Biomedical subjects

P Jeleń

Publications and source records attributed to P Jeleń.

4 recordsLinked to original sources

PubMed2001

Heart rate changes in partially restrained rats during behaviorally and pharmacologically evoked emotional states.

The effect of fear and relief from fear on heart rate (HR) was studied in partially restrained adult male rats. The emotional state was influenced behaviorally with the use of Pavlovian aversive conditioning procedure, and pharmacologically by injections of the selected anxiolytics and anxiogenics. A signal of danger (DS)--light or tone, preceded tail-shock (excitatory trials), while a signal of safety (SS), respectively tone or light, overlapped last 3s of 5s DS and predicted an omission of this expected aversive event (inhibitory trials). To assess the stability of HR changes to DS and SS we analyzed whether and how the experimental conditions (modality and position of signals, the ratio of numbers of excitatory to inhibitory trials in the session) influenced HR. HR changes to DS were different in pattern, stability and direction when compared to HR changes in response to SS. Reactions to DS, although accompanied mainly by conditioned bradycardia, were not consistent and depended on experimental conditions. However, the SS always evoked conditioned tachycardia. Anxiolitycs--benzodiazepines (diazepam and midazolam) and buspirone--influenced HR in nonconsistent manner. Anxiogenics--PTZ and FG7142 were without significant effects on HR. HR could not be trusted therefore as direct index of pharmacologically induced emotional states. The results are discussed in the context of possible biobehavioral meaning of HR changes in response to danger and safety and their reliability as fear/relief correlates.

Acoustic Stimulation↗

PubMed1996

Estimation of the distribution of the EMG signal amplitude.

Quantitative analysis of electromyographic (EMG) data still demands new methods. One of the methods is based on counting occurrences of signal crossings of "noise level" (per time unit). This provides an estimator of the so called "aggregate activity." These data can be obtained by a spike trigger connected to a computer. Comparison of total activity of firing motor units in intact and affected muscles may give important information about the neuromuscular system in norm and pathology. The aggregate activity method does not seem, however, to be completely objective, because its results depend on the value of noise level selected by the experimenter. Thus, we propose a modification that allows: (1) quantitative estimation of how the results obtained with the aggregate activity method depend on the value of selected level, and (2) assessment of the distribution of the EMG signal amplitude--i.e., appearance of particular height spikes in the signal. The advantages and disadvantages of the method are discussed in the context of two experimental models.

Animals↗

PubMed1996

Apparatus for studying behavior and learning in restrained rats.

A new treadmill/stand apparatus for a rat is described. It will be useful in behavioral experiments when control of the animal's position in the training chamber is required while considerable freedom of movement, including locomotion, is desired. The position and distance relative to sources of stimuli are thus kept constant. The speed and the distance of ambulation are easily monitored. The rats are sufficiently restrained to enable easy recording of various measures such as EKG, EMG or EEG, etc. Classical and instrumental conditioning procedures are easily implemented. An example of the data from acquisition training during Pavlovian conditioning is shown (diaphragm EMG, heart rate (HR), locomotion and vocalization).

Animals↗

PubMed1993

The alimentary and social instrumental performance in dogs is suppressed by various doses of amphetamine.

Amphetamine was administrated intramuscularly 20-25 min before each experimental session in doses of: 0.2 mg/kg, 0.5 mg/kg and 1.0 mg/kg. Each dose was applied twice and preceded by a regular experimental sessions without any treatment. An instrumental performance consisted of alimentary-social differentiation of two tones reinforced either by food or by sensory-social reward (petting by the experimenter). Amphetamine produced dose dependent decrease of the instrumental performance of both alimentary and social responses. This decrease was however not equal regarding both reactions. The dose of 1 mg/kg produced deep, statistically significant deterioration of alimentary as well as social responses. After the administration of the dose of 0.5 mg/kg the decrease of alimentary responses was equal to that produced by 1 mg/kg, whereas social responses were less deteriorated. After the dose of 0.2 mg/kg the reduction of alimentary responses was smaller than produced by 0.5 mg/kg but still more pronounced than in the case of socially reinforced reactions. The results confirm our previous data that amphetamine suppresses positively motivated instrumental performance in dogs. The results also show that amphetamine-evoked suppression is dose dependent and that it is different for alimentary and social responses. This might indicate that the positive reward system is not homogenous but consists of some subsystems related to different kinds of reward. It is concluded that the suppressing effect of amphetamine is due to the inhibitory effect on motivation, but not on purely instrumental mechanisms nor on hedonic processes.

Amphetamine↗