A speech planning network for interactive language use.

During conversation, people take turns speaking by rapidly responding to their partners while simultaneously avoiding interruption1,2. Such interactions display a remarkable degree of coordination, as gaps between turns are typically about 200 milliseconds3-approximately the duration of an eyeblink4. These latencies are considerably shorter than those observed in simple word-production tasks, which indicates that speakers often plan their responses while listening to their partners2. Although a distributed network of brain regions has been implicated in speech planning5-9, the neural dynamics underlying the specific preparatory processes that enable rapid turn-taking are poorly understood. Here we use intracranial electrocorticography to precisely measure neural activity as participants perform interactive tasks, and we observe a functionally and anatomically distinct class of planning-related cortical dynamics. We localize these responses to a frontotemporal circuit centred on the language-critical caudal inferior frontal cortex10 (Broca's region) and the caudal middle frontal gyrus-a region not normally implicated in speech planning11-13. Using a series of motor tasks, we then show that this planning network is more active when preparing speech as opposed to non-linguistic actions. Finally, we delineate planning-related circuitry during natural conversation that is nearly identical to the network mapped with our interactive tasks, and we find this circuit to be most active before participant speech during unconstrained turn-taking. Therefore, we have identified a speech planning network that is central to natural language generation during social interaction.

Functional geometry of auditory cortical resting state networks derived from intracranial electrophysiology.

Understanding central auditory processing critically depends on defining underlying auditory cortical networks and their relationship to the rest of the brain. We addressed these questions using resting state functional connectivity derived from human intracranial electroencephalography. Mapping recording sites into a low-dimensional space where proximity represents functional similarity revealed a hierarchical organization. At a fine scale, a group of auditory cortical regions excluded several higher-order auditory areas and segregated maximally from the prefrontal cortex. On mesoscale, the proximity of limbic structures to the auditory cortex suggested a limbic stream that parallels the classically described ventral and dorsal auditory processing streams. Identities of global hubs in anterior temporal and cingulate cortex depended on frequency band, consistent with diverse roles in semantic and cognitive processing. On a macroscale, observed hemispheric asymmetries were not specific for speech and language networks. This approach can be applied to multivariate brain data with respect to development, behavior, and disorders.

Analogous cortical reorganization accompanies entry into states of reduced consciousness during anesthesia and sleep.

Theories of consciousness suggest that brain mechanisms underlying transitions into and out of unconsciousness are conserved no matter the context or precipitating conditions. We compared signatures of these mechanisms using intracranial electroencephalography in neurosurgical patients during propofol anesthesia and overnight sleep and found strikingly similar reorganization of human cortical networks. We computed the "effective dimensionality" of the normalized resting state functional connectivity matrix to quantify network complexity. Effective dimensionality decreased during stages of reduced consciousness (anesthesia unresponsiveness, N2 and N3 sleep). These changes were not region-specific, suggesting global network reorganization. When connectivity data were embedded into a low-dimensional space in which proximity represents functional similarity, we observed greater distances between brain regions during stages of reduced consciousness, and individual recording sites became closer to their nearest neighbors. These changes corresponded to decreased differentiation and functional integration and correlated with decreases in effective dimensionality. This network reorganization constitutes a neural signature of states of reduced consciousness that is common to anesthesia and sleep. These results establish a framework for understanding the neural correlates of consciousness and for practical evaluation of loss and recovery of consciousness.

Distribution of multiunit pitch responses recorded intracranially from human auditory cortex.

