Abstract Actively avoiding threatening stimuli or situations is an adaptive defensive strategy that minimizes the risk of potential harm. Despite the prominent role avoidance plays in our daily lives, the mechanisms that reinforce avoidance behavior remain incompletely understood. Accumulating evidence implicates the mesolimbic dopamine reward system in the acquisition of avoidance, suggesting that the omission of an aversive event may acquire rewarding properties and function as a positive reinforcer of avoidance behavior. In a series of six experiments (N = 246 male Wistar rats), we examined whether safety signals that coincide with successful avoidance responses in a two-way active avoidance (2WAA) task facilitate avoidance acquisition and acquire reward-like properties, by assessing whether they elicit approach behavior and support the acquisition of a novel instrumental response. Although the presentation of a safety signal accelerated avoidance learning in some experiments, the effect was not consistent. Furthermore, the safety signal neither elicited approach behavior nor supported the acquisition of a novel instrumental response. Together, these findings question whether safety signals in avoidance learning acquire rewarding properties detectable through behavioral measures.
158Lesioning of the rat basal forebrain leads to memory impairments in passive and active avoidance tasks
Lesioning of the rat basal forebrain leads to memory impairments in passive and active avoidance tasks
8Loss of mGluR5 in D1 Receptor-Expressing Neurons Improves Stress Coping
The metabotropic glutamate receptor type 5 (mGluR5) has been proposed to play a crucial role in the selection and regulation of cognitive, affective, and emotional behaviors. However, the mechanisms by which these receptors mediate these effects remain largely unexplored. Here, we studied the role of mGluR5 located in D1 receptor-expressing (D1) neurons in the manifestation of different behavioral expressions. Mice with conditional knockout (cKO) of mGluR5 in D1 neurons (mGluR5D1 cKO) and littermate controls displayed similar phenotypical profiles in relation to memory expression, anxiety, and social behaviors. However, mGluR5D1 cKO mice presented different coping mechanisms in response to acute escapable or inescapable stress. mGluR5D1 cKO mice adopted an enhanced active stress coping strategy upon exposure to escapable stress in the two-way active avoidance (TWA) task and a greater passive strategy upon exposure to inescapable stress in the forced swim test (FST). In summary, this work provides evidence for a functional integration of the dopaminergic and glutamatergic system to mediate control over internal states upon stress exposure and directly implicates D1 neurons and mGluR5 as crucial mediators of behavioral stress responses.
Read more17Distinct mechanisms underlying memory modulation after the first and the second session of two avoidance tasks
Distinct mechanisms underlying memory modulation after the first and the second session of two avoidance tasks
23Effects of cholinergic stimulation of the caudate nucleus on active avoidance
Effects of cholinergic stimulation of the caudate nucleus on active avoidance
11Effects of early stimulation and/or perinatal flumazenil on emotional behavior of two psychogenetically-selected rat lines with divergent emotionality profiles
Effects of early stimulation and/or perinatal flumazenil on emotional behavior of two psychogenetically-selected rat lines with divergent emotionality profiles
Read more39Acute but not chronic administration of pioglitazone promoted behavioral and neurochemical protective effects in the MPTP model of Parkinson's disease
Acute but not chronic administration of pioglitazone promoted behavioral and neurochemical protective effects in the MPTP model of Parkinson's disease
Read more17COMPARISON OF LEARNING AND MEMORY IN MORPHINE DEPENDENT RATS USING DIFFERENT BEHAVIORAL MODELS
There are several conflicting evidences showing the effect of morphine on learning and memory processes. In the present study the effect of chronic morphine administration on passive avoidance, active avoidance and spatial learning and memory of morphine dependent male rats using Passive Avoidance shuttle box and Morris Water Maze tasks were investigated, respectively. Male rats received morphine sulfate in their drinking water for 21 days. Morphine dependency was assessed by injection of naloxone HCl (2 mg/kg) showing the withdrawal signs. Our results showed that in the passive avoidance experiments although the learning of the morphine dependent group was lower than the sham and control groups, but was not statistically significant. Also no significant difference was observed between the memory retention of these groups. In the 2-way active avoidance task, learning was increased significantly in morphine dependent rats in the first day of training with respect to the sham and control groups. But, there was no significant difference in memory of these three groups. Our data in the Morris Water Maze showed that learning of the dependent group in the 3rd day of training decreased significantly with respect to the sham and control groups. But no significant difference was observed in their memory retention and also in their motor activity. Our results showed that in the male rats, chronic morphine administration decreased spatial learning, but had no effect on spatial memory and motor activity. On the contrary, it facilitated 2-way active avoidance learning but had no effect on active and passive avoidance memory. In conclusion, it seems that the effect of morphine dependency on learning and memory in rats is task dependent and depends on the types of experimental learning and memory paradigms.
Read more38Analysis of the avoidance learning deficit induced by the serotonin releasing compound p-chloroamphetamine
Analysis of the avoidance learning deficit induced by the serotonin releasing compound p-chloroamphetamine
71DSP4-induced two-way active avoidance impairment in rats: involvement of central and not peripheral noradrenaline depletion.
