A Tetracarbene Iron(II) Complex with a Long-lived Triplet Metal-to-ligand Charge Transfer State due to a Triplet-Triplet Barrier.

Mixed N-heterocyclic carbene (NHC) / pyridyl iron(II) complexes have attracted a great deal of attention recently because of their potential as photocatalysts and light sensitizers made from Earth-abundant elements. The most decisive challenge for their successful implementation is the lifetime of the lowest triplet metal-to-ligand charge transfer state (3MLCT), which typically decays via a triplet metal-centered (3MC) state back to the ground state. We reveal by variable-temperature ultrafast transient absorption spectroscopy that the tripodal iron(II) bis(pyridine) complex isomers trans- and cis-[Fe(pdmi)2]2+with four NHC donors show 3MLCT→3MC population transfers with very different barriers and rationalize this by computational means. While trans-[Fe(pdmi)2]2+possesses an unobservable activation barrier, the cis isomer exhibits a barrier of 492 cm-1, which leads to a nanosecond 3MLCT lifetime at 77 K. The kinetic and quantum chemical data were analyzed in the context of semi-classical Marcus theory revealing a high reorganization energy and small electronic coupling between the two triplet states. This highlights the importance of detailed structural control and kinetic knowledge for the rational design of photosensitizers from first row transition metals such as iron.

Stable Molybdenum(0) Carbonyl Complex for Upconversion and Photoredox Catalysis.

Photoactive complexes with earth-abundant metals have attracted increasing interest in the recent years fueled by the promise of sustainable photochemistry. However, sophisticated ligands with complicated syntheses are oftentimes required to enable photoactivity with nonprecious metals. Here, we combine a cheap metal with simple ligands to easily access a photoactive complex. Specifically, we synthesize the molybdenum(0) carbonyl complex Mo(CO)3(tpe) featuring the tripodal ligand 1,1,1-tris(pyrid-2-yl)ethane (tpe) in two steps with a high overall yield. The complex shows intense deep-red phosphorescence with excited state lifetimes of several hundred nanoseconds. Time-resolved infrared spectroscopy and laser flash photolysis reveal a triplet metal-to-ligand charge-transfer (3MLCT) state as the lowest excited state. Temperature-dependent luminescence complemented by density functional theory (DFT) calculations suggest thermal deactivation of the 3MLCT state via higher lying metal-centered states in analogy to the well-known photophysics of [Ru(bpy)3]2+. Importantly, we found that the title compound is very photostable due to the lack of labilized Mo-CO bonds (as caused by trans-coordinated CO) in the facial configuration of the ligands. Finally, we show the versatility of the molybdenum(0) complex in two applications: (1) green-to-blue photon upconversion via a triplet-triplet annihilation mechanism and (2) photoredox catalysis for a green-light-driven dehalogenation reaction. Overall, our results establish tripodal carbonyl complexes as a promising design strategy to access stable photoactive complexes of nonprecious metals avoiding tedious multistep syntheses.

A novel rat model of Dravet syndrome recapitulates clinical hallmarks.

Dravet syndrome (DS) is a debilitating infantile epileptic encephalopathy characterized by seizures induced by high body temperature (hyperthermia), sudden unexpected death in epilepsy (SUDEP), cognitive impairment, and behavioral disturbances. The most common cause of DS is haploinsufficiency of the SCN1A gene, which encodes the voltage-gated sodium channel Nav1.1. In current mouse models of DS, the epileptic phenotype is strictly dependent on the genetic background and most mouse models exhibit drastically higher SUDEP rates than patients. Therefore, we sought to develop an alternative animal model for DS. Here, we report the generation and characterization of a Scn1a halploinsufficiency rat model of DS by disrupting the Scn1a allele. Scn1a+/- rats show reduced Scn1a expression in the cerebral cortex, hippocampus and thalamus. Homozygous null rats die prematurely. Heterozygous animals are highly susceptible to heat-induced seizures, the clinical hallmark of DS, but are otherwise normal in survival, growth, and behavior without seizure induction. Hyperthermia-induced seizures activate distinct sets of neurons in the hippocampus and hypothalamus in Scn1a+/- rats. Electroencephalogram (EEG) recordings in Scn1a+/- rats reveal characteristic ictal EEG with high amplitude bursts with significantly increased delta and theta power. After the initial hyperthermia-induced seizures, non-convulsive, and convulsive seizures occur spontaneously in Scn1a+/- rats. In conclusion, we generate a Scn1a haploinsufficiency rat model with phenotypes closely resembling DS, providing a unique platform for establishing therapies for DS.