The perception of pitch is a fundamental percept, which is mediated by the auditory system, requiring the abstraction of stimulus properties related to the spectro-temporal structure of sound. Despite its importance, there is still debate as to the precise areas responsible for its encoding, which may be due to species differences or differences in the recording measures and choices of stimuli used in previous studies. Moreover, it was unknown whether the human brain contains pitch neurons and how distributed such neurons might be. Here, we present the first study to measure multiunit neural activity in response to pitch stimuli in the auditory cortex of intracranially implanted humans. The stimulus sets were regular-interval noise with a pitch strength that is related to the temporal regularity and a pitch value determined by the repetition rate and harmonic complexes. Specifically, we demonstrate reliable responses to these different pitch-inducing paradigms that are distributed throughout Heschl's gyrus, rather than being localized to a particular region, and this finding was evident regardless of the stimulus presented. These data provide a bridge across animal and human studies and aid our understanding of the processing of a critical percept associated with acoustic stimuli.

Gamma Activation and Alpha Suppression within Human Auditory Cortex during a Speech Classification Task.

The dynamics of information flow within the auditory cortical hierarchy associated with speech processing and the emergence of hemispheric specialization remain incompletely understood. To study these questions with high spatiotemporal resolution, intracranial recordings in 29 human neurosurgical patients of both sexes were obtained while subjects performed a semantic classification task. Neural activity was recorded from posteromedial portion of Heschl's gyrus (HGPM) and anterolateral portion of Heschl's gyrus (HGAL), planum temporale (PT), planum polare, insula, and superior temporal gyrus (STG). Responses to monosyllabic words exhibited early gamma power increases and a later suppression of alpha power, envisioned to represent feedforward activity and decreased feedback signaling, respectively. Gamma activation and alpha suppression had distinct magnitude and latency profiles. HGPM and PT had the strongest gamma responses with shortest onset latencies, indicating that they are the earliest auditory cortical processing stages. The origin of attenuated top-down influences in auditory cortex, as indexed by alpha suppression, was in STG and HGAL. Gamma responses and alpha suppression were typically larger to nontarget words than tones. Alpha suppression was uniformly greater to target versus nontarget stimuli. Hemispheric bias for words versus tones and for target versus nontarget words, when present, was left lateralized. Better task performance was associated with increased gamma activity in the left PT and greater alpha suppression in HGPM and HGAL bilaterally. The prominence of alpha suppression during semantic classification and its accessibility for noninvasive electrophysiologic studies suggests that this measure is a promising index of auditory cortical speech processing.SIGNIFICANCE STATEMENT Understanding the dynamics of cortical speech processing requires the use of active tasks. This is the first comprehensive intracranial electroencephalography study to examine cortical activity within the superior temporal plane, lateral superior temporal gyrus, and the insula during a semantic classification task. Distinct gamma activation and alpha suppression profiles clarify the functional organization of feedforward and feedback processing within the auditory cortical hierarchy. Asymmetries in cortical speech processing emerge at early processing stages. Relationships between cortical activity and task performance are interpreted in the context of current models of speech processing. Results lay the groundwork for iEEG studies using connectivity measures of the bidirectional information flow within the auditory processing hierarchy.

Outcomes of Stented vs Nonstented Femoropopliteal Lesions Treated With Drug-Coated Balloon Angioplasty.

