The effect of a conditioned fear inhibitor (CS-) during response prevention upon extinction of an avoidance response

Pairing a Pavlovian safety signal (CS—) with a response prevention period was contrasted with other response prevention procedures to determine relative effectiveness for the elimination of learned avoidance behavior. After acquiring a one-way avoidance response, five groups of ten rats received various blocking or control treatments and were then compared on extinction performance. The four blocking treatments included blocking paired with a safety signal; blocking only; blocking paired with a novel stimulus; and blocking paired with a preexposed noncontingent tone. The fifth group served as a handling control. Compared to the handling control, all four blocking groups reached extinction criterion in fewer trials. Further, the safety signal group extinguished faster than the blocking only group or the blocking with noncontingent tone group. Results were viewed as an indication of the potential efficacy of pairing-conditioned fear-inhibiting cues with response prevention procedures for the elimination of fear-motivated behavior. Implications for behavioral therapy techniques were discussed.     

Memory reactivation effects independent of reconsolidation

Memory reactivation is an important process resulting from reexposure to salient training-related information whereby a memory is brought from an inactive to an active state. Reactivation is the first stage of memory retrieval but can result from the exposure to salient cues without any behavioral output. Such cue-induced reactivation, although frequently used by neuroscientists to study reconsolidation, has seldom been considered as a process in its own right and studied as such. This review presents arguments indicating that memory reactivation has two main consequences: (1) to enhance the accessibility of the target memory and (2) to make the memory malleable. Accordingly, reactivation creates a transient state during which the content of the memory is easily accessible and can be modified and/or updated. As both of these aspects can be observed shortly after memory reactivation, this review emphasizes that reconsolidation is not necessarily required for these processes and calls attention to reactivation as a factor in the dynamics of the memory.     

Auditory Processing Measures: Correlation with Neuropsychological Measures of Attention,Memory, and Behavior

It has been suggested that measures of auditory processing (AP) are sensitive measures of attention resulting in the high comorbidity of auditory processing disorder (APD) and attention deficit/hyperactivity disorder (ADHD). Others have found that selected AP measures share significant variance with memory tasks. The current study investigated the relation between AP measures and various neuropsychological measures presumed to measure attention and memory in 36 children with a mean age of 7.78 years (SD = 1.61) referred to an outpatient facility. Results indicate that AP measures significantly correlated with each other as well as with some measures of attention, memory, and behavior ratings. Results suggest that although AP measures include elements of both attention and memory, these measures also appear to assess processes not tapped by other measures of attention and memory. The correlation of AP measures with parent-and teacher-rated withdrawal, parent-rated somatization, conduct, and depression, as well as teacher-rated attention, anxiety, learning problems, social skills, and leadership suggest that auditory processing problems may manifest in myriad behaviors across settings. Implications for practice and future research are presented.     

Auditory processing measures: correlation with neuropsychological measures of attention, memory, and behavior.

It has been suggested that measures of auditory processing (AP) are sensitive measures of attention resulting in the high comorbidity of auditory processing disorder (APD) and attention deficit/hyperactivity disorder (ADHD). Others have found that selected AP measures share significant variance with memory tasks. The current study investigated the relation between AP measures and various neuropsychological measures presumed to measure attention and memory in 36 children with a mean age of 7.78 years (SD=1.61) referred to an outpatient facility. Results indicate that AP measures significantly correlated with each other as well as with some measures of attention, memory, and behavior ratings. Results suggest that although AP measures include elements of both attention and memory, these measures also appear to assess processes not tapped by other measures of attention and memory. The correlation of AP measures with parent-and teacher-rated withdrawal, parent-rated somatization, conduct, and depression, as well as teacher-rated attention, anxiety, learning problems, social skills, and leadership suggest that auditory processing problems may manifest in myriad behaviors across settings. Implications for practice and future research are presented.     

