Avoidance responding in pigeons

Four pigeons were trained in a one-way shuttle box avoidance situation. Three of the birds met the criterion of 90% avoidances; the fourth, although frequently avoiding successfully, was too erratic to meet the criterion. Avoidance responding in two of the birds was subsequently extinguished, showing that the response was true avoidance, and not escape from the buzzer warning stimulus. In Experiment 2, the three birds that had met criterion in Experiment 1 were trained in a two-way avoidance task, and all three met the criterion of 90% avoidances. The shuttle box therefore provides a rapid and reliable method of obtaining avoidance performance in pigeons.     

Strain differences in open field activity after learning in mice

Male mice of albino and pigmented strains were tested on their open field activity after maze learning and passive avoidance conditioning. The results indicated that the albino strains Balb/c, NMRI, Swiss albino and hybrids of these, reacted with an open field activity increase after maze learning in contrast to the pigmented strains C3H/He, C57BL/6J and DBA/2N. Only Swiss albino displayed an increased ambulatory level after passive avoidance conditioning for the whole experimental time. It is suggested that an ambulatory increase after learning is related to fur color and not to the initial open field activity level, nor to the learning time or the learning capacity.     

Open-field and avoidance behavior after neostriatal lesions in male and female rats.

The behavioral effects of lesions of the anterodorsal or posteroventral parts of the caudate-putamen were studied in adult male and femle rats that were gonadectomized or left untreated prior to brain surgery. Anterodorsal (ADC) lesions consistently impaired acquistion of one-way avoidance behavior and tended to interfere with the development of a two-way avoidance response; comparable effects were observed in gonadectomized and intact animals of both sexes. By contrast, ADC lesions increased activity in the open field only in intact females and increased rearing only in ovariectomized females. Posteroventral caudate (PVC) lesions caused transient aphagia and adipsia in both sexes but did not consistently affect open-field activity or the acquistion of one-way avoidance responses by either sex. These lesions profoundly impaired acquistion of shuttle box avoidance responses by intact males. By contrast, castrated males and intact and ovariectomized females with PVC lesions avoided normally in the shuttle box. The present results suggest that localization of behavioral functions within the striatum differs with the sex of the subject, in part because of activational effects of gonadal hormones.     

A comparison of simulated one-way and shuttle avoidance in an automated apparatus

The fully automated shuttle box employed in two experiments permitted the comparison within one apparatus of performance under a simulated one-way condition and the usual shuttle condition. Animals in the simulated one-way condition always ran from a white compartment into a black compartment, but alternated their direction of locomotion, as did the shuttle animals. In both experiments, animals run under the simulated one-way condition showed superior per cent avoidance performance relative to the shuttle animals. The results were compared with those obtained in other one-way avoidance and shuttle studies.     

Genetic differences in response to novelty and spatial memory using a two-trial recognition task in mice

A two-trial memory task, based on a free-choice exploration paradigm in a Y-maze, was previously developed to study recognition processes in Sprague-Dawley rats. Because this paradigm avoids the use of electric shock or deprivation that may have nonspecific effects and does not require learning of a rule, it may be particularly useful for studying memory in mice. Four inbred strains (Balb/cByJ, DBA/2J, C57BL/6J, and SJL/J), an F1 hybrid (C57BL/6 x SJL/J), and one outbred strain (CD1) were used to validate this task in mice and to characterize a strain distribution in response to novelty and working memory. Exploration was measured with a short (2 min) intertrial interval (ITI) between acquisition and retrieval, while memory was examined with longer intervals (30 min, 1 h, and 2 h). A study of the time course of the response to novelty revealed varying degrees of preference and/or habituation to novelty among the different strains, with CD1 exhibiting a very high response to novelty and others showing lower (C57 x SJL hybrids) to complete absence (SJL) of exploration of novelty. Memory span, assessed with increasing ITIs, varied widely among strains from 30 min (C57 x SJL hybrids) to at least 2 h (C57 and BALB). Such demonstrated sensitivity to a wide range of behavioral phenotypes supports the use of this spatial memory task as an effective tool for the study of genetic influences on the response to novelty and recognition processes in mice.     