Towards Luminescent Vanadium(II) Complexes with Slow Magnetic Relaxation and Quantum Coherence.

Molecular entities with doublet or triplet ground states find increasing interest as potential molecular quantum bits (qubits). Complexes with higher multiplicity might even function as qudits and serve to encode further quantum bits. Vanadium(II) ions in octahedral ligand fields with quartet ground states and small zero-field splittings qualify as qubits with optical read out thanks to potentially luminescent spin-flip states. We identified two V2+ complexes [V(ddpd)2 ]2+ with the strong field ligand N,N'-dimethyl-N,N'-dipyridine-2-yl-pyridine-2,6-diamine (ddpd) in two isomeric forms (cis-fac and mer) as suitable candidates. The energy gaps between the two lowest Kramers doublets amount to 0.2 and 0.5 cm-1 allowing pulsed EPR experiments at conventional Q-band frequencies (35 GHz). Both isomers possess spin-lattice relaxation times T1 of around 300 µs and a phase memory time TM of around 1 µs at 5 K. Furthermore, the mer isomer displays slow magnetic relaxation in an applied field of 400 mT. While the vanadium(III) complexes [V(ddpd)2 ]3+ are emissive in the near-IR-II region, the [V(ddpd)2 ]2+ complexes are non-luminescent due to metal-to-ligand charge transfer admixture to the spin-flip states.

Seasonal plasticity in the adult somatosensory cortex.

Seasonal cycles govern life on earth, from setting the time for the mating season to influencing migrations and governing physiological conditions like hibernation. The effect of such changing conditions on behavior is well-appreciated, but their impact on the brain remains virtually unknown. We investigate long-term seasonal changes in the mammalian brain, known as Dehnel's effect, where animals exhibit plasticity in body and brain sizes to counter metabolic demands in winter. We find large seasonal variation in cellular architecture and neuronal activity in the smallest terrestrial mammal, the Etruscan shrew, Suncus etruscus Their brain, and specifically their neocortex, shrinks in winter. Shrews are tactile hunters, and information from whiskers first reaches the somatosensory cortex layer 4, which exhibits a reduced width (-28%) in winter. Layer 4 width (+29%) and neuron number (+42%) increase the following summer. Activity patterns in the somatosensory cortex show a prominent reduction of touch-suppressed neurons in layer 4 (-55%), the most metabolically active layer. Loss of inhibitory gating occurs with a reduction in parvalbumin-positive interneurons, one of the most active neuronal subtypes and the main regulators of inhibition in layer 4. Thus, a reduction in neurons in layer 4 and particularly parvalbumin-positive interneurons may incur direct metabolic benefits. However, changes in cortical balance can also affect the threshold for detecting sensory stimuli and impact prey choice, as observed in wild shrews. Thus, seasonal neural adaptation can offer synergistic metabolic and behavioral benefits to the organism and offer insights on how neural systems show adaptive plasticity in response to ecological demands.

Pseudo-Octahedral Iron(II) Complexes with Near-Degenerate Charge Transfer and Ligand Field States at the Franck-Condon Geometry.

