Stimulus selection in eyelid conditioning in the rabbit (Oryctolagus cuniculus).

Conducted 2 experiments, using a total of 24 female New Zealand white rabbits, in which a "visual" stimulus (V), either flashes or electrical stimulation of the optic chiasma, was reinforced in compound with a differentially reinforced (CS+) or nonreinforced (CS–) nonvisual stimulus. Visual stimulus control of conditioned eyeblink activity was acquired if V was reinforced in compound with CS– but was "blocked" when reinforced in compound with CS+. Both effects were demonstrable within Ss and were independent of the method of visual stimulation. Extinction and backward conditioning of chiasmic stimulation preceded retraining of 6 Ss. The establishment and blocking of visual stimulus control were again evident within Ss. The data are interpretable in terms of either attentional or associative theory. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"The role of reinforcement symmetry and stimulus modality in successive delayed matching to sample in the rat": Correction.

Reports an error in "The role of reinforcement symmetry and stimulus modality in successive delayed matching to sample in the rat" by J. S. Cohen, M. Escott and P. Ricciardi (Canadian Journal of Psychology Revue Canadienne de Psychologie, 1984[Mar], Vol 38[1], 63-79). The last six words of the legend for Figure 1 should read "in the replication of Experiment 1." (The following abstract of the original article appeared in record 1985-05863-001.) 20 male Wister albino rats were trained and tested in asymmetrically and symmetrically reinforced successive delayed matching to sample (DMTS) tasks. The only difference between these discrimination problems was that correct omission of a leverpress to the test stimulus (S?), differing from the sample stimulus (S?), was reinforced in the symmetrically reinforced DMTS. Response biases during tests for retention of S? were reduced in the symmetrically reinforced DMTS. Greater losses in retention occurred to the visual than to the auditory S?. For the auditory S?, reduced response biases in the symmetrically reinforced DMTS led to reduced losses in S? retention scores over increased retention intervals. Methodological and theoretical implications are discussed in terms of the theory of signal detection. (French abstract) (28 ref). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of aversive stimuli on reaction time in schizophrenia.

"… the experiment was to assess the motivational role of aversive stimuli in modifying the performance of normal and… schizophrenic… males… [on] a visual reaction time task… . During… [one] series Ss responded under… experimental conditions… [part of which] involved the use of intense noise as an aversive stimulus. None of the experimental conditions appreciably altered the performance of normal Ss. However, schizophrenic Ss performing under… [conditions involving noise] displayed greater improvement than control Ss." 22 refs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anticipating the Attack: Temporal Conditioning During Amygdala Kindling in Rats.

The present study showed that amygdala-kindled rats use short-interval timing superimposed on phase or ordinal timing to predict when a convulsion will occur. In 2 experiments, rats received 1 stimulation and 1 sham stimulation each day, always at the same times (conditioned stimulus [CS]+ and CS- times, respectively) and 150 s after rats had been placed in the testing chamber (the preadministration interval). As kindling progressed, the rats displayed more defensive behavior at the CS+ time than at the CS- time. Then, a stimulation-free peak-procedure test was conducted: At the CS+ time, but not at the CS- time, defensive behavior increased progressively as the 150-s preadministration interval elapsed, and then it gradually declined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus control of shuttle avoidance in young and adult rats.

Investigated stimulus generalization of 2-way active avoidance behavior in young and adult rats. In Exp. I with 12 adult and 12 young male Holtzman albino rats, CS frequency gained marked and comparable control over responding in both age groups; variation of background frequency prior to a no-tone CS, however, failed to exert any substantial control over avoidance behavior in either age group. In Exp. II with 12 Ss, Pavlovian frequency discrimination training was interpolated between acquisition of the shuttle response and generalization testing. Relative to their respective single stimulus control groups, the adult Ss showed a reliable peak shift in modal responding and the young Ss revealed a distortion in the gradient at frequency values on the side of CS+, opposite that of CS-. Although the occurrence of a peak shift was somewhat surprising in light of the fact that CS- here served as a "safety" signal, the data are interpreted as consistent with explanations of discrimination learning based upon the summation of excitatory and inhibitory gradients. In general, both experiments suggest that variations of CS frequency in an active avoidance situation tends to result in similar gradients for both young and adult Ss. The disparity between the present and previous findings are discussed in terms of the response requirements of the test situation. (French summary) (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mechanics of suppression: An experimental investigation.

