Discriminative Avoidance Behavior Research Articles

Effects of response cost on discriminated avoidance behavior

Effects of response cost on discriminated avoidance behavior

Effects of Neonatal GM1 Administration on the Discriminative Avoidance Behavior of Adult Rats

Effects of Neonatal GM1 Administration on the Discriminative Avoidance Behavior of Adult Rats

Lesions of the entorhinal cortex disrupt behavioral and neuronal responses to context change during extinction of discriminative avoidance behavior.

Rabbits given either electrolytic lesions of the entorhinal cortex or sham-lesions were trained to prevent a foot-shock by stepping in an activity wheel after one tone, a positive conditioned stimulus (CS+), and to ignore a different tone, a negative conditioned stimulus (CS-). Neuronal activity was recorded simultaneously in the basolateral nucleus of the amygdala, the CA1 cell field of hippocampus, anterior cingulate cortical area 24b and posterior cingulate cortical area 29c/d. The activity of neurons in the entorhinal cortex was recorded in the controls. Acquisition of conditioned avoidance responses (CRs) was not affected by lesions of the entorhinal cortex. Discriminative neuronal activity (greater neuronal responses to the CS+ than to the CS-) during CR acquisition was significantly enhanced in hippocampal area CA1 and attenuated in the basolateral amygdala in rabbits with lesions. Following acquisition to a criterion, two counterbalanced extinction tests were administered, one in the original context and the other in the presence of novel contextual stimuli. CR frequency was significantly reduced in controls but not in rabbits with lesions, during extinction with novel contextual stimuli, relative to performance in the original context. The rabbits with lesions also showed fewer inter-trial responses than controls during extinction in the original context but intertrial response frequency in rabbits with lesions did not differ from the frequency in controls during extinction in the novel context. Neurons in the basolateral amygdala in controls showed discriminative activity during extinction in the original context but not in the novel context. Amygdalar neurons in the rabbits with lesions did not show discriminative activity during extinction in either context. Posterior cingulate cortical neurons in control rabbits did not show discriminative activity during extinction in the original context but these neurons exhibited robust discriminative activity in the novel context. Posterior cingulate cortical neurons in rabbits with lesions showed discriminative activity in both extinction sessions. The results indicated that the entorhinal cortex does not play a significant role in the acquisition of discriminative avoidance behavior, under the employed conditions of training. However, the interactions of neurons in the entorhinal cortex, amygdala and cingulate cortex are essential for contextual modulation of CRs during extinction.

The nomadic engram: overtraining eliminates the impairment of discriminative avoidance behavior produced by limbic thalamic lesions

Combined lesions of the medial dorsal and anterior thalamic nuclei severely impair the acquisition of discriminative avoidance behavior, wherein rabbits learn to prevent foot-shock by stepping after a tone conditional stimulus (CS +), and they learn to ignore a different tone (CS −) that does not signal foot-shock. Neurons in these thalamic nucleic exhibit training-induced firing pattern changes during behavioral acquisition to asymptotic performance levels. However, the changes decline in magnitude during the course of post-asymptotic training (overtraining), suggesting a declining participation of the thalamic neurons in task mediation. In order to test this hypothesis, electrolytic or sham limbic thalamic lesions were induced either immediately after asymptotic performance was reached, or after the administration of training to asymptote and ten additional overtraining sessions. Retention after the lesions was assessed using an extinction procedure (CS presentation without foot-shock) followed by re-acquisition. Rabbits given lesions after criterion attainment exhibited a significant retention deficit during both the extinction and re-acquisition tests. However, no significant retention deficit was found in rabbits given 10 days of overtraining prior to the lesions. These results support the prediction derived from the neuronal data, of a time-limited involvement of limbic thalamic neurons in mediation of discriminative avoidance behavior.