The effects of a target–stimulus reminder on performance in a novel object recognition task

The effects of original training-stimulus pre-test reminders were examined in a novel object recognition (NOR) task. NOR is a task that examines memory for complex stimuli, and is driven by the rats’ tendency to spend significantly more time exploring novel objects over those previously experienced. In this task, a delay is imposed between a training experience during which the animal is allowed to investigate a set of identical objects, and a later test exposure where the animal encounters one of the original objects and a novel object with which it has had no previous experience. Experiment 1 demonstrated that performance at 24 h is significantly worse than at an immediate delay (1 min). In the second experiment, it was demonstrated that neither a 10-s nor a 30-s reminder treatment, in the absence of training, resulted in a level of preference for novelty, a measure of memory for the original object, that was significantly greater than chance. Experiment 3 illustrated significant performance effects of a 30-s training stimulus reminder administered 15 min prior to test with a 24-h retention interval. The final experiment illustrated that the additional 30-s of object exposure is effective in enhancing performance only if it occurs shortly prior to test. Animals receiving the additional 30-s immediately following training did not experience such beneficial effects. It was concluded, based upon these results, that pre-test training-stimulus reminders in this task produce effects similar to those seen in more traditional tasks of learning and memory.     

Persistence of flavor neophobia as an indicator of state-dependent retention induced by pentobarbital, stress, and estrus

As fear conditioning paradigms have failed to find state-dependent retention (SDR) in rats dissociated by the estrous state, an attempt was made to establish a paradigm involving the attenuation of flavor neophobia as a more sensitive indicator of SDR. Experiment 1 established that the paradigm did indicate SDR in male rats dissociated by pentobarbital (10 mg/kg). Experiment 2 generalized the utility of the technique by employing an endogenous state, shock-induced stress, as the dissociative state. Having proved to be an indicator of SDR in the first two experiments, the technique was used in Experiment 3 to investigate the possible dissociative characteristics of the estrous state in female rats. Estrus was investigated because, due to the hormonal condition during estrus, it may provide a useful tool in investigating the dissociative aspects of human perimenstrual periodic psychosis. In Experiment 3, using ovariectomized female rats brought into estrus by injection of estrogen and progesterone in a sequence and amount comparable to the natural cycle, estrus was not demonstrated to be dissociative, i.e., did not produce SDR. The implications of these results in relation to perimenstrual periodic psychosis were discussed.     

Post-training glucose administration attenuates forgetting of passive-avoidance conditioning in 18-day-old rats.

The study of memory modulation in infant rats has typically focused on reminder/retrieval treatments involving reexposure to components of the internal or external training context. Rarely have studies employed pharmacological treatments to investigate the neurochemical substrates of memory storage in preweanling rats. The present study investigated the effect of 100 mg/kg of glucose, a common memory modulator in adult mammals, on memory for passive-avoidance conditioning in 18-day-old Sprague-Dawley rats. Subjects that were administered an immediate post-training injection of glucose performed significantly better, on a retention test 24 h following training, than those animals that received saline. The glucose group also performed comparably to a control group that was tested 10 min following training. These results are consistent with those of the memory modulation literature in adults and suggest that the rapid rate of forgetting in immature organisms may be the result of a deficiency in a general memory modulatory system.     

Increased generalization between drug-related interoceptive stimuli with delayed testing.

Although the flattening of generalization gradients over time has been widely investigated using exteroceptive stimuli, little attention has been given to generalization involving interoceptive stimuli. To investigate generalization between internal states, Sprague-Dawley rats were given either 0.835 ml/kg chloropent or 15 mg/kg sodium pentobarbital. Both drugs produced asymmetrical state-dependent retention of a passive avoidance response, that is, good retention in the "same state" conditions (i.e., the drug-drug and no drug-no drug conditions) as well as in the no drug-drug conditions but poor retention in the drug-no drug conditions, at both 1- and 7-day retention intervals. Furthermore, subjects trained in one drug state (pentobarbital or chloropent) demonstrated disrupted performance when tested 1 day later in another drug state, but good performance when tested 7 days later in the other drug state, indicating a decrement in the discriminability of the two drug states after 7 days. This outcome demonstrates that generalization gradients between drug states flatten over time. Moreover, these results suggest that memory for attributes of internal stimuli undergoes changes similar to those found for exteroceptive stimuli. Implications for contextual cues models of forgetting are considered.