Increasing the metal-to-ligand charge transfer (MLCT) excited state lifetime of polypyridine iron(II) complexes can be achieved by lowering the ligand's π* orbital energy and by increasing the ligand field splitting. In the homo- and heteroleptic complexes [Fe(cpmp)2 ]2+ (12+ ) and [Fe(cpmp)(ddpd)]2+ (22+ ) with the tridentate ligands 6,2''-carboxypyridyl-2,2'-methylamine-pyridyl-pyridine (cpmp) and N,N'-dimethyl-N,N'-di-pyridin-2-ylpyridine-2,6-diamine (ddpd) two or one dipyridyl ketone moieties provide low energy π* acceptor orbitals. A good metal-ligand orbital overlap to increase the ligand field splitting is achieved by optimizing the octahedricity through CO and NMe units between the coordinating pyridines which enable the formation of six-membered chelate rings. The push-pull ligand cpmp provides intra-ligand and ligand-to-ligand charge transfer (ILCT, LL'CT) excited states in addition to MLCT excited states. Ground and excited state properties of 12+ and 22+ were accessed by X-ray diffraction analyses, resonance Raman spectroscopy, (spectro)electrochemistry, EPR spectroscopy, X-ray emission spectroscopy, static and time-resolved IR and UV/Vis/NIR absorption spectroscopy as well as quantum chemical calculations.

Ovarian cancer: screening and future directions.

Ovarian cancer carries a lifetime risk of approximately 2% for women and is the leading cause of death from any gynecologic malignancy. Currently, no screening program for ovarian cancer exists for the general population in the UK. This review focuses on the evidence surrounding the efficacy of current markers and discusses future improvements in screening for this disease. One-off cancer antigen 125 (CA125) measurements for detecting ovarian cancer have been well researched. However, studies have highlighted low positive predictive values (5%) and high false positive rates leading to patient anxiety and unnecessary invasive follow-up. Commonly, in the UK, CA125 is combined with transvaginal ultrasound, but there is little evidence that this approach can decrease mortality from ovarian cancer. Recently the Risk of Ovarian Cancer Algorithm, involving a combination of serial CA125 measurements and age, has been shown to detect more early stage cancers. Nevertheless, these measures are not robust in decreasing mortality from ovarian cancer and are costly to implement. Newer markers, such as human epididymis protein 4, have shown greater specificity. Its combination with CA125 and menopausal status in the Risk of Ovarian Malignancy Algorithm can predict the risk of malignancy but provides no additional benefit as a screening tool. Advanced techniques are emerging, including ultrasound molecular imaging techniques using microbubbles targeted to kinase domain receptors, and fallopian tube cytology. To reduce mortality from ovarian cancer, detection of pre-invasive lesions is imperative as ovarian cancer may develop in the fallopian tube and spread to the peritoneal cavity before being detected systemically. It seems that screening tools for ovarian cancer are currently not worthwhile for implementation into a national program. An emphasis on reducing false positives rates, associated anxiety and subsequent overdiagnosis is needed.

Structural modularity and grid activity in the medial entorhinal cortex.

Following the groundbreaking discovery of grid cells, the medial entorhinal cortex (MEC) has become the focus of intense anatomical, physiological, and computational investigations. Whether and how grid activity maps onto cell types and cortical architecture is still an open question. Fundamental similarities in microcircuits, function, and connectivity suggest a homology between rodent MEC and human posteromedial entorhinal cortex. Both are specialized for spatial processing and display similar cellular organization, consisting of layer 2 pyramidal/calbindin cell patches superimposed on scattered stellate neurons. Recent data indicate the existence of a further nonoverlapping modular system (zinc patches) within the superficial MEC layers. Zinc and calbindin patches have been shown to receive largely segregated inputs from the presubiculum and parasubiculum. Grid cells are also clustered in the MEC, and we discuss possible structure-function schemes on how grid activity could map onto cortical patch systems. We hypothesize that in the superficial layers of the MEC, anatomical location can be predictive of function; thus relating functional properties and neuronal morphologies to the cortical modules will be necessary for resolving how grid activity maps onto cortical architecture. Imaging or cell identification approaches in freely moving animals will be required for testing this hypothesis.

