimuli compete for attentional resources is a critical area of investigation. Previous studies using rapid serial visual presentation (RSVP) paradigms observe that emotional distractors disrupt the detection of subsequent stimuli, referred to as emotion-induced blindness (EIB). Our study expands upon this work, characterizing how temporal and perceptual factors shape the emergence and intensity of EIB. Contrary to previous assumptions regarding temporal dynamics of EIB, we found that effects of emotional distractors persisted across prolonged image presentation durations. Further, we investigated the extent to which the depth of distractor processing influences EIB using a distractor recall task. While recall was predictive of EIB magnitude, a significant effect of emotional distractors on target detection was nonetheless present even without conscious recall of the distractor. These findings demonstrate the robustness of the EIB effect in RSVP in the context of temporal and perceptual manipulations.

The basal ganglia (BG) play a key role in decision-making, preventing impulsive actions in some contexts while facilitating fast adaptations in others. The specific contributions of different BG structures to this nuanced behavior remain unclear, particularly under varying situations of noisy and conflicting information that necessitate ongoing adjustments in the balance between speed and accuracy. Theoretical accounts suggest that dynamic regulation of the amount of evidence required to commit to a decision (a dynamic “decision boundary”) may be necessary to meet these competing demands. Through the application of novel computational modeling tools in tandem with direct neural recordings from human BG areas, we find that neural dynamics in the theta band manifest as variations in a collapsing decision boundary as a function of conflict and uncertainty. We collected intracranial recordings from patients diagnosed with either Parkinson’s disease (n=14) or dystonia (n=3) in the subthalamic nucleus (STN), globus pallidus internus (GPi), and externus (GPe) during their performance of a novel perceptual discrimination task in which we independently manipulated uncertainty and conflict. To formally characterize whether these task and neural components influenced decision dynamics, we leveraged modified diffusion decision models (DDMs). Behavioral choices and response time distributions were best characterized by a modified DDM in which the decision boundary collapsed over time, but where the onset and shape of this collapse varied with conflict. Moreover, theta dynamics in BG structures predicted the onset and shape of this collapse but differentially across task conditions. In STN, theta activity was related to a prolonged decision boundary (indexed by slower collapse and therefore more deliberate choices) during high-conflict situations. Conversely, rapid declines in GPe theta during low conflict conditions were related to rapidly collapsing boundaries and expedited choices, with additional complementary decision bound adjustments during high uncertainty situations. Finally, GPi theta effects were uniform across conditions, with increases in theta prolonging the collapse of decision bounds. Together, these findings provide a nuanced understanding of how our brain thwarts impulsive actions while nonetheless enabling behavioral adaptation amidst noisy and conflicting information.

BACKGROUND AND OBJECTIVES: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have gained increasing popularity since the approval of semaglutide by the United States Food and Drug Administration for chronic weight management. Significant benefits have been noted in glycemic control and cardiovascular health. However, as increasing numbers of patients are started on these medications, it is important for neurosurgeons to have knowledge of any perioperative considerations and side effects related to this class of drugs. METHODS: We performed a qualitative literature review using the PubMed and Embase databases, using the following key words: GLP-1 RAs adverse events; GLP-1 RAs and anesthesia; substance use disorders; and addiction, functional neurosurgery, nervous system rehabilitation, and spinal cord injury. Articles of relevance to perioperative management of these medications and specific benefits in the neurosurgical field were discussed. RESULTS: Recent guidance from the American Society of Anesthesiologists demonstrates the importance of tailored management of GLP-RA drugs for surgical patients. In addition, certain positive effects have been noted with relation to substance use disorders, neural protection and rehabilitation, and neurodegenerative disorders such as Alzheimer's disease. CONCLUSION: In this article, we review what the neurosurgeon needs to know about the perioperative management of GLP-1 RAs and discuss existing literature in clinical and preclinical studies for potential indications and benefits of these medications, which can influence the management of conditions treated by neurosurgeons.

Despite the importance of informed consent in healthcare, the readability and specificity of consent forms often impede patients’ comprehension. This study investigates the use of GPT-4 to simplify surgical consent forms and introduces an AI-human expert collaborative approach to validate content appropriateness. Consent forms from multiple institutions were assessed for readability and simplified using GPT-4, with pre- and post-simplification readability metrics compared using nonparametric tests. Independent reviews by medical authors and a malpractice defense attorney were conducted. Finally, GPT-4’s potential for generating de novo procedure-specific consent forms was assessed, with forms evaluated using a validated 8-item rubric and expert subspecialty surgeon review. Analysis of 15 academic medical centers’ consent forms revealed significant reductions in average reading time, word rarity, and passive sentence frequency (all P < 0.05) following GPT-4-faciliated simplification. Readability improved from an average college freshman to an 8th-grade level (P = 0.004), matching the average American’s reading level. Medical and legal sufficiency consistency was confirmed. GPT-4 generated procedure-specific consent forms for five varied surgical procedures at an average 6th-grade reading level. These forms received perfect scores on a standardized consent form rubric and withstood scrutiny upon expert subspeciality surgeon review. This study demonstrates the first AI-human expert collaboration to enhance surgical consent forms, significantly improving readability without sacrificing clinical detail. Our framework could be extended to other patient communication materials, emphasizing clear communication and mitigating disparities related to health literacy barriers.