Hippocampal sharp wave-ripples (SPW-Rs), neocortical slow oscillations, and thalamocortical sleep spindles are hypothesized to provide a temporal framework for coordinated information transfer during memory consolidation. Hippocampal replay supports this process, yet replayed sequences often unfold across multiple SPW-Rs, suggesting that individual ripples may not constitute the fundamental unit of hippocampal output. Here, using large-scale electrophysiological recordings from the hippocampus and retrosplenial cortex, we show that hippocampal output is organized into clusters of SPW-Rs (cSPW-Rs) during UP states, which are often phase-locked to spindle troughs. Extending this approach with wide-field imaging and unsupervised latent-variable modeling, we found that cSPW-Rs enhanced segregation between the default mode and somatomotor networks and preferentially replayed spatially extended maze trajectories following learning. We propose that SPW-R clusters enable reverberating hippocampal-cortical spike exchange and the concatenation of sequential experiences, establishing ripple clusters as a previously unrecognized syntactic unit of hippocampal-neocortical dialogue.

Efficient neutrophil chemotaxis requires the integration of mechanical forces and lipid-mediated signaling. While the signaling lipid leukotriene B4 (LTB 4 ) reinforces cellular polarity, how mechanical cues regulate its production remains unclear. We now show that cytosolic phospholipase A2α (cPLA₂α), which is essential for the synthesis of LTB 4 , functions as a nuclear curvosensor. cPLA₂α responds to nuclear constrictions by localizing to ceramide-rich inner nuclear membrane microdomains and incorporating onto the exofacial surface of nuclear envelope-derived exosomes. This unique topology enables localized LTB 4 synthesis, which promotes myosin light chain II phosphorylation, and sustains polarity and directional persistence after constriction. In neutrophils squeezing through small constrictions, loss of cPLA₂α impairs nuclear curvature sensing, exosomal LTB 4 production, and post-constriction motility. These findings uncover a cPLA 2 -dependent mechano-chemical axis linking nuclear architecture to chemotactic efficiency and offering new strategies to modulate inflammatory responses.

State-of-the-art neurotransmitter sensors use fast-scan cyclic-voltammetry (FSCV) to achieve high sensitivity and selectivity. The main challenge in FSCV is the need for high dynamic range (DR) and a low noise floor. We address this challenge by introducing a dynamic template-tracking sensor interface which takes advantage of the quasi-repetitive characteristics in non-faradaic (NF) currents. The prototype has a DR of 83.5 dB, a $73.8 \text{pA}_{\text{RMS}}$ noise floor, and is resilient to sensor drift. This work reports the highest DR and maintains simplicity of a one-working-electrode/channel setup.

OBJECTIVE:Recent neuroscientific research craves for understanding sophisticated brain networks formed by neuron ensembles across multiple regions. An ideal way to unveil the complex connectome is bidirectionally interacting (simultaneous recording and stimulation) with neurons at high spatiotemporal resolutions. Existing CMOS recording probes cannot provide micro-scale interactions with limited stimulation capability. Although optogenetics can achieve neuron-specific stimulation, conventional methods using optic fibers illuminate a large volume of tissue, resulting in unspecific perturbations. While our previous studies demonstrated micro-LED (µLED)-based optoelectrode for localized stimulation and recording, this work advances them into a fully integrated headstage combining the optoelectrode, CMOS IC, and flexible interposer for miniaturized implementation. The proposed system enables micro-scale interactions with high spatiotemporal precision through densely packed 256-neuron-size recording and 128-soma-size fiber-less opto-stimulation across multiple brain regions. METHODS:Such high resolutions yet wide coverage is achieved by (1) advanced micromachining techniques integrating recording electrodes and µLEDs, (2) micro-second, independent 384-channel interaction via a low-power, area-efficient circuit, and (3) compact and reliable polyimide-cable-based hybrid assembly. RESULTS:A compact (23.8×28.8 mm2) and lightweight (3.5-gram) headstage achieved the highest reported channel density in area (0.56 channels/mm2) and weight (109.71 channels/gram). A single acute in vivo experiment on a transgenic mouse identified >160 isolated pyramidal neurons and narrow/wide interneurons in the dorsal hippocampus, with local and broad-range effects from focal optogenetic stimulation. CONCLUSION AND SIGNIFICANCE:We implemented the hybrid integrated, large-scale opto-electrophysiology interface prototype and verified its feasibility in vivo, representing the first fully integrated platform extending our µLED-based probes into a complete system.