First Micelle-Free Photoredox Catalytic Access to Hydrated Electrons for Syntheses and Remediations with a Visible LED or even Sunlight.

Hydrated electrons are super-reductants, yet can be generated with visible light when two photons are pooled, most efficiently through storing the energy of the first photon in a radical pair formed by the reduction of an excited catalyst by a sacrificial donor. All previous such systems for producing synthetically useable amounts of hydrated electrons with an LED in the visible range had to resort to compartmentalization by SDS micelles to curb the performance-limiting recombination of the pair. To overcome micelle-imposed constraints on sustainability and applications, we have instead attached carboxylate groups to a ruthenium (tris)bipyridyl catalyst such that its pentaanionic radical strongly repels the dianionic radical of the bioavailable donor urate. We have explored the influence of the Coulombic interactions on the electron generation by a time-resolved study from microseconds to hours, including for comparison the unsubstituted complex, which forms a monocationic radical, with and without SDS micelles. The new homogeneous electron source is best with regard to stability and total electron output; it has a broader synthetic scope because it does not entail micellar shielding of less hydrophilic compounds, which particularly facilitates cross-couplings; and it tolerates supramolecular containers as carriers of water-insoluble substrates or products. As an application in the field, we demonstrate the solar remediation of a recalcitrant chloro-organic bulk chemical.

A Green-LED Driven Source of Hydrated Electrons Characterized from Microseconds to Hours and Applied to Cross-Couplings.

We present a novel photoredox catalytic system that delivers synthetically usable concentrations of hydrated electrons when illuminated with a green light-emitting diode (LED). The catalyst is a ruthenium complex protected by an anionic micelle, and the urate dianion serves as a sacrificial donor confined to the aqueous bulk. By virtue of its chemical properties, this donor not only suppresses charge recombination that would limit the electron yield, but also enables this system to perform cross-couplings through the action of hydrated electrons, the first examples of which are reported here. We have investigated the kinetics of all the steps involving the electron and its direct precursor in a comparative study by means of laser flash photolysis and by monitoring product formation during LED photolysis. Despite the differences in timescales, each approach on its own already gives a complete picture of the reaction over a temporal range spanning ten orders of magnitude. Discrepancies between the kinetic parameters obtained with the two complementary techniques can be rationalized with the slow secondary chemistry of the system; they reveal that the product-based method provides a more accurate description because it also responds to the changes of the system composition during a synthesis; hence, they demonstrate that in complex systems the timescale of the experimental observation should be matched to that of the actual application.

Micellized Tris(bipyridine)ruthenium Catalysts Affording Preparative Amounts of Hydrated Electrons with a Green Light-Emitting Diode.

We have explored alkyl substitution of the ligands as a means to improve the performance of the title complexes in photoredox catalytic systems that produce synthetically useable amounts of hydrated electrons through photon pooling. Despite generating a super-reductant, these electron sources only consume the bioavailable ascorbate and are driven by a green light-emitting diode (LED). The substitutions influence the catalyst activity through the interplay of the quenching parameters, the recombination rate of the reduced catalyst OER and the ascorbyl radical across the micelle-water interface, and the quantum yield of OER photoionization. Laser flash photolysis yields comprehensive information on all these processes and allows quantitative predictions of the activity observed in LED kinetics, but the latter method provides the only access to the catalyst stability under illumination on the timescale of the syntheses. The homoleptic complex with dimethylbipyridine ligands emerges as the optimum that combines an activity twice as high with an undiminished stability in relation to the parent compound. With this complex, we have effected dehalogenations of alkyl and aryl chlorides and fluorides, hydrogenations of carbon-carbon double bonds, and self- as well as cross-coupling reactions. All the substrates employed are impervious to ordinary photoredox catalysts but present no problems to the hydrated electron as a super-reductant. A particularly attractive application is selective deuteration with high isotopic purity, which is achieved simply by using heavy water as the solvent.

