Integrating across memory episodes: Developmental trends

Memory enables us to use information from our past experiences to guide new behaviours, calling for the need to integrate or form inference across multiple distinct episodic experiences. Here, we compared children (aged 9-10 years), adolescents (aged 12-13 years), and young adults (aged 19-25 years) on their ability to form integration across overlapping associations in memory. Participants first encoded a set of overlapping, direct AB- and BC-associations (object-face and face-object pairs) as well as non-overlapping, unique DE-associations. They were then tested on these associations and inferential AC-associations. The experiment consisted of four such encoding/retrieval cycles, each consisting of different stimuli set. For accuracy on both unique and inferential associations, young adults were found to outperform teenagers, who in turn outperformed children. However, children were particularly slower than teenagers and young adults in making judgements during inferential than during unique associations. This suggests that children may rely more on making inferences during retrieval, by first retrieving the direct associations, followed by making the inferential judgement. Furthermore, young adults showed a higher correlation between accuracy in direct (AB, BC) and inferential AC-associations than children. This suggests that, young adults relied closely on AB- and BC-associations for making AC decisions, potentially by forming integrated ABC-triplets during encoding or retrieval. Taken together, our findings suggest that there may be an age-related shift in how information is integrated across experienced episodes, namely from relying on making inferences at retrieval during middle childhood to forming integrated representations at different memory processing stages in adulthood

The Role Of The Ventromedial Prefrontal Cortex In Value-Based Decision-Making

The ventromedial prefrontal cortex (vmPFC) has been shown to correlate with the subjective value for options, across reward type and across hundreds of functional neuroimaging studies. Despite the prominence of its role in preference-based decision-making, its specific contributions to how decisions are made have not yet been well-characterised. Study 1 addresses what the vmPFC signal represents during decision-making. While the vmPFC signal has been shown to correlate highly with subjective value in past studies, this signal is also consistent with mental navigation through a conceptual attribute space using a grid-like code. We found that the mental navigation model lacked support in the evidence, and the subjective value model remains the best explanation for vmPFC signal during decision-making. After having established that the signal in vmPFC reflects subjective value, Study 2 addresses whether subjective value representations remain consistent for non-choice preference tasks, and when this representation comes online during the decision process. This study shows that the value network seen previously for choice tasks also is active during a matching bidding task, and that the vmPFC, interestingly, represents value only at the time of the final choice. Finally, in Study 3, I address the question of how the vmPFC is necessary for subjective value in my third chapter. Transitivity (the idea that if A \u3e B, and B \u3e C, then A \u3e C) is a key property of a value-based system. Individuals with ventromedial frontal lobe damage have been found to make more transitivity errors in the past, but it is not known whether vmPFC damage causes fundamentally intransitive choices (implying abolishment of value), or transitive but noisier choices (implying preservation of value but increased instability). We found strong evidence for the second case, demonstrating that vmPFC damage adds instability to valuation but does not abolish it. The evidence I present here is consistent with the theory that vmPFC is involved in a subjective value-based process during decision-making, yet that value is a distributed process over many brain regions where other regions may compensate for the loss of the vmPFC in calculating value

CNTRICS Final Task Selection: Long-term Memory

Long-term memory (LTM) is a multifactorial construct, composed of different stages of information processing and different cognitive operations that are mediated by distinct neural systems, some of which may be more responsible for the marked memory problems that limit the daily function of individuals with schizophrenia. From the outset of the CNTRICS initiative, this multidimensionality was appreciated, and an effort was made to identify the specific memory constructs and task paradigms that hold the most promise for immediate translational development. During the second CNTRICS meeting, the LTM group identified item encoding and retrieval and relational encoding and retrieval as key constructs. This article describes the process that the LTM group went through in the third and final CNTRICS meeting to select nominated tasks within the 2 LTM constructs and within a reinforcement learning construct that were judged most promising for immediate development. This discussion is followed by each nominating authors' description of their selected task paradigm, ending with some thoughts about future directions.Psycholog

Neuronal modulation in the prefrontal cortex in a transitive inference task: evidence of neuronal correlates of mental schema management

When informed that A > B and B > C, humans and other animals can easily conclude that A > C. This remarkable trait of advanced animals, which allows them to manipulate knowledge flexibly to infer logical relations, has only recently garnered interest in mainstream neuroscience. How the brain controls these logical processes remains an unanswered question that has been merely superficially addressed in neuroimaging and lesion studies, which are unable to identify the underlying neuronal computations. We observed that the activation pattern of neurons in the prefrontal cortex (PFC) during pair comparisons in a highly demanding transitive inference task fully supports the behavioral performance of the two monkeys that we tested. Our results indicate that the PFC contributes to the construction and use of a mental schema to represent premises. This evidence provides a novel framework for understanding the function of various areas of brain in logic processes and impairments to them in degenerative, traumatic, and psychiatric pathologies. SIGNIFICANCE STATEMENT: In cognitive neuroscience, it is unknown how information that leads to inferential deductions are encoded and manipulated at the neuronal level. We addressed this question by recording single-unit activity from the dorsolateral prefrontal cortex of monkeys that were performing a transitive inference (TI) task. The TI required one to choose the higher ranked of two items, based on previous, indirect experience. Our results demonstrated that single-neuron activity supports the construction of an abstract, mental schema of ordered items in solving the task and that this representation is independent of the reward value that is experienced for the single items. These findings identify the neural substrates of abstract mental representations that support inferential thinking

