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D L Hopper

Publications and source records attributed to D L Hopper.

12 recordsLinked to original sources
PubMed1992

Effects of yohimbine and idazoxan on motor behaviors in male rats.

Yohimbine, an alpha 2 adrenergic antagonist, facilitates copulatory behaviors in male rats. This facilitation may reflect nonspecific activation of behavior rather than a more selective activation of copulatory behaviors. The present experiments assessed the effects of yohimbine on locomotor behaviors at a dose (2.0 mg/kg) known to facilitate sexual behaviors. Experiment 1 used a computer pattern-recognition system to classify motor behaviors into specific acts and act groups. Male albino rats were tested in three conspecific conditions: estrous female, anestrous female, or no conspecific. Yohimbine decreased locomotor activity in all three conspecific conditions. Experiment 2 examined the effects of yohimbine (2.0 mg/kg) and amphetamine (1.0 mg/kg) on locomotor behavior in a photocell-equipped activity measurement system. Amphetamine increased and yohimbine decreased locomotor activity. Experiment 3 used the computer pattern-recognition system to compare the effects of yohimbine and idazoxan, another alpha 2 adrenergic antagonist, on motor behaviors. Yohimbine and idazoxan both decreased activity but produced different patterns of behavioral change. The facilitatory effects of yohimbine on copulatory behaviors at a dose of 2.0 mg/kg are apparently not mediated by nonspecific activation of behavior.

Adrenergic alpha-Antagonists↗
PubMed1992

Reproducibility of time structure in motor activity of rats under nocturnal conditions.

Computer pattern recognition systems for the study of spontaneous rat behavior have introduced a new analytical technique, the K functions, that expands the definition of experimentally induced changes in behavior. Such studies normally evaluate three measures, a measure of the number of initiations of specific behavioral acts, a measure of the total time of each act, and a measure of behavioral time structure, the K functions. Such measures have been shown to be very stable and reproducible among control rats observed under normal light conditions. This study examines the stability of results from these three measures as applied to nine different groups of control Sprague-Dawley male rats observed under red light during their normal nocturnal hours. All three measures provided stable and reproducible results, but the measure of time structure, the K function analysis, provided the greatest consistency, producing values that vary by only a few percent.

Adrenergic alpha-Antagonists↗
PubMed1990

The effects of yohimbine and four other antagonists on amitraz-induced depression of shuttle avoidance responses in dogs.

The ability of five antagonists to prevent the central nervous system's depressant effects of amitraz in dogs was evaluated using a shuttle avoidance paradigm. All drugs were injected iv into six male dogs trained to avoid a 1-mA shock by jumping over a hurdle within 10 sec of the start of a tone. Dogs were given an antagonist or saline followed in 5 min by 3 mg/kg amitraz dissolved in dimethyl sulfoxide (DMSO) or DMSO alone. After pretreatment with saline, amitraz decreased significantly the means number of avoidance responses and increased significantly the means latencies of avoidance responses. After pretreatment with the alpha 2-adrenoreceptor antagonist yohimbine (0.1 mg/kg), amitraz no longer decreased the means number of avoidance responses or lengthened the means latencies of avoidance responses. The nonselective alpha-adrenoreceptor antagonist tolazoline (3.3 mg/kg) prevented amitraz-induced increases in means latencies, but did not prevent the decreases in the means number of avoidances. The alpha 1-adrenoreceptor antagonist prazosin (1 mg/kg), the muscarinic receptor antagonist atropine (0.04 mg/kg), and the opioid receptor antagonist naloxone (1 mg/kg) did not prevent either of amitraz's effects. The data suggest that the amitraz-induced suppression of avoidance responding is mediated by alpha 2-adrenoreceptors rather than by alpha 1-adrenergic, muscarinic, or opioid receptors.

Animals↗
PubMed1989

Time structure analysis of behavioral acts using a computer pattern recognition system.

The spontaneous behavior of rats was monitored, classified and analyzed using a recently developed computer pattern recognition system. The K-function, a parameter developed for statistical research on spatial point processes and patterns, is used to analyze the temporal structure of behavioral acts or the joint relationship of separate acts. Forty male rats were observed in two experiments. In Experiment 1 untreated rats were observed and the temporal structure of their behavior was analyzed to establish an estimate of the false-positive error rate appropriate for use in such analyses. In Experiment 2, 20 control rats and 20 rats exposed to 2.0 mg/kg d-amphetamine were monitored using the computer pattern recognition system. The data from Experiment 1 showed that the false-positive rate was approximately ten percent or less. Experiment 2 demonstrated that the temporal structure of spontaneous motor behavior of amphetamine-treated rats was significantly disrupted.

Animals↗
PubMed1988

Analysis of the time distribution and time sequence of behavioral acts.

A technique for analyzing the temporal structure between various initiations of a particular behavioral act has been developed using a parameter known as the K-function, the cornerstone of recent statistical research on spatial point processes and patterns. The technique has been extended to the study of the joint relationship of separate acts. Bootstrap methods are used to estimate the uncertainty in these measures. The usefulness of these techniques is demonstrated using data from studies of rats exposed to phenytoin and nitrous oxide.

Animals↗
PubMed1987

Pattern recognition of rat behavior.

