An integrated circuit for stepwise or continuous microdrive advancement

A circuit for inexpensive automation of a hydraulic microdrive is described. The circuit uses two integrated timing circuits with output periods defined by resistance-capacitance circuits. The output of this circuit operates a relay that controls a small electric motor that runs the microdrive. This system can operate in either a continuous mode for long-term infusion of solutions or in a stepwise fashion for lowering electrodes. When attached to an appropriate microdrive, the circuit can be employed in experiments in which brain-behavior relationships are investigated within anatomical, pharmacological, or electrophysiological paradigms.     

Modulator and filter circuits for EEG biofeedback

Inexpensive designs for two components of an EEG biofeedback system are described. A two-channel modulator accepts a pair of input signals for modulation of two audio carrier frequencies a musical fifth apart. Carrier suppression is obtained with a simple balanced modulator circuit for each channel. The filter circuit is an integrated circuit adaptation of a successful vacuum tube design reported by other investigators a number of years ago. Various configurations of this equipment for two-channel EEG biofeedback are described.     

A delay timer for presenting auditory and visual probes

A circuit designed to present auditory or visual probes is described. The circuit allows the probes to be delayed by a specified amount of time, and the volume (for auditory probes) or intensity (for visual probes) may also be adjusted. The circuit may be triggered by any device capable of emitting an electronic pulse-such as a computer or a tachistoscope.     

A simple inexpensive computer-controlled tone generator

A simple circuit for a keyed tone generator is described. The total construction cost is less than $5. Various adaptations and modifications of the circuit are discussed.     

Functional neuroimaging studies of reading and reading disability (developmental dyslexia)

Converging evidence from a number of neuroimaging studies, including our own, suggest that fluent word identification in reading is related to the functional integrity of two consolidated left hemisphere (LH) posterior systems: a dorsal (temporo-parietal) circuit and a ventral (occipito-temporal) circuit. This posterior system is functionally disrupted in developmental dyslexia. Reading disabled readers, relative to nonimpaired readers, demonstrate heightened reliance on both inferior frontal and right hemisphere posterior regions, presumably in compensation for the LH posterior difficulties. We propose a neurobiological account suggesting that for normally developing readers the dorsal circuit predominates at first, and is associated with analytic processing necessary for learning to integrate orthographic features with phonological and lexical-semantic features of printed words. The ventral circuit constitutes a fast, late-developing, word identification system which underlies fluent word recognition in skilled readers.     

Converting an electronic calculator into a combination stopwatch-calculator

A method for adding electronic stopwatch capabilities to a calculator is described. An integrated circuit (NE555) is used for a time base. The circuit drives an opto-isolator or light-emitting diode that operates a photocell. The opto-isolator or photocell substitutes for a switch closure to increment the calculator in .10-sec intervals.     

Simplified method based on an intelligent model to obtain the extinction angle of the current for a single-phase half wave controlled rectifier with resistive and inductive load

With the aim of calculating the extinction angle of the current of a single-phase half wave controlled rectifier with resistive and inductive load, present work shows a method to obtain a regression model based on intelligent methods. This type of circuit is a typical non-linear case of study that requires a hard work to solve it by hand. To create the intelligent model, a dataset has been obtained with a computational method for the working range of the circuit. Then, with the dataset, to achieve the final solution, several methods of regression were tested from traditional to intelligent types. The model was verified empirically with electronic circuit software simulation, analytical methods and with a practical implementation. The advantage of the proposed method is its low computational cost. Then, the final solution is very appropriate for applications where high computational requirements are not possible, like low-performance microcontrollers or web applications.     

Conditioning circuits

A circuit of mutually exciting neurones capable of approaching and maintaining a state of permanent excitation has been described by Rashevsky as a possible mechanism for the production of conditioned reflexes. The mode of approach of such a circuit to the steady state is examined in some detail under slightly more general assumptions, and an estimate is made of the order of magnitude of the time required to reach this state.     