PURPOSE: Drug-coated balloon (DCB) angioplasty has been increasingly used for the treatment of lower limb peripheral artery disease (PAD). However, bail-out stenting may be necessary in cases of suboptimal angioplasty. This study investigated the outcomes of femoropopliteal disease treated with DCB with/without bail-out stenting. MATERIALS AND METHODS: This was a single-center retrospective study enrolling 166 consecutive patients (DCB+stent: n=81 vs DCB: n=85) with 253 femoropopliteal lesions (DCB+stent: n=99 vs DCB: n=154) treated with DCB with/without stenting. Bail-out stenting was performed at the operator discretion for postangioplasty dissections or otherwise suboptimal angiographic result (>30% residual stenosis). Cox regression analysis was performed to examine the outcomes of DCB with/without stenting during 2-year follow-up. RESULTS: The baseline clinical characteristics were similar between the 2 groups. About half of the patients presented with critical limb ischemia, with most of the lesions located at the superficial femoral artery. The overall mean lesion length was 147±67 mm. The most frequent bail-out stent types were bare metal stents (BMS) (53.5%) followed by drug-eluting stents (DES) (41.4%). Lesions requiring bail-out stenting were on average longer (177±67 mm vs 127±59 mm; p<0.01) and on average had higher prevalence of flow-limiting postangioplasty dissections. The overall procedural success rate was 94% without any differences between the 2 groups. Both the stented and nonstented treatment modalities were effective and safe, demonstrating similar rates of 2-year freedom from major adverse limb event (stented: 71.3% vs nonstented: 64.4%) and 2-year freedom from target lesion revascularization (stented: 77.1% vs nonstented: 72.3%) during following up. The use of DES as bail-out therapy was associated with a lower risk of 2-year death compared with the use of BMS (DES: 97.2% vs BMS: 75.8%; p=0.01). CONCLUSION: Drug-coated balloon with bail-out stenting is a viable treatment option for cases of suboptimal DCB results, promising similar efficacy with DCB-alone procedures. However, as the patency of stents at the femoropopliteal segment may be a challenge due to the biomechanical stress of the artery, the efficacy of DCB+bail-out stenting should be further evaluated. In addition, future studies are needed to determine which grades of post-DCB dissections should be treated and optimize current bail-out strategies.

Speech artifact is also present in spike data.

Bush et al. (2022) highlight that brain recordings examining speech production can be significantly affected by microphonic artifact, which would change the interpretation of these kinds of data. While these findings are vital in determining whether data are artifactual or physiological in origin, frequencies were only examined up to 250 Hz (i.e., local field potentials), which would imply that spike-related data (single or multi-neuron recordings) are unaffected. We highlight here that this type of contamination may also be present in unit recordings, with the same aim to understand genuine neural mechanisms rather than mis-interpreting artifactual data.

Electrophysiology of the Human Superior Temporal Sulcus during Speech Processing.

The superior temporal sulcus (STS) is a crucial hub for speech perception and can be studied with high spatiotemporal resolution using electrodes targeting mesial temporal structures in epilepsy patients. Goals of the current study were to clarify functional distinctions between the upper (STSU) and the lower (STSL) bank, hemispheric asymmetries, and activity during self-initiated speech. Electrophysiologic properties were characterized using semantic categorization and dialog-based tasks. Gamma-band activity and alpha-band suppression were used as complementary measures of STS activation. Gamma responses to auditory stimuli were weaker in STSL compared with STSU and had longer onset latencies. Activity in anterior STS was larger during speaking than listening; the opposite pattern was observed more posteriorly. Opposite hemispheric asymmetries were found for alpha suppression in STSU and STSL. Alpha suppression in the STS emerged earlier than in core auditory cortex, suggesting feedback signaling within the auditory cortical hierarchy. STSL was the only region where gamma responses to words presented in the semantic categorization tasks were larger in subjects with superior task performance. More pronounced alpha suppression was associated with better task performance in Heschl's gyrus, superior temporal gyrus, and STS. Functional differences between STSU and STSL warrant their separate assessment in future studies.

Radial Artery Access for Acute Coronary Syndromes: a Review of Current Evidence.

PURPOSE OF REVIEW: To review the evidence supporting the use of transradial access (TRA) for percutaneous coronary intervention (PCI) in acute coronary syndromes (ACS). RECENT FINDINGS: There have been five major randomized controlled trials (RCTs) and two recent meta-analyses comparing outcomes of TRA and femoral access (FA) in ACS. Additional studies have explored the impact of TRA on STEMI door-to-balloon (D2B) times, TRA in high-risk ACS patients, the potential conflict between TRA and coronary artery bypass graft (CABG) surgery employing the radial artery, and distal radial artery (DRA) access. TRA is associated with a reduction in net adverse clinical events, major bleeding, acute renal injury, and access site complications compared to FA in ACS patients undergoing PCI. TRA is not associated with significant delays in STEMI D2B times that impact patient outcomes. Further studies are needed to evaluate the role of TRA in high-risk ACS patients, the interplay between TRA and radial artery CABG, and use of DRA in ACS.

