Beta-band power classification of go/no-go arm-reaching responses in the human hippocampus.

Objective.Can we classify movement execution and inhibition from hippocampal oscillations during arm-reaching tasks? Traditionally associated with memory encoding, spatial navigation, and motor sequence consolidation, the hippocampus has come under scrutiny for its potential role in movement processing. Stereotactic electroencephalography (SEEG) has provided a unique opportunity to study the neurophysiology of the human hippocampus during motor tasks. In this study, we assess the accuracy of discriminant functions, in combination with principal component analysis (PCA), in classifying between 'Go' and 'No-go' trials in a Go/No-go arm-reaching task.Approach.Our approach centers on capturing the modulation of beta-band (13-30 Hz) power from multiple SEEG contacts in the hippocampus and minimizing the dimensional complexity of channels and frequency bins. This study utilizes SEEG data from the human hippocampus of 10 participants diagnosed with epilepsy. Spectral power was computed during a 'center-out' Go/No-go arm-reaching task, where participants reached or withheld their hand based on a colored cue. PCA was used to reduce data dimension and isolate the highest-variance components within the beta band. The Silhouette score was employed to measure the quality of clustering between 'Go' and 'No-go' trials. The accuracy of five different discriminant functions was evaluated using cross-validation.Main results.The Diagonal-Quadratic model performed best of the 5 classification models, exhibiting the lowest error rate in all participants (median: 9.91%, average: 14.67%). PCA showed that the first two principal components collectively accounted for 54.83% of the total variance explained on average across all participants, ranging from 36.92% to 81.25% among participants.Significance.This study shows that PCA paired with a Diagonal-Quadratic model can be an effective method for classifying between Go/No-go trials from beta-band power in the hippocampus during arm-reaching responses. This emphasizes the significance of hippocampal beta-power modulation in motor control, unveiling its potential implications for brain-computer interface applications.

Beta-band power modulation in the human amygdala differentiates between go/no-go responses in an arm-reaching task.

Objective. Traditionally known for its involvement in emotional processing, the amygdala's involvement in motor control remains relatively unexplored, with sparse investigations into the neural mechanisms governing amygdaloid motor movement and inhibition. This study aimed to characterize the amygdaloid beta-band (13-30 Hz) power between 'Go' and 'No-go' trials of an arm-reaching task.Approach. Ten participants with drug-resistant epilepsy implanted with stereoelectroencephalographic (SEEG) electrodes in the amygdala were enrolled in this study. SEEG data was recorded throughout discrete phases of a direct reach Go/No-go task, during which participants reached a touchscreen monitor or withheld movement based on a colored cue. Multitaper power analysis along with Wilcoxon signed-rank and Yates-correctedZtests were used to assess significant modulations of beta power between the Response and fixation (baseline) phases in the 'Go' and 'No-go' conditions.Main results. In the 'Go' condition, nine out of the ten participants showed a significant decrease in relative beta-band power during the Response phase (p⩽ 0.0499). In the 'No-go' condition, eight out of the ten participants presented a statistically significant increase in relative beta-band power during the response phase (p⩽ 0.0494). Four out of the eight participants with electrodes in the contralateral hemisphere and seven out of the eight participants with electrodes in the ipsilateral hemisphere presented significant modulation in beta-band power in both the 'Go' and 'No-go' conditions. At the group level, no significant differences were found between the contralateral and ipsilateral sides or between genders.Significance.This study reports beta-band power modulation in the human amygdala during voluntary movement in the setting of motor execution and inhibition. This finding supplements prior research in various brain regions associating beta-band power with motor control. The distinct beta-power modulation observed between these response conditions suggests involvement of amygdaloid oscillations in differentiating between motor inhibition and execution.

Stereotactic Frame-Based Electrode Insertion: The Accuracy of Increasingly Oblique Insertion Angles.

AIM: To investigate the relationship between planned drill approach angle and angular deviation of the stereotactically placed intracranial electrode tips. MATERIAL AND METHODS: Stereotactic electrode implantation was performed in 13 patients with drug resistant epilepsy. A total of 136 electrodes were included in our analysis. Stereotactic targets were planned on pre-operative magnetic resonance imaging (MRI) scans and implantation was carried out using a Cosman-Roberts-Wells stereotactic frame with the Ad-Tech drill guide and electrodes. Post implant electrode angles in the axial, coronal, and sagittal planes were determined from post-operative computerized tomography (CT) scans and compared with planned angles using Bland-Altman plots and linear regression. RESULTS: Qualitative assessment of correlation plots between planned and actual angles demonstrated a linear relationship for axial, coronal, and sagittal planes, with no overt angular deflection for any magnitude of the planned angle. CONCLUSION: The accuracy of CRW frame-based electrode placement using the Ad-Tech drill guide and electrodes is not significantly affected by the magnitude of the planning angle. Based on our results, oblique electrode insertion is a safe and accurate procedure.

