A simple electronic unit allowing extracellular recording and stimulation through the same wire hook or suction electrode

A simple and easily constructed unit was designed using a buffer amplifier, a programmable transconductance amplifier and an active filter. The unit allows extracellular recording and stimulation through the same electrode. Thus in experiments where it is required to stimulate a nerve and record the effects of the stimulation from the same nerve, the stimulating and the recording electrodes can be combined in one.     

MEG-compatible force sensor

By use of an insulating material we constructed a strain gauge based sensor to measure isometric forces in parallel with magneto-encephalographic recordings (i.e. without interference). The sensor can be used in different geometries to measure force production in different dimensions. Furthermore, it can easily be adapted or modified for specific experimental applications. Finally, on-line processing of the recorded forces, e.g., for the purpose of feedback, can be realized using standard MEG equipment.     

A simple in vitro technique to measure the release of endogenous dopamine and dihydroxyphenylacetic acid from striatal tissue using high performance liquid chromatography with electrochemical detection

An easily constructed, inexpensive and simple system is described for the superfusion of neural tissue. To characterize the system, the dynamics of endogenous dopamine and dihydroxyphenylacetic acid release from striatal tissue were studied before and after exposure to potassium, amphetamine or cocaine.     

Rat brain slicer. A simple device for rapidly obtaining serial slabs of fresh brain

A simple, two-part device is described which has been used to provide rapid serial sectioning of fresh rat brain in experiments in which identifiable brain regions were microdissected for biochemical analysis. This device is easily constructed at low cost, and offers several advantages over other devices and techniques.     

A simple cannula for intraventricular drug administration in rodents

We describe a new cannula for the intraventricular administration of drugs which is easily and rapidly constructed, is inexpensive and has significant advantages over other cannulas of similar type. The structure of the cannula includes a guiding funnel which greatly facilitates insertion of the injection needle. The cannula also has a locking cap/stylet which is rat-tamper-resistant.     

A simple modular tissue bath developed for 'in vitro' studies of the isolated spinal cord

A tissue bath for studies of the mammalian spinal cord in vitro is described. The modular construction of the bath permits considerable flexibility for accommodating different tissue preparations. The individual components of the bath are easily constructed and the design permits multiple compartment baths to be simply formed. The design principle on which the bath is based may have much wider application than that described.     

Construction of a simple auditory stimulus polarity indicator

A device is described which gives a fast, reliable indication of the onset polarity of transient auditory stimuli. The instrument can be inexpensively constructed and is easily calibrated. It greatly simplifies the task of polarity calibration both in new equipment and in existing equipment after modifications have been made. This device will be of use to research laboratories and clinical departments who are currently recording auditory evoked potentials.     

A vertical flow chamber for Xenopus oocyte electrophysiology and automated drug screening

Xenopus laevis oocytes are used extensively in the study of ion channel coupled receptors. Efficient use of oocytes for ion channel characterization requires a system that is inherently stable, reproducible, minimizes drug volumes, and maximizes oocyte longevity. We have constructed a vertical flow oocyte recording chamber to address the aforesaid issues, where the oocyte is placed in a funnel-shaped chamber and perfused from the bottom of the funnel. The vertical rather than horizontal flow of perfusate results in an unusually stable environment for oocyte recording. Two-electrode voltage clamp recordings from a single oocyte are acquired easily and routinely over several hours while maintaining stable baseline currents and reproducible response profiles. Chamber characteristics were tested using a serotonin ligand-gated ion channel receptor (5-HT3R). Data obtained from this system corresponds well with published data. To further test the stability and reliability of this perfusion chamber, we constructed an automated oocyte perfusion system utilizing a commonly available HPLC autosampler. We were able to obtain dose-response curves for various 5-HT3AR ligands using the automated perfusion system with minimal user intervention. Such a system can easily satisfy need for automated oocyte electrophysiology in academic settings, especially small to medium sized laboratories.     

beta-Galactosidase expressing recombinant pseudorabies virus for light and electron microscopic study of transneuronally labeled CNS neurons.

A beta-galactosidase expression pseudorabies virus (Bartha strain) was constructed, injected into the adrenal gland of rats, and subsequently shown to transneuronally label the CNS autonomic neurons that project to the sympathoadrenal preganglionic neurons. Virally infected neurons were visualized with a one-step histochemical reaction using the Bluo-Gal substrate (halogenated indolyl-beta-D-galactoside) for the localization of beta-galactosidase activity. In some infected neurons, a Golgi-like staining of the primary and sometimes secondary dendrites could be obtained. For electron microscopic studies, the Bluo-Gal substrate produces an electron-dense reaction product that is easily identified at both low and high magnification. This virus may be useful for the study of the cell architecture and synaptic organization of transneuronally labeled neurons of functionally defined neural circuits. These results also demonstrate that it is possible to deliver foreign genes into specific chains of neurons in the mammalian CNS by means of the retrograde transneuronal vial labeling method.     