Outcomes of urgent/emergent transcatheter mitral valve repair (MitraClip): A single center experience.

OBJECTIVES: To describe the outcomes of urgent/emergent transcatheter edge-to-edge mitral valve repair (TMVr) and compare the clinical, echocardiographic, and procedural characteristics of survivors and nonsurvivors. BACKGROUND: TMVr is a treatment strategy for select patients with severe primary or secondary mitral regurgitation. However, knowledge regarding outcomes for urgent/emergent TMVr is limited. METHODS: All urgent or emergent TMVr procedures using MitraClip performed at the University of Washington Medical Center between January 2018 and March 2019 were identified and clinical, echocardiographic, hemodynamic, procedural, and outcomes data were obtained by chart review. Outcomes included all-cause mortality, hospital mortality, procedural success, periprocedural complications, and hospital readmission. RESULTS: Of the 20 patients who underwent urgent/emergent TMVr, eight were treated for cardiogenic shock (CS), four for acute decompensated heart failure (ADHF) with hypoxemic respiratory failure requiring mechanical ventilation, and eight for ADHF with failure of inpatient medical therapy. Mechanical circulatory support (MCS) was used in six patients; preceding TMVr in three patients and immediately post-TMVr in three patients. Overall, 30-day mortality and hospital readmission rates were 21 and 13%, respectively. Over a median 153 days (IQR 20-491) of follow-up, 10 patients (50%) died. Preprocedure CS, new or ongoing MCS post-TMVr, refractory respiratory failure post-TMVr, and acute kidney injury post-TMVr were associated with mortality. CONCLUSIONS: In a single-center retrospective analysis, urgent/emergent TMVr in high-risk patients with ADHF or CS was associated with high short-term mortality and periprocedural complications. Prospective studies are warranted to inform patient selection and periprocedural management for urgent/emergent TMVr.

Comparison of rotational and orbital atherectomy for the treatment of calcific coronary lesions: Insights from the VA clinical assessment reporting and tracking (CART) program.

BACKGROUND: Previous studies suggested that pre-treatment of coronary artery calcification (CAC) with rotational atherectomy (RA) prior to stent deployment improved procedural success but was not associated with a concomitant improvement in clinical outcomes. Orbital atherectomy (OA) has demonstrated similar benefits, though there are few data comparing the safety and efficacy of the two modalities. METHODS: Patients who underwent PCI of a native coronary lesion with RA or OA from 2014 to 2018 within the Veterans Affairs Healthcare System were identified. Propensity matched cohorts were generated to compare the clinical and safety outcomes following either RA or OA. The primary endpoint was the rate of 30-day major adverse cardiovascular and cerebrovascular events (MACCE), including all-cause mortality, repeat myocardial infarction, target vessel revascularization, and stroke. RESULTS: We identified 1,091 patients that underwent atherectomy during the study period, 640 (59%) treated with RA and 451 (41%) treated with OA. Among a propensity-matched cohort consisting of 950 patients, there was no significant difference in MACCE for patients who underwent RA or OA (7.1 vs. 8.2%, p = .36). Components of the primary outcome including 30-day mortality, myocardial infarction, target vessel revascularization, and stroke were also similar in the matched cohort. Additionally, procedural complications including perforation, no-reflow, dissection, and in-stent thrombosis were comparable across both treatment strategies. CONCLUSIONS: Both rotational and orbital atherectomy are safe and effective strategies for the treatment of calcified coronary plaque prior to stent deployment, with similarly low rates of peri-procedural adverse events.

Association of Postangioplasty Femoropopliteal Dissections With Outcomes After Drug-Coated Balloon Angioplasty in the Femoropopliteal Arteries.

