Test-taking behaviors by hypertensive and normotensive individuals

Systematic ratings were made on the Tulane Test-Behavior Scale of the global and integrated behaviors observable for hypertensive and normotensive subjects as they worked to complete a battery of neuropsychological tests--the degree of attention and effort displayed, for example, self-confidence and self-criticism. The results for 82 subjects (41 subject pairs matched for age, race, and education) revealed substantial and consistent differences between groups. Early, mild hypertensive subjects (unmedicated) displayed significantly less optimal behaviors than did normotensive controls. These may be best understood as subtle functional consequences of the abnormal physiological state imposed on the brain by a chronically elevated blood pressure, just as the functional disruptions of reduced kidney filtration fraction or minor abnormalities of the electrocardiogram appear early in the course of the disorder for other target organs. Certain testable implications of this hypothesis are discussed.     

Adult blood pressure reduction in spontaneously hypertensive rats reared by normotensive Sprague-Dawley mothers.

Spontaneously hypertensive (SHR), Wistar-Kyoto (WKY) normotensive, and Sprague-Dawley (SD) normotensive rats were either reared by their natural mothers (controls) or fostered to a mother of one of the other strains. The effects of rearing environment were assessed by measures of body weight at weaning and adult resting mean arterial blood pressure (MAP) and heart rate (HR). At weaning, SHR control rats weighed less than WKY controls which in turn weighed less than SD controls. SHR and WKY rats reared by SD mothers weighed significantly more than their respective controls, whereas SD rats reared by either SHR or WKY mothers weighed less than SD control rats. Manipulation of the maternal environment was attended by a change in adult resting MAP in only one group. SHR rats reared by SD mothers had MAPs which were significantly lower than SHRs reared by their natural mothers. No within-strain adult HR differences were observed between control and cross-fostered groups. These data indicate that the effects of cross-fostering on adult resting MAP previously reported for SHR and WKY animals are generalizable to another normotensive strain. That is, genetically hypertensive (SHR) animals exposed to a normotensive (WKY or SD) maternal environment display a reduction in adult resting MAP, whereas hypertension or an increase in adult MAP is not induced in normotensive rats (WKY or SD) as a consequence of exposure to a hypertensive maternal environment.     

Exploration, fear and maze learning in spontaneously hypertensive and normotensive rats

In this study the performance of normotensive (WKY) rats was compared with that of hypertensive (SHR) rats on a Novel Object Test, a standardized Fear Test, and the Hebb-William's maze. We found no strain differences for exploration; however, WKY rear and ambulate more than SHR near the walls of the apparatus. There were no strain differences apparent in the Fear Test. WKY showed markedly different behavior compared with SHR on the Hebb-William's maze; WKY showed a high level of stereotyped displacement behaviors and failed to improve their performance over successive trials. Overall, WKY appear to be more reactive to environmental conditions than SHR. The behavior of both strains is highly context dependent.     

Open-field behavior in two models of genetic hypertension and the behavioral effects of salt excess

In order to assess the relationship of behavior to blood pressure and salt intake, open-field behavior was studied in 123 rats of the spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), Sprague-Dawley (SD), and Dahl resistant (DR) and sensitive (DS) strains. DS rats become hypertensive upon exposure to either high dietary salt or psychogenic stress, while DR rats remain normotensive. A circular photobeam open field was used under full room illumination. Three 5-min trials were given on consecutive days. Rats were tested with or without 5 days of an 8% NaCl diet. We found that DS rats were less active than DR rats, regardless of diet. In contrast, SHR rats were more active than WKY rats. However, DS and SHR rats were equally active. Thus, behavioral differences between these two models of hypertension are expressed by the normotensive control strains. The relative ranking of activity levels between strains was DR = SD greater than SHR = DS greater than WKY. High-salt-enhanced intertrial habituation, defined as the decrease in activity across trials (DS, 100%; SD, 82%; SHR, 90%; WKY, 1350%; but DR, -50%) as well as intratrial habituation, defined as the decrease from the first to the second half of the trial (14%, all subjects). Defecation was increased with high salt (DS, 975%; SD, 59%; SHR, 267%; WKY, 89%; but DR, 40%). These effects of high salt may reflect an increase in an emotionality factor. DR rats were largely resistant to the behavioral effects of salt. Total activity was positively correlated with blood pressure in hypertensive rats, r(42) = 0.33, p less than .01, but negatively correlated in normotensive rats, r(81) = -0.34, p less than .01. The proportion of total activity occurring in the first half of the trial for the initial test day was correlated with blood pressure in normotensive rats r(81) = 0.44, p less than .01. Dietary salt excess has behavioral as well as cardiovascular consequences.     