Stimulus-related and movement-related single-unit activity in rabbit cingulate cortex and limbic thalamus during performance of discriminative avoidance behavior

Neuronal discharges related to acoustic conditional stimuli and locomotive behavioral responses of 152 anterior and medial dorsal (MD) thalamic and cingulate cortical single-units sorted from multi-unit activity were recorded as rabbits performed in a discriminative avoidance task. The goals were: (1) to document the single-unit constituents of multi-site, multi-unit activity recorded previously in response to the conditional stimuli used for avoidance training; and (2) to document neuronal activity related to the onset of the behavioral avoidance response. Ninety-five units showed discriminative discharges: significantly different firing rates 90–700 ms after a foot shock-predictive conditional stimulus (CS + ) than to a safety-predictive conditional stimulus (CS - ). In accord with the multi-unit data, a majority of these units discharged at higher rates after the CS + than after the CS - . The discharge rates of 87 units were greater during the 2-s period preceding the onset of avoidance responses than during comparable trial periods after CS - presentations followed by no response. Fifty-six of the 87 avoidance-related units exhibited a progressive ramp-like firing increase 2 s before the avoidance response, with the maximal discharge rate occurring 200 ms before the response. These dynamic pre-avoidance discharges occurred first in limbic thalamus then in cingulate cortex, suggesting that cortical pre-motor processing may confer temporal specificity upon a more generalized command volley relayed from thalamus. Unlike the multi-unit data, 24 neurons exhibited inverse discrimination, i.e., significantly greater discharges in response to the CS - than to the CS + . Also 27 neurons showed significantly more firing in the 2-s period before the end of CS - trials in which no behavioral response occurred, than in the 2-s pre-avoidance period on CS + trials with responses. This ‘inverse’ CS-related and pre-avoidance activity occurred at low incidence ( < 15%) in all areas except the MD nucleus, wherein it was exhibited by 45% of the recorded units. The inverse activity may reflect the operation of local inhibitory neurons which suppress the discharges of other neurons in response to the CS - . The prevalence of inverse activity in the MD nucleus suggested an involvement of this area in behavioral inhibition.

Topographic relationship between anteromedial thalamic nucleus neurons and their cortical terminal fields in the rat

The present study has examined the topographic relationship between cells in the anteromedial thalamic nucleus (AM) and their cortical terminal fields, with retrograde transport of Fluoro Gold in the rat. Projections to the frontal area 2 originate from the ventrolateral part of the AM and the entire interanteromedial nucleus (IAM). Projections to the anterior cingulate area originate from the peripheral part of the rostral AM and the entire IAM. Fibers to the rostral retrosplenial area arise from the caudodorsal part of the AM, whereas those to the caudal retrosplenial area arise from the rostralmost and the rostrodorsomedial parts. Fibers to the rostral area 29D originate from the rostrocentral part of the AM, whereas those to the caudal area 29D originate from the rostroventrolateral and the ventromedial parts. Projections to the medial half of the entorhinal area originate from the rostrodorsomedial part of the AM. In contrast, projections to the lateral half of the entorhinal area originate from the IAM and the central part of the AM. The results show a complex topographic relationship between cells of origin of the AM and their cortical terminal fields, suggesting complex functional roles played by the AM in learning behavior such as discriminative avoidance behavior.

Efferent projections from the anterior thalamic nuclei to the cingulate cortex in the rat