Simple circuit for grating contrast adjustment

A multiplication circuit that can facilitate generation of variable-contrast luminance gratings via a microcomputer is described. The circuit is inexpensive and easy to build.     

Electronic windows

A circuit is described which allows the definition of target zones or windows for use in motor coordination experiments. The outputs of the circuit are logic levels and pulses which can be used to automate the experiments.     

An automated open-field apparatus utilizing an improved resistance detection circuit

An open-field apparatus that can be automatically operated is described. Detection of movement is electronic and based upon the fact that the S will complete a circuit path when crossing an open field. The circuit is very sensitive yet quite immune to the usual problem of 60-Hz interference.     

An electronic stimulus randomizer

A circuit is described which enables two stimuli to be presented in random sequence with either equal or different probabilities. The choice of stimuli is determined by sampling the condition of a two-state circuit. Experimental tests of randomness have been satisfactory.     

Integrated circuit measurement of skin conductance

An active skin-conductance measuring device, utilizing integrated circuit operational amplifiers, is described. The transducer offers accurate measurement despite fluctuations in source voltage. The circuit also provides protection in case of accidental short circuit.     

Apparatus noiseless electronic switch and timer

In psychoacoustic testing and experimentation the avoidance of extraneous stimuli is most important, but the elimination of such cues is often difficult. A circuit is described which enables sound stimuli to be switched on and off in a manner which produces no unwanted transient signals. The circuit may be adapted to function as a noiseless changeover switch.     

The silicon-controlled rectifier as an input latch for digital laboratory computer interfaces

Several standard solutions have been developed for problems encountered when monitoring laboratory response sensors with microcomputers. These problems include voltage-level translation, power-supply isolation, contact debouncing, and temporary data storage. Data storage has typically been accomplished through the use of edge-sensitive devices, which introduce difficulties when a researcher wishes to monitor the duration of a response. A circuit is described that includes an optoisolator with a silicon-controlled rectifier at its output stage. The circuit acts as a latch for the detection of brief responses, and, because it is not edge-sensitive, it can also be used to record the duration of sustained responses.     

Low-cost equipment for schedule generation: II. Time-dependent schedules

Complementary metal oxide semiconductor (CMOS) logic provides an efficient and convenient technology for the generation of schedules of reinforcement. A single circuit provides a module capable of use as either a fixed-interval timer or one generating a differential reinforcement of low-rate schedule. A second circuit provides for a programmable variable-interval generator with 16 independent intervals. Both modules are fully compatible with previously described circuits for ratio schedules.     

A deglitching circuit for the AA50 D/A converter

Switching transients or “glitches” are frequently encountered in signal processing applications involving digital-to-analog (D/A) conversion. A low-cost “deglitching” circuit is described and implemented for the Digital Equipment Corporation AA50 D/A converter option on the PDP-8/e minicomputer. Switching transients were eliminated using a noninverting, unity-gain sample-and-hold circuit (employing Datei System’s SHM-IC-1). Switching transients were reduced to below-noise levels across a wide range of output levels and sampling rates.     

A simple infrared photocell device and its interface to an Apple computer

This paper describes a simple infrared photocell circuit that is inexpensive and easy to construct. The light source and detector are housed inexpensively and are focused so the light and detector may be separated over significant distances. The circuit may be used in a variety of conditions, including total darkness and bright fluorescent lighting, without having to readjust or recalibrate the circuitry. Output from the circuit may be used to drive other transistors or electromechanical relays. With minimal additional circuitry and hardware the signal may be interfaced with an Apple computer.     

An inexpensive circuit for beta,alpha, theta,or delta EEG biofeedback

An inexpensive circuit is described for EEG biofeedback or measurement. The circuit is designed to interface easily with most basic EEG machines. It taps the output from a single recording channel of the basic EEG instrument and provides the following for each EEG band (beta, alpha, theta, and delta): (a) very selective bandpass discrimination, (b) variable center frequency, (c) variable threshold at which feedback will be provided, or the measurement made, and (d) use with any biofeedback stimulus or measurement device that one wishes to switch contingent with S’s EEG rhythms.