A simple graphical technique for assessing timer accuracy of computer systems

Timing accuracy is of perennial concern to researchers conducting reaction time studies, especially for those using computers that were not designed with millisecond accuracy in mind. Inaccuracies can manifest themselves in the form of quantization of the continuous time data stream. The method proposed here is simply to inspect the graph of the order statistics because quantization is readily apparent in such graphs. The method is illustrated with timing measurements of keypresses on an IBM PC.     

A simple technique for lateralizing visual input that allows prolonged viewing

A simplified technique is described for obtaining lateralization of visual input with prolonged viewing. This technique is based on the presence of constant normal lateral limits for horizontal rotation of the eyes with reference to the head. With head movement prevented by use of a standard bite bar, and the eyes rotated to the left and held at their lateral limit, the temporal half of the visual field of the left eye may be used for lateralized input to the right hemisphere or vice versa for input to the left hemisphere. Any form of visual stimuli or visually monitored task can be used if confined within one of the extreme temporal hemifields. In comparison to previous methods, this technique is technically simple, inexpensive, without significant risk or discomfort to the subject, readily applicable to normal and various brain-lesioned subjects, and permits prolonged in-depth viewing. An alternative version of this technique uses a stabilized spectacle frame fitted with adjustable central occluders set to allow vision through only one or both of the extreme temporal hemifields.     

A simple technique for correlating film and EMG in locomotion studies

Two recurring problems hampering investigations of muscular activity patterns during locomotion are electrical “noise” and movement artifact in the electromyographic (EMG) signal and proper synchronization of behavioral events to the EMG. A relatively simple technique for achieving these ends is presented. Vigorous locomotor movements of unrestrained animals are recorded on 16-mm film and synchronized with one or more EMGs from selected muscles with little electrical noise or movement artifact interference. The system employs telemetry which is compared to hardwire techniques.     

A simple technique for tracking visual fixations without restricting head movements

A system for tracking visual fixations without restricting head movements is described. Method and circuitry are provided along with the calibration technique.     

A simple technique for delivering liquids directly to the mouth of an unrestrained rat

A simple surgical procedure is described that makes it possible to deliver liquids directly into the mouth of a freely mobile rat. Data presented show that an 8% sucrose solution delivered by this technique is an effective reinforcer in a variety of simple and discriminative schedules of reinforcement.     

A simple histological technique for localizing electrode tracks and lesions within the brain.

Histological procedures are necessary in brain stimulation or lesion work to determine the neural area which has been stimulated or damaged. Preparation of brain tissue often involves embedding and staining techniques that require specialized training, and the expense of a technician and a large assortment of special apparatus and supplies. In addition, the results of such techniques are unavailable for at least several days. A photographic method, which requires little special skill and a minimal amount of apparatus, is described here. Results can be available within minutes after the subject is sacrificed. This method has been shown to be adequate for the gross determination of lesion boundaries and electrode or cannula tip loci in brains of rats, cats, and squirrel monkeys.     

A simple technique for improving the quality of parameter estimates in learning hierarchy validation studies

Learning hierarchy research has been characterized by the use of ad hoc statistical procedures to determine the validity of postulated hierarchical connections. The two most substantial attempts to legitimize the procedure are due to White & Clark and Dayton & Macready, although both of these methods suffer from serious inadequacies. Data from a number of sources is analyzed using a restricted maximum likelihood estimation procedure and the results are compared with those obtained using the method suggested by Dayton and Macready. Improved estimates are evidenced by an increase in the computed value of the log likelihood function.     

Behavioral thermoregulation with microwave radiation of albino rats

The objective of this exploratory study was to investigate the extent to which microwave radiation would reinforce operant behavior in a cold environment. A reversal-design with the single subject serving as its own control was used for testing the reinforcing properties of microwaves. Six albino rats were conditioned to produce 6-sec. pulses of microwave radiation within a refrigerated environment. The schedule of reinforcement was continuous (crf). Each lever press produced a 6-sec. output of microwave radiation. The intensity of radiation was varied across blocks of sessions in the reversal design. Microwave values used were as follows: 62.5 W, 125 W, 250 W, and 437.5 W. Sessions lasted from 8 to 9 hr. over an approximate 7-mo. period. Results showed that rates of operant responding varied as a direct function of microwave intensity. Relatively high mean rates were associated with moderate microwave intensity (250 W), whereas lower mean rates of responding were associated with extreme microwave intensities (62.5 W and 437.5 W) in the reversal design. These data are explained in terms of satiation and deprivation of the reinforcing value of microwave radiation.     

A tailshock-restraint technique for acute induction of gastric lesions in rats

A procedure using tailshock plus body restraint is described for the rapid induction (6 h) of glandular stomach lesions in the rat. In a group of 50 rats, a 92% ulceration rate was achieved.     

Degranulation of brain mast cells in young albino rats

Quantitative measurements were made of brain mast cell (MC) degranulation in juvenile albino rats. Neither acute nor chronic intraperitoneal injections of Compound 48/80 (C 48/80) evoked any clear degranulation. Fifteen to thirty minutes after the injection of either C 48/80 or physiological saline into the right anterior thalamus, frank degranulation in the leptomeninges and some degranulation in the parenchyma were evident. The injected sides contained about twice as much degranulated cells as the noninjected sides. In a second experiment, animals were killed 10, 100, 1000, and 10,000 min after a single 10-microliters injection of C 48/80 into the anterior thalamus. Although about 40% of the leptomeningeal and 20% of the parenchymal MCs were degranulated within 10 min, more than 50% of the MCs in both areas were degranulated within 100 min after the injection. More extensive degranulation was evident at both times within the parenchyma of the injected sides. Degranulated MCs were not obvious after this period although nuclei surrounded by sparse granules (in the parenchyma) or by fused, globular metachromatic material (in the leptomeninges or their ventricular processes) were still discernable 7 days later. The implications of brain mast cell degranulation for psychoneuroimmunology are considered.