PURPOSE: Balloon angioplasty for the treatment of femoropopliteal lesions is often complicated by postangioplasty dissections. While dissections are known to affect patency and reintervention after balloon angioplasty, the association between dissections and major adverse limb event (MALE) after drug-coated balloon (DCB) angioplasty remains uncertain. Thus, the postangioplasty dissection and bailout stenting patterns were investigated. MATERIALS AND METHODS: This was a single-center retrospective study enrolling patients with de novo femoropopliteal lesions treated with DCB with/without stenting. Postangioplasty target vessel dissection was graded based to the coronary artery classification grades A-F, with grade C-F considered "severe." Cox regression analysis was performed to examine the association of dissection severity with outcomes during 2-year follow up, among nonstented cases. RESULTS: In 85.3% of the cases (N=203/238) a postangioplasty dissection was observed. The average dissection length was 55.57 mm (SD 36.71 mm), with 1 dissection present in 91.8% (N=180/196) and 2 or more dissections present in 8.2% (N=16/196). Dissection severity was grade A (19.8%), B (20.6%), C (23.1%), D (10.9%), E (10.1%), and F (0.8%). Bailout stenting was required in 40.4% of the patients, being more prevalent among grade C and grade E cases. Among 142 nonstented cases, dissections were present in 85.2%. A total of 75 (52.8%) of these dissections were grade A and B, while 46 (32.4%) were grade C to F. Among nonstented cases, grade C (hazard ratio [HR] 5.83; 95% CI 1.25 to 27.31; p=0.025) and grade D (HR 6.32; 95% CI 1.39 to 28.86; p=0.017) vs grade A dissections were associated with a higher risk for 2-year MALE. Multivariate analysis adjusting for several lesion characteristics demonstrated a statistically significant higher risk for 2-year MALE among the severe dissection group (HR 2.94; 95% CI 1.27 to 6.79; p = 0.012). Interestingly, the risks of limb loss (HR 1.30; 95% CI 0.22 to 7.79; p=0.774) and repeat revascularization (HR 0.95; 95% CI 0.40 to 2.26; p=0.905) during follow-up were similar between the 2 groups. CONCLUSION: This study indicated that nonstented moderate and severe postangioplasty dissections after DCB angioplasty were associated with higher risk for MALE. Future studies are needed to validate our results and determine other dissection characteristics (eg, total dissection length, lumen area, total number of dissections) that may affect the efficacy of DCB.

Impact of the COVID-19 pandemic on cardiac arrest systems of care.

PURPOSE OF REVIEW: The emergence of severe acute respiratory syndrome coronavirus 2 virus, which causes coronavirus disease 2019 (COVID-19), led to the declaration of a global pandemic by the World Health Organization on March 11, 2020. As of February 6, 2021, over 105 million persons have been infected in 223 countries and there have been 2,290,488 deaths. As a result, emergency medical services and hospital systems have undergone unprecedented healthcare delivery reconfigurations. Here, we review the effects of the COVID-19 pandemic on out-of-hospital cardiac arrest (OHCA) epidemiology and systems of care. RECENT FINDINGS: Areas severely affected by the pandemic have reported increased incidence of OHCA, lower rates of successful resuscitation, and increased mortality. COVID-19 has significantly impacted patient outcomes through increased disease severity, decreased access to care, and the reshaping of emergency medical response and hospital-based healthcare systems and policies. The pandemic has negatively influenced attitudes toward resuscitation and challenged providers with novel ethical dilemmas provoked by the scarcity of healthcare resources. SUMMARY: The COVID-19 pandemic has had direct, indirect, psychosocial, and ethical impacts on the cardiac arrest chain of survival.

Direct electrical stimulation of the amygdala enhances declarative memory in humans.