Ss were given a TAT-like picture with a limited number of prominent stimulus objects and asked to tell stories which excluded 1 of the stimuli. A 2nd condition involved the introduction of the "idea" of a stimulus, without a related visual image, with the subsequent instruction not to use the introduced idea in storytelling. 2 groups of Ss—a group of average high school students and 1 of intellectually superior university graduate students—were used. Responses were classified according to process utilized in suppressing the forbidden stimulus. Both higher and lower IQ Ss utilized essentially the same types of methods, which were found to be somewhat primitive in nature. In addition, however, the graduate group introduced some seemingly more refined operations to achieve successful suppression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Temporal encoding in fear conditioning revealed through associative reflex facilitation": Correction to Lindquist and Brown (2004).

Reports an error in "Temporal Encoding in Fear Conditioning Revealed Through Associative Reflex Facilitation" by Derick H. Lindquist and Thomas H. Brown (Behavioral Neuroscience, 2004[Apr], Vol 118[2], 395-402). The article contained several errors. On page 396, second paragraph, the sentence beginning on line 6 should read as follows: "Having a stable baseline is critical for studies of reflex facilitation because the experimental designs invariably entail repetitive CR testing, if only to achieve reasonable statistical power (see Choi et al., 2001b; Lindquist & Brown, 2004)." On page 400, the first heading should read as follows: "Comparison of New and Old Reflex Facilitation Procedures." On page 400, the first sentence under the abovementioned heading should read as follows: "We decided not to use the original measure of reflex facilitation, developed by J. S. Brown et al. (1951), because it suffers from severe interpretational limitations, elaborated in detail elsewhere (Choi et al., 2001b; Leaton & Cranney, 1990; Lindquist & Brown, 2004)." (The following abstract of the original article appeared in record 2004-12681-016.) Temporal encoding in Pavlovian fear conditioning was examined through conditional facilitation of the short-latency (Rl) component of the rat eyeblink reflex. Rats were fear-conditioned to a tone conditional stimulus (CS) with either a 3- or 9-s interstimulus interval (ISI) between CS onset and the onset of the grid-shock unconditional stimulus (US). Rl facilitation was tested over 2 days, in counterbalanced order, at a latency of 3 s and 9 s from CS onset. CS-produced Rl facilitation, the conditional response (CR), was 3-4 times larger when the test latency equaled the conditioning ISI. These results, coupled with the known neurophysiology of Rl facilitation, suggest that this CR could disclose differences in the time course of CS-generated output from the amygdala when driven by cortical versus subcortical CS-CR pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of selective excitotoxic lesions of the nucleus accumbens core, anterior cingulate cortex, and central nucleus of the amygdala on autoshaping performance in rats.

The nucleus accumbens core (AcbC), anterior cingulate cortex (ACC), and central nucleus of the amygdala (CeA) are required for normal acquisition of tasks based on stimulus-reward associations. However, it is not known whether they are involved purely in the learning process or are required for behavioral expression of a learned response. Rats were trained preoperatively on a Pavlovian autoshaping task in which pairing a visual conditioned stimulus (CS+) with food causes subjects to approach the CS+ while not approaching an impaired stimulus (CS-). Subjects then received lesions of the AcbC, ACC, or CeA before being retested. AcbC lesions severely impaired performance; lesioned subjects approached the CS + significantly less often than controls, failing to discriminate between the CS + and CS-. ACC lesions also impaired performance but did not abolish discrimination entirely. CeA lesions had no effect on performance. Thus, the CeA is required for learning, but not expression, of a conditioned approach response, implying that it makes a specific contribution to the learning of stimulus-reward associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Partial Reinforcement Extinction Effect Despite Equal Rates of Reinforcement During Pavlovian Conditioning.