The organization of projections from the anterior thalamic nuclei to the cingulate cortex was analyzed in the rat by the anterograde transport of Phaseolus vulgaris-leucoagglutinin. The rostral part of the anteromedial nucleus projects to layers I, V and VI of the anterior cingulate areas 1 and 2, layers I and III of the ventral orbital area, layers I, V and VI of area 29D of the retrosplenial area, and layers I and V of the caudal part of the retrosplenial granular and agranular areas. In contrast, the caudal part of the anteromedial nucleus projects to layer V of the frontal area 2, and layers I and V of the rostral part of the retrosplenial granular and agranular areas. The interanteromedial nucleus projects to layers I, III and V of the frontal area 2, layer V of the agranular insular area, and layers I, V and VI of area 29D. The anteroventral nucleus projects to layers I and IV of the retrosplenial granular area, whereas the anterodorsal nucleus projects to layers I, III and IV of the same area. Projections from the anteroventral and anterodorsal nuclei were, furthermore, organized such that their ventral parts project to the rostral part of the retrosplenial granular area, whereas their dorsal parts project to the more caudal part. The results suggest that the anterior thalamic nuclei project to more widespread areas and laminae of the cingulate cortex than was previously assumed. The projections are organized such that the anteromedial and interanteromedial nuclei project to layer I and the deep layers of the anterior cingulate and retrosplenial cortex, whereas the anteroventral and anterodorsal nuclei project to the superficial layers of the retrosplenial cortex. These thalamocortical projections may play important roles in behavioral learning such as discriminative avoidance behavior.

Loss of discriminative avoidance behavior by local application of kynurenic acid into the nucleus accumbens of the rat

Male Sprague-Dawley rats, trained to perform a visual discrimination, were administered kynurenic acid, an antagonist of excitatory amino acid receptors, 4.7 micrograms bilaterally into the nucleus accumbens. The performance of the visual discrimination was impaired 15, but not 360, min after administration. In addition, motor activity in the test apparatus was markedly increased by the treatment, whereas no effects were noted when the animals were observed in an open field. The abnormal behavior produced by kynurenic acid has previously been observed after administration of high doses of compounds like d-amphetamine and L-DOPA, and generally discriminative behavior has been shown to be highly dependent on normal impulse mediated release of dopamine in brain. The present results show that this behavior also is dependent on an intact excitatory amino acid neurotransmission.

Multiple-unit activity of the prefrontal cortex and mediodorsal thalamic nucleus during reversal learning of discriminative avoidance behavior in rabbits

Multiple-unit activity of the prefrontal cortex (PFC) and the mediodorsal (MD) thalamic nucleus was recorded during reversal training following differential conditioning of a locomotory (wheel rotation) avoidance response in rabbits. The positive and negative conditional stimuli (CS+ and CS−) were pure tones and the unconditional stimulus (UCS) was footshock. A major objective was to compare the activity in the PFC and MD nucleus with that in the neighboring cingulate cortical and anteroventral (AV) thalamic system, studied previously. During the first session of reversal training the rostral-sulcal subfield of the PFC manifested significant discriminative activity appropriate to the original habit, i.e., a greater discharge to the original CS+ than to the original CS−. The difference between the CS+ and CS− elicited discharges diminished as reversal learning progressed, but discriminative activity appropriate to the reversal problem did not develop. The medial subdivision of the MD nucleus which is interconnected reciprocally with the rostral-sulcal PFC subfield did not manifest discriminative activity during reversal training (nor had it done so during original learning). The caudal subfield of the PFC (which had shown rapidly developing acquisition of the discriminative discharges followed by diminution of the discriminative discharges during original training) manifested an original discriminative effect in the initial session of reversal training followed by the reverse discriminative discharge in the criterial session. The lateral subdivision of the MD nucleus which is interconnected reciprocally with the caudal PFC subfield, also manifested the original discriminative effect in the initial session of reversal training, followed by the reverse discriminative effect during the subsequent (precriterial and criterial) sessions. Thus, as in the AV nucleus, the lateral MD subdivision showed earlier and more robust development of discriminative activity appropriate to the reversal problem, than its cortical counterpart. The present results also suggested that cerebral cortical areas such as the caudal PFC, which transfer discriminative activity to their respective thalamic nuclei during discriminative acquisition, are subsequently more likely to manifest the reverse discriminative activity, than are cortical areas such as the rostral-sulcal subfields of the PFC, which do not transfer their discriminative activity.