Stress ulcer and open-field behavior of spontaneously hypertensive,normotensive, and Wistar rats

Spontaneously hypertensive rats (SHRs) and the normotensive Wistar/Kyoto (WKY) rat were observed, along with Wistar rats (which represent the parent strain), on various open-field behaviors. All three strains were subsequently exposed to the activity-stress (A-S) ulcerogenic procedure. SHR and Wistar rats were very active in most open-field measures as compared with WKY rats, but only SHRs were active during the A-S treatment. WKY rats were very ulcer prone and had significantly more ulcers than SHRs, which in turn had more ulcers than Wistar rats. It was anticipated that Wistar rats would resemble the WKY rats, but in most measures the Wistars resembled the SHRs. The study suggests that although WKY rats function as an appropriate control for hypertension studies, these rats may be inappropriate as controls for other physiological and behavioral studies.     

Inbreeding of Wistar-Kyoto rat strain with hyperactivity but without hypertension

A genetic inbreeding program using Wistar-Kyoto rat strains as progenitors was used to combine the hyperactivity trait of the spontaneously hypertensive rat (SHR) with the normotensive trait of the WKY genetic control strain. From an SHR X WKY cross we produced a gene-assorting F2 population from which selected brother-sister matings were carried out through seven successive inbred populations. This program produced a new strain of hyperactive rats with normotensive mean systolic blood pressure levels, and we have designated the new strain as the Wistar-Kyoto hyperactive (WK/HA) rat. Another behavioral characteristic of the SHR rat, poor habituation in a nonreinforcing novel environment, did not appear as a characteristic trait of the new strain of WK/HA rats, suggesting a separate underlying genetic basis for the two traits that had been apparently fortuitously fixed in the SHR genotype as a result of intensive inbreeding of that strain. The new WK/HA strain, together with the WKY control strain, is considered as more suitable for subjects in studying hyperactivity in rats than the original SHR strain with its concomitant hypertension and poor habituation traits.     

Auditory startle in normotensive and hypertensive rats

In the present experiment auditory startle was examined in male and female rats of the spontaneously hypertensive (SHR) and Wistar-Kyoto normotensive (WKY) strains and borderline hypertensive rats (BHR) derived from cross-breeding SHR females with WKY males. The magnitude of auditory startle declined over trials and was significantly higher in WKYs than in both SHRs and BHRs which did not differ from each other. These data add to an increasing body of literature concerning behavioral differences between hypertensive and normotensive rats and are discussed as they relate to the possible strain differences in either behavioral reactivity or tonic fear.     

Emotional inhibition in essential hypertension: obstacle to communication during medical visits?

A substantial literature on the "hypertensive personality" links essential hypertension (EH) with the suppression of negative emotions, implying that suppression may elevate blood pressure. Yet affective inhibition might also impair communication with health care providers and exacerbate EH by limiting therapeutic collaboration. We studied 542 patient-physician interviews from a national sample to see if patients with EH (n = 203) were less likely to exhibit negative emotions than normotensive patients (n = 339) as rated by their physicians and independent observers. EH patients did not differ from others on self-rated emotional or physical health. However, physicians were less accurate in characterizing the emotional states of EH patients than those of normotensive patients, and they rated EH patients as exhibiting fewer signs of distress during the visit. Independent observers also judged the EH patients as less distressed than normotensives, thereby validating the physicians' appraisals. Content analysis disclosed that physicians paid less attention to psychosocial concerns and concentrated on biomedical matters to a greater degree with hypertensive patients than with their normotensive patients. EH patients, particularly those experiencing emotional distress, appear to have patterns of self-presentation that could present an obstacle to effective communication with their physicians, and this difficulty may be amplified by physicians' disinclination to probe for emotional difficulty.     

The influence of different therapists on functional analysis outcomes

Recently, researchers have demonstrated that certain antecedent variables can affect the results of a functional analysis. The purpose of the current study was to evaluate the effects of family members versus a direct‐care staff member on the occurrence of problem behaviors during three concurrently conducted functional analyses. The results of the functional analyses demonstrated that the participant's problem behaviors were maintained by positive reinforcement (i.e. access to tangible items) and negative reinforcement (i.e. escape from demands) when either his mother or stepfather was the therapist in the functional analysis; however, no problem behaviors were displayed when a direct‐care staff member was the therapist in the functional analysis. Copyright © 2004 John Wiley & Sons, Ltd.     