Understanding the human conflict processing network: A review of the literature on direct neural recordings during performance of a modified stroop task.

The Stroop Task is a well-known neuropsychological task developed to investigate conflict processing in the human brain. Our group has utilized direct intracranial neural recordings in various brain regions during performance of a modified color-word Stroop Task to gain a mechanistic understanding of non-emotional human conflict processing. The purpose of this review article is to: 1) synthesize our own studies into a model of human conflict processing, 2) review the current literature on the Stroop Task and other conflict tasks to put our research in context, and 3) describe how these studies define a network in conflict processing. The figures presented are reprinted from our prior publications and key publications referenced in the manuscript. We summarize all studies to date that employ invasive intracranial recordings in humans during performance of conflict-inducing tasks. For our own studies, we analyzed local field potentials (LFPs) from patients with implanted stereotactic electroencephalography (SEEG) electrodes, and we observed intracortical oscillation patterns as well as intercortical temporal relationships in the hippocampus, amygdala, and orbitofrontal cortex (OFC) during the cue-processing phase of a modified Stroop Task. Our findings suggest that non-emotional human conflict processing involves modulation across multiple frequency bands within and between brain structures.

A review of neurophysiological effects and efficiency of waveform parameters in deep brain stimulation.

Neurostimulation has diverse clinical applications and potential as a treatment for medically refractory movement disorders, epilepsy, and other neurological disorders. However, the parameters used to program electrodes-polarity, pulse width, amplitude, and frequency-and how they are adjusted have remained largely untouched since the 1970 s. This review summarizes the state-of-the-art in Deep Brain Stimulation (DBS) and highlights the need for further research to uncover the physiological mechanisms of neurostimulation. We focus on studies that reveal the potential for clinicians to use waveform parameters to selectively stimulate neural tissue for therapeutic benefit, while avoiding activating tissue associated with adverse effects. DBS uses cathodic monophasic rectangular pulses with passive recharging in clinical practice to treat neurological conditions such as Parkinson's Disease. However, research has shown that stimulation efficiency can be improved, and side effects reduced, through modulating parameters and adding novel waveform properties. These developments can prolong implantable pulse generator lifespan, reducing costs and surgery-associated risks. Waveform parameters can stimulate neurons based on axon orientation and intrinsic structural properties, providing clinicians with more precise targeting of neural pathways. These findings could expand the spectrum of diseases treatable with neuromodulation and improve patient outcomes.

Baseline hippocampal beta band power is lower in the presence of movement uncertainty.

Objective.This study aimed to characterize hippocampal neural signatures of uncertainty by measuring beta band power in the period prior to movement cue.Approach. Participants with epilepsy were implanted with hippocampal depth electrodes for stereo electroencephalographic (SEEG) monitoring. Hippocampal beta (13-30 Hz) power changes have been observed during motor tasks such as the direct reach (DR) and Go/No-Go (GNG) tasks. The primary difference between the tasks is the presence of uncertainty about whether movement should be executed. Previous research on cortical responses to uncertainty has found that baseline beta power changes with uncertainty. SEEG data were sampled throughout phases of the DR and GNG tasks. Beta-band power during the fixation phase was compared between the DR and GNG task using a Wilcoxon rank sum test. This unpaired test was also used to analyze response times from cue to task completion between tasks.Main results.Eight patients who performed both reaching tasks were analyzed in this study. Movement response times in the GNG task were on average 210 milliseconds slower than in the DR task. All patients exhibited a significantly increased response latency in the GNG task compared to the DR task (Wilcoxon rank-sum p-value < 0.001). Six out of eight patients demonstrated statistically significant differences in beta power in single hippocampal contacts between the fixation phases of the GNG and DR tasks. At the group level, baseline beta power was significantly lower in the GNG task than in the DR task (Wilcoxon rank-sum p-value < 0.001).Significance. This novel study found that, in the presence of task uncertainty, baseline beta power in the hippocampus is lower than in its absence. This finding implicates movement uncertainty as an important factor in baseline hippocampal beta power during movement preparation.

