[Episodic memory: from mind to brain]

Episodic Autobiographical Memory Impairment and Differences in Pronoun Use: Study of Self-Awareness in Functional Amnesia and Transient Global Amnesia

The subjective experience associated to memory processing is the core of the definition of episodic autobiographical memory (EAM). However, while it is widely known that amnesia affects the content of memories, few studies focused on the consequences of an impairment of EAM on the subjective self, also called the I-self. In the present study, we explored the I-self in two puzzling disorders that affect EAM: functional amnesia, which has an impact on autobiographical memory, and transient global amnesia (TGA), which only affects episodic memory. I-self was assessed through an original measure of self-integration in autobiographical narratives, namely the use of general or personal pronouns. Results showed that patients with functional amnesia tended to use general pronouns, whereas patients with TGA preferentially used the first person. The link between I-self and depersonalization-derealisation tendencies was also explored, showing dissociative tendencies in patients with functional amnesia but not in patients with TGA. We discuss these results from a combined neuropsychological and psychopathological perspective, with a view to proposing an explanatory model of the links between self-awareness and the episodic component of autobiographical memory.

Projecting the self in aging: an exploratory study of self-defining future projections

The concept of "Self-Defining Future Projections" (SDFPs) has been recently introduced to better explore the link between future thinking and identity. To date, SDFPs have only been examined in young adults and it remains unknown how self-defining future thoughts evolve in aging. In this cross-sectional study, 43 young adults (age range = 19-28; mean age = 23.06) and 43 older adults (age range 60-80; mean age = 69.46) were asked to generate three SDFPs. Our results indicated that SDFPs were less specific in older adults compared to young adults, but there was no difference between the two groups concerning autobiographical reasoning. However, regarding subjective experience, older adults rated imagined future events as containing more sensory details and contextual information and reported a higher feeling of pre-experiencing the personal future. Additionally, older participants described future events that were more positive and less distant in the future, with fewer narratives about future achievements but more narratives describing leisure time, with a similar probability between the two groups that the event will occur in the future. Our study extends previous aging research and adds to the literature by better understanding how future event representations are formed in older adults.

Multifunctional Polymer Memory via Bi-Interfacial Topography for Pressure Perception Recognition

Emerging memory devices, that can provide programmable information recording with tunable resistive switching under external stimuli, hold great potential for applications in data storage, logic circuits, and artificial synapses. Realization of multifunctional manipulation within individual memory devices is particularly important in the More-than-Moore era, yet remains a challenge. Here, both rewritable and nonerasable memory are demonstrated in a single stimuli-responsive polymer diode, based on a nanohole-nanowrinkle bi-interfacial structure. Such synergic nanostructure is constructed from interfacing a nanowrinkled bottom graphene electrode and top polymer matrix with nanoholes; and it can be easily prepared by spin coating, which is a low-cost and high-yield production method. Furthermore, the resulting device, with ternary and low-power operation under varied external stimuli, can enable both reversible and irreversible biomimetic pressure recognition memories using a device-to-system framework. This work offers both a general guideline to fabricate multifunctional memory devices via interfacial nanostructure engineering and a smart information storage basis for future artificial intelligence.

Hypothesized Mechanisms Through Which Exercise May Attenuate Memory Interference

In this paper we introduce a mechanistic model through which exercise may enhance episodic memory, specifically via attenuating proactive and retroactive memory interference. We discuss the various types of memory, different stages of memory function, review the mechanisms behind forgetting, and the mechanistic role of exercise in facilitating pattern separation (to attenuate memory interference).

Comparison of different protocols of Morris water maze in cognitive impairment with heart failure

AIM

This study aimed to find a more sensitive and systematic behavioral evaluation protocol to evaluate the cognitive impairment in rats with heart failure (HF).

METHODS AND RESULTS

An HF rat model was built by ligating the left anterior descending coronary artery. The cardiac function and structure were detected using echocardiography. Myocardial histopathological changes were observed by nitro blue tetrazolium and hematoxylin-eosin staining. The cognitive functions were evaluated using the acquisition task, probe trial, reversal test, and matching-to-sample test of the Morris water maze. In the probe trial, the number of times the rats in the model group crossed the platform site significantly decreased compared with that in the sham group. In the reversal test, the average latency was significantly longer in the sham group compared with the model group in the first trial but was shorter in the second and third trials. In the matching-to-sample test, the average latency of Trial1 increased significantly in the model group compared with the sham group, while no obvious difference was observed in Trial2. Therefore, the difference in the average latency between Trial1 and Trial2 of the model group was significantly larger.

