Expression of Fos and Jun Proteins Following Passive Avoidance Training in the Day-Old Chick

It has been shown previously that the immediate-early genes, c-fos and c-jun mRNA are induced in the 1-day-old chick forebrain after one-trial passive avoidance training in which chicks learn to avoid pecking at a bitter-tasting bead. Here, we have studied the expression of their proteins using antibodies to Fos and Jun. Western blotting disclosed two immunoreactive bands for the anti-Fos antibody (47 and 54 kD) and two immunoreactive bands for the anti-Jun antibody (39 and 54 kD). Two hours post-training there was an increase in the number of Fos-positive stained nuclei in right intermediate medial hyperstriatum ventrale (IMHV) (P<0.01), left IMHV (P<0.05), right lobus parolfactorius (LPO) (P<0.025) and left LPO (P<0.05) of birds trained on the bitter bead compared with controls that had pecked a water-coated bead. Staining for Jun protein was significantly greater in the right LPO of trained chicks (P<0.01). Other forebrain regions showed no increase over quiet control levels. The findings are discussed in the context of the cascade of events involved in passive avoidance memory consolidation in the day-old chick.     

Effects of Dark Rearing and Light Exposure on Memory for a Passive Avoidance Task in Day-Old Chicks

Light exposure during embryogenesis is necessary for functional and morphological maturation in the domestic chick. In the present study, dark incubation was demonstrated to induce a weak amnestic effect on retention for a passive avoidance task and a diminution in discriminative memory ability in day-old chicks. Putative explanations based on possible motor, attentional, or visual impairment were excluded. Light exposure of dark-reared eggs, specifically during embryonic days E19 to E20, alleviated the retention and discrimination deficits. The processes which might mediate between prehatch light stimulation and posthatch behavioral effects are discussed.     

High Level of Footshock during Inhibitory Avoidance Training Prevents Amnesia Induced by Intranigral Injection of GABA Antagonists

Disruption of synaptic activity of a number of cerebral structures (e.g., neostriatum, amygdala, and thalamus) produces marked deficits in retention of instrumentally conditioned behaviors. When animals are given a relatively high number of training trials or high intensities of footshock during learning, however, such disruption is considerably less effective. Since there is a close anatomical and functional relationship between the neostriatum and the substantia nigra, it was of interest to determine whether enhanced training with a high level of footshock would prevent the reported amnesic state induced by injections of GABA antagonists into the latter structure. Rats were trained in a one-trial inhibitory task, using 0.2 or 0.4 mA, and then injected with microgram quantities of picrotoxin or bicuculline into the substantia nigra and posterior region of the zona incerta; retention was measured 24 h later. Only those groups that had been injected into the nigra and trained with 0.2 mA showed amnesia. These results support the hypotheses that (a) the normal activity of a set of structures is essential for the development of memory consolidation and (b) after an enhanced learning experience these structures may participate in memory consolidation, but are not necessary for the occurrence of this process.     

Inhibition of Intermediate-Term Memory Following Passive Avoidance Training in Neonate Chicks by a Presynaptic Cholinergic Blocker

The effects of a specific presynaptic cholinergic antagonist, toosendanin, on memory formation following a passive avoidance training experience in day-old chicks was investigated. Bilateral injection of toosendanin into the neostriatal/hyperstriatal region of the chick forebrain produced memory impairment in a dose-dependent manner. Retention deficits were apparent from 20 min following training in chicks treated with toosendanin, regardless of the injection time relative to training. Chicks that received injections of the drug at corresponding times prior to retention tests showed normal retention levels, suggesting that toosendanin has no effect on performance and memory retrieval. These results indicate an involvement of cholinergic transmission during an early stage of memory formation.     

Involvement of the σ Receptor inPassive-Avoidance Learning in the Day-Old Chick during the Second Wave of Neuronal Activity

The specific σ-receptor agonist (+)-SKF 10047 and antagonist BD 1047 were used to investigate whether this receptor was involved in passive-avoidance training in the day-old chick. We found 300 μM (+)-SKF 10047 to be amnesic when injected into the lobus parolfactorius 5 h after training (p < .01). Higher or lower concentrations of (+)-SKF 10047 did not disrupt memory formation. The amnesia produced by the efficacious dose of (+)-SKF 10047 was reversed by the specific antagonist, BD 1047. It is suggested that the σ-receptor may exert its effect on passive-avoidance memory consolidation during the later stages of long-term memory formation by modulation of memory-related neurotransmission.     

Leverpress Escape/Avoidance Training Increases Neurotrophin Levels in Rat Brain

In addition to their well-known role in neural development, the neurotrophins BDNF and NGF help mediate the plasticity that occurs in the brain to promote learning. Exposure to learning procedures often leads to increases in neurotrophins, while exposure to stress often results in decreases. It is unclear how the neurotrophins would respond to an aversive learning task. Therefore, BDNF and NGF content in the dorsal striatum, hippocampus, and basal forebrain was measured following discrete trial lever-press escape/avoidance conditioning. Conditioning significantly increased levels of both neurotrophins in hippocampus and basal forebrain, relative to home cage controls (HCC). Contrary to expectations, the dorsal striatum did not show any significant changes. However, significant correlations were observed between dorsal striatal neurotrophins and aspects of avoidance performance. This may indicate that the dorsal striatum is involved in the performance aspects of the task. Results are discussed in terms of the role of neurotrophins in the acquisition of new information, and the neural structures involved in different types of memory.     