In 4 experiments rats received appetitive Pavlovian conditioning followed by extinction. Food accompanied every trial with the conditioned stimulus (CS) for the continuously reinforced groups and only half of the trials for the partially reinforced groups. In contrast to previous experiments that have compared the effects of partial and continuous reinforcement, the rate at which food was delivered during the CS was the same for both groups. The strength of the conditioned response during extinction weakened more rapidly in the continuously than in the partially reinforced groups. The results demonstrate that the partial reinforcement extinction effect is a consequence of the nonreinforced trials with the CS, rather than the rate at which the unconditioned stimulus is delivered during the CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditional stimulus probability and activity of hippocampal, cingulate cortical, and limbic thalamic neurons during avoidance conditioning in rabbits.

Multi-unit and field potential responses in the anterior (AC) and posterior cingulate cortices (PC), dentate gyrus (DG), and anterior ventral (AV) and medial dorsal (MD) thalamic nuclei of rabbits were recorded during acquisition and performance of a locomotor conditioned response (CR). The CR, stepping in an activity wheel in response to a tone (conditioned stimulus [CS+]), prevented the occurrence of a shock unconditioned stimulus (UCS) scheduled 5 sec after CS+ onset. Ss also learned to ignore a different tone (CS–), not predictive of the UCS. Training was given daily until behavioral discrimination reached criterion. After criterion, asymmetric probability (AP) sessions were given that were the same as the conditioning session except for probability manipulation. A significant discriminative response developed in all regions during behavioral acquisition. The unit response in the AP session was enhanced in all areas by rare presentation of the CS–, compared with the equal and frequent CS– conditions. Rare presentation of the CS+ enhanced the unit response in the AC, PC, and DG, but it suppressed the firing of AV and MD neurons. Rare CS+ presentations did not alter AV and PC neuronal activity in Ss with subicular lesions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in gradients of stimulus generalization as a function of "Abstract" and "Concrete" attitude.

Goldstein's concept of the loss of abstract attitude in psychopathology, was related to stimulus generalization along a visual-spatial dimension, with an apparatus requiring a voluntary response. Measurement was made of the gradient of stimulus generalization (GSG) of 34 "abstract" Ss, and 34 "concrete" Ss. These Ss were selected on the basis of their performance on 2 abstraction tasks (i.e., the Weigl-Goldstein-Scheerer Color Form Sorting Test, and the Wechsler-Bellevue block design subtest). The hypothesis that "concrete" Ss would have a lower GSG than "abstract" Ss, was tested and supported. The prediction that any differences observed would be independent of diagnostic category, was also substantiated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Summation and configuration in conditioning of the rabbit's nictitating membrane response to compound stimuli.

Two experiments, with 64 female albino rabbits, examined the acquisition of the nictitating membrane response to a tone plus light compound and its components in (a) compound conditioning (CC), which entailed reinforced presentations of the compound; and (b) stimulus compounding (SCP), which entailed reinforced presentations of the separate components. In CC, responding to the compound reached high levels, but the level of responding on component test trials declined to low levels as the conditioned stimulus (CS)–unconditioned stimulus (UCS) interval was increased. In SCP, there was substantial responding to both components, but all groups showed even higher levels to the compound. In Exp II, Ss received reinforced presentations of the compound and its components in proportions intermediate to those of CC and SCP. Differentiation between the compound and its components increased as the proportion of reinforced compound trials increased. Results are discussed with respect to atomistic summation and to perceptual, distributive, and unique stimulus hypotheses. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Additional exposures to a compound of two preexposed stimuli deepen latent inhibition.

