Dorsal horn projection targets of ON and OFF cells in the rostral ventromedial medulla

1. The rostral ventromedial medulla (RVM) participates in the modulation of nociceptive transmission by spinal cord neurons. Previous anatomic studies have demonstrated that RVM neurons project to laminae I, II, and V of the dorsal horn; laminae VII and VIII of the intermediate and ventral horns; the intermediolateral column; and lamina X. The RVM contains at least three physiologically defined classes of neurons, two of which, the ON and the OFF cells, have been implicated in nociceptive modulation. Because these cells classes are intermingled in the RVM, it has not been possible to determine the spinal laminar projection targets of ON and OFF cells by anatomic methods. Therefore in the current study we employed antidromic microstimulation methods to determine the laminar projections of two of the three classes of RVM neurons, the ON and the OFF cells. 2. In lightly anesthetized (with methohexital sodium) rats, single-unit extracellular recordings were made from 48 RVM neurons that were physiologically characterized as ON (30) or OFF (18) cells. The recording locations of 45 of these neurons were recovered. Thirty-seven were found in the nucleus raphe magnus and eight were located near its dorsal and lateral borders. 3. Thirty-two physiologically identified RVM neurons (18 ON and 14 OFF cells) were antidromically activated from the cervical spinal cord using a monopolar stimulating electrode. The stimulating electrode was moved systematically in the white matter until antidromic activation could be produced with currents of < or = 20 microA (6.1 +/- 0.7 microA, mean +/- SE). The points from which minimum currents were required to antidromically activate the neurons were located mainly in the ipsilateral dorsolateral funiculus (DLF) (27 of 32). In a few cases, lowest antidromic threshold currents were found near the border between the DLF and ventrolateral funiculus (VLF) or, rarely, in the VLF itself. In these cases, the cell recordings were found to be near the dorsal boundary of the RVM. 4. While one electrode was used to stimulate the parent axon in the lateral funiculus, a second was used to explore the gray matter for the presence of collateral branches. The identification of a branch was initially determined by an increase in antidromic latency. At the same rostrocaudal plane of the spinal cord, stimulation of the DLF induced an antidromic spike that invaded the neuron earlier than the antidromic spike elicited by stimulation in the gray matter. Collateral branches were confirmed by establishing that the location of the minimum threshold point for antidromic activation of the neurons from the second electrode was in the gray matter, that the minimum current required to antidromically activate the neuron from that point was too low to activate the parent axon in the DLF, and that a collision occurred between the spikes induced by the two stimulating electrodes. 5. In 17 cases, physiologically identified RVM neurons (10 ON and 7 OFF cells) were antidromically activated from the gray matter of the cervical spinal cord using a current of 8.4 +/- 2.1 (SE) microA. Minimum threshold points for antidromic activation were found in laminae I-II (3 ON and 4 OFF cells), lamina V (5 ON and 6 OFF cells), and regions ventral to the lateral reticulated area (3 ON and 2 OFF cells) of the gray matter. As indicated by these numbers, some neurons were antidromically activated from more than one gray matter region. In general, all OFF cells and 9 of 10 ON cells were antidromically activated from low threshold points in either laminae I-II or lamina V. 6. In six cases, neurons were activated from separate points located in two or three different laminae of the gray matter. Three OFF cells were activated from laminae I-II and V, one OFF cell and one ON cell were activated from lamina V and from more ventral points, and one ON cell was activated from laminae I-II and from points ventral to lamina V.     

Impaired priming on the general knowledge task in amnesia.

The status of priming on the general knowledge test was examined in amnesia. Twenty amnesic and 20 control participants studied words (e.g., CHEETAH) under semantic and nonsemantic encoding conditions and attempted to answer general knowledge questions (e.g., "What is the fastest animal on earth"?) under implicit and explicit retrieval instructions. The measure of memory was how many more test questions participants answered correctly using studied than nonstudied words. Amnesic patients showed impaired memory under implicit and explicit retrieval instructions. Control participants showed equal memory under implicit and explicit retrieval instructions, a result indicating that they engaged in explicit retrieval in both instruction conditions. General-knowledge priming appears to involve explicit retrieval that depends on medial-temporal and diencephalic regions damaged in amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simple and economical culture of Campylobacter jejuni and Campylobacter coli in CO2 in moist air.