N-2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP4) (50 mg/kg IP), a new selective noradrenaline (NA) neurotoxin, was found to cause a severe impairment of the acquisition of a two-way active avoidance task 1 week following administration, an effect that was blocked by the selective NA uptake inhibitor desipramine. In a second experiment, systemically injected 6-OHDA (2 x 30 mg/kg IP) was not found to cause any avoidance impairment, although its effects upon peripheral NA were still evident 21 days after administration: The peripheral NA depletion caused by DSP4 almost disappeared 14 days after injection. In a third experiment, the avoidance impairment induced by DSP4 was produced even 10 weeks after treatment. Data from both the shuttlebox experiment and an activity box experiment suggest that the acquisition impairment is not readily explained on the basis of some deficit in spontaneous behavior or an altered perception of pain. The present data suggest that the effect of DSP4 upon active avoidance acquisition is mediated via central, and not peripheral NA neurons.
Read more17Genetics, septal lesions, and avoidance behavior in mice
Genetics, septal lesions, and avoidance behavior in mice
85Differential Neuromodulation of Acquisition and Retrieval of Avoidance Learning by the Lateral Habenula and Ventral Tegmental Area
Several studies suggest an opponent functional relationship between the lateral habenula (LHb) and the ventral tegmental area (VTA). Previous work has linked LHb activation to the inhibition of dopaminergic neurons during loss of reward, as well as to deficits in escape and avoidance learning. We hypothesized that a dopamine signal might underlie the negative reinforcement of avoidance responses and that LHb activation could block this signal and thereby cause avoidance deficits. To test this idea, we implanted stimulating electrodes in either the VTA or LHb of gerbils engaged in two-way active avoidance learning, a task that shows learning-associated dopamine changes and that is acquired faster following LHb lesions. We delivered brief electrical brain stimulation whenever the animal performed a correct response, i.e., when the successful avoidance of foot shock was hypothesized to trigger an intrinsic reward signal. During the acquisition phase, VTA stimulation improved avoidance performance, while LHb stimulation impaired it. VTA stimulation appeared to improve both acquisition and asymptotic performance of the avoidance response, as VTA-stimulated animals reached above-normal performance but reverted to normal responding when stimulation was discontinued. The effects of LHb stimulation during avoidance acquisition were long lasting and persisted even after stimulation was discontinued. However, when given after successful acquisition of avoidance behavior, LHb stimulation had no effect, indicating that LHb stimulation specifically impaired avoidance acquisition without affecting memory retrieval or motivation or ability to perform the avoidance response. These results demonstrate opponent roles of LHb and VTA during acquisition but not during retrieval of avoidance learning.
Read more27Exploration and avoidance learning after ibotenic acid and radio frequency lesions in the rat amygdala
Exploration and avoidance learning after ibotenic acid and radio frequency lesions in the rat amygdala
38Irreversible impairment of active avoidance behavior in rats prenatally exposed to mild concentrations of carbon monoxide.
Wistar female rats were exposed to relatively mild concentrations of carbon monoxide (75 and 150 ppm) from day 0 to day 20 of pregnancy. The results show that prenatal exposure to CO (150 ppm) significantly impairs the acquisition of a two-way active avoidance task in 3-month-old male rats as well as the acquisition and reacquisition of this schedule in 18-month-old animals subjected to six daily 20-trial sessions. These deficits do not seem to be attributable to alterations of a non-associative nature, as the intertrial activity and the escape response latencies in CO exposed animals were not significantly affected with respect to controls. These findings, showing that gestational exposure to CO induces in rat offspring permanent learning and memory impairment, confirm that the offspring of smoking mothers may be at considerably greater risk than current epidemiological studies on birthweight and neonatal mortality suggest.
Read more38Learning deficits after unilateral AF64A lesions in the rat basal forebrain: Role of cholinergic and noncholinergic systems
Learning deficits after unilateral AF64A lesions in the rat basal forebrain: Role of cholinergic and noncholinergic systems
Read more20Contribution of Emotional and Motivational Neurocircuitry to Cue-Signaled Active Avoidance Learning
Many animal and human subjects can learn to avoid punishment or noxious stimuli by exploiting the sensory cues predicting them. In cue-signaled active avoidance (AA) learning, subjects first learn about the predictive properties of cues and subsequently learn a behavioral strategy of an avoidance response (e.g., crossing a hurdle that divides a two-compartment cage in order to avoid a mild but unpleasant footshock). AA learning develops with fear reduction as an intervening variable (Mowrer and Lamoreaux, 1946; Miller, 1948). If execution of avoidance action occurs on the pursuit of seeking safety, an overlap of recruitments of neurocircuitry essential for reward processing and for avoidance can be expected on the basis of two-process theory. Recent insights from two-way AA (2WAA) studies, which integrate both Pavlovian and instrumental components, provide strong evidence for the recruitment of emotional circuitry centered on the amygdala and motivational circuitry centered around midbrain dopaminergic structures. In this review, we address the following: (1) the role of emotional neurocircuitry in the formation of AA, (2) the involvement of reward circuitry and its input-output pathways on AA, and (3) the possible serial and parallel processing within and between these circuitries.
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