Recovery of memory from infantile amnesia is developmentally constrained

Episodic memories formed during infancy are rapidly forgotten, a phenomenon associated with infantile amnesia, the inability of adults to recall early-life memories. In both rats and mice, infantile memories, although not expressed, are actually stored long term in a latent form. These latent memories can be reinstated later in life by certain behavioral reminders or by artificial reactivations of neuronal ensembles activated at training. Whether the recovery of infantile memories is limited by developmental age, maternal presence, or contingency of stimuli presentation remains to be determined. Here, we show that the return of inhibitory avoidance memory in rats following a behavioral reactivation consisting of an exposure to the context (conditioned stimuli [CS]) and footshock (unconditioned stimuli [US]) given in a temporally unpaired fashion, is evident immediately after US and is limited by the developmental age at which the reactivations are presented; however, it is not influenced by maternal presence or the time interval between training and reactivation. We conclude that one limiting factor for infantile memory reinstatement is developmental age, suggesting that a brain maturation process is necessary to allow the recovery of a “lost” infantile memory.

Hippocampus-dependent episodic memories formed early in life are rapidly forgotten. This process of forgetting is evolutionarily conserved and is associated with infantile amnesia, the inability of adults to recall early-life memories (Campbell and Spear 1972; Rovee-Collier 1999; Hayne 2004; Josselyn and Frankland 2012; Callaghan et al. 2014; Madsen and Kim 2016; Alberini and Travaglia 2017).Although they are rapidly forgotten, early-life experiences influence brain functions throughout life (Jacobs and Nadel 1985; Meaney et al. 1988; Sroufe et al. 1990; Brunson et al. 2005; Pryce et al. 2005; Mineka and Zinbarg 2006; Bale et al. 2010; Poulos et al. 2014; Perry and Sullivan 2014) and produce long-lasting biological changes in the brain. For example, aversive early-life experiences regulate the expression of hippocampal glucocorticoid receptor and hypothalamic–pituitary–adrenal (HPA) functions in a persistent fashion (Champagne and Curley 2009). Moreover, threatening experiences in early life can predispose individuals to psychopathologies such as post-traumatic stress disorder (PTSD) and mood and anxiety disorders (Heim and Nemeroff 2001). Consistent with this long-lasting influence on behavior, studies in rodent models have shown that, in contrast to what was previously believed, memories formed in infancy (at postnatal days 16–18 [PN16–PN18]) although not expressed, are not lost. Rather, they are stored over the longer term in a latent form and can reemerge at later times, up to adulthood, following behavioral reactivations or artificial stimulation of the neuronal ensembles activated at learning (Travaglia et al. 2016; Guskjolen et al. 2018; Bessières et al. 2020).In our previous studies based on rat inhibitory avoidance (IA), a paradigm in which the animal learns to avoid a context previously paired with a footshock, we confirmed that an infantile episodic learning event given at PN17 resulted in the typical rapid forgetting. We then found that, however, this memory was stored long term in a latent form, as demonstrated by the observation that it could reemerge following a behavioral reactivation consisting of exposure to the training context (conditioned stimulus [CS]) and a later time footshock of the same intensity that was used during training (unconditioned stimulus [US]) but now given in a distinct context. Reexperiencing either the context or the footshock alone failed to reinstate the infantile memory (Travaglia et al. 2016), suggesting that the return of infantile memory is limited by certain boundaries.Several questions about the conditions for the recovery of latent, infantile episodic memories remain to be addressed. First, is infantile memory reinstatement following the unpaired US presentation temporally regulated? Second, is there an age limit for memory reinstatement? Third, given that other types of learning, such as non-hippocampus-dependent cued conditioning, are regulated by the maternal presence during infancy (Moriceau and Sullivan 2006), is infantile episodic memory reinstatement limited or regulated by the presence of the mother? In this study, we set out to address these questions using IA in infant rats.     

A Comparison of Five Reinforcement Schedules for use in Contingency Management-Based Treatment of Methamphetamine Abuse

The Psychological Record - One variation of contingency management involves providing vouchers with monetary value for the provision of a biological sample indicating no recent drug use. These...     

