The Spatial Reach of Neuronal Coherence and Spike-Field Coupling across the Human Neocortex.

Neuronal coherence is thought to be a fundamental mechanism of communication in the brain, where synchronized field potentials coordinate synaptic and spiking events to support plasticity and learning. Although the spread of field potentials has garnered great interest, little is known about the spatial reach of phase synchronization, or neuronal coherence. Functional connectivity between different brain regions is known to occur across long distances, but the locality of synchronization across the neocortex is understudied. Here we used simultaneous recordings from electrocorticography (ECoG) grids and high-density microelectrode arrays to estimate the spatial reach of neuronal coherence and spike-field coherence (SFC) across frontal, temporal, and occipital cortices during cognitive tasks in humans. We observed the strongest coherence within a 2-3 cm distance from the microelectrode arrays, potentially defining an effective range for local communication. This range was relatively consistent across brain regions, spectral frequencies, and cognitive tasks. The magnitude of coherence showed power law decay with increasing distance from the microelectrode arrays, where the highest coherence occurred between ECoG contacts, followed by coherence between ECoG and deep cortical local field potential (LFP), and then SFC (i.e., ECoG > LFP > SFC). The spectral frequency of coherence also affected its magnitude. Alpha coherence (8-14 Hz) was generally higher than other frequencies for signals nearest the microelectrode arrays, whereas delta coherence (1-3 Hz) was higher for signals that were farther away. Action potentials in all brain regions were most coherent with the phase of alpha oscillations, which suggests that alpha waves could play a larger, more spatially local role in spike timing than other frequencies. These findings provide a deeper understanding of the spatial and spectral dynamics of neuronal synchronization, further advancing knowledge about how activity propagates across the human brain.SIGNIFICANCE STATEMENT Coherence is theorized to facilitate information transfer across cerebral space by providing a convenient electrophysiological mechanism to modulate membrane potentials in spatiotemporally complex patterns. Our work uses a multiscale approach to evaluate the spatial reach of phase coherence and spike-field coherence during cognitive tasks in humans. Locally, coherence can reach up to 3 cm around a given area of neocortex. The spectral properties of coherence revealed that alpha phase-field and spike-field coherence were higher within ranges <2 cm, whereas lower-frequency delta coherence was higher for contacts farther away. Spatiotemporally shared information (i.e., coherence) across neocortex seems to reach farther than field potentials alone.

Risk factors for massive transfusion in obstetrical hemorrhage and consideration of a whole blood program.

BACKGROUND: Postpartum hemorrhage (PPH) is one of the leading causes of obstetric complications. The goal of this study was to identify risk factors for obstetric (OB) massive transfusion (MT) and determine the feasibility of developing a low-titer group O RhD-positive whole blood (LTO + WB) protocol for OB hemorrhage. STUDY DESIGN AND METHODS: A retrospective study of OB patients who received transfusion within 24 h. MT patients were those who received >3 U of pRBC within 1 h or > 10 U in 24 h. Patient demographics, OB history, comorbidities, blood type, antibody status, and known risk factors for PPH and maternal-fetal outcomes were compared. Logistic regression was used for univariate and multivariate analyses. RESULTS: Of the 610 transfused OB patients, 12.0% (n = 73) required MT. Groups were well matched for body mass index (BMI), maternal comorbidities, and history of spontaneous vaginal deliveries. The incidence of the previous cesarean section was higher in the MT group. Exactly 93.9% of patients were RhD-positive and 3.77% of all patients possessed an antibody on pretransfusion testing. Patients with MT had a longer length of stay (LOS), higher rate of intensive care unit (ICU) admission, fetal death, and hysterectomy. Multivariate analysis found age >35, PPH, placenta percreta, accreta, and increta to be significant (p < .05) risk factors for MT. DISCUSSION: Patients over 35 years and those with abnormal placentation are at increased risk of requiring MT. With a time to delivery of 2 days, potential MT patients can be identified early, and with a 94% rate of RhD-positive+, they are eligible to receive low-titer O whole blood (LTOWB) providing hemostatic resuscitation with reduced donor exposure.

Whole blood for postpartum hemorrhage: early experience at two institutions.

BACKGROUND: Death from postpartum hemorrhage (PPH) remains a significant preventable problem worldwide. Cold-stored, low-titer, type-O whole blood (LTOWB) is increasingly being used for resuscitation of injured patients, but it is uncommon in PPH patients, and it is unclear what its role may be in this population. STUDY DESIGN AND METHODS: Brief report of the early experience of WB use for PPH in two institutions, one university hospital and one private hospital. RESULTS: Different approaches have been implemented at the two institutions, one designed for emergency release, uncrossmatched transfusion of LTOWB as part of a massive transfusion protocol (MTP) and one for high-risk obstetric patients with known placental abnormalities. A total of 7 PPH patients have received a total of 17 units of LTOWB between the two institutions. No severe adverse transfusion reactions were observed clinically in either institution and the clinical outcomes were favorable in all cases. CONCLUSION: In our early experience, LTOWB can be implemented for two different PPH clinical scenarios. Larger studies are needed to compare outcomes between LTOWB and traditional component resuscitation strategies.

