The hippocampal formation and action at a distance

2021 ◽  
Vol 118 (51) ◽  
pp. e2119670118
Author(s):  
Lynn Nadel

The question of why our conceptions of space and time are intertwined with memory in the hippocampal formation is at the forefront of much current theorizing about this brain system. In this article I argue that animals bridge spatial and temporal gaps through the creation of internal models that allow them to act on the basis of things that exist in a distant place and/or existed at a different time. The hippocampal formation plays a critical role in these processes by stitching together spatiotemporally disparate entities and events. It does this by 1) constructing cognitive maps that represent extended spatial contexts, incorporating and linking aspects of an environment that may never have been experienced together; 2) creating neural trajectories that link the parts of an event, whether they occur in close temporal proximity or not, enabling the construction of event representations even when elements of that event were experienced at quite different times; and 3) using these maps and trajectories to simulate possible futures. As a function of these hippocampally driven processes, our subjective sense of both space and time are interwoven constructions of the mind, much as the philosopher Immanuel Kant postulated.

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
A A A Baraka ◽  
K A Hafez ◽  
A I A Othman ◽  
A M M Sadek

Abstract Introduction In recent year deterioration in cognitive, learning, and memory become one of the significant problems in human life. Hippocampus is a pivotal part of the brain’s limbic system which serves a critical role in memory, learning process and regulating the emotions. In most regions of the brain, neurons are generated only at specific periods of early development, and not born in the adulthood. In contrast, hippocampal neurons are generated throughout development and adult life. The hippocampal dentate gyrus was reported to be one of the few regions of the mammalian brain where neurogenesis continue to occur throughout adulthood. The neurogenesis in the dentate gyrus was thought to play an important role in hippocampus-dependent learning and memory. The hippocampal formation is composed of the hippocampus proper, the dentate gyrus and the subiculum. The hippocampus proper is the largest part and is subdivided into fields designated as Cornu Ammonis or Ammon’s horn (CA) from CA1 to CA4. Ammon's horn is continuous with the subiculum, which acts as the main output source of the hippocampal formation. Aim of the Study To study the postnatal development of the hippocampal formation. Materials and Methods Five male albino rats from the following postnatal ages day 1, week 1, week 2, week3 and week 4 were studied by histological, immunohistochemical, and morphometric methods. Results The general architecture of the hippocampus proper with its polymorphic, pyramidal, and molecular layers was present at day1, whereas the details of the adult structure appeared at week 2. In the dentate gyrus, distinct lamination appeared at week 1 and its maturation continued with the production of neurons at the interhilar zone that peaked at week 2. The number and density of pyramidal axons and dendrites increase by age. Astrocytes increased in size and staining affinity for glial filaments, and acquired a stellate shape with age. Furthermore, the number of granule cell layers increased concomitantly with the increase in thickness of the molecular and polymorphic layers of both the hippocampus proper and the dentate gyrus. Conclusion The important sequences of events in the growth and maturation of the hippocampal formation in male albino rat occurred in the first 2 postnatal weeks.


Philosophy ◽  
1936 ◽  
Vol 11 (42) ◽  
pp. 131-145
Author(s):  
W. R. Inge

My subject is the place of myth in philosophy, not in religion. If I were dealing with the philosophy of religion, I should, of course, have much to say on the place of myth in theology; and what I have to say may have some bearing on this subject; but I am not dealing with particular dogmas of Christianity or of any other religion. My thesis is that when the mind communes with the world of values its natural and inevitable language is the language of poetry, symbol, and myth. And, further, that philosophy has to deal with a number of irreducible surds which cannot be rationalized. They must be accepted as given material for reason to work upon. For example, we do not know why there is a world; we cannot unify the world of what we call facts and the world of values; there are antinomies in space and time which do not seem to disappear when we put a hyphen between them. Our reason–some would say reason itself— has reached its limits. We are driven to mythologize, confessing that we have left the realm of scientific fact. We give rein to the imagination, not exactly claiming with Wordsworth that it is reason in her most exalted mood, but hoping that the creative imagination may reveal to us some of the real meaning of questions which we cannot answer.