CONCLUSIONS

The cognitive impairment in rats with HF mainly reflected in the long-term and working memory, spatial learning, and reversal learning ability. The probe trial and reversal test in the water maze may be more sensitive and preferred to evaluate cognitive function after HF. These findings would provide a brief evaluation protocol for further studies on the relationship between cognitive function and HF.

A Real-world What-Where-When Memory Test

Episodic memory is a complex memory system which allows recall and mental re-experience of previous episodes from one's own life. Real-life episodic memories are about events in their spatiotemporal context and are typically visuospatial, rather than verbal. Yet often, tests of episodic memory use verbal material to be recalled (word lists, stories). The Real-World What-Where-When memory test requires participants to hide a total of 16 different objects in 16 different locations over two temporal occasions, 2 h apart. Another two hours later, they are then asked to recall which objects (What) they had hidden in which locations (Where) and on which of the two occasions (When). In addition to counting the number of correctly recalled complete what-where-when combinations, this task can also be used to test real-world spatial memory and object memory. This task is sensitive to normal cognitive aging, and correlates well with performance on other episodic memory tasks, while at the same time providing more ecological validity and being cheap and easy to run.

The emergence of primary anoetic consciousness in episodic memory

Based on an interdisciplinary perspective, we discuss how primary-process, anoetic forms of consciousness emerge into higher forms of awareness such as knowledge-based episodic knowing and self-aware forms of higher-order consciousness like autonoetic awareness. Anoetic consciousness is defined as the rudimentary state of affective, homeostatic, and sensory-perceptual mental experiences. It can be considered as the autonomic flow of primary-process phenomenal experiences that reflects a fundamental form of first-person “self-experience,” a vastly underestimated primary form of phenomenal consciousness. We argue that this anoetic form of evolutionarily refined consciousness constitutes a critical antecedent that is foundational for all forms of knowledge acquisition via learning and memory, giving rise to a knowledge-based, or noetic, consciousness as well as higher forms of “awareness” or “knowing consciousness” that permits “time-travel” in the brain-mind. We summarize the conceptual advantages of such a multi-tiered neuroevolutionary approach to psychological issues, namely from genetically controlled primary (affective) and secondary (learning and memory), to higher tertiary (developmentally emergent) brain-mind processes, along with suggestions about how affective experiences become more cognitive and object-oriented, allowing the developmental creation of more subtle higher mental processes such as episodic memory which allows the possibility of autonoetic consciousness, namely looking forward and backward at one’s life and its possibilities within the “mind’s eye.”

What is Basic about Basic Emotions? Lasting Lessons from Affective Neuroscience

A cross-species affective neuroscience strategy for understanding the primary-process (basic) emotions is defended. The need for analyzing the brain and mind in terms of evolutionary stratification of functions into at least primary (instinctual), secondary (learned), and tertiary (thought-related) processes is advanced. When viewed in this context, the contentious battles between basic-emotion theorists and dimensional-constructivist approaches can be seen to be largely nonsubstantial differences among investigators working at different levels of analysis.

Anatomical pathways for auditory memory in primates

Episodic memory or the ability to store context-rich information about everyday events depends on the hippocampal formation (entorhinal cortex, subiculum, presubiculum, parasubiculum, hippocampus proper, and dentate gyrus). A substantial amount of behavioral-lesion and anatomical studies have contributed to our understanding of the organization of how visual stimuli are retained in episodic memory. However, whether auditory memory is organized similarly is still unclear. One hypothesis is that, like the “visual ventral stream” for which the connections of the inferior temporal gyrus with the perirhinal cortex are necessary for visual recognition in monkeys, direct connections between the auditory association areas of the superior temporal gyrus and the hippocampal formation and with the parahippocampal region (temporal pole, perhirinal, and posterior parahippocampal cortices) might also underlie recognition memory for sounds. Alternatively, the anatomical organization of memory could be different in audition. This alternative “indirect stream” hypothesis posits that, unlike the visual association cortex, the majority of auditory information makes one or more synapses in intermediate, polymodal areas, where they may integrate information from other sensory modalities, before reaching the medial temporal memory system. This review considers anatomical studies that can support either one or both hypotheses – focusing on anatomical studies on the primate brain, primarily in macaque monkeys, that have reported not only direct auditory association connections with medial temporal areas, but, importantly, also possible indirect pathways for auditory information to reach the medial temporal lobe memory system.