Learning About Categories in the Absence of Training: Profound Amnesia and the Relationship Between PerceptualCategorization and Recognition Memory

Previous evidence suggests that amnesics can categorize stimuli as well as normal individuals but are significantly worse at recognizing those stimuli. In an extreme case, a profoundly amnesic individual, E.P., was found to have near-normal categorization, yet, unlike most amnesics, was unable to recognize better than chance. This evidence has been used to argue against the possibility that a common memory system underlies these cognitive processes. However, we provide evidence that the experimental procedures typically used to test amnesic individuals may be flawed in that initial exposure to category members may be unnecessary to observe accurate categorization of test stimuli. We experimentally "induced" profound amnesia in normal individuals by telling them they had viewed subliminally presented stimuli, which were never actually presented. Using the same experimental paradigm used to test amnesics, we observed that participants' recognition performance was completely at chance, as should be expected, yet categorization performance was quite good.     

Muscimol Induces Retrograde Amnesia for Changes in Reward Magnitude

These experiments examined the effect of the GABA_A, agonist, muscimol (MUS), on memory for changes in reward magnitude. In Experiment 1 rats were trained to run a straight alley for either a large or small food reward. After reaching asymptotic performance rats in the high reward group were shifted to the small food reward. Half the animals received 1.0 or 3.0 mg/kg (ip) of MUS or the equivalent volume of saline immediately after training. Shifted training continued for 3 more days and no further injections were given. Shifted saline animals displayed an increase in response latencies compared to unshifted controls with a sharp peak on the day after the shift. Shifted MUS receiving 1.0 mg/kg performed comparably to shifted saline animals. In contrast, shifted MUS animals receiving 3.0 mg/kg displayed performance comparable to shifted saline animals on the day of the shift but displayed a sharp increase in response latencies on the second day after the shift. These findings indicate that post-training systemic MUS injections delay the peak increase in response latencies and suggest that MUS induces retrograde amnesia for reward reduction. Experiment 2 examined the effect of MUS on the memory of a reward increase. Rats were first trained as in Experiment 1 and rats under the high reward condition were then shifted to the small reward. On the next training session, the large food reward was reinstated. Immediately after the session all animals were injected with saline or 3.0 mg/kg of MUS. The large food reward was continued for the remainder of training and no further injections were given. On the following session, the performance of the shifted saline animals was comparable to that of the unshifted controls while shifted MUS animals displayed significantly higher response latencies. The findings that MUS prevented the reduction in response latencies seen in saline-injected animals suggest that MUS also induces retrograde amnesia for reward increases.     

2-Deoxy-d-Galactose Effects on Passive Avoidance Memorization in the Rat

2-Deoxy-d-galactose (do-gal) hinders glycoprotein fucosylation. This compound was intracerebroventricularly administered to male adult Wistar rats in order to assess whether it could exert amnesic effects on a passive avoidance response (PAR) to be learned in the light–dark box apparatus. Three experiments were performed. In the first, do-gal was administered immediately after the acquisition trials at three dosages (2, 4, and 8 μmol). It was found that only the 4-μmol dosage was followed by PAR disruption. In the second, do-gal was administered at the adequate dosage (4 μmol) either 30 min before the acquisition trial or 30 min before retrieval testing. It was found that only the preretrieval administration was followed by PAR impairment. In the third, do-gal (4 μmol) was administered in postacquisition, at increasing postacquisition delays (0.25, 1.5, 4, and 6 h). It was found that there was PAR disruption only after do-gal administration at the shortest (0.25 h) delay. The results confirm that in the rat, glycoprotein fucosylation is involved in some of the phases of memory trace processing, and they are discussed in relation to other findings in the rat and the chick.     

Relativism and Two Kinds of Branching Time

This essay examines the case for relativism about future contingents in light of a distinction between two ways of interpreting the ‘branching time’ framework. The first step of the relativist argument is to argue for the ‘Non-Determination Thesis’, the view that there is no unique actual future. The second step is to argue from the Non-Determination Thesis to relativism. I show that first step of this argument fails. But despite that result, the second step is still of interest, because one might hold the Non-Determination Thesis on alternative grounds. I then argue that whether the second step of the argument succeeds depends on how the branches in question are interpreted. If the branches are ersatz possible worlds, then the argument for relativism might go through. But if the branches are concrete parts of a ‘branching multiverse’, then the argument for relativism turns out to make implausible assumptions about the nature of personal identity over time.     