Emotional events are often remembered better than neutral events, a benefit that many studies have hypothesized to depend on the amygdala's interactions with memory systems. These studies have indicated that the amygdala can modulate memory-consolidation processes in other brain regions such as the hippocampus and perirhinal cortex. Indeed, rodent studies have demonstrated that direct activation of the amygdala can enhance memory consolidation even during nonemotional events. However, the premise that the amygdala causally enhances declarative memory has not been directly tested in humans. Here we tested whether brief electrical stimulation to the amygdala could enhance declarative memory for specific images of neutral objects without eliciting a subjective emotional response. Fourteen epilepsy patients undergoing monitoring of seizures via intracranial depth electrodes viewed a series of neutral object images, half of which were immediately followed by brief, low-amplitude electrical stimulation to the amygdala. Amygdala stimulation elicited no subjective emotional response but led to reliably improved memory compared with control images when patients were given a recognition-memory test the next day. Neuronal oscillations in the amygdala, hippocampus, and perirhinal cortex during this next-day memory test indicated that a neural correlate of the memory enhancement was increased theta and gamma oscillatory interactions between these regions, consistent with the idea that the amygdala prioritizes consolidation by engaging other memory regions. These results show that the amygdala can initiate endogenous memory prioritization processes in the absence of emotional input, addressing a fundamental question and opening a path to future therapies.

A Sound-Sensitive Source of Alpha Oscillations in Human Non-Primary Auditory Cortex.

The functional organization of human auditory cortex can be probed by characterizing responses to various classes of sound at different anatomical locations. Along with histological studies this approach has revealed a primary field in posteromedial Heschl's gyrus (HG) with pronounced induced high-frequency (70-150 Hz) activity and short-latency responses that phase-lock to rapid transient sounds. Low-frequency neural oscillations are also relevant to stimulus processing and information flow, however, their distribution within auditory cortex has not been established. Alpha activity (7-14 Hz) in particular has been associated with processes that may differentially engage earlier versus later levels of the cortical hierarchy, including functional inhibition and the communication of sensory predictions. These theories derive largely from the study of occipitoparietal sources readily detectable in scalp electroencephalography. To characterize the anatomical basis and functional significance of less accessible temporal-lobe alpha activity we analyzed responses to sentences in seven human adults (4 female) with epilepsy who had been implanted with electrodes in superior temporal cortex. In contrast to primary cortex in posteromedial HG, a non-primary field in anterolateral HG was characterized by high spontaneous alpha activity that was strongly suppressed during auditory stimulation. Alpha-power suppression decreased with distance from anterolateral HG throughout superior temporal cortex, and was more pronounced for clear compared to degraded speech. This suppression could not be accounted for solely by a change in the slope of the power spectrum. The differential manifestation and stimulus-sensitivity of alpha oscillations across auditory fields should be accounted for in theories of their generation and function.SIGNIFICANCE STATEMENT To understand how auditory cortex is organized in support of perception, we recorded from patients implanted with electrodes for clinical reasons. This allowed measurement of activity in brain regions at different levels of sensory processing. Oscillations in the alpha range (7-14 Hz) have been associated with functions including sensory prediction and inhibition of regions handling irrelevant information, but their distribution within auditory cortex is not known. A key finding was that these oscillations dominated in one particular non-primary field, anterolateral Heschl's gyrus, and were suppressed when subjects listened to sentences. These results build on our knowledge of the functional organization of auditory cortex and provide anatomical constraints on theories of the generation and function of alpha oscillations.

Cortical functional connectivity indexes arousal state during sleep and anesthesia.

