Improved low-cost,MR-compatible olfactometer to deliver tobacco smoke odor

We describe a low-cost, MRI-compatible olfactometer that delivers fresh cigarette smoke odor, a challenging odorant to present, as well as other odorants. This new olfactometer retains all of the advantages of an earlier design that was capable of only delivering volatile odors (Lowen & Lukas, Behavior Research Methods, 38, 307–313, 2006). The new system incorporates a novel switching mechanism that allows it to deliver fresh smoke generated from a burning cigarette during a stimulus presentation paradigm that might be employed in a cue-reactivity experiment. An evaluation study established that the olfactometer reliably delivered smoke to the participants and that tobacco smoke was discriminated from other odorants; there were no adverse reactions to the device.     

A computer-controlled vapor-dilution olfactometer

A computer-controlled olfactometer with several innovations leading to closer control over the stimulus parameters and minimization of nonolfactory cues is presented. A microcomputer is used to control the stimulus duration and interstimulus interval. Electronic mass flow con-trollers are employed to maintain close control over the flow in the pure air line and the stimulus-bearing line. Both humidity and temperature are closely regulated. Using a nasal catheter, this stimulus delivery system coupled with velopharyngeal closure and oral breathing permits accurate specification of the quantity of stimulus material actually entering a subject’s nares. The design is such that the computer programming, patch panel interface, and threaded tubing allow versatility in the type of olfactometric study that can be conducted. This system is amenable for threshold, electrophysiological, and sensory adaptation studies of olfaction.     

A simple 5-DoF MR-compatible motion signal measurement system

The purpose of this study was to develop a simple motion measurement system with magnetic resonance (MR) compatibility and safety. The motion measurement system proposed here can measure 5-DoF motion signals without deteriorating the MR images, and it has no effect on the intense and homogeneous main magnetic field, the temporal-gradient magnetic field (which varies rapidly with time), the transceiver radio frequency (RF) coil, and the RF pulse during MR data acquisition. A three-axis accelerometer and a two-axis gyroscope were used to measure 5-DoF motion signals, and Velcro was used to attach a sensor module to a finger or wrist. To minimize the interference between the MR imaging system and the motion measurement system, nonmagnetic materials were used for all electric circuit components in an MR shield room. To remove the effect of RF pulse, an amplifier, modulation circuit, and power supply were located in a shielded case, which was made of copper and aluminum. The motion signal was modulated to an optic signal using pulse width modulation, and the modulated optic signal was transmitted outside the MR shield room using a high-intensity light-emitting diode and an optic cable. The motion signal was recorded on a PC by demodulating the transmitted optic signal into an electric signal. Various kinematic variables, such as angle, acceleration, velocity, and jerk, can be measured or calculated by using the motion measurement system developed here. This system also enables motion tracking by extracting the position information from the motion signals. It was verified that MR images and motion signals could reliably be measured simultaneously.     

Breast milk odor via olfactometer for tube-fed,premature infants

Human newborns use odor cues to orient to their source of nutrition. However, tube-fed, premature infants have restricted chemosensory experience. New methods of introducing breast milk odor to tube-fed premature infants will permit empiric tests of the effect of controlled exposure to nutrient odor. We therefore developed an infant olfactometer and piloted its use in 7 tube-fed, premature infants in the neonatal intensive care unit. Since nonnutritive sucking shortens the amount of time required to wean from tube-feeding, we tested the effect of breast milk odor on nonnutritive sucking. Six out of 7 subjects responded to breast milk odor with an increase in number of sucks. Statistical analysis supported the hypothesis that breast milk odor reinforces nonnutritive sucking. These results indicate the feasibility and potential of this experimental approach, and warrant further study of the effect of controlled nutrient odor exposure on feeding behavior of premature infants.     

A computer-controlled olfactometer for fMRI and electrophysiological studies of olfaction

A design for an inexpensive and reliable olfactometer is presented. The design has several advantages for fMRI and electrophysiology investigators. These advantages include relatively rapid odorant rise times, computer control, multiple odor administration, and no ferrous materials near the subjects. In addition, the device is contamination resistant, and, because the air is neither warmed nor humidified, it is unlikely to become an incubator for bacteria. The olfactometer is constructed of off-the-shelf chromatography parts that require little modification.     