Behavioral hyperreactivity in the spontaneously hypertensive rat compared to its normotensive progenitor

The spontaneously hypertensive rat (SHR) is an excellent model of essential hypertensive disease. Hyperreactivity has been postulated as a contributing factor in the development of high blood pressure in the SHR and in man. In the maturing organism recurring hypertensive stress responses may promote permanent vascular changes and result in a fixed hypertension. Simple behavioral activity and emotionality rating scales were used to compare a large number of SHR with equally large groups of closely-related and distantly-related normotensive rats. As predicted, the SHR were clearly more active and emotional than their ancestral Wistar Kyoto (WKY) strain. However, the distantly-related normotensive Wistars did not differ from the SHR in either activity or emotionality. These results indicate that behavior and hypertension are not necessarily related in the rat. Nonetheless, the behavioral differences between the SHR and their closest genetic match, the WKY, suggest that arousal and blood pressure levels may be causally linked in this case of naturally occurring hypertension.     

Use of peer-mediated intervention in children with attention deficit hyperactivity disorder

The present experiment extended and replicated the use of functional analysis and a peer-mediated intervention to decrease disruptive behavior displayed by children diagnosed with attention deficit hyperactivity disorder in an afterschool program. After determining that the participants displayed off-task behavior maintained by peer attention via a functional analysis, peer-implemented differential reinforcement of other behavior with extinction was effective in reducing participants' off-task behaviors. The use of peers as behavior-change agents is discussed, as are avenues for future research.     

Independence of blood pressure and locomotor hyperactivity in normotensive and genetically hypertensive rat

The spontaneously hypertensive rat (SHR) exhibits locomotor hyperactivity in comparison to its normotensive progenitor Wistar-Kyoto (WKY) strain. We asked whether the hyperactive behavior was a direct consequence of elevated blood pressure in the hypertensive rat. Three experimental protocols were used to chronically alter blood pressure. In the first protocol, a group of adult SHRs was given hydralazine (20 mg/kg/day) in their drinking water to lower blood pressure. These animals exhibited a significant decrease in blood pressure, but no change in locomotor activity. In the second protocol, young SHRs (4 weeks of age) were treated with the same dosage of hydralazine until 16 weeks of age. Blood pressure was significantly decreased in these animals with no change in locomotor activity. In the third protocol, normotensive WKY and Sprague-Dawley (SD) rats were made hypertensive with unilateral renal clips. The resulting increase in blood pressure in these animals did not alter locomotor activity. These results suggest that locomotor hyperactivity is an inherent property of the SHR and is independent of blood pressure.     

COGNITIVE AND MOTIVATIONAL INFLUENCES ON SPONTANEOUS COMFORTING BEHAVIOR

Most previous research concerned with comforting communication skills has studied comforting by having subjects respond to hypothetical situations. A major goal of the present study was to examine the relation of several cognitive and motivational variables to the comforting behaviors displayed by persons in a “real world” situation. Subjects (73 female college students) interacted with a female confederate who appeared to be emotionally distressed about having been left by her boyfriend. These interactions were covertly videotaped and content analyzed. Measures of interpersonal construct differentiation, emotional empathy, communication apprehension, and locus of control orientation were also obtained. As expected, interpersonal construct differentiation was positively related to qualitative features of the comforting behaviors exhibited by subjects. Also as expected, highly apprehensive subjects tended to avoid interacting with the distressed confederate and engaged in relatively little comforting behavior. Emotional empathy and locus of control orientation were unrelated to the comforting behaviors of subjects. These results are discussed in terms of a general model of comforting behavior.     

The borderline hypertensive rat: a model for studying the mechanisms of environmentally induced hypertension

The borderline hypertensive rat (BHR) is a first-generation cross between the spontaneously hypertensive rat and the normotensive Wistar-Kyoto rat. The BHR develops frank hypertension when chronically stressed or when fed a high-sodium diet. Stress-induced hypertension can be blocked by exercise. The role of the central nervous system and kidney in hypertension development in this model is discussed.     

Lifelong hyperarousal in the spontaneously hypertensive rat indicated by operant behavior

Instrumental conditioning techniques were used to obtain objective evidence of differences in behavioral arousal between the spontaneously hypertensive rat (SHR) and the normotensive ancestral Wistar Kyoto (WKY) strain. Subjective emotionality ratings previously indicated that the genetically hypertensive rats were more active and aggressive than their normotensive cousins. In a lengthy series of operant conditioning sessions using a small number of adult female SHR and WKY rats, hyperarousal in the SHR was confirmed by their significantly higher response outputs on either response contingent or time contingent schedules of reinforcement. Conditioned emotionality tests during this series of experiments also suggested hyperarousal and aggressiveness in the SHR, since the fear-conditioned stimulus suppressed bar-pressing in the SHR much less than in the WKY. Further experiments with young prehypertensive SHR rats provided the same evidence of hyperresponsivity in the SHR compared to the WKY strain. Furthermore, these young SHR failed to develop hypertension by the end of the study (14 weeks of age), while their nonconditioned SHR cousins had become clearly hypertensive by the same age. This suggests that factors related to the conditioning methods modified the development of high blood pressure in this animal model of essential hypertension.     