The effects of preexposure to a learning apparatus

ICR mice were given exposure to a one-way shuttle apparatus until locomotor activity had been habituated. When compared with nonexposed animals, the exposed animals displayed superior shuttle avoidance learning. Animals exposed to both the apparatus and the CS did not differ from the nonexposed group. It was concluded that preexposure to the learning apparatus facilitated acquisition, while preexposure to the apparatus in the presence of the CS did not. The relationship between this effect and habituation was considered.     

Behavioral effects of neurotoxic lesions of the ascending monoamine pathways in the rat brain

Intracranial microinjections of 6-hydroxydopamine or 5,6-dihydroxytryptamine into six ascending monoamine pathways produced the expected patterns of depletion of telencephalic serotonin, dopamine, and norepinephrine. Serotonin level was specifically lowered after dorsal or median raphe lesions but not after mesolimbic or nigrostriatal system lesions which lowered both norepinephrine and dopamine. Lesions in the locus coeruleus or ventral nor-adrenergic bundle lowered only norepinephrine, and locus coeruleus lesions elevated serotonin level. Behavior was examined in an open field, one-way active avoidance, and two passive avoidance tasks, and measures were taken of water consumption and body weight. Dorsal raphe lesions had no effect on any of the measures; the other five lesion groups exhibited deficient acquisition of the one-way active avoidance task. In the appetitive passive avoidance task, only the substantia nigra lesion group exhibited a deficiency. In the step-through passive avoidance task, both the substantia nigra and the median raphe groups exhibited a deficit, with the median raphe group exhibiting hyperactivity in the start box during testing. Water consumption was decreased by lesions in the ventral noradrenergic bundle during the first postoperative week and was increased in the median raphe group by the fourth postoperative week. Lastly, lesions in the locus coeruleus dramatically decreased activity in the open field. The results are discussed in regard to the search for specificity of behavioral functions of the distinct ascending monoamine pathways.     

Some behavioral effects of transecting ventral or dorsal fiber connections of the septum in the rat.

The behavioral effects of large electrolytic lesions in the septal area were compared with those of knife cuts that severed the ventral or dorsal connections of this structure. Rats with septal lesions lost weight and were transiently hyperdipsic. Ventral cuts produced similar effects, but dorsal cuts did not. All three operations decreased the latency to eat in a novel environment, increased the intake of sweetened milk, enhanced acquisition of a food-rewarded running response, and facilitated acquisition of a shuttle box avoidance response, The lesion, but neither of the knife cuts, reduced the effects of punishment and impaired the acquisition of a one-way avoidance response.     

Oral administration of guanosine impairs inhibitory avoidance performance in rats and mice

Extracellular guanine-based purines, mainly the nucleoside guanosine, have recently been shown to exert neuroprotective effects, which seem to be related to antagonism of the glutamatergic system. In this study, we investigated the effects of acute oral administration of guanosine on inhibitory avoidance task in rats and mice. We also studied its effects on locomotor activity, anxiety-related behaviors and mechanisms of action involving the purinergic system. Guanosine (2.0 and 7.5mg/kg, per os), administered 75min pretraining, dose-dependently impaired retention of the inhibitory avoidance task in rats and mice, an effect not prevented by the adenosine receptor antagonist caffeine. Guanosine presented no effects on locomotor activity and anxiety-related behaviors. This amnesic effect of guanosine may be compatible with inhibition of glutamatergic system and seems to be not mediated by adenosine.     