Microelectrode arrays (MEAs) are devices capable of recording extracellular action potentials (spikes) from many neurons simultaneously and with high spatial and temporal resolution. MEAs have emerged as an invaluable tool for understanding how networks of neurons govern complex sensory, motor and decision-making processes. In this Primer, we introduce various in vivo MEA designs and describe their construction, characterization and applications. We describe approaches for effective device implantation and the use of MEA recordings in behavioural experiments. We then discuss strategies for obtaining high-quality and stable electrophysiological recordings, including through mitigating the foreign body reaction. We introduce the reader to spike sorting approaches with a focus on semi-automated sorting of high-channel-count data, as well as to the analysis of sorted spikes and their uses. Finally, we cover future trends and emerging MEA technology designed to expand current capabilities and overcome limitations, with a focus on biomimetic and multifunctional devices. This Primer should provide the reader with a foundation in the fundamental principles of MEA technology for in vivo use. In vivo microelectrode arrays allow the measurement of action potentials from individual neurons in awake animals to better understand the function of the brain and the peripheral nervous system. In this Primer, Williams et al. cover the different designs, experimental set-ups and applications of this technology and discuss data processing steps for electrophysiological data.

We present a CMOS image sensor (CIS) with on-chip energy-efficient face detection circuits for low-latency vision-based tracking systems. The embedded charge-domain computing circuits compute early stages of cascaded machine-learning classifiers for the images acquired from a global-shutter pixel array while simultaneously providing the digitized image readout. This approach improves the system energy-latency product by 2.3x , compared to the conventional high-speed tracking systems, because the backend computational load can be significantly reduced with no latency overhead. In addition, charge-domain computing within the pixel array allows for little energy overhead. The prototype image sensor was fabricated in a 180-nm CIS process with 240x240 voltage-domain global shutter pixels. On-chip face detection rejects 98% of 3500 scanning windows and reduces the backend workload by 5.3x , while consuming only 421 pJ/pixel at 120 frames/s. This translates to the best in-class energy efficiency of 8.2 TOPS/W among CIS with near-sensor computing. In addition, the fabricated sensor supports illumination-invariant and multi-scale detection for robust operation, which is important in real applications.

Over recent decades, optogenetics has become a pivotal technique for elucidating the functionality of neuronal circuits in living organisms. By genetically modifying specific cells within targeted tissues to respond to particular optical stimuli, researchers can achieve precise activation or inhibition of these cells. This capability enables detailed investigations of neural circuitry with unprecedented accuracy. However, there is a rising need for hardware that supports bidirectional control in conjunction with electrophysiological recording. A significant challenge in this domain is the compact integration of dual light sources and a recording system. This study addresses this challenge through the development of a novel microfabrication and assembly technique for embedding dual-color micro-LEDs and recording electrodes into a Michigan-type neural probe structure, designated as DuoLite (Dual-color micro-LEDs Integrated Neural-Interface Optoelectrode for Multi-Control Optogenetic Electrophysiology). We present two device variants: (a) a small-group and (b) a large-group cell-targeted design, each incorporating micro-LEDs with a minimal area of <100 um^2 for both red and blue light. The design and assembly techniques for integrating all three components within a shank width of <100 um are thoroughly detailed, and the functionality of the devices is validated through in vivo experiments. ### Competing Interest Statement The authors have declared no competing interest.

Flexible intracortical neural probes have drawn attention for their enhanced longevity in high-resolution neural recordings due to reduced tissue reaction. However, the conventional monolithic fabrication approach has met significant challenges in: (i) scaling the number of recording sites for electrophysiology; (ii) integrating of other physiological sensing and modulation; and (iii) configuring into three-dimensional (3D) shapes for multi-sided electrode arrays. We report an innovative self-assembly technology that allows for implementing flexible origami neural probes as an effective alternative to overcome these challenges. By using magnetic-field-assisted hybrid self-assembly, multiple probes with various modalities can be stacked on top of each other with precise alignment. Using this approach, we demonstrated a multifunctional device with scalable high-density recording sites, dopamine sensors and a temperature sensor integrated on a single flexible probe. Simultaneous large-scale, high-spatial-resolution electrophysiology was demonstrated along with local temperature sensing and dopamine concentration monitoring. A high-density 3D origami probe was assembled by wrapping planar probes around a thin fiber in a diameter of 80∼105 μm using optimal foldable design and capillary force. Directional optogenetic modulation could be achieved with illumination from the neuron-sized micro-LEDs (μLEDs) integrated on the surface of 3D origami probes. We could identify angular heterogeneous single-unit signals and neural connectivity 360° surrounding the probe. The probe longevity was validated by chronic recordings of 64-channel stacked probes in behaving mice for up to 140 days. With the modular, customizable assembly technologies presented, we demonstrated a novel and highly flexible solution to accommodate multifunctional integration, channel scaling, and 3D array configuration.