Emergency preparedness for mass casualty events: South Texas commentary on the development of a statewide emergency response system.

Mass casualty incidents (MCIs) are on the rise in the USA, and hemorrhage is the leading cause of preventable death in trauma. The need for rapid access to life-saving blood and blood products is essential for preventing death due to hemorrhage. It is well established that most major cities in the USA are underprepared to meet blood transfusion requirements in the event of an MCI. The South Texas Whole Blood Consortium sought to rectify this and vowed to be prepared to provide low-titer type O-positive whole blood (LTOWB) and blood components to the people who need it, where and when they need it. This system was able to transport 25 units of LTOWB and packed red blood cells almost 100 miles away to Uvalde Memorial Hospital within just 67 minutes after notification of an active shooter. The regional consortium has created a pool of dedicated LTOWB donors affectionately called Heroes in Arms who can be called on to instantly augment locoregional blood supply. Previously pregnant women have historically been excluded from donating plasma and LTOWB due to the increased rates of human leukocyte antigen (HLA) antibody (Ab) positivity, which is associated with transfusion-related acute lung injury. However, the South Texas Blood and Tissue Center in San Antonio had a large number of qualified, previously pregnant females desire to join the Heroes in Arms program prompting them to assess the feasibility of providing HLA Ab testing for this demographic and the results were promising. This is the first report of previously pregnant women being included in the pool for donation of LTOWB.

A novel non-word speech preparation task to increase stuttering frequency in experimental settings for longitudinal research.

PURPOSE: The variable and intermittent nature of stuttering makes it difficult to consistently elicit a sufficient number of stuttered trials for longitudinal experimental research. This study tests the efficacy of using non-word pairs that phonetically mimic English words with no associated meaning, to reliably elicit balanced numbers of stuttering and fluent trials over multiple sessions. The study also evaluated the effect of non-word length on stuttering frequency, the consistency of stuttering frequency across sessions, and potential carry-over effects of increased stuttering frequency in the experimental task to conversational and reading speech after the task. METHODS: Twelve adults who stutter completed multiple sessions (mean of 4.8 sessions) where they were video-recorded during pre-task reading and conversation, followed by an experimental task where they read 400 non-word pairs randomized for each session, and then a post-task reading and conversation sample. RESULTS: On average, across sessions and participants, non-word pairs consistently yielded a balanced distribution of fluent (60.7%) and stuttered (39.3%) trials over five sessions. Non-word length had a positive effect on stuttering frequency. No carryover effects from experimental to post-task conversation and reading were found. CONCLUSIONS: Non-word pairs effectively and consistently elicited balanced proportions of stuttered and fluent trials. This approach can be used to gather longitudinal data to better understand the neurophysiological and behavioral correlates of stuttering.

Transfusion-related cost comparison of trauma patients receiving whole blood versus component therapy.

INTRODUCTION: With the emergence of whole blood (WB) in trauma resuscitation, cost-related comparisons are of significant importance to providers, blood banks, and hospital systems throughout the country. The objective of this study was to determine if there is a transfusion-related cost difference between trauma patients who received low titer O+ whole blood (LTO+WB) and component therapy (CT). METHODS: A retrospective review of adult and pediatric trauma patients who received either LTO+WB or CT from time of injury to within 4 hours of arrival was performed. Annual mean cost per unit of blood product was obtained from the regional blood bank supplier. Pediatric and adult patients were analyzed separately and were compared on a cost per patient (cost/patient) and cost per patient per milliliter (cost/patient/mL) basis. Subgroup analysis was performed on severely injured adult patients (Injury Severity Score, >15) and patients who underwent massive transfusion. RESULTS: Prehospital LTO+WB transfusion began at this institution in January 2018. After the initiation of the WB transfusion, the mean annual cost decreased 17.3% for all blood products, and the average net difference in cost related to component blood products and LTO+WB was more than $927,000. In adults, LTO+WB was associated with a significantly lower cost/patient and cost/patient/mL compared with CT at 4 hours ( p < 0.001), at 24 hours ( p < 0.001), and overall ( p < 0.001). In the severely injured subgroup (Injury Severity Score, >15), WB was associated with a lower cost/patient and cost/patient/mL at 4 hours ( p < 0.001), 24 hours ( p < 0.001), and overall ( p < 0.001), with no difference in the prehospital setting. Similar findings were true in patients meeting massive transfusion criteria, although differences in injury severity may account for this finding. CONCLUSION: With increased use of LTO+WB for resuscitation, cost comparison is of significant importance to all stakeholders. Low titer O+ WB was associated with reduced cost in severely injured patients. Ongoing analyses may improve resource utilization and benefit overall healthcare cost. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.