Exploration and avoidance in rats with lesions in amygdala and piriform cortex

Lesions localized to specific areas of the amygdala and overlying cortex in rats produced differential effects in several behavioral tasks. Three different types of lesions were tested: central, basolateral, and cortex lateral to the amygdala. Lesions restricted to the central nucleus produced increased activity on all parameters studied in an open-field test, but the other two groups were not changed. In one-way active avoidance all three groups with lesions showed deficits. The most pronounced change was observed in the central group. All groups showed the same degree of retention loss, but in forced extinction of one-way active avoidance after retraining, the cortical and basolateral groups were most defective. A fear-reduction hypothesis is proposed for the central lesion. The basolateral and cortical areas may be more specifically involved in passive avoidance behavior.     

Effects of intrahippocampal injections of the cholinergic neurotoxin AF64A on open-field activity and avoidance learning in the rat

The effects of direct intrahippocampal administration of the cholinergic neurotoxin, AF64A, were investigated in male rats. Bilateral injections of AF64A (5 nmole/2 microliters) produced a significant decrease in choline acetyltransferase (CAT) activity in the dorsal hippocampus (25%) and overlying frontoparietal cortex (30%) but no changes in the striatum. Rats lesioned with AF64A exhibited increased levels of open-field activity, which was most marked at 1 week after the lesion; however, the rates of intrasession habituation were similar in lesioned and control rats. Lesioned rats also displayed deficits in acquisition and retention of a passive avoidance task and less dramatic deficits in acquisition of two-way shuttle box avoidance. These findings indicate that lesioning of cholinergic terminals in the hippocampus and/or cerebral cortex with AF64A leads to long-term deficits in learning and memory as well as increases in open-field activity.     

Extinction of avoidance in rats: response availability and stimulus presentation effects

A conditioned a versive stimulus presented in prolonged, continuous fashion is said to be flooded. Using a two-way shuttle avoidance task. Polin (1959) found that animals allowed to respond to flooded stimuli extinguish faster than animals prevented from responding to discrete stimuli of equal total duration. But, as Shearman (1970) noted, the CS presentation and response availability factors were confounded. He arranged them factorially, in a 2 × 2 design, again utilizing two-way avoidance, but found no differences between any of the experimental groups, although all groups extinguished faster than a regular extinction control group, the only group for which CS termination was response-contingent. Since there is evidence from one-way avoidance studies that response prevention facilitates extinction of avoidance with CS exposure held constant (Shipley et al., 1971). we repeated the Shearman design, using a one-way avoidance paradigm, and including a group for whom the aversive CS would be presented in discrete trials at increasing intensities. A separate aspect of the present investigation concerned the measurement of a fear response as well as the avoidance response. Results of several investigations have shown (e.g. Coulter et al. 1969; Linton et al.. 1970) that avoidance behaviour can be extinguished without the extinction of fear. It was thought useful to assess the generality of this result, since in two-factor theory, fear and avoidance are related.Two supplementary experiments replicated important conditions of the initial one, while examining whether response prevention and response non-availability have similar effects (II), and the relation between the fear test and the test for extinction (III).     

Lasting increases in basolateral amygdala activity after emotional arousal: implications for facilitated consolidation of emotional memories

Manipulations that reduce or enhance the activity of basolateral amygdala (BLA) neurons in the minutes to hours after training have been shown to respectively impair or facilitate retention on the inhibitory avoidance task. Although this suggests that BLA activity is altered after emotional arousal, such changes have not been directly demonstrated. To test this, we devised a feline analog of the inhibitory avoidance task and recorded BLA unit activity before and after a single inescapable footshock. Single-unit recordings revealed that the firing rate of many BLA neurons gradually increased after the footshock, peaking 30-50 min post-shock and then subsiding to baseline levels 2 h later. During this period of increased activity, the discharges of simultaneously recorded BLA cells were more synchronized than before the shock. Although it was known that pairing innocuous (conditioned stimulus, CS) and noxious stimuli modifies the responsiveness of BLA neurons to the CS, our results constitute the first demonstration that emotional arousal produces lasting increases in the spontaneous firing rates of BLA neurons. We propose that these changes in BLA activity may promote Hebbian interactions between coincident but spatially distributed activity patterns in BLA targets, facilitating the consolidation of emotional memories.     