We present an incremental $\Delta\Sigma$ frontend that can resolve $\mu \mathrm{V}$ - level neural signals superimposed with large $(> 100\text{m V})$ and fast $(> 100\text{mV}/\text{ms})$ interferences without quality degradation. Unlike conventional approaches that stretch conversion range to accept the large input by sacrificing resolution, the proposed work tracks the large transient with constant high-resolution but variable tracking speed adaptive to its input slope. Thus, this frontend acquires neural information without quality loss even when exposed to large and fast artifacts that overwhelm small neural signals. With the proposed high-resolution tracking scheme, this work achieves the highest SNDR (79.2dB) and FoM SNDR (165.7dB) among the state-of-the-art frontends using the conventional transient tracking techniques.

Supplementary Figure from p53 Inhibits Bmi-1-driven Self-Renewal and Defines Salivary Gland Cancer Stemness

Supplemental Figure 4. Confirmation of JAK2 depletion by siRNA

Supplemental Figure 2. FACS analysis of CD24 and CD133 expression of CD24+ or CD24- tumors

We report a power-efficient analog front-end integrated circuit (IC) for multi-channel, dual-band subcortical recordings. In order to achieve high-resolution multi-channel recordings with low power consumption, we implemented an incremental ΔΣ ADC (IADC) with a dynamic zoom-and-track scheme. This scheme continuously tracks local field potential (LFP) and adaptively adjusts the input dynamic range (DR) into a zoomed sub-LFP range to resolve tiny action potentials. Thanks to the reduced DR, the oversampling rate of the IADC can be reduced by 64.3% compared to the conventional approach, leading to significant power reduction. In addition, dual-band recording can be easily attained because the scheme continuously tracks LFPs without additional on-chip hardware. A prototype four-channel front-end IC has been fabricated in 180 nm standard CMOS processes. The IADC achieved 11.3-bit ENOB at 6.8 μW, resulting in the best Walden and SNDR FoMs, 107.9 fJ/c-s and 162.1 dB, respectively, among two different comparison groups: the IADCs reported up to date in the state-of-the-art neural recording front-ends; and the recent brain recording ADCs using similar zooming or tracking techniques to this work. The intrinsic dual-band recording feature reduces the post-processing FPGA resources for subcortical signal band separation by >45.8%. The front-end IC with the zoom-and-track IADC showed an NEF of 5.9 with input-referred noise of 8.2 μVrms, sufficient for subcortical recording. The performance of the whole front-end IC was successfully validated through in vivo animal experiments.

Recent neuroscientific research seeks to comprehend the sophisticated deep-brain networks of neural circuits consisting of large scale neuronal ensembles across multiple brain regions. An ideal way to unveil the complex connectome might be stimulating individual neurons with high spatial resolution in a broad range of brain, while seamlessly monitoring the correspondent neuronal activities. Optogenetics is known as a key technology to enable such a goal thanks to its high spatial and temporal selectivity in neuromodulation. Existing silicon probe technologies have been able to partially achieve such a goal by recording broad region of brain activities through multiple electrodes per shank, but those cannot complete perfect coverage due to the limited channel counts for the optogenetic stimulation. Here, we present an high-channel-count optogenetic system with simultaneous 256 recoding and 128 optogenetic stimulation sites, exhibiting the highest channel density ever reported, enabled by a flexible polyimide cable-based hybrid-integration of a low-stimulation-artifact micro-LED (µLED) opto-electrode with a low-power and -noise, area-efficient CMOS interfacing integrated-circuit (IC). The presented optogenetic system provides 256-neuron-size electrodes (11 × 15 µm 2 ) with a 40 µm inter-electrode pitch for high spatial oversampling in recording and 128-soma-size µLEDs (8 × 11 µm 2 ) with a 20 µm inter-LED pitch for single-cell resolution in stimulation, resulting in a vertical span of 640 µm and a horizontal span of 2,100 µm with a total 8 shanks. For versatility in optogenetics-based experiments from small rodents to primates with user-preferable settings, the system base that provides programmability of recording and stimulation parameters and rest of signal processing, such as filtering, digitization, and data transmission including serial peripheral interface (SPI) has also been designed within small area of 23.8 × 28.8 mm 2 with only 3.5-gram weight, resulting in the highest channel density both in size (0.56 channels/mm 2 ) and weight (109.71 channels/gram) among the state-of-the-art optogenetics-based neuromodulation systems. To verify the system operation in vivo , a compact optogenetics headstage has been also fabricated. Using the prepared optogenetic headstage, 169 isolated neurons have been observed with various stimulation intensities. The results offered in this article indicate that the presented hybrid integrated ultrahigh-density, high-channel-count headstage can be used to realize the massive-scale in-depth brain studies with optogenetics.

