Susan E. Brandon

Modulation of a discrete Pavlovian conditioned reflex by a putative emotive Pavlovian conditioned stimulus

Three experiments showed the modulation of a rabbit eyeblink conditioned response (CR) to a Pavlovian conditioned stimulus (CS) by 30-s stimuli (A & B) that had been differentially paired with paraorbital shock. The CS (Y) was a 1,050-ms cue that had been paired with paraorbital shock outside A or B. In testing, the amplitude of CRs was greater when Y was presented within A than within B. Differential modulation occurred whether shock in A had been preceded by another 1,050-ms cue, X(AX+,BX-;Experiment 1) or not (A+B-;Experiment 2). Experiment 3 compared the technique of Experiment 1 (AX+) with that of Experiment 2 (A+) and found the latter to be advantageous for facilitation of CRs to Y by A. These data are consistent with the predictions of a model of Pavlovian conditioning (AESOP, Wagner & Brandon, 1989) that distinguishes between emotive and sensory conditioning as did Konorski (1967).

Neuroethics and National Security

Neuroethics and National Security Turhan Canli a , Susan Brandon b , William Casebeer c , Philip J. Crowley d , Don DuRousseau e , Henry T. Greely f & Alvaro Pascual-Leone g a Stony Brook University, b Yale University, c United States Air Force, NATO Military Headquarters, d Center for American Progress, e Human Bionics LLC, f Stanford University, g Harvard Medical School and Beth Israel Deaconess Medical Center,

Modulation of unconditioned defensive reflexes by a putative emotive Pavlovian conditioned stimulus

Four experiments showed differential modulation of defensive unconditioned responses (URs) in rabbits by contextual stimuli that Brandon and Wagner (1991) have shown similarly to modulate conditioned eyeblink responses. Two 30-s auditory cues, A and B, were differentially paired with shock. Tests were presentations of a response-eliciting probe stimulus within A, B, or a comparable blank interval, Experiments 1 and 2 demonstrated that A and B differentially facilitated eyeblink URs, and Experiments 3 and 4 showed that A and B similarly differentially facilitated startle responses elicited by airpuffs to the ear. These data are consistent with a characterization of Pavlovian conditioning that distinguishes between emotive and sensory conditioning and assumes that conditioned emotional responses similarly modulate specific conditioned and unconditioned defensive reflexes (Konorski, 1967; Wagner & Brandon, 1989).

Divergence of conditioned eyeblink and conditioned fear in backward Pavlovian training

Two experiments of Pavlovian conditioning with rabbits evaluated the effects of initiating or continuing a conditioned stimulus (CS) after a paraorbital unconditioned stimulus (US). In Experiment 1, backward pairings, in which a CS came on after the US, produced a CS that appeared inhibitory on a measure of eyeblink conditioning but excitatory on a potentiated-startle measure of conditioned fear. In Experiment 2, extending the duration of a CS that came on prior to the US, so that it continued after the US, decreased eyeblink conditioned responses, whereas it increased conditioned fear. The data from the two experiments confirm and extend those of Tait and Saladin (1986), supporting the suppositions of AESOP (Wagner & Brandon, 1989) that conditioned eyeblink and conditioned fear can be dissociated under various temporal relationships between the CS and US.

DISSOCIATION OF THE BLOCKING OF CONDITIONED EYEBLINK AND CONDITIONED FEAR FOLLOWING A SHIFT IN US LOCUS

Two experiments with rabbits investigated the concordance of two measures of conditioning, eyeblink and potentiated startle, during a blocking sequence with paraorbital shock reinforcement. In both, a shift in the locus of shock from one eye to the other between the conditioning of an element and a compound of that element and a new cue had differential effects on the two measures of conditioning to the new cue. When the shock was unchanged, diminished conditioning in relation to controls (i.e., blocking) was observed on both measures. When the shock was changed, little conditioning was observed in startle, but control-equivalent amounts were observed in eyeblink (i.e., blocking occurred on the former but not the latter). The results are interpreted as showing a dissociation of the associative learning involving the emotive features of Pavlovian reinforcers and that involving the remaining sensory-perceptual features, and more compatible with a diminished US-processing, than with a CSprocessing, view of blocking.