Styles of problem solving in suicidal individuals

This study compared qualitative aspects of problem solving among suicide attempters, suicide ideators, and nonsuicidal patients. The subjects completed a suicidal intent scale and a problem-solving task involving three dilemmas. Problem solving was analyzed along eight qualitative categories: versatility of the various solutions, reliance on self versus others, activity versus passivity, confrontation versus avoidance, relevance of the solution to the problem, positive versus negative affect, reference to the future, and extremity of the solution. The statistical analysis yielded differences among the three groups. In general, the solutions of suicidal patients showed less versatility, more avoidance, less relevance, more negative affect, and less reference to the future than the solutions of the nonsuicidal patients. The suicide attempters and nonsuicidal patients offered more active solutions than did the suicide ideators. Our findings emphasize the importance of general coping styles, as well as energetic/motivational aspects and affective aspects of the problem-solving process. Some applications to therapy are discussed.     

Androgens' effects to enhance learning may be mediated in part through actions at estrogen receptor-beta in the hippocampus

Testosterone (T) may enhance cognitive performance. However, its mechanisms are not well understood. First, we hypothesized that if T's effects are mediated in part through actions of its 5alpha-reduced metabolites, dihydrotestosterone (DHT) and/or 3alpha-androstanediol (3alpha-diol) in the hippocampus, then T, DHT, and 3alpha-diol-administration directly to the hippocampus should enhance learning and memory in the inhibitory avoidance task. In order to test this hypothesis, gonadectomized (GDX) male rats were administered T, DHT, or 3alpha-diol via intrahippocampal inserts immediately following training in the inhibitory avoidance task. We found that T tended to increase, and DHT and 3alpha-diol significantly increased, performance in the inhibitory avoidance task compared to vehicle-administered GDX rats. Second, we hypothesized that, if androgens' effects are due in part to actions of 3alpha-diol in the hippocampus, then systemic or intrahippocampal administration of 3alpha-diol should significantly enhance cognitive performance of GDX male rats. Third, we hypothesized that, if androgen metabolites can have actions at estrogen receptors (ERs) in the hippocampus, then administration of ER antisense oligonucleotides (AS-ODNs) directly to the hippocampus of GDX, 3alpha-diol replaced, rats would decrease learning in the inhibitory avoidance task. We found that intrahippocampal administration of AS-ODNs for ERbeta, but not ERalpha, significantly decreased learning and memory of 3alpha-diol replaced rats. Together, these findings suggest that T's effects to enhance learning and memory may take place, in part, through actions of its metabolite, 3alpha-diol, at ERbeta in the dorsal hippocampus.     

Exploration and avoidance learning after ibotenic acid and radio frequency lesions in the rat amygdala

Open-field activity, avoidance behavior, and plasma corticosterone levels were studied after intraamygdala injections of 3.0 micrograms ibotenic acid (IBO) and radio-frequency (RF) lesions in the amygdala complex of male Wistar rats. The experiments were undertaken to evaluate the importance of amygdala neurons versus axons of passage in fear-motivated behavior. The IBO lesions led to increased open-field activity, but no impairments in active avoidance learning, nor changes in basal or experimental levels of plasma corticosterone. The RF lesions, on the other hand, led to an increase in experimental plasma corticosterone levels. In the one-way avoidance task the RF lesions, in contrast to the IBO lesions, led to significant impairments in the acquisition of the avoidance response. Although the long-term axon-sparing effect of IBO is questioned since cavities were detected in the affected areas 8 weeks after the injections, the differences in avoidance learning and in corticosterone levels between the RF and the IBO lesions indicate that the axons were functionally active at the time of testing (14-26 days postoperatively). The increase in open-field activity is attributed to the destruction of amygdala neurons and neurons in the overlying cortex, while an avoidance deficit seem to depend on the destruction of axons. On the basis of the behavioral results and the corticosterone data in these experiments, it is suggested that the behavioral changes are not attributable to a general reduction in the arousal of fear. However, since the IBO lesions did not affect the most medial parts of the amygdala complex including the central amygdala nucleus, the role of this nucleus in fear arousal has to be investigated further.     