Proceedings From the 1st International Conference 'Current Concepts and Controversies in Gynecologic and Urologic Oncology'.

The N.N. Alexandrov National Cancer Center of Belarus organized a collaborative international conference entitled 'Current Concepts and Controversies in Gynecologic and Urologic Oncology' with the International Gynecologic Cancer Society and the United States National Cancer Institute. International, regional, and national experts presented recent developments and local conditions in the treatment of gynecologic cancers. Findings were reviewed with the intent of optimizing the management of women with gynecologic cancers across the Commonwealth of Independent States region. At the end of the conference, a resolution was adopted to identify areas for improvement and future collaborations.

Generating Hydrated Electrons for Chemical Syntheses by Using a Green Light-Emitting Diode (LED).

We present the first working system for accessing and utilizing laboratory-scale concentrations of hydrated electrons by photoredox catalysis with a green light-emitting diode (LED). Decisive are micellar compartmentalization and photon pooling in an intermediate that decays with second-order kinetics. The only consumable is the nontoxic and bioavailable vitamin C. A turnover number of 1380 shows the LED method to be on par with electron generation by high-power pulsed lasers, but at a fraction of the cost. The extreme reducing power of the electron and its long unquenched life as a ground-state species are synergistic. We demonstrate the applicability to the dechlorination, defluorination, and hydrogenation of compounds that are inert towards all other visible-light photoredox catalysts known to date. A comprehensive mechanistic investigation from microseconds to hours yields results of general validity for photoredox catalysis with photon pooling, allowing optimization and upscaling.

Functional Architecture of the Rat Parasubiculum.

The parasubiculum is a major input structure of layer 2 of medial entorhinal cortex, where most grid cells are found. Here we investigated parasubicular circuits of the rat by anatomical analysis combined with juxtacellular recording/labeling and tetrode recordings during spatial exploration. In tangential sections, the parasubiculum appears as a linear structure flanking the medial entorhinal cortex mediodorsally. With a length of ∼5.2 mm and a width of only ∼0.3 mm (approximately one dendritic tree diameter), the parasubiculum is both one of the longest and narrowest cortical structures. Parasubicular neurons span the height of cortical layers 2 and 3, and we observed no obvious association of deep layers to this structure. The "superficial parasubiculum" (layers 2 and 1) divides into ∼15 patches, whereas deeper parasubicular sections (layer 3) form a continuous band of neurons. Anterograde tracing experiments show that parasubicular neurons extend long "circumcurrent" axons establishing a "global" internal connectivity. The parasubiculum is a prime target of GABAergic and cholinergic medial septal inputs. Other input structures include the subiculum, presubiculum, and anterior thalamus. Functional analysis of identified and unidentified parasubicular neurons shows strong theta rhythmicity of spiking, a large fraction of head-direction selectivity (50%, 34 of 68), and spatial responses (grid, border and irregular spatial cells, 57%, 39 of 68). Parasubicular output preferentially targets patches of calbindin-positive pyramidal neurons in layer 2 of medial entorhinal cortex, which might be relevant for grid cell function. These findings suggest the parasubiculum might shape entorhinal theta rhythmicity and the (dorsoventral) integration of information across grid scales. SIGNIFICANCE STATEMENT: Grid cells in medial entorhinal cortex (MEC) are crucial components of an internal navigation system of the mammalian brain. The parasubiculum is a major input structure of layer 2 of MEC, where most grid cells are found. Here we provide a functional and anatomical characterization of the parasubiculum and show that parasubicular neurons display unique features (i.e., strong theta rhythmicity of firing, prominent head-direction selectivity, and output selectively targeted to layer 2 pyramidal cell patches of MEC). These features could contribute to shaping the temporal and spatial code of downstream grid cells in entorhinal cortex.

Green-light ionization of 3-aminoperylene in SDS micelles-a promising access to hydrated electrons despite a myth debunked.