Multiple-unit activity of the prefrontal cortex and mediodorsal thalamic nucleus during acquisition of discriminative avoidance behavior in rabbits

Multiple-unit activity of the prefrontal cortex (PFC) and the mediodorsal (MD) thalamic nucleus was recorded during discriminative conditioning of a locomotory avoidance response in rabbits. A major objective was to compare the results with those previously obtained from the posterior limbic (cingulate) cortex, and the anteroventral (AV) thalamic nucleus. The results indicated the development, with training, of discriminative neuronal activity, i.e., greater neuronal discharges to presentation of the positive conditional stimulus (CS+, a tone paired with a footshock unconditional stimulus), relative to the negative conditional stimulus (CS—, a tone not paired with the footshock). The rostral-sulcal subfield of the PFC developed the discriminative activity during the first session of conditioning, prior to the acquisition of discriminative behavioral responding. This effect persisted throughout training to the asymptote of behavioral acquisition. The medial subdivision of the MD nucleus, with which the rostral-sulcal PFC is interconnected, did not develop discriminative effects. The caudal (supragenual) subfield of the PFC also developed discriminative activity in the first session of training but the effect declined progressively in the remaining acquisition sessions. The lateral subdivision of the MD nucleus, with which the caudal PFC is interconnected, manifested robust discriminative activity in the late acquisition sessions, concomitant with acquisition of significant behavioral discrimination. Thus, as in the cingulate cortical-AV nuclear system, a corticothalamic sequential progression of discriminative activity occured in the PFC-MD nuclear system during behavioral acquisition. However, the effect was confined to one subsystem: the caudal subfield of the PFC and the lateral subdivision of the MD nucleus. Also, discriminative activity developed more rapidly in the PFC than in the cingulate cortex, and it developed more rapidly in the MD nucleus than in the AV nucleus. Implications are considered concerning the contributions to learning and memory processes, of the PFC-MD thalamic system.

Anterior thalamic lesions and neuronal activity in the cingulate and retrosplenial cortices during discriminative avoidance behavior in rabbits.

Anterior thalamic lesions and neuronal activity in the cingulate and retrosplenial cortices during discriminative avoidance behavior in rabbits.

Anterior thalamic lesions and neuronal activity in the cingulate and retrosplenial cortices during discriminative avoidance behavior in rabbits.

Bilateral electrolytic lesions of the anteroventral (AV) nucleus of the thalamus given after training impaired retention performance (extinction and reacquisition) of rabbits in a differential avoidance conditioning task. In addition, the lesions abolished the excitatory, discriminative multiple-unit discharges that had developed in the cingulate and retrosplenial cortices to the auditory conditional stimuli (CSs) during the course of behavioral acquisition, prior to the induction of the lesions. The excitatory discharges were supplanted in the subjects with lesions by CS-elicited reduction of neuronal firing to levels below the prestimulus baseline. Lesions given before training did not disrupt behavioral acquisition, but they did eliminate the excitatory tone-elicited neuronal discharges that normally occur in the cortex before and during training. The CS-elicited reduction of neuronal firing did not occur at the beginning of training in the subjects given lesions before training, but it developed during the course of training. The lesions did not eliminate the excitatory and discriminative neuronal activity of the prefrontal cortex. These results demonstrate that excitatory and discriminative neuronal discharges in the cingulate and retrosplenial cortices are critically dependent on the connections of these areas with the anterior thalamic nuclei. Also the lesion-induced disruption of performance during extinction and reacquisition but not during original learning confirms a prediction from past electrophysiological studies, that the AV thalamic nucleus is involved in the mediation of the maintenance and retention of the conditioned avoidance behavior, but not in its original acquisition.