Modulation of a conditioned eyeblink response by a putative emotive stimulus conditioned with hindleg shock

Two experiments with rabbits showed that the differential modulation of a conditioned eyeblink response (CR) by 30-s auditory stimuli previously paired with shock was independent of the locus of shock application. In Experiment 1, the modulation occurred when the CR was trained with paraorbital shock and the 30-s stimuli were trained with either hindleg or paraorbital shock. Experiment 2 replicated the observed adequacy of hindleg shock for modulation training, under 2 different conditions of eyeblink conditioning. The data, along with the findings that the same 30-s stimuli similarly facilitate the unconditioned eyeblink and the airpuff-elicited startle response (Brandon, Bombace, Falls & Wagner, 1991), were viewed as supporting the notion that the CR-modulation is dependent upon a conditioned fear response elicited by the 30-s cues (Wagner & Brandon, 1989).

Modulation of the acquisition of the rabbit eyeblink conditioned response by conditioned contextual stimuli

Three experiments were conducted to ask if conditioned emotional responses (CERs) controlled by contextual cues modulate the acquisition of eyelid conditioned responses (CRs) to discrete conditioned stimuli (CSs). Experiment 1 showed that 30-s auditory stimuli that were paired with aversive shocks to one paraorbital region or the other controlled discriminated CERs, as measured by potentiation of a startle response. In Experiments 2 and 3, similarly trained 30-s stimuli served as contexts in which 1.050-ms CSs were paired with a paraorbital unconditioned stimulus (US). Reinforced contexts both impaired (Experiments 2A and 2B) and facilitated (Experiment 3B) acquisition of the eyeblink CR, depending on the locus of the USs involved. The data are consistent with the interpretation that CERs controlled by contextual cues facilitate CR acquisition, but do so in the face of blocking effects of CR tendencies also conditioned to the contextual cues.

Discriminated lateralized eyeblink conditioning in the rabbit: an experimental context for separating specific and general associative influences.

Four experiments are reported that demonstrate discriminated lateralized eyeblink conditioning in rabbits and show how the phenomenon may be used to differentiate between the reflexive and emotive consequences of Pavlovian conditioning. Experiments 1, 2, and 3 characterized how 2 conditioned stimuli (CSs), contemporaneously trained with left vs. right paraorbital unconditioned stimuli (USs), can produce different conditioned reflexes (CRs), each involving predominant closure of the eye ipsilateral to its US. Experiment 4 showed how the associative tendencies controlled by additional stimuli could be evaluated by presentations in compound with such discriminanda: A 30-s stimulus, presumed to acquire a conditioned emotional response but no eyeblink CR, equally potentiated the eyelid CRs elicited by both CSs; a 1,050-ms CS that evoked an eyeblink CR in isolation also increased the responding to both CSs but biased it toward its own lateralized CR.

Computational Theories of Classical Conditioning

Computational theories of classical conditioning are theories whose propositions are stated as mathematical relationships. From such propositions one can compute, that is to say, deduce, presumed consequences for conditioned responding in circumstances addressed by the theory. This chapter is an attempt to roughly categorize and briefly summarize the major computational theories that have been developed to understand behavior in classical conditioning. It is organized around the essential ideas about conditioning that the various theories embrace. This chapter is not intended to provide a relative evaluation of the theories mentioned; to do so is considerably beyond the scope of what can be accomplished in the space available. Data are mentioned and judgments made, but only to provide understanding of the inspiration for the different models.

A device for concurrent bilateral measurement of outer eyelid closures in the rabbit

This paper describes a transducer that allows for the concurrent recording of outer eyelid closure on both the left and the right eyes of a rabbit. The device makes use of voltage induced across a current-carrying conductor when the conductor is exposed to a magnetic field perpendicular to its axis (the Hall effect). The transducer is relatively compact, inexpensive, and allows the animal to be loosely restrained.