The bit in the middle and why it's important: a computational analysis of the linguistic features of body paragraphs.

This study examines the relationship between the linguistic characteristics of body paragraphs of student essays and the total number of paragraphs in the essays. Results indicate a significant relationship between the total number of paragraphs and a variety of linguistic characteristics known to affect student essay scores. These linguistic characteristics (e.g., semantic overlap, syntactic complexity) contribute to two underlying factors (i.e., textual cohesion and difficulty) that are used as dependent variables in mixed-effect models. Results suggest that student essays with 5-8 paragraphs tend to be more linguistically consistent than student essays with 3, 4, and 9 paragraphs. Essays with totals of 5-8 paragraphs, considered by many educators to contain an optimal number of paragraphs, may include functionally and structurally similar paragraphs. These findings could aid writing researchers and educators in obtaining a clearer view of the relationship between the total number of paragraphs comprising an essay and the linguistic characteristics that affect essay evaluation. Consequently, writing interventions may become better equipped to pinpoint student difficulties and facilitate student writing skills by providing more detailed and informed feedback.

Widespread theta coherence during spatial cognitive control.

Cognitive control allows humans to process relevant sensory information while minimizing distractions from irrelevant stimuli. The neural basis of cognitive control is known to involve frontal regions of the brain such as the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC), but the temporal dynamics of larger scale networks is unclear. Here we used EEG with source localization to identify how the neural oscillations localized to the mPFC and ACC coordinate with parietal, sensory, and motor areas during spatial cognitive control. Theta coherence (3-8 Hz) between the mPFC and ACC increased with task difficulty and predicted individual differences in reaction time. Individual differences in accuracy were predicted by earlier activation of ACC-motor coherence, highlighting the relationship between processing speed and task performance. Our results provide evidence that successful cognitive control requires dynamic coordination between a widespread network of brain regions. Long range theta coherence may be a key mechanism for efficient cognitive control across the neocortex.

Sensorimotor Integration Can Enhance Auditory Perception.

Whenever we move, speak, or play musical instruments, our actions generate auditory sensory input. The sensory consequences of our actions are thought to be predicted via sensorimotor integration, which involves anatomical and functional links between auditory and motor brain regions. The physiological connections are relatively well established, but less is known about how sensorimotor integration affects auditory perception. The sensory attenuation hypothesis suggests that the perceived loudness of self-generated sounds is attenuated to help distinguish self-generated sounds from ambient sounds. Sensory attenuation would work for louder ambient sounds, but could lead to less accurate perception if the ambient sounds were quieter. We hypothesize that a key function of sensorimotor integration is the facilitated processing of self-generated sounds, leading to more accurate perception under most conditions. The sensory attenuation hypothesis predicts better performance for higher but not lower intensity comparisons, whereas sensory facilitation predicts improved perception regardless of comparison sound intensity. A series of experiments tested these hypotheses, with results supporting the enhancement hypothesis. Overall, people were more accurate at comparing the loudness of two sounds when making one of the sounds themselves. We propose that the brain selectively modulates the perception of self-generated sounds to enhance representations of action consequences.

Single-Trial Classification of Disfluent Brain States in Adults Who Stutter.

Normal human speech requires precise coordination between motor planning and sensory processing. Speech disfluencies are common when children learn to talk, but usually abate with time. About 5% of children experience stuttering. For most, this resolves within a year. However, for approximately 1% of the world population, stuttering continues into adulthood, which is termed 'persistent developmental stuttering'. Most stuttering events occur at the beginning of an utterance. So, in principle, brain activity before speaking should differ between fluent and stuttered speech. Here we present a method for classifying brain network states associated with fluent vs. stuttered speech on a single trial basis. Brain activity was recorded with EEG before people who stutter read aloud pseudo-word pairs. Offline independent component analysis (ICA) was used to identify the independent neural sources that underlie speech preparation. A time window selection algorithm extracted spectral power and coherence data from salient windows specific to each neural source. A stepwise linear discriminant analysis (sLDA) algorithm predicted fluent vs. stuttered speech for 81% of trials in two subjects. These results support the feasibility of developing a brain-computer interface (BCI) system to detect stuttering before it occurs, with potential for therapeutic application.