Supplemental Figure 5. FACS isolation strategy and purity of sort

The study of a localcuit inside the brain requires a tool to precisely modulate a few selected neurons and simultaneously monitor the neuronal responses. Optogenetics provides the capability to excite or inhibit activities of specific neurons in intact animals with millisecond precision. This light-induced stimulation technique can be combined with electrophysiology to enable simultaneous control of target neurons and recording of the associated neuronal activities in the brain. In this chapter, we introduce the state-of-the-art optoelectrodes that enable precise optical stimulation and electrical recording in behaving animals. For experiments with behaving animals, it is important that the light sources are integrated within the headstage so that light can be delivered to multiple stimulation sites without causing a tethering problem. Two fiberless implementation approaches that promote easier scaling are discussed in detail: the integration of optical waveguides on the probe shank for light delivery to a distal end located near the recording electrodes and the direct integration of neuron-sized (similar to 10 mu m) microLEDs in the vicinity of the recording electrodes. The design principles and the fabrication processes, as well as the advantages and the limitations of each approach, will be presented along with the results of in vivo validation experiments.

Optogenetics are a powerful tool for testing how a neural circuit influences neural activity, cognition, and behavior. Accordingly, the number of studies employing optogenetic perturbation has grown exponentially over the last decade. However, recent studies have highlighted that the impact of optogenetic stimulation/silencing can vary depending on the construct used, the local microcircuit connectivity, extent/power of illumination, and neuron types perturbed. Despite these caveats, the majority of studies employ optogenetics without simultaneously recording neural activity in the circuit that is being perturbed. This dearth of simultaneously recorded neural data is due in part to technical difficulties in combining optogenetics and extracellular electrophysiology. The recent introduction of μLED silicon probes, which feature independently controllable miniature LEDs embedded at several levels of each of multiple shanks of silicon probes, provides a tractable method for temporally and spatially precise interrogation of neural circuits. Here, we provide a protocol addressing how to perform chronic recordings using μLED probes. This protocol provides a schematic for performing causal and reproducible interrogations of neural circuits and addresses all phases of the recording process: introduction of optogenetic construct, implantation of the μLED probe, performing simultaneous optogenetics and electrophysiology in vivo, and post-processing of recorded data. SUMMARY This method allows a researcher to simultaneously perturb neural activity and record electrophysiological signal from the same neurons with high spatial specificity using silicon probes with integrated μLEDs. We outline a procedure detailing all stages of the process for performing reliable μLED experiments in chronically implanted rodents.

Recurrent connectivity between excitatory neurons and the strength of feedback from inhibitory neurons are critical determinants of the dynamics and computational properties of neuronal circuits. Toward a better understanding of these circuit properties in regions CA1 and CA3 of the hippocampus, we performed optogenetic manipulations combined with large-scale unit recordings in rats under anesthesia and in quiet waking, using photoinhibition and photoexcitation with different light-sensitive opsins. In both regions, we saw striking paradoxical responses: subsets of cells increased firing during photoinhibition, while other cells decreased firing during photoexcitation. These paradoxical responses were more prominent in CA3 than in CA1, but, notably, CA1 interneurons showed increased firing in response to photoinhibition of CA3. These observations were recapitulated in simulations where we modeled both CA1 and CA3 as inhibition-stabilized networks in which strong recurrent excitation is balanced by feedback inhibition. To directly test the inhibition-stabilized model, we performed large-scale photoinhibition directed at (GAD-Cre) inhibitory cells and found that interneurons in both regions increased firing when photoinhibited, as predicted. Our results highlight the often-paradoxical circuit dynamics that are evidenced during optogenetic manipulations and indicate that, contrary to long-standing dogma, both CA1 and CA3 hippocampal regions display strongly recurrent excitation, which is stabilized through inhibition.

Supplemental Figure 1. Bioluminescent images of cancer stem cell markers evaluated