The present experiments studied the role of error correction mechanisms in the latent inhibition of conditioned fear responses by conditioned stimulus (CS) preexposure. They demonstrated that a preexposed CS subjected to additional exposures in compound with either another preexposed stimulus or a novel stimulus was more latently inhibited than a preexposed CS which received additional exposures in isolation. They also showed that a preexposed CS subjected to additional exposures in compound with another preexposed stimulus was more latently inhibited than a preexposed CS given additional exposures in compound with a novel stimulus. These results were discussed in terms of the Hall–Rodriguez (2010) model of latent inhibition. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

De novo conditioning in trauma-exposed individuals with and without posttraumatic stress disorder.

Differential conditioning was assessed in 15 medication-free individuals meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) criteria for chronic posttraumatic stress disorder (PTSD) and 18 trauma-exposed individuals who never developed PTSD (non-PTSD). Conditioned stimuli (CSs) were colored circles, and the unconditioned stimulus was a "highly annoying" electrical stimulus. Individuals with PTSD had higher resting heart rate (HR) and skin conductance (SC) levels and produced larger SC orienting responses. During conditioning, the PTSD group showed larger differential SC, HR, and electromyogrant responses to the reinforced vs. nonreinforced stimuli (CS+ vs. CS-) compared with the non-PTSD group. Only PTSD participants continued to show differential SC responses to CS+ vs. CS- during extinction trials. Results suggest that individuals with PTSD have higher sympathetic nervous system arousal at the time of conditioning and are more conditionable than trauma-exposed individuals without PTSD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal Encoding in Fear Conditioning Revealed Through Associative Reflex Facilitation.

[Correction Notice: An erratum for this article was reported in Vol 118(3) of Behavioral Neuroscience (see record 2007-16851-001). The article contained several errors. On page 396, second paragraph, the sentence beginning on line 6 should read as follows: "Having a stable baseline is critical for studies of reflex facilitation because the experimental designs invariably entail repetitive CR testing, if only to achieve reasonable statistical power (see Choi et al., 2001b; Lindquist & Brown, 2004)." On page 400, the first heading should read as follows: "Comparison of New and Old Reflex Facilitation Procedures". On page 400, the first sentence under the abovementioned heading should read as follows: "We decided not to use the original measure of reflex facilitation, developed by J. S. Brown et al. (1951), because it suffers from severe interpretational limitations, elaborated in detail elsewhere (Choi et al., 2001b; Leaton & Cranney, 1990; Lindquist & Brown, 2004)."] Temporal encoding in Pavlovian fear conditioning was examined through conditional facilitation of the short-latency (Rl) component of the rat eyeblink reflex. Rats were fear-conditioned to a tone conditional stimulus (CS) with either a 3- or 9-s interstimulus interval (ISI) between CS onset and the onset of the grid-shock unconditional stimulus (US). Rl facilitation was tested over 2 days, in counterbalanced order, at a latency of 3 s and 9 s from CS onset. CS-produced Rl facilitation, the conditional response (CR), was 3-4 times larger when the test latency equaled the conditioning ISI. These results, coupled with the known neurophysiology of Rl facilitation, suggest that this CR could disclose differences in the time course of CS-generated output from the amygdala when driven by cortical versus subcortical CS-CR pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unconditioned stimulus devaluation effects in nutrient-conditioned flavor preferences.

Experiments with different temporal relations between the conditioned stimulus (CS) and the unconditioned stimulus (US) in conditioning assessed whether US devaluation effects can be obtained after nutrient-conditioned flavor preference learning. One flavor (CScarb) was paired with a carbohydrate, Polycose; a 2nd flavor (CSprot) was paired with a protein, casein; and a 3rd flavor (CS-) was presented by itself. Following conditioning, one of the nutrients was devalued through pairings with lithium chloride in the absence of the CS flavors. In a subsequent 2-bottle test, rats preferred CScarb over CSprot; however, this preference was smaller when the carbohydrate was devalued than when the protein was devalued. Results suggest that CS flavors are able to form associations with the sensory features of nutrient USs under a wide variety of circumstances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Need for achievement and schedules of variable reinforcement.