Erupción polimorfa durante el puerperio inmediato / Polymorphic eruption during the postpartum period / Erupção polimórfica durante o puerpério imediato

Introducción. En el embarazo, las dermatosis afectan a menos del 20 % de las gestantes y representan un grupo heterogéneo de afecciones cutáneas, con una forma variada de presentación y evolución. El objetivo es presentar un caso de erupción polimorfa de inicio durante el puerperio, con una breve revisión de la literatura en torno a la patología y su tratamiento. Reporte de caso. Se presenta el caso de una paciente de 38 años en puerperio de su primera gestación, quien debutó con un cuadro clínico de erupción cutánea y prurito que inició en la zona abdominal y se extendió hacia los miembros inferiores. Las lesiones estaban constituidas por pápulas eritematosas que confluían hasta formar placas. Se diagnosticó con erupción polimorfa del embarazo y se dio manejo con antihistamínicos logrando la resolución de la patología. Discusión. La erupción polimórfica del embarazo es un trastorno inflamatorio benigno de la piel. Inicia con la aparición de pápulas pruriginosas que confluyen hasta formar placas eritematosas, que aparecen primero en el abdomen con excepción de la zona umbilical y parten, generalmente, de las estrías y se diseminan a las extremidades. El tratamiento consiste en la utilización de emolientes y antihistamínicos para el control de las lesiones y el prurito. Conclusiones. Aunque se trata de una patología benigna y autolimitada, es importante llegar al diagnóstico correcto e iniciar un manejo médico adecuado ya que síntomas como el prurito pueden generar lesiones por rascado que suelen infectarse y comprometer el estado de salud de las pacientes. Cómo citar: Picón-Jaimes YA, Orozco-Chinome JE, Mejía-Antolínez LA, Garcés-Salamanca CT. Erupción polimorfa durante el puerperio inmediato. MedUNAB. 2019;22(1):64-70. doi:10.29375/01237047.3461

Introduction. During pregnancy, at least 20% of the expectant mothers are affected by several forms of dermatosis, which involve a heterogeneous group of skin conditions with a variety of manifestations and evolution. The objective is to present a case of initial polymorphic eruption during the postpartum period with a brief review of the literature related to the pathology and its treatment. Case report. We present the case of a 38 year-old postpartum patient in her first pregnancy, who exhibited a clinical case of skin eruption and pruritus that started in the abdominal area and extended to the lower limbs. The lesions consisted of erythematous papules that clustered together to form plaques. She was diagnosed with polymorphic eruption of pregnancy and was treated with antihistamines, which resolved the pathology. Discussion. Polymorphic eruption of pregnancy is a benign inflammatory disorder of the skin It starts with the appearance of pruritic papules that cluster together to form erythematous plaques that initially appear in the abdomen (with the exception of the umbilical area) and generally start at the stretch marks and disseminate to the extremities. Treatment consists of the use of emollients and antihistamines to control the lesions and the pruritus. Conclusions. Although this is a benign, self-limiting condition, it is important to reach a correct diagnosis and initiate adequate medical treatment, as symptoms like pruritus can generate lesions from scratching that usually become infected and compromiso the patients' health. Cómo citar: Picón-Jaimes YA, Orozco-Chinome JE, Mejía-Antolínez LA, Garcés-Salamanca CT. Erupción polimorfa durante el puerperio inmediato. MedUNAB. 2019;22(1):64-70. doi:10.29375/01237047.3461

Introdução. Na gravidez, as dermatoses afetam menos de 20% das gestantes e representam um grupo heterogêneo de condições da pele, com uma forma variada de apresentação e evolução. O objetivo é apresentar um caso de erupção polimorfa que iniciou durante o puerpério, com uma breve revisão de literatura sobre a patologia e seu tratamento. Relato de caso. Apresentamos o caso de uma paciente de 38 anos no puerpério de sua primeira gestação, quem desenvolveu um quadro clínico de erupção cutânea e prurido que iniciou na região abdominal e espalhou-se nos membros inferiores. As lesões estavam constituídas por pápulas eritematosas que confluíam até formar placas. Foi diagnosticada com erupção polimórfica da gravidez e recebeu anti-histamínicos, conseguindo a resolução da patologia. Discussão. A erupção polimórfica da gravidez é uma doença inflamatória benigna da pele. Começa com o aparecimento de pápulas pruriginosas que confluem até formar placas eritematosas, que aparecem primeiro no abdômen com exceção da área umbilical e geralmente parte das estrias e se espalham para as extremidades. O tratamento consiste no uso de emolientes e anti-histamínicos para o controle das lesões e o prurido. Conclusão. Ainda seja uma patologia benigna e autolimitada, é importante acertar o diagnóstico e iniciar o tratamento médico adequado, uma vez que sintomas como o prurido podem gerar arranhões que tendem a se infectar e comprometer o estado de saúde das pacientes. Cómo citar: Picón-Jaimes YA, Orozco-Chinome JE, Mejía-Antolínez LA, Garcés-Salamanca CT. Erupción polimorfa durante el puerperio inmediato. MedUNAB. 2019;22(1):64-70. doi:10.29375/01237047.3461