Disruption of cortical connectivity likely contributes to loss of consciousness (LOC) during both sleep and general anesthesia, but the degree of overlap in the underlying mechanisms is unclear. Both sleep and anesthesia comprise states of varying levels of arousal and consciousness, including states of largely maintained conscious experience (sleep: N1, REM; anesthesia: sedated but responsive) as well as states of substantially reduced conscious experience (sleep: N2/N3; anesthesia: unresponsive). Here, we tested the hypotheses that (1) cortical connectivity will exhibit clear changes when transitioning into states of reduced consciousness, and (2) these changes will be similar for arousal states of comparable levels of consciousness during sleep and anesthesia. Using intracranial recordings from five adult neurosurgical patients, we compared resting state cortical functional connectivity (as measured by weighted phase lag index, wPLI) in the same subjects across arousal states during natural sleep [wake (WS), N1, N2, N3, REM] and propofol anesthesia [pre-drug wake (WA), sedated/responsive (S), and unresponsive (U)]. Analysis of alpha-band connectivity indicated a transition boundary distinguishing states of maintained and reduced conscious experience in both sleep and anesthesia. In wake states WS and WA, alpha-band wPLI within the temporal lobe was dominant. This pattern was largely unchanged in N1, REM, and S. Transitions into states of reduced consciousness N2, N3, and U were characterized by dramatic changes in connectivity, with dominant connections shifting to prefrontal cortex. Secondary analyses indicated similarities in reorganization of cortical connectivity in sleep and anesthesia. Shifts from temporal to frontal cortical connectivity may reflect impaired sensory processing in states of reduced consciousness. The data indicate that functional connectivity can serve as a biomarker of arousal state and suggest common mechanisms of LOC in sleep and anesthesia.

Sequence learning modulates neural responses and oscillatory coupling in human and monkey auditory cortex.

Learning complex ordering relationships between sensory events in a sequence is fundamental for animal perception and human communication. While it is known that rhythmic sensory events can entrain brain oscillations at different frequencies, how learning and prior experience with sequencing relationships affect neocortical oscillations and neuronal responses is poorly understood. We used an implicit sequence learning paradigm (an "artificial grammar") in which humans and monkeys were exposed to sequences of nonsense words with regularities in the ordering relationships between the words. We then recorded neural responses directly from the auditory cortex in both species in response to novel legal sequences or ones violating specific ordering relationships. Neural oscillations in both monkeys and humans in response to the nonsense word sequences show strikingly similar hierarchically nested low-frequency phase and high-gamma amplitude coupling, establishing this form of oscillatory coupling-previously associated with speech processing in the human auditory cortex-as an evolutionarily conserved biological process. Moreover, learned ordering relationships modulate the observed form of neural oscillatory coupling in both species, with temporally distinct neural oscillatory effects that appear to coordinate neuronal responses in the monkeys. This study identifies the conserved auditory cortical neural signatures involved in monitoring learned sequencing operations, evident as modulations of transient coupling and neuronal responses to temporally structured sensory input.

Neurog2 and Ascl1 together regulate a postmitotic derepression circuit to govern laminar fate specification in the murine neocortex.

A derepression mode of cell-fate specification involving the transcriptional repressors Tbr1, Fezf2, Satb2, and Ctip2 operates in neocortical projection neurons to specify six layer identities in sequence. Less well understood is how laminar fate transitions are regulated in cortical progenitors. The proneural genes Neurog2 and Ascl1 cooperate in progenitors to control the temporal switch from neurogenesis to gliogenesis. Here we asked whether these proneural genes also regulate laminar fate transitions. Several defects were observed in the derepression circuit in Neurog2-/-;Ascl1-/- mutants: an inability to repress expression of Tbr1 (a deep layer VI marker) during upper-layer neurogenesis, a loss of Fezf2+/Ctip2+ layer V neurons, and precocious differentiation of normally late-born, Satb2+ layer II-IV neurons. Conversely, in stable gain-of-function transgenics, Neurog2 promoted differentiative divisions and extended the period of Tbr1+/Ctip2+ deep-layer neurogenesis while reducing Satb2+ upper-layer neurogenesis. Similarly, acute misexpression of Neurog2 in early cortical progenitors promoted Tbr1 expression, whereas both Neurog2 and Ascl1 induced Ctip2. However, Neurog2 was unable to influence the derepression circuit when misexpressed in late cortical progenitors, and Ascl1 repressed only Satb2. Nevertheless, neurons derived from late misexpression of Neurog2 and, to a lesser extent, Ascl1, extended aberrant subcortical axon projections characteristic of early-born neurons. Finally, Neurog2 and Ascl1 altered the expression of Ikaros and Foxg1, known temporal regulators. Proneural genes thus act in a context-dependent fashion as early determinants, promoting deep-layer neurogenesis in early cortical progenitors via input into the derepression circuit while also influencing other temporal regulators.