VRT (verbal reasoning test): a new test for assessment of verbal reasoning. Test realization and Italian normative data from a multicentric study

open14noopenBasagni, Benedetta; Luzzatti, Claudio; Eduardo, Navarrete; Caputo, Marina; Scrocco, Gessica; Damora, Alessio; Giunchi, Laura; Gemignani, Paola; Caiazzo, Annarita; Gambini, Maria Grazia; Avesani, Renato; Mancuso, Mauro; Trojano, Luigi; De Tanti, AntonioBasagni, Benedetta; Luzzatti, Claudio; Navarrete, Eduardo; Caputo, Marina; Scrocco, Gessica; Damora, Alessio; Giunchi, Laura; Gemignani, Paola; Caiazzo, Annarita; Gambini, Maria Grazia; Avesani, Renato; Mancuso, Mauro; Trojano, Luigi; De Tanti, Antoni

Transitivity performance, relational hierarchy knowledge and awareness: Results of an instructional framing manipulation.

The transitive inference (TI) paradigm has been widely used to examine the role of the hippocampus in generalization. Here we consider a surprising feature of experimental findings in this task: the relatively poor transitivity performance and levels of hierarchy knowledge achieved by adult human subjects. We focussed on the influence of the task instructions on participants' subsequent performance - through a single-word framing manipulation which either specified the relation between items as transitive (i.e

Specialization of the rostral prefrontal cortex for distinct analogy processes

Analogical reasoning is central to learning and abstract thinking. It involves using a more familiar situation (source) to make inferences about a less familiar situation (target). According to the predominant cognitive models, analogical reasoning includes 1) generation of structured mental representations and 2) mapping based on structural similarities between them. This study used functional magnetic resonance imaging to specify the role of rostral prefrontal cortex (PFC) in these distinct processes. An experimental paradigm was designed that enabled differentiation between these processes, by temporal separation of the presentation of the source and the target. Within rostral PFC, a lateral subregion was activated by analogy task both during study of the source (before the source could be compared with a target) and when the target appeared. This may suggest that this subregion supports fundamental analogy processes such as generating structured representations of stimuli but is not specific to one particular processing stage. By contrast, a dorsomedial subregion of rostral PFC showed an interaction between task (analogy vs. control) and period (more activated when the target appeared). We propose that this region is involved in comparison or mapping processes. These results add to the growing evidence for functional differentiation between rostral PFC subregions

The role of the hippocampus in generalizing configural relationships

The hippocampus has been implicated in integrating information across separate events in support of mnemonic generalizations. These generalizations may be underpinned by processes at both encoding (linking similar information across events) and retrieval (“on-the-fly” generalization). However, the relative contribution of the hippocampus to encoding- and retrieval-based generalizations is poorly understood. Using fMRI in humans, we investigated the hippocampal role in gradually learning a set of spatial discriminations and subsequently generalizing them in an acquired equivalence task. We found a highly significant correlation between individuals’ performance on a generalization test and hippocampal activity during the test, providing evidence that hippocampal processes support on-the-fly generalizations at retrieval. Within the same hippocampal region there was also a correlation between activity during the final stage of learning (when all associations had been learnt but no generalization was required) and subsequent generalization performance. We suggest that the hippocampus spontaneously retrieves prior events that share overlapping features with the current event. This process may also support the creation of generalized representations during encoding. These findings are supportive of the view that the hippocampus contributes to both encoding- and retrieval-based generalization via the same basic mechanism; retrieval of similar events sharing common features

The interplay of hippocampus and ventromedial prefrontal cortex in memory-based decision making

Episodic memory and value-based decision making are two central and intensively studied research domains in cognitive neuroscience, but we are just beginning to understand how they interact to enable memory-based decisions. The two brain regions that have been associated with episodic memory and value-based decision making are the hippocampus and the ventromedial prefrontal cortex, respectively. In this review article, we first give an overview of these brain–behavior associations and then focus on the mechanisms of potential interactions between the hippocampus and ventromedial prefrontal cortex that have been proposed and tested in recent neuroimaging studies. Based on those possible interactions, we discuss several directions for future research on the neural and cognitive foundations of memory-based decision making

Memory integration in humans with hippocampal lesions

Adaptive behavior frequently depends on inference from past experience. Recent studies suggest that the underlying process of integrating related memories may depend on interaction between hippocampus and prefrontal cortex. Here, we investigated how hippocampal damage affects memory integration. Subjects with mediotemporal lesions and healthy controls learned a set of overlapping AB- and BC-associations (object-face- and face-object pairs) and were then tested for memory of these associations (“direct” trials) and of inferential AC-associations (“indirect” trials). The experiment consisted of four encoding/retrieval cycles. In direct trials, performance of patients and controls was similar and stable across cycles. By contrast, in indirect trials, patients and controls showed distinct patterns of behavior. Whereas patients and controls initially showed only minor differences, controls increased performance across subsequent cycles, while patient performance decreased to chance level. Further analysis suggested that this deficit was not merely a consequence of impaired associative memory but rather resulted from an additional hippocampal contribution to memory integration. Our findings further suggest that contextual factors modulate this contribution. Patient deficits in more complex memory-guided behavior may depend on the flexible interaction of hippocampus-dependent and -independent mechanisms of memory integration