Using an improved methodology, we have carefully reinvestigated the title reaction by laser flash photolysis and disproved an earlier study (J. K. Thomas and P. Piciulo, J. Am. Chem. Soc., 1978, 100, 3239), which claimed this green-light ionization to be monophotonic, the only instance of such a scenario ever reported for a stable compound. We show it to be biphotonic instead, in accordance with thermodynamic considerations, and present a photokinetic model that accurately represents the intensity dependences throughout the whole excitation range in the green (532 nm) and the near UV (355 nm), up to near-quantitative electron release in the latter case. A major artifact deceptively similar to a chemical decay arises from an SDS-related laser-induced turbidity but can be eliminated by difference experiments or careful selection of excitation intensities and temporal windows. The ionization step is not accompanied by side processes, and affords an extremely long-lived (0.35 s) radical cation remaining solubilized. The micelles completely block attacks of hydrated electrons or hydroxyl radicals on the starting material and its radical cation but allow a post-ionization regeneration by high concentrations of the hydrophilic ascorbate monoanion.

3-Aminoperylene and ascorbate in aqueous SDS, one green laser flash and action! Sustainably detoxifying a recalcitrant chloro-organic.

The hydrated electron represents a "super-reductant" in water, providing 2.9 eV of reductive power, which suffices to decompose nonactivated aliphatic halides. We show that 3-amino-perylene in SDS micelles, when combined with the bioavailable ascorbate as an extramicellar sacrificial donor, sustainably produces hydrated electrons through photoredox catalysis with green light, from a metal-free system, and at near-physiological pH. Photoionization of the amine with a 532 nm laser yields an extremely long-lived radical cation as the by-product, and a subsequent reaction of the latter with the sacrificial donor across the micelle/water interface regenerates the catalyst. The regeneration step involves parallel reactions between differently protonated forms, causing a bell-shaped pH dependence in basic medium. We have separated these processes kinetically. Employing this catalytic cycle for the laboratory-scale decomposition of chloroacetate, an accepted model compound for toxic and persistent halo-organic waste, gave turnover numbers of about 170. Even though both the substrate and the sacrificial donor compete for the hydrated electron, their consumption ratio is practically independent of the initial concentration ratio because the formal radical anion of the ascorbate undergoes secondary scavenging by the chloroacetate. In the course of the reaction, the initial hydrophobic catalyst is converted into a secondary species that is hydrophilic and still exhibits catalytic activity.

Combined static and dynamic quenching in micellar systems-closed-form integrated rate laws verified using a versatile probe.

We demonstrate that the 3-aminoperylene radical cation is a near-ideal probe for investigating kinetic and transport processes in SDS micellar systems. Its isolated generation by two-photon ionization at a wavelength where most quenchers are transparent (532 nm) is free from side reactions; no exit from the micelles is detectable on a millisecond timescale; and its unquenched lifetime is as long as 350 ms, thus allowing the study of quenching processes over a time frame spanning at least 7 orders of magnitude. The lipophilic antioxidant ascorbyl palmitate reconverts it to its parent compound through the interplay of static and fast dynamic intramicellar quenching as well as through subsequent slow intermicellar migration. Using this radical-cation probe, we have successfully validated closed-form expressions which we derived for the probe decay in all these situations. From these functions, we also obtained an exact and closed-form analytical result for Stern-Volmer experiments with combined static and dynamic intramicellar quenching.

On the Value of Reptilian Brains to Map the Evolution of the Hippocampal Formation.

Our ability to navigate through the world depends on the function of the hippocampus. This old cortical structure plays a critical role in spatial navigation in mammals and in a variety of processes, including declarative and episodic memory and social behavior. Intense research has revealed much about hippocampal anatomy, physiology, and computation; yet, even intensely studied phenomena such as the shaping of place cell activity or the function of hippocampal firing patterns during sleep remain incompletely understood. Interestingly, while the hippocampus may be a 'higher order' area linked to a complex cortical hierarchy in mammals, it is an old cortical structure in evolutionary terms. The reptilian cortex, structurally much simpler than the mammalian cortex and hippocampus, therefore presents a good alternative model for exploring hippocampal function. Here, we trace common patterns in the evolution of the hippocampus of reptiles and mammals and ask which parts can be profitably compared to understand functional principles. In addition, we describe a selection of the highly diverse repertoire of reptilian behaviors to illustrate the value of a comparative approach towards understanding hippocampal function.