Music listening while you learn: no influence of background music on verbal learning

Background

Whether listening to background music enhances verbal learning performance is still disputed. In this study we investigated the influence of listening to background music on verbal learning performance and the associated brain activations.

Methods

Musical excerpts were composed for this study to ensure that they were unknown to the subjects and designed to vary in tempo (fast vs. slow) and consonance (in-tune vs. out-of-tune). Noise was used as control stimulus. 75 subjects were randomly assigned to one of five groups and learned the presented verbal material (non-words with and without semantic connotation) with and without background music. Each group was exposed to one of five different background stimuli (in-tune fast, in-tune slow, out-of-tune fast, out-of-tune slow, and noise). As dependent variable, the number of learned words was used. In addition, event-related desynchronization (ERD) and event-related synchronization (ERS) of the EEG alpha-band were calculated as a measure for cortical activation.

Results

We did not find any substantial and consistent influence of background music on verbal learning. There was neither an enhancement nor a decrease in verbal learning performance during the background stimulation conditions. We found however a stronger event-related desynchronization around 800 - 1200 ms after word presentation for the group exposed to in-tune fast music while they learned the verbal material. There was also a stronger event-related synchronization for the group exposed to out-of-tune fast music around 1600 - 2000 ms after word presentation.

Conclusion

Verbal learning during the exposure to different background music varying in tempo and consonance did not influence learning of verbal material. There was neither an enhancing nor a detrimental effect on verbal learning performance. The EEG data suggest that the different acoustic background conditions evoke different cortical activations. The reason for these different cortical activations is unclear. The most plausible reason is that when background music draws more attention verbal learning performance is kept constant by the recruitment of compensatory mechanisms.

The flow of anoetic to noetic and autonoetic consciousness: a vision of unknowing (anoetic) and knowing (noetic) consciousness in the remembrance of things past and imagined futures

In recent years there has been an expansion of scientific work on consciousness. However, there is an increasing necessity to integrate evolutionary and interdisciplinary perspectives and to bring affective feelings more centrally into the overall discussion. Pursuant especially to the theorizing of Endel Tulving (1985, 2004, 2005), Panksepp (1998a, 2003, 2005) and Vandekerckhove (2009) we will look at the phenomena starting with primary-process consciousness, namely the rudimentary state of autonomic awareness or unknowing (anoetic) consciousness, with a fundamental form of first-person 'self-experience' which relies on affective experiential states and raw sensory and perceptual mental existences, to higher forms of knowing (noetic and autonoetic) and self-aware consciousness. Since current scientific approaches are most concerned with the understanding of higher declarative states of consciousness, we will focus on these vastly underestimated primary forms of consciousness which may be foundational for all forms of higher 'knowing consciousness'.

[Neuropsychological impairment in the early Alzheimer's disease]

This analysis is centered on the study of cognitive disorders in Alzheimer's disease (AD), mainly for major neuro-psychological functions. We insist on the heterogeneity of the clinical picture peculiarly in the early stages of the illness, even if the deficits of episodic memory and of attentional/executive capacities are the first to deteriorate, preceding impairment in perceptual and language function and potentially having a substantial impact on the patient's capacity to cope independently. An episodic memory deficit is the hallmark of AD, but it must be stressed that this deficit may take different forms and its origin may be traced back to different cognitive mechanisms. One of the most striking aspects of episodic memory impairment in AD is the rapidity of forgetfulness on which screening and diagnostic tests of AD are based. There is some evidence that the episodic memory deficit in AD is one of learning (encoding and storage) of information rather than to a deficit of retrieval. Furthermore, episodic memory performance in AD depends on the integrity of semantic memory abilities, so giving support to a hierarchical model of organization of human memory. Finally, recent results show that an impairment of conscious recollection is responsible for the poor performance of AD patients in recognition memory. Executive deficits appear predominantly in tasks requiring cognitive flexibility and self-monitoring. With the progression of the disease, additional deficits are observed in the verbal concept formation abilities. These findings might be also very useful in the differential diagnosis between AD and the other cortical and subcortical dementias, as well as in the differentiation between AD and fronto-temporal dementia. We consider that studying early stages of the illness is necessary to delineate the diagnostic signs, to validate the new therapeutic experiments, to predict stages of decline. Recent research suggested that onset of AD is commonly preceded by an interim phase known as mild cognitive impairment (MCI). MCI refers to the clinical condition in which persons experience memory loss to a greater extent than one would expect for age, yet they do not meet currently accepted criteria for clinically probable AD. Persons who experience this condition are at increased risk for the development of AD. In MCI, despite the comparable global cognitive functioning, the findings show more impaired retrieval from long-term storage than in NC. The cued recall improves slightly the total recall but the recognition is significantly impaired. Moreover, the data indicate that MCI patients had additional problems with response inhibition, switching and cognitive flexibility. This suggests, that MCI may be identified by using a more detailed procedure for the assessment of cognitive decline than the evaluation of memory alone. As preventive strategies are developed and new cognitive enhancing therapies emerge, these results may also help us to define which domains are expected to improve in MCI populations.