FURTHER ANALYSIS OF PROBLEM BEHAVIOR IN RESPONSE CLASS HIERARCHIES

A functional analysis identified the reinforcers for 3 participants' problem behavior, but only relatively mild problem behaviors (e.g., screaming, disruption) were observed when all topographies produced tested consequences. We then conducted an extinction analysis in which specific topographies produced a reinforcer while all other topographies were on extinction. The extinction analysis confirmed that the same reinforcer identified in the initial functional analysis maintained more severe topographies of problem behavior (e.g., aggression). In addition, results of the extinction analysis indicated that 2 of the participants displayed patterns of responding consistent with a response class hierarchy hypothesis, in which less severe problem behavior frequently occurred prior to more severe topographies. The 3rd participant displayed a response pattern indicative of differential reinforcement effects.     

Intelligence is differentially related to neural effort in the task-positive and the task-negative brain network

Previous studies on individual differences in intelligence and brain activation during cognitive processing focused on brain regions where activation increases with task demands (task-positive network, TPN). Our study additionally considers brain regions where activation decreases with task demands (task-negative network, TNN) and compares effects of intelligence on neural effort in the TPN and the TNN. In a sample of 52 healthy subjects, functional magnetic resonance imaging was used to determine changes in neural effort associated with the processing of a working memory task. The task comprised three conditions of increasing difficulty: (a) maintenance, (b) manipulation, and (c) updating of a four-letter memory set. Neural effort was defined as signal increase in the TPN and signal decrease in the TNN, respectively. In both functional networks, TPN and TNN, neural effort increased with task difficulty. However, intelligence, as assessed with Raven's Matrices, was differentially associated with neural effort in the TPN and TNN. In the TPN, we observed a positive association, while we observed a negative association in the TNN. In terms of neural efficiency (i.e., task performance in relation to neural effort expended on task processing), more intelligent subjects (as compared to less intelligent subjects) displayed lower neural efficiency in the TPN, while they displayed higher neural efficiency in the TNN. The results illustrate the importance of differentiating between TPN and TNN when interpreting correlations between intelligence and fMRI measures of brain activation. Importantly, this implies the risk of misinterpreting whole brain correlations when ignoring the functional differences between TPN and TNN.     

The borderline hypertensive rat (BHR): A new model for the study of environmental factors in the development of hypertension

While many studies have attempted to produce hypertension through the use of various environmental Stressors, few have succeeded in producing chronic elevations in blood pressure beyond levels considered to be borderline hypertensive (140–160 mm Hg systolic). The problem with most studies stems from the use of genetically normotensive animals and the selection of Stressors to which animals readily adapt. A new approach is suggested, which recognizes the role of genetics in human essential hypertension. Animals with one hypertensive parent do not develop spontaneous hypertension but show a more sensitive cardiovascular response to environmental Stressors than animals with normotensive parents. Preliminary studies revealed that animals with a mixed genetic history of hypertension develop spontaneous borderline hypertension. When subjected to shock-shock conflict, these borderline hypertensive rats (BHR) developed permanent hypertension that failed to abate even after a ten-week, shock-free recovery period. The hypertension was accompanied by elevated heart weight to body weight ratios and by significant cardiac pathology. Subsequent work has demonstrated that these animals also become hypertensive when fed a high-sodium diet. Finally, in a series of exercise studies, we found that BHRs subjected to a shock stressor were protected against stress-induced hypertension if they exercised daily. The potential of this model for studies of the mechanisms by which environmental variables produce permanent hypertension is discussed.     

THE FUNCTIONAL RELATIONSHIP BETWEEN ARTIFICIAL FOOD COLORS AND HYPERACTIVITY

The presence of a functional relationship between the ingestion of artificial food colors and an increase in the frequency and/or duration of selected behaviors that are representative of the hyperactive behavior syndrome was experimentally investigated. Two eight-year-old females, who had been on the Feingold K-P diet for a minimum of 11 months, were the subjects studied. The experimental design was a variation of the BAB design, with double-blind conditions. This design allowed an experimental analysis of the placebo phases as well as challenge phases. Data were obtained by trained observers on Out of Seat, On Task, and Physically Aggressive behaviors, as they occurred in the subjects' regular class setting. Results indicated (a) the existence of a functional relationship between the ingestion of artificial food colors and an increase in both the duration and frequency of hyperactive children.