A head-attachable device for injecting nanoliter volumes of drug solutions into brain sites of freely moving rats

We describe a head-mounted micropump-injection system designed for the infusion of nanoliter volumes of drug solutions into discrete brain regions of the freely moving rats. Using a miniature step motor, the micropump-injection system can be readily constructed from commercially available supplies. In calibrating the micropump-injection system, we found that it will deliver a reliable volume of 50 nl per infusion over a 1-h period, with an infusion given every 1 min. From in vivo testing, we also found that rats readily self-administered up to 100 infusions of D-amphetamine into the nucleus accumbens at regular intervals, suggesting that this system can deliver constant volumes of infusions over time in freely moving rats. It (1) attaches easily to an implanted guide, (2) is compact and durable, (3) weighs only 10 g, and (4) is well tolerated with no apparent discomfort to the animal. This system overcomes some of the weaknesses of currently used intracranial self-administration systems.     

Continuous sampling of cerebrospinal fluid in the conscious rabbit

A cannulation technique for continuous sampling of cerebrospinal fluid (CSF) in unanesthetized freely moving rabbits is described. A permanent stainless steel cannula constructed easily and inexpensively from commercially available material is placed into the third ventricle and fixed to the skull by anchoring screws and dental cement. This procedure allows a continuous CSF sampling with a flow rate of 11.2 +/- 4.5 microliters/min without any sign of disturbing the animal. The penetration of the third ventricle or the periodic drainage of CSF, during a one month period, does not result in a variation of CSF protein (356 +/- 20 mg/l), glucose (4.5 +/- 0.2 mmol/l) or lactate (1.80 +/- 0.05 mmol/l) concentrations. Our technique has some advantages for pharmacological or pharmacokinetic investigations. The third ventricle CSF data will complete that of cisterna magna or lateral ventricle CSF. This method allows studies in the same animal during a period of one month without any problem. Moreover, it lends itself to experiments in which physiological conditions are required.     

A simple nomogram prediction model to identify relatively young patients with mild cognitive impairment who may progress to Alzheimer’s disease

Aim: Construct a clinical predictive model based on easily accessible clinical features and imaging data to identify patients 65 years of age and younger with mild cognitive impairment(MCI) who may progress to Alzheimer’s disease(AD).Methods: From the ADNI database, patients with MCI who were less than or equal to 65 years of age and who had been followed for 6–60 months were selected.We collected demographic data, neuropsychological test scale scores, and structural magnetic images of these patients. Clinical characteristics were then screened, and VBM and SBM analyses were performed using structural nuclear magnetic images to obtain imaging histology characteristics. Finally, predictive models were constructed combining the clinical and imaging histology characteristics.Results: The constructed nomogram has a cross-validated AUC of 0.872 in the training set and 0.867 in the verification set, and the calibration curve fits well.We also provide an online model-based forecasting tool.Conclusion: The model has good performance and uses convenience,it should be able to provide assistance in clinical work to screen relatively young MCI patients who may progress to AD.     

A sleep continuity scale in Alzheimer’s disease: validation and relationship with cognitive and functional deterioration

Considering that disrupted sleep may be detrimental to daytime performance in people with dementia, we set out to construct a questionnaire able to identify sleep patterns potentially associated with clinical and functional disease variables in this population. Two subsets of items indicative of patterns of unstable sleep and of disordered rapid eye movement sleep (REM) were selected. The first included items investigating sleep continuity, with low sleep continuity markers considered indicative of high arousability; the second included items investigating the frequency and quality of dreams and the frequency of clinically identifiable REM sleep behaviour disorder episodes. The questionnaire was administered to 140 outpatients with a diagnosis of mild-to-moderate Alzheimer’s disease. The Mini-Mental State Examination (MMSE), Activities of Daily Living (ADL), Instrumental Activities of Daily Living, Neuropsychiatric Inventory and Clinical Dementia Rating (CDR) were administered to quantify cognitive, functional and behavioural impairment. A subscale comprising items investigating sleep discontinuity/fragmentation and showing high internal consistency was constructed and found to correlate significantly with variables considered indexes of cognitive and functional deterioration in AD (MMSE, ADL and CDR). Conversely, it did not prove possible to obtain a subscale of dysfunctional REM phenomena. The use of a rapidly and easily administered sleep scale, like the one we constructed, appears to be suitable for early identification and longitudinal monitoring of sleep disturbances in AD.     