[Alzheimer's disease and human memory]

Memory disorders observed in Alzheimer's disease gave rise, from the eighties, to a detailed analysis into the framework of cognitive neuropsychology which aimed at describing the deficits of very specific processes. Beyond their clinical interest, these studies contributed to the modelisation of human memory thanks to the characterization of different memory systems and their relationships. The first part of this paper gives an overview of the memory deficits in Alzheimer's disease and insists on particular cognitive phenomena. Hence, several examples are developed in the domains of semantic memory (such as hyperpriming and hypopriming effects) and autobiographical memory. Recent results highlight the existence of severe autobiographical amnesia observed in all neurodegenerative diseases, though with contrasting profiles: Ribot's gradient in Alzheimer's disease (showing that remote memories are better preserved than recent ones), reverse gradient in semantic dementia and no clear gradient in the frontal variant of frontotemporal dementia. The second part of this article presents advances in cognitive neuroscience searching to disclose the cerebral substrates of these cognitive deficits in Alzheimer's disease. The studies using functional imaging techniques are the most informative regarding this problematic. While showing the dysfunctions of an extended network, they emphasize the selectivity of cerebral damages that are at the root of very specific cognitive dysfunctions, coming close in that way to the conceptions of cognitive neuropsychology. These neuroimaging studies unravel the existence of compensatory mechanisms, which until recently were clearly missing in the literature on neurodegenerative diseases. These different researches lead to a wide conception of human memory, not just limited to simple instrumental processes (encoding, storage, retrieval), but necessarily covering models of identity and continuity of the subject, which interact in a dynamic way with eminently changing memory representations.

Le cerveau, machine à apprendre et à mémoriser

Following a previous paper describing how memory appeared in the nervous system in mammalians, during evolution, and how its significant growth led to hominization, the present paper intends to show the prevailing place it occupies in human brain. Memory, an attribute of cortex, is an engraving of neuronal circuits created during information analysis of data input in the cortex. It is created either by repetition of information or by increase in brain activity, under the influence of a central brain system. In the brain of human newborns, immature and unprogrammed, but endowed with a great capacity for learning, the whole organization and programming will be possible through learning and remembering. Communication pathways between functions are memory pathways. Brain becomes a memory machine and every cortical area is a memory territory. Its lesion results in a disturbance corresponding exactly to forgetting what has been stored in that territory.

Human cognition during REM sleep and the activity profile within frontal and parietal cortices: a reappraisal of functional neuroimaging data

In this chapter, we aimed at further characterizing the functional neuroanatomy of the human rapid eye movement (REM) sleep at the population level. We carried out a meta-analysis of a large dataset of positron emission tomography (PET) scans acquired during wakefulness, slow wave sleep and REM sleep, and focused especially on the brain areas in which the activity diminishes during REM sleep. Results show that quiescent regions are confined to the inferior and middle frontal cortex and to the inferior parietal lobule. Providing a plausible explanation for some of the features of dream reports, these findings may help in refining the concepts, which try to account for human cognition during REM sleep. In particular, we discuss the significance of these results to explain the alteration in executive processes, episodic memory retrieval and self representation during REM sleep dreaming as well as the incorporation of external stimuli into the dream narrative.