Strains of Campylobacter jejuni and C. coli representing the 18 serogroups (Lior) most commonly isolated from humans in Canada were grown on solid media in an atmosphere of 10% CO2 in moist air, 99% relative humidity. When the growth of all 18 serogroups on Mueller Hinton agar in a microaerobic atmosphere (5% O2, 10% CO2 and 85% N2) was compared with the growth of all 18 serogroups on the same media in 10% CO2 in moist air, colony sizes were significantly larger (p less than 0.05) for strains grown in 10% CO2 in moist air. No significant difference in colony numbers was seen between the two atmospheres. The addition of blood to the media significantly enhanced the growth of the campylobacters in both types of atmospheres (p less than 0.05). This simple CO2 atmosphere permitted the use of a common CO2 incubator thereby reducing the cost and difficulty of culturing these organisms.     

Heterocyclic modification of chitosan for the adsorption of Cu (II) and Cr (VI) ions

A heterocyclic modification of chitosan has been attempted for development of an effective adsorbent material for removal of metal ions. The modified polymer was characterized using infrared (IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) techniques. The adsorption capacity exhibited for Cu (II) and Cr (VI) were 83.75 and 85.0 mgg^?1, respectively, which is a significant improvement over chitosan. The adsorption on the modified polymer was a second-order kinetic process and followed Langmuir isotherm model. The thermodynamic analysis indicated exothermic and spontaneous nature of adsorption. About 80% of the adsorbed metal ions were desorbed in appropriate stripping solutions indicating reusability.     

Low power analog comb filter for biomedical applications

An analog topology is proposed to implement a comb filter for removal of power-line interference from various low-amplitude biomedical signals. In this proposed methodology, an n-number of all-pass filters (APFs) and an adder circuit are used to suppress n-number of frequencies. All the APFs as well as the adder circuit are designed using a current conveyor to utilize the various properties of the current-mode circuits. The active and passive components used to design the comb filter include second-generation current conveyor (CCII±), resistor, and capacitor. The circuit is designed for n?=?4 to remove the power-line frequency of 50 Hz, and its three odd harmonics such as 150 Hz, 250 Hz, and 350 Hz. A PSPICE simulation is done to verify the performance of the proposed circuit. In simulation, all CCII±?are designed using macro model of commercially-available current feedback operational amplifier integrated circuit (IC) AD844 as well as dynamic threshold voltage metal oxide semiconductor technology. The proposed circuit is also implemented also using commercially available IC AD844 on breadboard for n?=?3. The output result on digital storage oscilloscope confirm the effectiveness of the proposed comb filter circuit in removing the power line interference i.e. the power-line frequency and its odd harmonics.     

Nth order voltage-mode universal filter employing only plus type differential difference current conveyor

Analog Integrated Circuits and Signal Processing - A general topology for realizing nth order voltage-mode universal filter responses with multiple-input and single-output using only plus type...     

Vulnerability assessment of a power transmission network employing complex network theory in a resilience framework

Microsystem Technologies - The functionality of electric power network are continuously challenged by dynamic and diverse disruptions. The vulnerability analysis in the context of resiliency, using...     

Fin shape influence on analog and RF performance of junctionless accumulation-mode bulk FinFETs

Microsystem Technologies - The non-planar 3D structure of multi-gate FinFETs makes them able to be scaled down to 20&nbsp;nm and beyond and also have greater performance. But any variation of...     

Lower Bounds for Depth-Three Arithmetic Circuits with small bottom fanin

Shpilka & Wigderson (IEEE conference on computational complexity, vol 87, 1999) had posed the problem of proving exponential lower bounds for (nonhomogeneous) depth-three arithmetic circuits with bounded bottom fanin over a field \({{\mathbb{F}}}\) of characteristic zero. We resolve this problem by proving a \({N^{\Omega(\frac{d}{\tau})}}\) lower bound for (nonhomogeneous) depth-three arithmetic circuits with bottom fanin at most \({\tau}\) computing an explicit \({N}\)-variate polynomial of degree \({d}\) over \({{\mathbb{F}}}\). Meanwhile, Nisan & Wigderson (Comp Complex 6(3):217–234, 1997) had posed the problem of proving super-polynomial lower bounds for homogeneous depth-five arithmetic circuits. Over fields of characteristic zero, we show a lower bound of \({N^{\Omega(\sqrt{d})}}\) for homogeneous depth-five circuits (resp. also for depth-three circuits) with bottom fanin at most \({N^{\mu}}\), for any fixed \({\mu < 1}\). This resolves the problem posed by Nisan and Wigderson only partially because of the added restriction on the bottom fanin (a general homogeneous depth-five circuit has bottom fanin at most \({N}\)).