In a simple stimulus discrimination experiment Ss were selected on the basis of their achievement need (n Ach) and assigned to 1 of 3 reinforcement conditions. Later 14 of the persons who had operated under a 5:1 schedule of reinforcement were paired on the basis of n Ach scores. The new persons were told it was a new type intelligence test and urged to do their best. Results indicated that the schedule of reinforced responses made for persons emitting more reinforced responses while n Ach was associated with a higher ratio of S responses over total response. The arousal made a difference in the ratio and seemingly had most effect on the low n Ach persons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal cortex lesions differentially disrupt cocaine-reinforced conditioned place preference but not conditioned taste aversion.

Male rats were anesthetized, and 1 of 3 subfields (medial, orbital, or precentral) of the prefrontal cortex (mesocortical dopaminergic [DA] target regions) was removed by aspiration, or no brain injury was done (sham Ss). In 4 experiments, Ss were tested on conditioned place preference, conditioned taste aversion (saccharin conditioned stimulus [CS], cocaine [CE] unconditioned stimulus [UCS]), general activity in the running wheel and open field, and food-reinforced spatial alternation in the T-maze. Results show that sham Ss showed a CE-induced place preference, medial frontal lesion Ss showed a CE-induced place aversion, and other Ss showed neither. All Ss showed a conditioned taste aversion of equal magnitude, and there were no lesion-induced differences in activity in either the running wheel or the open field. Medial frontal Ss were impaired relative to the precentral and sham Ss on learning to alternate choices in the T-maze, but orbital frontal Ss' performance was not different from that of any other group. Results indicate that mesocortical DA projection regions are involved with mediating the reinforcing properties of CE, and there is a separate system mediating the aversive properties of CE. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning of ictal and interictal behaviors in rats by amygdala kindling: Context as the conditional stimulus.

The authors showed that conditional effects of the stimulation environment modulate both the ictal and interictal behaviors of rats subjected to amygdala kindling. Rats received 53 stimulations to the left basolateral amygdala in 1 conditional stimulus (CS) context (CS+) and 53 sham stimulations (the stimulation lead was attached but no current was delivered) in another context (CS-), quasirandomly over 54 days. Three kinds of conditional effects were observed, First, after several stimulations, less ambulatory activity, more freezing, and less rearing reliably occurred in the CS + context than in the CS context. Second, after 45 stimulations, all of the rats chose the CS - context over the CS + context in a conditioned place preference test. Third, when the rats were finally stimulated in the CS- context, their motor seizures were less severe: Latencies were longer, motor seizures were shorter, convulsive patterns were of a lower class, and there were fewer falls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Facilitative and disruptive effects of prior exposure to shock on subsequent avoidance performance": Erratum.

Reports an error in "Facilitative and disruptive effects of prior exposure to shock on subsequent avoidance performance" by H. Anisman and T. Waller (Journal of Comparative and Physiological Psychology, 1972[Jan], Vol 78[1], 113-122). On page 114, the sentence beginning on Line 56, Column 2, should read: "Thirty seconds after placement in the compartment one half of the rats were given 10 CS (light and tone) presentations in which the CS was 9 sec. in duration, while the remaining rats received 10 CS-US presentations in which the US was a 1-ma. shock (constant current, ac) 2 sec. in duration." (The following abstract of this article originally appeared in record 1972-22565-001.) Subjected 40 male rats from each of 5 strains to 10 signaled inescapable 1-ma shock presentations. Shock facilitated subsequent 1-way and shuttle-avoidance performance (1-ma shock) in Charles River hooded, Wistar, Holtzman, and Sasco Ss, but did not significantly affect avoidance learning in Sprague-Dawley Ss. A 2nd experiment employing 120 male Holtzman rats indicated that inescapable shock of 1 ma. facilitated subsequent 1-way and shuttle-avoidance performance, while exposure to shock of 2 ma. facilitated 1-way and interfered with shuttle-avoidance performance. Movement ratings recorded during both CS and intershock intervals in pretraining were found to be good predictors of subsequent avoidance performance in preshocked Ss. Results are interpreted in terms of response repertoire changes produced by shock in conjunction with the defense reaction necessary in acquiring the avoidance response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)