A self-contained,regulated, burst-firing constant-current ac shock generator

A line- and load-regulated constant-current ac shock generator has been designed for animal behavior experiments. The self-contained unit has four operating modes, amplitude adjustment, and a leakage current detection circuit. A unique feature of this generator is that the good load regulation achieved by using a high-voltage source is preserved without such problems as arcing and high current density effects. Circuit schematics, along with a discussion of selected circuits, are included. Experimental data are presented to demonstrate the utility of the device.     

A cable-swivel device for delivering shock to tail or harness electrodes

An inexpensive cable-swivel device for delivering shock to tail or harness electrodes is described.     

A system for providing tactile EMG biofeedback

This report describes a flexible and inexpensive biofeedback system for providing discrete pulses against the skin surface at a frequency proportional to the level of activity from selected muscle groups. The primary components consist of a voltage controlled pulse generator and a tactile transducer. Other system capabilities include the production of digital information for recording devices and the providing of pulsed auditory EMG biofeedback. The system may be particularly applicable for the experimental reduction of psychological and muscle tension.     

A parallel printer port to matrix driver with high current DAC output

The circuit described here takes data from an IBM PC, or a compatible, parallel printer port and expands it to drive a matrix of devices. The matrix size is user definable up to a maximum size of 16 by 16 elements (256 elements), but as drawn is an 8 by 24 matrix (196 elements). Each element in the matrix can be inductive, resistive, or capacitive, with a maximum voltage of about 18 volts, and a total maximum current of 15 amps peak, or 8 amps continuous with adequate heat sinks (dissipating 80 watts maximum per driver device). Several matrix elements may be asserted simultaneously. The voltage applied across the matrix “rails” is controlled by a digital-to-analog converter with 4096 steps (12-bit accuracy).     

A direct method for multidimensional ratio scaling

A generalization of direct ratio scaling methods to multidimensional ratio scaling is described. This method requires an observer to report the proportion of a standard percept that is contained in a given percept and vice versa. The method was developed to meet requirements for experimentation in such areas as color vision, gustation, and olfaction.This investigation was supported by research grants from the Swedish Medical Research Council and the Wallenberg Foundation. The experimental work was carried out by Mr. G. Kylén.     

Transcranial direct current stimulation versus intermittent theta-burst stimulation for the improvement of working memory performance

Non-invasive brain stimulation (NIBS) techniques have been increasingly used over the dorsolateral prefrontal cortex (DLPFC) to enhance working memory (WM) performance. Notwithstanding, NIBS protocols have shown either small or inconclusive cognitive effects on healthy and neuropsychiatric samples. Therefore, we assessed working memory performance and safety of transcranial direct current stimulation (tDCS), intermittent theta-burst stimulation (iTBS), and both therapies combined vs placebo over the neuronavigated left DLPFC of healthy participants. Twenty-four subjects were included to randomly undergo four sessions of NIBS, once a week: tDCS alone, iTBS alone, combined interventions and placebo. The 2-back task and an adverse effect scale were applied after each NIBS session. Results revealed a significantly faster response for iTBS (b= -21.49, p= 0.04), but not for tDCS and for the interaction tDCS vs. iTBS (b= 13.67, p= 0.26 and b= 40.5, p= 0.20, respectively). No changes were observed for accuracy and no serious adverse effects were found among protocols. Although tolerable, an absence of synergistic effects for the combined protocol was seen. Nonetheless, future trials accessing different outcomes for the combined protocols, as well as studies investigating iTBS over the left DLPFC for cognition and exploring sources of variability for tDCS are encouraged.     

Resistance to continuous delay of reinforcement or extinction following partial delay or partial reinforcement in acquisition: A direct comparison

Rats received either partial reward (PR) or partial delay (PD) in acquisition with one, two, or three delay or nonreward trials followed by an immediately rewarded trial or one delay or nonreward trial followed by an immediately rewarded trial. These four groups were then split in half and given either continuous delay or continuous nonreward (extinction) in a “response persistence” phase. In addition, two continuously reinforced groups, one experiencing continuous delay, and the other experiencing extinction were included. The results showed that response persistence was greater when PD groups were given continuous delay rather than extinction, but the opposite was true for PR groups. The “length” (1, 2, or 3 versus 1 nonreward or delay trial) also transferred to the response persistence phase with the length 1, 2, and 3 conditions being more persistent than the 1 length conditions. The results were discussed with respect to theoretical notions of response persistence.     

A comparison of two methods of assessing representation-mediated food aversions based on shock or illness

In experiments that measured food consumption, Holland (1981; Learning and Motivation, 12, 1-18) found that food aversions were formed when an exteroceptive associate of food was paired with illness, but not when such an associate was paired with shock. By contrast, measuring the ability of food to reinforce instrumental responding, Ward-Robinson and Hall (1999; Quarterly Journal of Experimental Psychology, 52B, 335-350) found that pairing an associatively activated representation of food with shock readily established an aversion to that food. Two experiments considered the origins of these apparently discrepant results. The results did not support either the possibility that instrumental reinforcement power is a more sensitive measure of aversion learning than consumption, or the hypothesis that illness particularly devalues properties of food representations that determine consumption (such as palatability) whereas shock devalues more general properties critical to reinforcement. The results suggested instead that whereas the effects of pairings of a food associate with illness are mediated by changes in the value of the food itself, the effects of pairings with shock are mediated by the conditioning of fear or other competing responses to the site of food delivery, and not by modification of the value of food itself.     

The effect of bicephalic stimulation of the dorsolateral prefrontal cortex on the attentional bias for threat: A transcranial direct current stimulation study

Previous stimulation studies demonstrated that the dorsolateral prefrontal cortex (DLPFC) is involved in threat processing. According to a model of emotional processing, an unbalance between the two DLPFCs, with a hyperactivation of right frontal areas, is involved in the processing of negative emotions and genesis of anxiety. In the present study, we investigated the role of the right and left DLPFC in threat processing in healthy women who also completed the State-Trait Anxiety Inventory (STAI). We simultaneously modulated the activity of the right and left dorsolateral prefrontal cortex by applying bicephalic transcranial direct current stimulation (tDCS) before participants completed a modified version of the classic Posner task using threatening and nonthreatening stimuli as spatial cues. Anodal stimulation on the right DLPFC with a simultaneous cathodal stimulation over the left side induced a disengagement bias in individuals with low STAI scores and a facilitation bias in individuals with high STAI scores. Anodal stimulation on the left DLPFC with the simultaneous cathodal stimulation over the right side did not affect threat processing. The findings of the present study provided specific support to the hypothesis that unbalanced activation between left and right hemispheres with enhanced activation of the right DLPFC is critical in early top-down threat processing in healthy individuals.     

Rape myth acceptance: A case for providing educational expert testimony in rape jury trials

The prevalence and content of rape myth acceptance indicate a need for educational expert testimony in rape jury trials. It is proposed that expert testimony regarding common misconceptions about rape and rape victim behavior, conceptualized in terms of a social framework, would help to compensate for societal bias against the complainant in a rape trial. Rape trauma syndrome, eyewitness identification, and general educational testimony concerning rape are discussed. Evidence is presented that suggests inclusion of such testimony serves the purpose of expert testimony according to the Federal Rules of Evidence.     

A new device for the application of electrical shock

A new apparatus has been developed for the simple, safe, and effective delivery of electric shock. It delivers a single-pulse high-voltage shock of very short duration. Both voltage and current are easily measured and the applied energy can be calculated. Constant energy applications depend less upon skin contact resistance than is the case with 600-V 60-Hz shockers.