The effect of response-contingent feedback stimuli under two types of avoidance extinction conditions

Four groups of rats were conditioned to avoid shock in a two-way shuttlebox. During acquisition. each response both precluded a brief programmed shock and produced a I-sec feedback signal. CS termination was not permitted during either acquisition or' extinction. During extinction, response-produced or yoked feedback was combined with either 100% response-independent shock or no-shock conditions. Greatest resistance to extinction of avoidance behavior was obtained when response-produced feedback occurred in the absence of shock relative to any other combination of these events. These results, when compared to those of previous studies investigating the role of warning signal termination in combination with the presence or absence of shock in extinction (Hartley, 1968), clearly reveal a functional similarity between feedback and CS termination. The most prevalent interpretation of discriminative avoidance behavior has been the two-factor theory, originally discussed by Mowrer and Lamoreaux (1946) and more recently by Solomon and Brush (1956). According to the theory, conditioning is accomplished by both Pavlovian and operant processes. A classically conditioned fear response develops by repeated pairings of CS and US. This fear reaction motivates the subject to avoid the US. Reinforcement of avoidance occurs when fear is reduced by response-produced termination of the CS and preclusion of the US. An alternative explanation of avoidance views the CS, CS termination, and the presence or absence of the US as having discriminative rather than motivational prop­ erties (Mowrer & Jones, 1945; Sheffield, 1949). When one or all of these cues are altered during extinction, avoidance behavior declines due to generalization decrement. Thus, if a subject is avoiding either a high proportion of shocks during terminal acquisition or all of them, a no-shock extinction procedure should pro­ long extinction over a procedure in which shocks occur on all extinction trials . Similarly , any extinction pro­ cedure that alters the consequences of responding from those occurring during the acquisition phase, whether the events be CS termination, US avoidance, or any other highly discriminable events, should facilitate extinction of the behavior.

An overtraining-reversal effect with differential avoidance conditioning in rabbits

Two groups were formed from a large sample of rabbits used as subjects in ongoing studies of the neural correlates of discriminative avoidance conditioning and reversal. The members of one group (N = 9) received conditioning to criterion, whereas members of the second group (N = 9) received conditioning to criterion followed by three sessions of overtraining. All subjects received 5 days of reversal training. The groups were matched for mean number of sessions to the acquisition criterion. The CS+ and CS− were pure tones which differed in frequency, and the UCS was shock delivered through the grid floor of a rotating wheel apparatus. The response was locomotion within the wheel. The overtrained group showed a significantly greater discrimination appropriate to the reversal problem than did the nonovertrained group on Day 5 of reversal training. This result indicates that an overtraining reversal effect (ORE) occurs in the context of acoustically cued, aversively motivated discriminative avoidance behavior of rabbits.

Behavioral studies on the enantiomers of butaclamol demonstrating absolute optical specificity for neuroleptic activity.

Butaclamol is a member of a new chemical class for which antipsychotic activity in humans has been demonstrated. Butaclamol, a racemate, has been resolved into its optical isomers and a separation of activities was found to occur between the (+) and (-) enantiomers. The present experiments show that at doses ranging from 0.1 to 0.3 mg/kg the (+) enantiomer abolished amphetamine-induced (a) stereotyped behavior and (b) rotational behavior in rats with unilateral lesions in the substantia nigra. It also inhibited the lever-pressing response in the continuous (Sidman) avoidance procedure, blocked discriminated avoidance behavior, and decreased ambulation and rearing in the open field. In contrast, the (-) enantiomer was devoid of behavioral activity at 100-500 times larger doses. At considerably higher doses (+)-butaclamol antagonized epinephrine-induced mortality. Again, the (-)-butaclamol was devoid of this activity as well. The significance of absolute optical specifity manifested by a neuroleptic drug is discussed in the light of dopaminergic and adrenergic mechanisms.