Anatomical Organization and Spatiotemporal Firing Patterns of Layer 3 Neurons in the Rat Medial Entorhinal Cortex.

Layer 3 of the medial entorhinal cortex is a major gateway from the neocortex to the hippocampus. Here we addressed structure-function relationships in medial entorhinal cortex layer 3 by combining anatomical analysis with juxtacellular identification of single neurons in freely behaving rats. Anatomically, layer 3 appears as a relatively homogeneous cell sheet. Dual-retrograde neuronal tracing experiments indicate a large overlap between layer 3 pyramidal populations, which project to ipsilateral hippocampus, and the contralateral medial entorhinal cortex. These cells were intermingled within layer 3, and had similar morphological and intrinsic electrophysiological properties. Dendritic trees of layer 3 neurons largely avoided the calbindin-positive patches in layer 2. Identification of layer 3 neurons during spatial exploration (n = 17) and extracellular recordings (n = 52) pointed to homogeneous spatial discharge patterns. Layer 3 neurons showed only weak spiking theta rhythmicity and sparse head-direction selectivity. A majority of cells (50 of 69) showed no significant spatial modulation. All of the ∼28% of neurons that carried significant amounts of spatial information (19 of 69) discharged in irregular spatial patterns. Thus, layer 3 spatiotemporal firing properties are remarkably different from those of layer 2, where theta rhythmicity is prominent and spatially modulated cells often discharge in grid or border patterns. Significance statement: Neurons within the superficial layers of the medial entorhinal cortex (MEC) often discharge in border, head-direction, and theta-modulated grid patterns. It is still largely unknown how defined discharge patterns relate to cellular diversity in the superficial layers of the MEC. In the present study, we addressed this issue by combining anatomical analysis with juxtacellular identification of single layer 3 neurons in freely behaving rats. We provide evidence that the anatomical organization and spatiotemporal firing properties of layer 3 neurons are remarkably different from those in layer 2. Specifically, most layer 3 neurons discharged in spatially irregular firing patterns, with weak theta-modulation and head-directional selectivity. This work thus poses constraints on the spatiotemporal patterns reaching downstream targets, like the hippocampus.

Postmarketing Analysis of a Novel, Cordless Ultrasonic Dissector.

Introduction Tissue dissection and vessel sealing is performed using a variety of energy sources and surgical devices. We describe the postmarketing analysis of a cordless ultrasonic dissector and vessel sealer in a series of general and gynecological procedures. Methods Patients were prospectively screened and consented for participation. Data collected included demographics, device activations/seals and failures, and patient complications. Surgeons were surveyed following each case. Data was analyzed using standard statistical methods. Results A total of 110 patients were consented and participated in the study. The most frequently performed procedures were bilateral salpingo-oophorectomy (n = 48) and total laparoscopic hysterectomy (n = 36). Mean age was 54.2 years and 79.2% were female. The most frequent number of device activations per case was between 26 and 50 (36.6%). Five failed seals occurred out of 4858 total estimated seals (0.11%). Failed seals were felt to be due to thickened, scarred tissue not amenable to device compression. There were no patient intraoperative complications related to the device itself. Overall, surgeons felt the device was extremely easy to use (97.6%) and no visual obstruction due to steam from the device was encountered (95%). Ninety-five percent of surgeons felt the device was beneficial for soft tissue dissection and vessel sealing. Conclusion Sonicision is safe and effective for use in dissection of soft tissues and vessel sealing in a variety of laparoscopic and open procedures. In this study, there were no complications related to the device itself. The remarkable cordless design of this device enhances its ease of use with overall excellent effectiveness.