Author(s):  
Jauhan Budiwan

Immanuel Kant is one of the most influential philosophers in the history of Western philosophy. His contributions to metaphysics, epistemology, ethics, and aesthetics have had a profound impact on almost every philosophical movement that followed him. This portion will focus on his metaphysics and epistemology in one of his most important works. The Critique of Pure Reason, A large part of Kant’s work addresses the question “What can we know?” The answer, if it can be stated simply, is that our knowledge is constrained to mathematics and the science of the -natural, empirical world. It is impossible, Kant argues, to extend knowledge to the supersensible realm of speculative metaphysics. The reason that knowledge has these constraints, Kant argues, is that the mind plays an active role in constituting the features of experience and limiting the mind's access to the empirical realm of space and time. In order to understand Kant's position, we must understand the philosophical background that he was reacting to. First, 1 will present a brief overview of his predecessor's positions with a brief statement of Kant's objections, then I will return to a more detailed exposition of Kant's arguments. There are two major historical movements in the early modem period of philosophy that had a significant impact on Kant; Empiricism and Rationalism,


Author(s):  
G. A. Cohen

This chapter examines G. W. F. Hegel's dialectic of the master and the slave which he articulated in his book Phenomenology of Spirit and how it is related to his general philosophy. Hegel thought that everything the mind, any mind, experiences is in some sense a product of mind itself. One way of explaining how he arrived at this strange idea is by describing how he responded to the thought of Immanuel Kant. Kantian philosophy features a set of dualities or oppositions, such as those between freedom and necessity, between the sensibility and the understanding, between the analytic and the synthetic, and between the infinite and the finite. Whereas Kant loved dichotomies, Hegel abhorred ultimate dichotomies in the scheme of things. The chapter considers some tenets of Absolute Idealism in order to elucidate some of the more general philosophical questions with which Hegel was concerned in the course of his master/slave discussion.


Author(s):  
David Fate Norton

Francis Hutcheson is best known for his contributions to moral theory, but he also contributed to the development of aesthetics. Although his philosophy owes much to John Locke’s empiricist approach to ideas and knowledge, Hutcheson was sharply critical of Locke’s account of two important normative ideas, those of beauty and virtue. He rejected Locke’s claim that these ideas are mere constructs of the mind that neither copy nor make reference to anything objective. He also complained that Locke’s account of human pleasure and pain was too narrowly focused. There are pleasures and pains other than those that arise in conjunction with ordinary sensations; there are, in fact, more than five senses. Two additional senses, the sense of beauty and the moral sense, give rise to distinctive pleasures and pains that enable us to make aesthetic and moral distinctions and evaluations. Hutcheson’s theory of the moral sense emphasizes two fundamental features of human nature. First, in contrast to Thomas Hobbes and other egoists, Hutcheson argues that human nature includes a disposition to benevolence. This characteristic enables us to be, sometimes, genuinely virtuous. It enables us to act from benevolent motives, whereas Hutcheson identifies virtue with just such motivations. Second, we are said to have a perceptual faculty, a moral sense, that enables us to perceive moral differences. When confronted with cases of benevolently motivated behaviour (virtue), we naturally respond with a feeling of approbation, a special kind of pleasure. Confronted with maliciously motivated behaviour (vice), we naturally respond with a feeling of disapprobation, a special kind of pain. In short, certain distinctive feelings of normal observers serve to distinguish between virtue and vice. Hutcheson was careful, however, not to identify virtue and vice with these feelings. The feelings are perceptions (elements in the mind of observers) that function as signs of virtue and vice (qualities of agents). Virtue is benevolence, and vice malice (or, sometimes, indifference); our moral feelings serve as signs of these characteristics. Hutcheson’s rationalist critics charged him with making morality relative to the features human nature happens at present to have. Suppose, they said, that our nature were different. Suppose we felt approbation where we now feel disapprobation. In that event, what we now call ‘vice’ would be called ‘virtue’, and what we call ‘virtue’ would be called ‘vice’. The moral sense theory must be wrong because virtue and vice are immutable. In response, Hutcheson insisted that, as our Creator is unchanging and intrinsically good, the dispositions and faculties we have can be taken to be permanent and even necessary. Consequently, although it in one sense depends upon human nature, morality is immutable because it is permanently determined by the nature of the Deity. Hutcheson’s views were widely discussed throughout the middle decades of the eighteenth century. He knew and advised David Hume, and, while Professor of Moral Philosophy at Glasgow, taught Adam Smith. Immanuel Kant and Jeremy Bentham, among other philosophers, also responded to his work, while in colonial America his political theory was widely seen as providing grounds for rebellion against Britain.


2019 ◽  
Vol 30 (5) ◽  
pp. 3102-3115 ◽  
Author(s):  
Yafei Wang ◽  
Zhiheng Lu ◽  
Yilan Zhang ◽  
Yuqun Cai ◽  
Di Yun ◽  
...  