The Knee Nook

Although the effects of a stroke vary, survivors often have limited use of one side of their body. Stroke survivors may wear an ankle-foot orthosis (AFO) to prevent their weak foot from dragging and hindering ambulation. Because of the added bulk of an AFO, donning a shoe becomes difficult. The design team, composed of freshman engineering students in the Engineering Design and Communication course at Northwestern University, interviewed stroke survivors to understand the problem and then constructed several prototypes as possible solutions. After stroke survivors tested and critiqued each prototype, the Knee Nook emerged as the most promising. Stroke survivors often place their weak foot on top of their strong knee, similar to the position of crossing one's legs, to allow them to easily reach their foot. Keeping the weak leg in place on the strong thigh while donning the AFO is often difficult. The Knee Nook is a hands-free device that holds the user's leg in this position. The device is placed on top of the user's strong knee and employs a neoprene pad to easily hold the weak leg over the strong knee. This design allows stroke survivors to independently don an AFO and shoe.     

Microelectrode tip in five seconds. A new simple, rapid, inexpensive method.

A method using a oxyacetylene torch flame is described; it makes it possible to obtain easily and rapidly, without skill or special equipment, a tungsten micro-electrode tip in a very few seconds.     

Controlling chaos in a chaotic neural network.

The chaotic neural network constructed with chaotic neuron shows the associative memory function, but its memory searching process cannot be stabilized in a stored state because of the chaotic motion of the network. In this paper, a pinning control method focused on the chaotic neural network is proposed. The computer simulation proves that the chaos in the chaotic neural network can be controlled with this method and the states of the network can converge in one of its stored patterns if the control strength and the pinning density are chosen suitable. It is found that in general the threshold of the control strength of a controlled network is smaller at higher pinned density and the chaos of the chaotic neural network can be controlled more easily if the pinning control is added to the variant neurons between the initial pattern and the target pattern.     

Word classes and hemispheric specialization

The effects of noun-class on recognition accuracy in the two visual half-fields are examined. It is found that agentive nouns are more easily recognized than either simple nouns or category-ambiguous (noun/verb) items with RVF presentation, and that both agentive and category-ambiguous nouns are more easily recognized than simple nouns with LVF presentation. This result, which contradicts an earlier hypothesis on the subject, is discussed for the implications it has for a theory of hemispheric specialization.     

A novel superfusion chamber for the measurement of endogenous glutamate release from cerebellar slices

Methods are described for use in the study of potassium-stimulated release of endogenous glutamate and aspartate from perfused cerebellar slices using high performance liquid chromatography (HPLC) with fluorometric detection. Slices were cut at 250 micron in one direction only, and were thus similar to those used for electrophysiological techniques. Details of an easily constructed, simple superfusion system are given. HPLC isocratic separation was used to assay aspartate and glutamate release, glutamate alone showing calcium-dependent release. Repetitive pulses of high potassium-containing artificial cerebrospinal fluid induced release of glutamate (six pulses), demonstrating that the tissue was viable and capable of repeated release.     

Tools for physiology labs: an inexpensive high-performance amplifier and electrode for extracellular recording

The cost of electronic equipment can be a critical barrier to including neurophysiology exercises in biology teaching programs. We describe the construction of a simple and inexpensive AC preamplifier with performance comparable to that of commercial products. The amplifier consists of two integrated circuits in five stages: differential input, fixed gain, variable gain (100 or 1000), low-pass filter (5 or 20 kHz), and 50 or 60 Hz notch filter. We compared our amplifier with two commercial units, the A-M Systems Model 1700 and the Grass P15. The quality of extracellular recording from a typical student preparation (spontaneously active crayfish motor nerve) was the same for all three amplifiers, although our amplifier has slightly higher internal noise than the P15 and slightly lower common-mode rejection than the 1700 and P15. In addition, we describe a simple suction electrode for extracellular nerve recording. It is easily constructed from readily available materials and uses a disposable plastic pipette tip, instead of the traditional glass tip, to contact the nerve. This tip is easily replaced if broken or clogged, and can be adapted to different recording conditions by selecting a different tip size or stretching the plastic. Development of this equipment is part of an ongoing project to promote neuroscience education by expanding the neurophysiology options available to laboratory instructors.     

Kindling Phenomenon: Impairment by Auditory Stimuli

By coupling kindling stimuli with tones, it is shown that kindled epileptiform activity is not easily classically conditioned such that it can be evoked by an auditory stimulus. On the contrary, a tone presented 400 msec before and during the kindling stimulus impedes the rate of kindling.