Analysis of animal behavior has been an arduous task requiring a human observer to record and classify individual motor acts. A computer pattern recognition system is introduced which simplifies this task by minimizing the need for human intervention. This system uses two video cameras with horizontal and vertical views of the behavior of a control and an experimental rat as they explore a simple environment for 15 minutes. Their behavior is sampled at a rate of one frame/second. Data from the video cameras are then converted into a form acceptable to Micro Vax I and VAX 11/750 computers. Each video picture is reduced to a 256 by 256 array, and ultimately each 15 minute observation session generates 28,800 blocks of information at 512 bytes each. Using a mathematically complete set of moments to the fourth order and the associated scalar invariants, the computer is programmed to identify the five major body positions of the rat including standing, sitting, rearing, walking and lying down. The computer also is programmed to identify the behaviors of grooming, head turning, whole body turning, looking, smelling, sniffing and washing face. This computer pattern recognition system not only speeds up behavioral classification, it alleviates the much criticized subjectivity introduced by human observers.

Animals↗
PubMed1986

Effect of yohimbine on amitraz-induced CNS depression and bradycardia in dogs.

Yohimbine was studied to examine its effectiveness in preventing central nervous system(CNS) depression and bradycardia induced by amitraz (N'-(2,4-dimethylphenyl)-N-[(2,4-dimethylphenyl-imino)-methyl]-N-methyl- methanimide). In control open-field activity experiments, the dogs showed high numbers of grid-line crossings in the first 5 min (exploratory phase), and subsequently low numbers of grid-line crossings (nonexploratory phase). An iv injection of amitraz (1 mg/kg) abolished both the exploratory and nonexploratory phases and caused bradycardia. Yohimbine alone caused a trend to increase the open-field activity in the nonexploratory phase. In addition, yohimbine prevented the bradycardia and suppression of open-field activity induced by amitraz. The results suggest that yohimbine has a potential to be used as an antidote for amitraz overdose.

Animals↗
PubMed1986

The behavioral effects of prenatal and early postnatal lead exposure in the primate Macaca fascicularis.

Female Macaca fascicularis monkeys were given daily oral doses of 3.0 and 4.25 mg/kg lead, as lead nitrate, prior to breeding, and exposure was maintained throughout gestation and terminated at parturition. No overt signs of lead toxicity were observed in the maternal monkeys. The offspring were tested at 6 to 18 months of age on a three-choice non-spatial form discrimination paradigm, and at 19 to 26 months of age on a response inhibition task. When compared to controls, the lead-exposed infants showed a deficit in form discrimination performance which continued during the entire period of testing. A deficit in response inhibition performance was also observed in exposed infants when compared to controls. However, the deficit was temporary, as the performance of all groups was similar at the termination of testing. The observation of a persistent deficit in form discrimination up to 18 months following the termination of exposure suggests that lead-induced behavioral changes may be permanent. These findings are cause for concern since behavioral deficits in the offspring were observed at maternal gestational whole blood lead levels within a concentration range (30 to 70 micrograms/dl) associated with occupational exposure.

Animals↗
PubMed1986

Antagonism of xylazine-induced depression of shuttle-avoidance responses in dogs by administration of 4-aminopyridine, doxapram, or yohimbine.

The effectiveness of 4-aminopyridine, doxapram, or yohimbine as antagonists against xylazine-induced CNS depression in dogs was evaluated and compared, using the 2-way shuttle-avoidance paradigm. All drugs were given IV to 5 male dogs trained to avoid mild shock by jumping over a hurdle within 10 s after initiation of an audible tone. At dosages of 1 and 2 mg/kg of body weight, xylazine abolished or significantly decreased the mean number of avoidance responses and significantly increased the mean latency of avoidance responses. The analeptic 4-aminopyridine (0.5 mg/kg) did not significantly antagonize xylazine in all dogs. One dog convulsed both times it was given xylazine followed by 4-aminopyridine, but did not convulse when given either drug alone. Doxapram (5.5 mg/kg), a short-acting analeptic and respiratory stimulant, was only partially effective in antagonizing xylazine, and its antagonistic actions were brief. Yohimbine (0.1 mg/kg), an alpha 2-adrenoreceptor-blocking agent, was superior to 4-aminopyridine and doxapram in its ability to antagonize xylazine-induced CNS depression. Yohimbine consistently increased the mean number of avoidance responses to the maximum of 8 and consistently decreased the mean latency of avoidance responses to control values in dogs given 1 or 2 mg of xylazine/kg. In dogs given 2 mg of xylazine/kg, yohimbine was significantly more effective than 4-aminopyridine or doxapram in its ability to increase the mean number of avoidance responses and decrease the mean latency of avoidance responses.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMedDate not supplied

Computer pattern recognition: an automated method for evaluating motor activity and testing for neurotoxicity.

An economical computer-based pattern recognition system, which has been designed to observe, classify, analyze, and record the spontaneous motor activity of the laboratory rat, is presented. The advantages and disadvantages of the system are assessed in terms of characteristics generally held to be desirable for a motor activity screen of potentially neurotoxic chemicals. Data from rats exposed to 1 mg/kg d-amphetamine are compared with similar data previously taken with an earlier version of the system at another laboratory.

Animals↗
PubMedDate not supplied

Work sampling: a tool in management.

"Work sampling" was used to determine the productivity of the employees of a small occupational therapy department and the nature and extent of the activities in which they were involved. Twelve general categories of activities were identified--peak loads occurred on Wednesday each week between 9:10 to 11:30 a.m., and daily between 1:40 to 3:20 p.m. It was found that the therapists spent more of their working hours productively compared to an aide's productive time. "Work sampling" is a convenient and inexpensive technique that may be used by small or large departments to justify staff size, hours of work, and assignments on the basis of activities and productivity.

Allied Health Personnel↗