Ronald M. Kadden

Classical conditioning of heart rate and blood pressure in Macaca mulatta

Classical delay conditioning of heart rate, and of systolic and diastolic blood pressures, was carried out in 16 rhesus monkeys. Blood pressure and inter-systolic interval were measured from an in-dwelling arterial catheter; recordings were taken prior to conditioned stimulus (CS) on each trial, during a 20 sec visual stimulus that filled the conditioned-unconditioned stimulus (CS-UCS) interval, and following UCS (a brief electric tail-shock). The heart rate response both to CS and to UCS was biphasic (acceleration followed by deceleration); the blood pressure response functions were more complex, and were different for the CS and post-UCS periods. Comparison of the patterns of cardiac and blood pressure responses on any trial indicates a possible sequence of baroreceptor reflex activity.

Classically conditioned heart rate responses in Macaca mulatta after beta-adrenergic, vagal and ganglionic blockade

Heart rates of 5 rhesus monkeys (Macaca mulatta) were monitored during classical conditioning trials consisting of a visual conditioned stimulus followed after 10 sec by an electric shock to the tail. Heart rates typically increased at the onset of the visual stimulus, and returned to baseline before shock delivery. Autonomic blocking agents were subsequently administered; their effects on resting heart rates, and on acceleratory and deceleratory phases of the biphasic conditioned heart rate responses were examined, both in the raw data, and with a statistical regression technique. Beta-adrenergic blockade by propranolol lowered resting heart rates and was found, after regression analysis, to reduce the heart rate increase phase, and to weakly enhance the subsequent heart rate decrease phase of the conditioned response. Vagal blockade by atropine sulfate elevated resting heart rate, and markedly reduced both acceleratory and deceleratory heart rate phases of the conditioned responses. Ganglionic blockade by chlorisondamine also elevated resting heart rates (less than atropine), and almost completely eliminated conditioned heart rate changes. Several sources of evidence suggest a predominant vagal tone over resting heart rates, as well as mostly vagal mediation (with some sympathetic contribution) of the biphasic conditioned rate response.

Effects of pharmacological autonomic blockade upon cardiac rate and blood pressure conditioned and unconditioned responses in Macaca Mulatta

Heart rate, systolic and diastolic blood pressures were recorded during classical delay conditioning of rhesus macaque monkeys. When portions of the autonomic nervous system were selectively blocked by pharmacological agents, it appeared that the initial increases in heart rate and blood pressures in response to the conditioned stimulus were the result of increased sympathetic activity and a concomitant decrease in parasympathetic activity. Towards the end of the conditioned stimulus, an increase in parasympathetic activity was indicated. Blockade of the autonomic system which produced total elimination of the conditioned cardiac rate response and substantial reduction or elimination of the conditioned blood pressure response, was not necessarily or always accompanied by a corresponding elimination of the respective unconditioned responses. Such a finding suggests a different underlying neural mediation of these conditioned and unconditioned responses.

An introduction to state notation and SKED

SKED is a minicomputer operating system based on the functional use of state notation as a programming language. An overall view of the operating system, state notation, and the hardware necessary to simultaneously control as many as 12 experimental stations is provided.

Stimulus intrusion on fixed-interval responding in the rat: The effects of electric shock intensity, temporal location, and response contingency

Abstract After a scalloped lever-press response pattern had developed under a fixed-interval food reinforcement schedule, a 15-sec electric shock was intruded for different groups of rats in the first, second, third, or fourth quarter of each inter-reinforcement interval. Shock intensity was systematically increased for individual rats over 70 sessions, from 0.05 to 1.6 mA. Additional between-groups comparisons involved response-dependent versus clock-dependent fixed-interval schedules, and response-dependent versus response-independent electric shock intrusion. Response rates within each fixed interval prior to, during, and following electric shock intrusion showed regular and reproducible increases and decreases under systematic application of the experimental variables. These results provide further evidence that the functions of a stimulus are determined in part by the parameters of intensity, response contingency, and temporal location with respect to reinforcement.

State notation and SKED: A general system for control and recording of behavioral experiments

State notation is a language for describing behavioral procedures and data acquisition formats. A minicomputer system has been developed for translating state notation into operating computer programs, which can control 10 simultaneous and independent experiments. A description of the system is provided, including the hardware necessary to interface the computer with the experimental environment

Cardiac pacing and the law of initial value in rhesus monkeys

A cardiac pacemaker was used to produce a wide range of pre-CS heart rates in Pavlovian conditioning, and correlations were computed between pre-CS and CS heart rates. Two rhesus monkeys were presented trials in which 30 sec of light (CS) was followed by a brief electric shock (UCS). Pacing rates during the inter-trial intervals were varied from 150 to 350 bpm. Pacing was discontinued during CS. Unpaced control sessions showed that the maximum heart rate in CS on each trial was proportional to the pre-CS heart rate. Following pacing, however, heart rate in CS did not depend on the pacing rate; rather, the rates were not different from those of the unpaced control sessions. Pacing at high rates shifted the maximum heart rate toward the end of CS.

Time-Share SKED acquisition of analog data: Blood pressure and heart rate

A computer program records, within the framework of the SKED minicomputer operating system, blood pressure and heart rate data in behavioral experiments. By repetitive (500-Hz) analog-to-digital conversions of a blood pressure waveform, the program finds and stores successive-beat systolic and diastolic pressures, and intersystolic intervals. SKED initiates and terminates blood pressure recording periods, and controls all experimental procedures. The program is currently operational, servicing four independent stations simultaneously, with sufficient computer operating time remaining to service low-priority background programs.

Varying temporal placement during CS of an added stimulus correlated with non-delivery of UCS

This experiment extends Pavlov’s method of contrasts for training a stimulus discrimination to the case of the cardiac conditional response in the rhesus monkey. It explores the parameter of temporal placement of an additional stimulus (“CS2”) within a 10-sec CS (or “CS1”), with the appearance of the former stimulus on any trial signalling the absence of UCS (electric shock) on that trial. This experimental paradigm is a parallel to that of the “intruded stimulus” studies in operant conditioning. In both cases, several ways of describing the function of the added stimulus are possible, but all seem reducible to the same operational terms. Data were taken in the present study with respect to the form and latency of the cardiac rate changes produced by intrusion of CS2 (light), across a range of placements varying from simultaneity with CS1 (a different light) onset to two sec before UCS would have been delivered. The control of CS2 over the cardiac rate CR was occasionally exhibited with a latency as short as three beats after stimulus onset. The order of CS2 temporal placements to which a subject was exposed was a factor in determining the form of the conditioned cardiac rate response to CS1.