Abstract The dentate gyrus (DG) of the hippocampal formation plays essential roles in learning and memory. Defective DG development is associated with neurological disorders. Here, we show that transcription factor 4 (Tcf4) is essential for DG development. Tcf4 expression is elevated in neural progenitors of the dentate neuroepithelium in the developing mouse brain. We demonstrate that conditional disruption of Tcf4 in the dentate neuroepithelium leads to abnormal neural progenitor migration guided by disorganized radial glial fibers, which further leads to hypoplasia in the DG. Moreover, we reveal that Wnt7b is a key downstream effector of Tcf4 in regulating neural progenitor migration. Behavioral analysis shows that disruption of integrity of the DG impairs the social memory highlighting the importance of proper development of the DG. These results reveal a critical role for Tcf4 in regulating DG development. As mutations in TCF4 cause Pitt–Hopkins syndrome (PTHS) characterized by severe intellectual disability, our data also potentially provide insights into the basis of neurological defects linked to TCF4 mutations.


2020 ◽  
pp. 105971232096646
Author(s):  
Frederick L Coolidge

The purpose of this article is to review the evolution and function of the cerebellum, particularly in regard to its role in creativity and expert stone knapping. First, the article reviews the history of the cerebellum, its evolution and phylogenetics, and its concerted evolution with various brain regions. It also notes the critical role of the cerebellum and the cerebro-cerebellar network in its traditionally recognized control of gross and fine motor movements and in its exaptation for basic and higher level cognitive processes, particularly in regard to increasingly more sophisticated stone knapping. Also, reviewed are various theories, advanced over the past three decades, of how the cerebellum tweaks and refines thoughts, images, and ideas just as it refines and smooths motor movements. Baddeley’s working memory model is also prominently featured, as are the works of Ito, Vandervert, and others on the cerebellum’s role in novel problem-solving, insight, and creativity. Finally, this article reviews two “Cognitive Rubicons” in stone tool knapping, Theory of Mind and stone knapping, and Malafouris’ Material Engagement Theory. The article concludes with a novel hypothesis that the automaticity provided by the cerebellum derived from extensive practice in stone knapping may have freed Baddeley’s central executive from its attentional demands and allows the mind to “wander and wonder.”


Literator ◽  
2003 ◽  
Vol 24 (1) ◽  
pp. 125-144
Author(s):  
J. Anker

The role and function of deictic context in a prose text This article examines the nature and function of deictics in a prose text. By referring to different theories of pragmatics and literature, the nature of communication in literary texts and the role that deixis plays in these texts become evident. In a prose text a process of communication exists in which the utterance produced by the speaker (author) is interpreted by a hearer (reader). The reader reconstructs a context for this communication by the interpretation of the speaker’s references to person, place and time – the deictic elements. The reader determines the deictic context in a text by defining and interpreting the communication of the abstract author, the different speaker’s references to persons, space and time and by interpreting the implications in the linguistic utterance. In this way a deictic context is formed in the mind of the reader which forms the basis for his understanding of the message in the text.


2020 ◽  
Vol 11 ◽  
Author(s):  
Pejman Sehatpour ◽  
Anahita Bassir Nia ◽  
Devin Adair ◽  
Zhishun Wang ◽  
Heloise M. DeBaun ◽  
...  

The term perceptual closure refers to the neural processes responsible for “filling-in” missing information in the visual image under highly adverse viewing conditions such as fog or camouflage. Here we used a closure task that required the participants to identify barely recognizable fragmented line-drawings of common objects. Patients with schizophrenia have been shown to perform poorly on this task. Following priming, controls and importantly patients can complete the line-drawings at greater levels of fragmentation behaviorally, suggesting an improvement in their ability to perform the task. Closure phenomena have been shown to involve a distributed network of cortical regions, notably the lateral occipital complex (LOC) of the ventral visual stream, dorsal visual stream (DS), hippocampal formation (HIPP) and the prefrontal cortex (PFC). We have previously demonstrated the failure of closure processes in schizophrenia and shown that the dysregulation in the sensory information transmitted to the prefrontal cortex plays a critical role in this failure. Here, using a multimodal imaging approach in patients, combining event related electrophysiological recordings (ERP) and functional magnetic resonance imaging (fMRI), we characterize the spatiotemporal dynamics of priming in perceptual closure. Using directed functional connectivity measures we demonstrate that priming modifies the network-level interactions between the nodes of closure processing in a manner that is functionally advantageous to patients resulting in the mitigation of their deficit in perceptual closure.


Author(s):  
Marco Sgarbi ◽  

«Two things fill the mind with ever new and increasing admiration and awe, the more often and steadily reflection is occupied with them: the starry heaven above me and the moral law within me». With these famous words written on paper and inscribed in stone, Immanuel Kant concludes the Critique of Practical Reason. In this paper, I intend to show how this sentence is closely linked with: 1) the kantian doctrine on the sublime and 2) to the foundation of the logic of the irrational in the Critique of Judgement.


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