EFFECTS OF CYCLE LENGTH ON PERFORMANCE ON A TEMPORALLY DEFINED AVOIDANCE SCHEDULE1

Three rats were trained on a temporally defined avoidance schedule logically similar to a fixed-interval, limited-hold positive reinforcement schedule. This avoidance schedule was composed of time periods during which responses had no scheduled consequences alternating with time periods during which a response precluded shock. As with fixed-interval length and response rate on positive reinforcement schedules, an inverse relationship was obtained between the length of the no-consequence interval and response rate during the no-consequence interval. An inverse relationship was also obtained between the length of the no-consequence interval and the per cent of shocks avoided. A rate increase within the no-consequence interval, similar to that typically produced by fixed-interval positive reinforcement procedures, was displayed by one of the rats where the no-consequence interval was at intermediate values and frequency of shock was relatively high. The introduction of a discriminative stimulus correlated with the avoidance interval produced typical discriminated avoidance behavior as well as alterations in temporal patterning of responses during the no-consequence interval in the two rats exposed to this procedure. These alterations in temporal patterning disappeared when the discriminative stimulus was removed. The results were consonant with those reported in the literature involving food reinforcement and fixed-interval, limited-hold schedules.

Signal functions in discriminated avoidance behavior.

Four rats were trained to lever press under a discriminated avoidance/escape schedule in which separately signalled safe and warning periods were 100 sec and 32 sec respectively. The auditory and not the visual component of the compound warning signal became associated with the discriminative control of lever pressing. Avoidance behavior also came under temporal control, in that the probability of lever pressing increased as the warning period progressed. Timing began with the onset of the warning signal rather than the offset of the safe signal. However, after the warning signal had been progressively eliminated, timing began with the offset of the safe signal. When neither signal was normally available, the temporal distribution of avoidance behavior changed markedly. Drifts in the temporal distribution of lever pressing occurred throughout the study; these were manipulated for two animals.

Social disruption of discriminated avoidance behavior

Two groups of rats were trained to respond on a discriminated avoidance schedule. For those animals that were initially trained together, escape rather than avoidance behavior occurred. Sexual mounting behavior and attack behavior were also observed. Those animals that were trained individually on the avoidance schedule seldom attacked when later paired with an unrestrained naive animal. Furthermore, the relative position of the naive animal in the chamber appeared to determine whether an avoidance or an escape response occurred. Disruption of discriminated avoidance responding appeared to be due not only to competing attack behavior, but also to the presence and position of the other animal in the chamber.

TITRATION SCHEDULE WITH RATS IN A RESTRAINING DEVICE

In a restraining device, providing a constant localization and easy placement of stimulating electrodes, rats were conditioned to push a front panel in order to reduce the intensity of a shock which otherwise increased regularly every 10 sec. Rapid conditioning was obtained from all subjects. They showed a very stable behavior, with negligible inter- or intra-individual variability throughout very long experimental sessions. The operant nature of the response was demonstrated further in extinction, where no shock was delivered, and in situations where the animal could not change the predetermined intensity of the shock. The interpretation of the obtained threshold was discussed with reference to previous studies on titration schedule. It was suggested that, with the parameters used, the shock intensity at which it was maintained by the rats' behavior, had the value of a warning signal, and that, in this particular case, the titration schedule generated mainly discriminative avoidance behavior rather than escape behavior.

Some behavioral aspects of retrograde amnesia produced by hypothermia

Abstract In order to determine whether retention deficits following deep body cooling were attributable to punishment effects, disinhibition of a conditioned emotional response (CER), or loss of discriminated avoidance, 6 groups of albino rats received a single passive avoidance training trial in a black-white chamber. The groups differed as to whether they received pre-trial injections of strychnine sulphate, shock for entry into the black compartment, and/or post-trial hypothermia treatments. Testing was conducted 24 hr later. Both the duration of CER and the latency to enter the black chamber were recorded. Rats subjected to hypothermia immediately after the training trial showed marked deficits in retention. Administration of strychnine prior to training further reduced retention in cooled animals but had no effect on performance of controls. Data from non-shocked groups demonstrated that the single hypothermic treatment was not punishing. Since none of the shocked groups differed in CER duration, the performance decrement obtained in rats receiving hypothermia does not appear to be based upon disruption of conditioned motor suppression in this situation. These data support the view that hypothermia, serving as a retrograde amnesic agent, acts primarily upon discriminated avoidance behavior.