Expanding neurochemical investigations with multi-modal recording: simultaneous fast-scan cyclic voltammetry, iontophoresis, and patch clamp measurements.

Multi-modal recording describes the simultaneous collection of information across distinct domains. Compared to isolated measurements, such studies can more easily determine relationships between varieties of phenomena. This is useful for neurochemical investigations which examine cellular activity in response to changes in the local chemical environment. In this study, we demonstrate a method to perform simultaneous patch clamp measurements with fast-scan cyclic voltammetry (FSCV) using optically isolated instrumentation. A model circuit simulating concurrent measurements was used to predict the electrical interference between instruments. No significant impact was anticipated between methods, and predictions were largely confirmed experimentally. One exception was due to capacitive coupling of the FSCV potential waveform into the patch clamp amplifier. However, capacitive transients measured in whole-cell current clamp recordings were well below the level of biological signals, which allowed the activity of cells to be easily determined. Next, the activity of medium spiny neurons (MSNs) was examined in the presence of an FSCV electrode to determine how the exogenous potential impacted nearby cells. The activities of both resting and active MSNs were unaffected by the FSCV waveform. Additionally, application of an iontophoretic current, used to locally deliver drugs and other neurochemicals, did not affect neighboring cells. Finally, MSN activity was monitored during iontophoretic delivery of glutamate, an excitatory neurotransmitter. Membrane depolarization and cell firing were observed concurrently with chemical changes around the cell resulting from delivery. In all, we show how combined electrophysiological and electrochemical measurements can relate information between domains and increase the power of neurochemical investigations.

Measuring recovery related outcomes: a psychometric investigation of the recovery markers inventory.

The concept of recovery can be operationalized from either the point of view of the consumer or from the perspective of the provider of services. The Recovery Markers Inventory (RMI) was created to assess recovery-related factors (i.e., actions/events associated with consumer's recovery) from the provider's perspective. Evidence, which established the psychometric properties of the RMI, was obtained through the use of: (a) construct validity (i.e., confirmatory factor analysis and Rasch principal components analysis of residuals); (b) concurrent validity (i.e., the calculation of Pearson correlations between the RMI and other recovery-oriented instruments); and (c) reliability (i.e., Rasch Partial Credit models). Evidence presented in this article shows that the RMI scale is unidimensional, has an adequate level of correlation, and acceptable reliability. The current analysis provides evidence to support the RMI as a valid, reliable measure of recovery-related factors, which can complement consumer based instruments in the assessment of changes in recovery.

A Peltier thermal cycling unit for radiopharmaceutical synthesis.

We have investigated the use of Peltier devices to rapidly cycle the temperature of reaction vessels in a radiopharmaceutical synthesis system. Peltier devices have the advantage that they can be actively cooled as well as heated, allowing precise and rapid control of vessel temperatures. Reaction vessel temperatures of between -6 degrees C and 110 degrees C have been obtained with commercially available devices with reasonable cycle times. Two devices have been used as the basis for a general purpose, two-pot synthesis system for production of [11C] compounds such as raclopride.

Hardware and software for tachistoscopy: how to make accurate measurements on any PC utilizing the Microsoft Windows operating system.

Methods for automated stimulus display and accurate response time measurement with IBM-compatible PCs are of great importance in cognitive research designs. Accurate measurements of reaction times are required to interpolate other measures, such as speed of mental processing. We present a description of hardware and software that displays stimulus images and performs reaction timing that is not dependent on PC performance characteristics. This is accomplished by electronically bypassing timing errors normally inherent to the operation of the computer. A high-precision external timer measures the time between stimulus onset and a subject's push-button response while a video blanking circuit controls the video presented to the monitor screen. Two options for accurately detecting stimulus onset are presented: (1) A photodetector can be used to sense the actual onset of the stimulus on a secondary video monitor screen; (2) the video blanking circuit can provide a signal coincident with the initiation of video to the monitor. Both methods result in a system timing accuracy of 100 microseconds.