Reasoning by exclusion in the kea (<Emphasis Type="Italic">Nestor notabilis</Emphasis>)

Reasoning by exclusion, i.e. the ability to understand that if there are only two possibilities and if it is not A, it must be B, has been a topic of great interest in recent comparative cognition research. Many studies have investigated this ability, employing different methods, but rarely exploring concurrent decision processes underlying choice behaviour of non-human animals encountering inconsistent or incomplete information. Here, we employed a novel training and test method in order to perform an in-depth analysis of the underlying processes. Importantly, to discourage the explorative behaviour of the kea, a highly neophilic species, the training included a large amount of novel, unrewarded stimuli. The subsequent test consisted of 30 sessions with different sequences of four test trials. In these test trials, we confronted the kea with novel stimuli that were paired with either the rewarded or unrewarded training stimuli or with the novel stimuli of previous test trials. Once habituated to novelty, eight out of fourteen kea tested responded to novel stimuli by inferring their contingency via logical exclusion of the alternative. One individual inferred predominantly in this way, while other response strategies, such as one trial learning, stimulus preferences and avoiding the negative stimulus also guided the responses of the remaining individuals. Interestingly, the difficulty of the task had no influence on the test performance. We discuss the implications of these findings for the current hypotheses about the emergence of inferential reasoning in some avian species, considering causal links to brain size, feeding ecology and social complexity.     

Gaze behaviour in hereditary prosopagnosia

Prosopagnosia is the inability to recognize someone by the face alone in the absence of sensory or intellectual impairment. In contrast to the acquired form of prosopagnosia we studied the congenital form. Since we could recently show that this form is inherited as a simple monogenic trait we called it hereditary form. To determine whether not only face recognition and neuronal processing but also the perceptual acquisition of facial information is specific to prosopagnosia, we studied the gaze behaviour of four hereditary prosopagnosics in comparison to matched control subjects. This rarely studied form of prosopagnosia ensures that deficits are limited to face recognition. Whereas the control participants focused their gaze on the central facial features, the hereditary prosopagnosics showed a significantly different gaze behaviour. They had a more dispersed gaze and also fixated external facial features. Thus, the face recognition impairment of the hereditary prosopagnosics is reflected in their gaze behaviour.     

Implementing the Boulder Model of Training in a Psychology Training Clinic

The scientist–practitioner (S–P) model of training has guided professional psychology in the United States for nearly six decades. However, since its inception, the model has been hotly debated and implementation of the model has been chronically problematic. One counseling psychologist who is working as both a faculty member and psychology training clinic director describes how scientific principles can be retained in a practice setting. He overviews the Boulder model of training, provides a brief review of the psychology training clinic (PTC), describes his current work setting and unique faculty appointment, and outlines five strategies for integrating science and practice in applied clinical settings. He also highlights how embracing the Boulder model has promoted a strong professional identity and presents the PTC as a model professional home for S–Ps.     

Justification pressure in risky decision making: search for risk defusing operators

Under justification pressure, the decision maker knows in advance that the decision has to be justified to somebody afterwards. The effect of justification pressure on the search for risk defusing operators (RDOs) and the role of RDOs in the justification texts were investigated. An RDO is an action intended by the decision maker to be performed in addition to an otherwise attractive alternative to decrease the risk. As predicted, in Experiment 1 participants (60 non-students) under justification pressure searched more RDOs. Additionally, in Experiment 2 (80 non-students) RDO search success was varied. Under justification pressure, persistence of RDO search was higher when no RDO could be detected. In the justification texts, the existence or non-existence of RDOs played a prominent role. Searching for RDOs supports people in their goal to make a good decision and in their attempt to convince the addressee of their justification that the decision was good.     

Understanding how engagement in a self‐managed shelter contributes to empowerment

Participant empowerment is a foundational goal of self‐organised homeless care. We aim to understand how a self‐organised setting contributes to participants' empowerment. The data we analysed (56 interviews, both open and semi‐structured) were generated in a longitudinal participatory case study into Je Eigen Stek (Your own place, JES), a low‐cost shelter for people experiencing homelessness in the Netherlands. JES participants experienced the freedom of choice and influence on their living environment. JES' fluid structure allowed participants to adapt the program to their desires and needs, though participants were sometimes negative about having to live together. Most participants preferred JES over regular shelters. Unlike empowerment literature, participants mostly emphasised freedom of choice over capacity development. JES offered opportunities for social and organisational engagement, through which participants developed roles, skills and self‐image. However, a limited number of participants developed leadership roles through self‐management. Literature suggests setting aspects to be either enabling or entrapping. We found some aspects (e.g., size, freedom of choice) could be entrapping or enabling, depending on personal factors. Our analysis revealed individual freedom of choice, balancing freedom of choice with support, offering opportunities for engagement and maintaining fluidity in program management as core aspects of how JES contributed to participants' empowerment.