An olfactometer for small rodents

An olfactometer that captures and delivers biological odors at experimenter-controlled times, without dilution, is described. The apparatus is quiet, efficient, versatile, animal-safe, and fairly inexpensive. Tests indicate that the device is successful in isolating transitory odors.     

A low-cost universal feeder

Construction of a universal feeder for a cost of less than $200 is described. The feeder consists of two plywood panels, the first of which is circular and has grooves cut around its margin to hold reinforcers. This circular panel is secured to the second, rectangular panel so that it is free to rotate. A brush fixed onto the axle of a stepper motor above the circular panel sweeps the reinforcers away from the circular panel. Another stepper motor rotates the circular panel after each delivery to prepare the next reinforcer for delivery.     

The construction of a programmable olfactometer

A new type of multichannel olfactometer is described, and the results are given for gas chromatographical standardization of this equipment. The olfactometer keeps 24 odorous substances available for presentation, consecutively, two per trial, or combinations of the two. It produces concentrations of odorous gas in the air between 1 × l0^?5 and 1 × 10^?11 molecules/liter. The principle of construction is gradual dilution of an odorous gas in streaming purified air. The design provides for electronic control of stimulus sequence and response registration via punched tapes.     

A low-cost,low-drain signal generator for time-sampling observation

A battery-powered interval timer is described. The low-cost circuit is detailed.     

A low-cost interactive coordinate plotter

An inexpensive system for on-line coordinate plotting is described. Users with access to a computer running ALGOL or FORTRAN, and equipped with analog-to-digital converters, can build the system for less than $50. The program is readily modified for the individual user’s requirements, and interactive features allow data correction and analysis to be carried out during coordinate plotting, with operators warned of plotting errors as they occur.     

A low-cost integrated circuit comparator system

This paper describes a circuit that allows multiple-unit neural activity to be converted to standardized pulses for computer data acquisition. Positive or negative spikes can be converted at any voltage level from positive 25 V to. negative 25 V with visual identification of exactly where on the amplified spike potential conversion occurs. This circuit provides active output voltages compatible with TTL logic.     

An air dilution olfactometer suitable for group threshold measurements

An apparatus is described by means of which a series of smelling points may be kept independently supplied with constant controlled concentrations of odorous material.     

A low-cost spatial contrast sensitivity display driver

The circuit described here can provide the line and frame signals to drive anx, y display scope or oscilloscope at high resolution (1,000 lines) and repetition rate (50 Hz). Synchronizing circuitry at the input of the circuit allows the raster scan to be locked to an input signal, such as the square-wave output from a function generator, while another waveform from the same function genera-tor, the sine output, drives the z (intensity) input of the display scope. A stable spatial contrast display results. Spatial contrast depth is a direct function of z input modulation voltage. Spatial frequency is a direct function of the function generator frequency. The circuit can be used with a programmable function generator under computer control.     

Measurement of olfactory signal detectability using an air-dilution olfactometer

The Cheesman air dilution olfactometer, although designed for group threshold measurements, was modified to allow individual testing of subjects. However, adaptation effects of olfactory stimuli precluded use of interstimulus intervals of less than 30 sec. so that 3-hr. testing sessions were necessary to obtain a single measurement of sensitivity. Four subjects were tested intensively with isopropyl alcohol (CH3CH(OH)CH3) at concentration levels determined by previous group threshold studies. In the first condition, one concentration only was presented in testing sessions, while in the second condition, six concentrations were presented and the limits of concentrations adjusted to allow subthreshold presentations. Signal detectability indices (dc') were calculated more frequently and more reliably in the second condition than in the first.     

A low-cost, accurate method of producing large quantities of digitally filtered images

We demonstrate how to produce complex image transformations of bitmap files for vision experiments using the Cogimatic Vision Starter Kit (VSK) library of mathematical routines along with Visual Basic, C++, or the Delphi Pascal compiler. Implementing this system on an IBM-compatible PC running Windows 95, 98, or NT4 enables researchers to quickly and economically manipulate images for vision research. The VSK includes a simple stand-alone image-processing application. In addition, VSK has the ability to automate image transformations and to fully integrate image processing into new experimental software on the PC platform.