Changes of Cingulothalamic Topographic Excitation Patterns and Avoidance Response Incubation over Time Following Initial Discriminative Conditioning in Rabbits

Neurons in particular layers of cingulate cortex and in limbic thalamic nuclei exhibit peak firing rates in response to a positive conditional stimulus (CS+) in particular stages of discriminative learning. A given area is maximally activated by the CS+ in the initial, an intermediate, or a late stage of behavioral acquisition, and activation in all of the areas diminishes as training continues after the peak of activation occurs. Thus, the topographic distribution of activation in these areas depends on the stage of behavioral acquisition. The present study determined whether the acquisition-related changes of the topographic distributions of peak firing rates in CS-elicited activity are driven exclusively by the repetition of conditioning trials (i.e., practice) or may occur as well with the passage of time, similar to putative processes of memory consolidation. Multiunit activity was recorded in cingulate cortex and in the anterior dorsal (AD), anterior ventral (AV), and medial dorsal (MD) thalamic nuclei as rabbits learned to step in response to a warning tone (CS+) to prevent a scheduled foot-shock, and to ignore a different tone (CS-) not predictive of foot-shock. The rabbits received two training sessions, S1 and S2. S2 followed S1 immediately in one group of rabbits and after 48 h in a different group. Significant neuronal discharge increments occurred from S1 to S2 in the 48-h group but not in the 0-h group, for the areas (posterior cingulate cortex, AV thalamic nucleus) that previously showed only late-stage activation. Significant discharge increments occurred from S1 to S2 in the 0-h group but not in the 48-h group in areas (anterior cingulate cortex, the AD, and MD thalamic nuclei) that previously exhibited early stage activation. These results indicate that the trial-driven topographic distribution changes also occur with the passage of time after limited initial training. It is suggested that the trial-driven and time-related changes may have a common functional relevance concerning memory consolidation.     

Moving Beyond an Exclusive Focus on Harm Avoidance in Obsessive-Compulsive Disorder: Behavioral Validation for the Separability of Harm Avoidance and Incompleteness

There is increasing recognition that symptoms of obsessive-compulsive disorder (OCD) may be associated not only with harm avoidance, but also with sensations of things being incomplete or not “just right.” Although preliminary research supports the presence of both harm avoidance and incompleteness in OCD, their validity as separate constructs has not been tested beyond the use of self-report measures. Therefore, the aim of the current study was to behaviorally validate the separability of harm avoidance and incompleteness using an unselected student sample. Consistent with hypotheses, self-reported levels of incompleteness and harm avoidance uniquely predicted participants' ratings of their experiences while performing OCD-relevant behavioral tasks (e.g., washing dirty dishes, arranging books on a bookshelf). Results suggest that harm avoidance is associated with anxiety/nervousness and a desire to prevent harm, whereas incompleteness is linked to feelings of tension/discomfort and a desire to perform tasks perfectly or just right. Theoretical and clinical implications are discussed.     

Avoidance conditioning of general activity in the goldfish

Goldfish were trained with light as CS and brief shock as US under conditions in which specified amounts of general activity prevented shock both for experimental animals and for their yoked controls. The relation of the results to those of some recent shuttlebox experiments are considered.     

On the Positive Side of Avoidance Motivation: An Increase in Avoidance Motivation Reduces Procrastination among Students

People who procrastinate often pay a heavy price in terms of illness, stress, and poor performance. Because procrastination has harmful consequences, we predicted that avoidance motivation, a self‐regulation system that protects people from harm, would also protect them against procrastination. We hypothesised that avoidance motivation reduces procrastination, despite the known destructive effects avoidance motivation has on thriving. In Study 1, students high in chronic‐avoidance motivation had the lowest dropout rates from a bonus‐granting longitudinal study. In Study 2, avoidance motivation was negatively related to delay in submitting a term paper, when controlling for chronic procrastination, self‐efficacy, impulsiveness, and age. In Study 3, an experimental manipulation of avoidance motivation reduced procrastination three times, but only once significantly. In Study 4, manipulations of both avoidance motivation and approach motivation, relative to a control motivation, using a within‐subjects design, indicated that the avoidance manipulation reduced procrastination in submitting subsequent reading reports, whereas the approach manipulation did not. We subjected all our results to a meta‐analysis that indicated that avoidance motivation had a significant preventive effect on procrastination. We conclude that avoidance motivation can reduce procrastination, and suggest that our avoidance‐manipulation techniques could be applied across a variety of organisational and educational settings.     

STOP-IT: Windows executable software for the stop-signal paradigm

The stop-signal paradigm is a useful tool for the investigation of response inhibition. In this paradigm, subjects are instructed to respond as fast as possible to a stimulus unless a stop signal is presented after a variable delay. However, programming the stop-signal task is typically considered to be difficult. To overcome this issue, we present software called STOP-IT, for running the stop-signal task, as well as an additional analyzing program called ANALYZE-IT. The main advantage of both programs is that they are a precompiled executable, and for basic use there is no need for additional programming. STOP-IT and ANALYZE-IT are completely based on free software, are distributed under the GNU General Public License, and are available at the personal Web sites of the first two authors or at expsy.ugent.be/tscope/stop.html.