Retention of massed vs distributed response-prevention treatments in rats and a revised training procedure.

Two experiments were conducted to estimate the retention of response-prevention effects using massed vs distributed treatments in a model of animal avoidance-learning. In Exp. I, 120 rats were trained to avoid shock in a one-way platform avoidance apparatus. Groups received response-prevention treatment or nontreatment in a 36-min. massed session or in several sessions distributed over a four-day period. In Exp. II, 160 rats were given two trials of escape training in a one-way shuttle box. Groups received response-prevention treatment or nontreatment in a 24-min. session of massed or distributed treatments delivered in one day. Subjects in both studies were tested using a passive-avoidance paradigm immediately following treatment, 24 hours later, and 30 days later. Analysis showed that response-prevention treatments were effective in reducing avoidance behavior and there were no significant differences in retention of avoidance associated with massed vs distributed response-prevention treatments. Implications for animals and humans are discussed, and researchers are encouraged to change from a criterion training procedure to an escape procedure since the latter is a closer analogue to the human condition.     

Amitriptyline administered after consolidation of inhibitory avoidance does not affect memory retrieval

In Experiment 1, the effect of the administration of the antidepressant amitriptyline (30 mg/kg) for 21 days on the acquisition and consolidation of the inhibitory avoidance task was studied in male and female mice. In Experiment 2, it was evaluated whether amitriptyline administered after the consolidation of this task would block the memory retrieval. Anxiety and spontaneous activity in the elevated plus maze were also assessed. When amitriptyline was given before the training phase of inhibitory avoidance it blocked learning in males and there was a tendency in the same direction in females. However, the drug administered between training and test phases did not affect conditioning. These effects of amitriptyline seem to be independent of its actions on anxiety and locomotor activity. It may be that the effects observed are related to the therapeutic effects of antidepressants.     

Intracerebroventricular effects of angiotensin II on a step-through passive avoidance task in rats

A wealth of evidence indicates that angiotensin II (Ang II) is involved in learning and memory. However, the precise role of this peptide in these cognitive processes is still controversial, with data indicating either an inhibitory or an enhancing action. The present study was designed to further investigate the effects of intracerebroventricular injections of Ang II (0.5, 1 or 3nmol/5microl) on a step-through passive avoidance task in male adult Wistar rats. When administered pretraining, Ang II did not affect the acquisition of passive avoidance, but markedly improved avoidance performance when given before the retrieval test. The latter effect was observed in retest sessions performed up to 72h after training. Administration of the peptide five minutes after training impaired retention of inhibitory avoidance. Therefore, Ang II may exert opposite effects on passive avoidance memory according to its interference with brain mechanisms leading to the storage or retrieval of this aversively motivated task.     

Effects of emotional response on the Stroop‐like task in preschool children and young adults

This study investigated the effects of emotional response on an inhibitory task, the Stroop‐like day‐night task, in which participants are presented with two pictures. They are then requested to inhibit naming what the card shown to them represents and instead state what the other card represents. Specifically, 35 4‐ to 6‐year‐old children and 15 young adults were administered the emotion‐related happy‐sad task and the emotion‐unrelated up‐down task using the same stimulus set (happy and sad cartoon faces). The results suggested that vulnerability to errors in the happy‐sad task was not derived from increased inhibitory demand. The results also suggested that the happy‐sad task is more inhibitory‐demanding in terms of response time. These results suggested that the happy‐sad task elicits interference more than other variants of this task, not because the task involves emotional stimuli per se but because the task involves both emotional stimuli and emotional responses.