Direct electrophysiological mapping of human pitch-related processing in auditory cortex.

This work sought correlates of pitch perception, defined by neural activity above the lower limit of pitch (LLP), in auditory cortical neural ensembles, and examined their topographical distribution. Local field potentials (LFPs) were recorded in eight patients undergoing invasive recordings for pharmaco-resistant epilepsy. Stimuli consisted of bursts of broadband noise followed by regular interval noise (RIN). RIN was presented at rates below and above the LLP to distinguish responses related to the regularity of the stimulus and the presence of pitch itself. LFPs were recorded from human cortical homologues of auditory core, belt, and parabelt regions using multicontact depth electrodes implanted in Heschl's gyrus (HG) and Planum Temporale (PT), and subdural grid electrodes implanted over lateral superior temporal gyrus (STG). Evoked responses corresponding to the temporal regularity of the stimulus were assessed using autocorrelation of the evoked responses, and occurred for stimuli below and above the LLP. Induced responses throughout the high gamma range (60-200 Hz) were present for pitch values above the LLP, with onset latencies of approximately 70 ms. Mapping of the induced responses onto a common brain space demonstrated variability in the topographical distribution of high gamma responses across subjects. Induced responses were present throughout the length of HG and on PT, which is consistent with previous functional neuroimaging studies. Moreover, in each subject, a region within lateral STG showed robust induced responses at pitch-evoking stimulus rates. This work suggests a distributed representation of pitch processing in neural ensembles in human homologues of core and non-core auditory cortex.

Outcomes of Emergency Transcatheter Aortic Valve Replacement.

OBJECTIVE: To identify outcomes of patients undergoing emergency transcatheter aortic valve replacement (TAVR) and determine predictors of in-hospital mortality. BACKGROUND: Emergency TAVR has emerged as a viable treatment strategy for patients with decompensated severe aortic stenosis and/or regurgitation; however, data on patients undergoing emergency TAVR are limited. METHODS: All emergency TAVR procedures were identified from a single tertiary academic center between January 2015 and August 2018. RESULTS: 31 patients underwent emergency TAVR due to cardiogenic shock (26 patients), electrical instability with incessant ventricular tachycardia (2 patients), severe refractory angina (2 patients), and decompensated heart failure with hypoxemic respiratory failure requiring mechanical ventilation (1 patient). Mechanical circulatory support (MCS) was used in 16 (51.6%). MCS initiation occurred immediately prior to TAVR in 10 patients and placed post-TAVR in 6 patients. 6 patients died before hospital discharge (in-hospital mortality 19.4%). 1-year and 2-year survival rates were 61.0% and 55.9%, respectively. Univariate predictors of in-hospital mortality were preprocedural pulmonary artery pulsatility index (PAPi) ≤1.8 (66.7% vs. 20.0%, p=0.01), intraprocedural cardiopulmonary resuscitation (CPR) (83.3% vs 4.0%, p ≤ 0.001), acute kidney injury post-TAVR (80.0% vs. 4.2%, p ≤ 0.001), initiation of dialysis post-TAVR (60.0% vs. 4.2%, p ≤ 0.001), and MCS initiation post-TAVR (50.0% vs. 12.0%, p=0.03). MCS initiation before TAVR was associated with improved survival compared with post-TAVR initiation. CONCLUSION: Emergency TAVR in extreme risk patients with acute decompensated heart failure or cardiogenic shock secondary to severe aortic valve disease is associated with high in-hospital mortality rates. Careful patient selection taking into account right heart function, assessed by PAPi, and early utilization of MCS may improve survival following emergency TAVR.