The hippocampus and cerebellum in adaptively timed learning, recognition, and movement

The concepts of declarative memory and procedural memory have been used to distinguish two basic types of learning. A neural network model suggests how such memory processes work together as recognition learning, reinforcement learning, and sensory-motor learning take place during adaptive behaviors. To coordinate these processes, the hippocampal formation and cerebellum each contain circuits that learn to adaptively time their outputs. Within the model, hippocampal timing helps to maintain attention on motivationally salient goal objects during variable task-related delays, and cerebellar timing controls the release of conditioned responses. This property is part of the model's description of how cognitive-emotional interactions focus attention on motivationally valued cues, and how this process breaks down due to hippocampal ablation. The model suggests that the hippocampal mechanisms that help to rapidly draw attention to salient cues could prematurely release motor commands were not the release of these commands adaptively timed by the cerebellum. The model hippocampal system modulates cortical recognition learning without actually encoding the representational information that the cortex encodes. These properties avoid the difficulties faced by several models that propose a direct hippocampal role in recognition learning. Learning within the model hippocampal system controls adaptive timing and spatial orientation. Model properties hereby clarify how hippocampal ablations cause amnesic symptoms and difficulties with tasks which combine task delays, novelty detection, and attention towards goal objects amid distractions. When these model recognition, reinforcement, sensory-motor, and timing processes work together, they suggest how the brain can accomplish conditioning of multiple sensory events to delayed rewards, as during serial compound conditioning.Air Force Office of Scientific Research (F49620-92-J-0225, F49620-86-C-0037, 90-0128); Advanced Research Projects Agency (ONR N00014-92-J-4015); Office of Naval Research (N00014-91-J-4100, N00014-92-J-1309, N00014-92-J-1904); National Institute of Mental Health (MH-42900

Persons Versus Brains: Biological Intelligence in Human Organisms

I go deep into the biology of the human organism to argue that the psychological features and functions of persons are realized by cellular and molecular parallel distributed processing networks dispersed throughout the whole body. Persons supervene on the computational processes of nervous, endocrine, immune, and genetic networks. Persons do not go with brains

At clinically relevant concentrations the anaesthetic/amnesic thiopental but not the anticonvulsant phenobarbital interferes with hippocampal sharp wave-ripple complexes

<p>Abstract</p> <p>Background</p> <p>Many sedative agents, including anesthetics, produce explicit memory impairment by largely unknown mechanisms. Sharp-wave ripple (SPW-R) complexes are network activity thought to represent the neuronal substrate for information transfer from the hippocampal to neocortical circuits, contributing to the explicit memory consolidation. In this study we examined and compared the actions of two barbiturates with distinct amnesic actions, the general anesthetic thiopental and the anticonvulsant phenobarbital, on in vitro SPW-R activity.</p> <p>Results</p> <p>Using an in vitro model of SPW-R activity we found that thiopental (50–200 μM) significantly and concentration-dependently reduced the incidence of SPW-R events (it increased the inter-event period by 70–430 %). At the concentration of 25 μM, which clinically produces mild sedation and explicit memory impairment, thiopental significantly reduced the quantity of ripple oscillation (it reduced the number of ripples and the duration of ripple episodes by 20 ± 5%, n = 12, <it>P </it>< 0.01), and suppressed the rhythmicity of SPWs by 43 ± 15% (n = 6, <it>P </it>< 0.05). The drug disrupted the synchrony of SPWs within the CA1 region at 50 μM (by 19 ± 12%; n = 5, <it>P </it>< 0.05). Similar effects of thiopental were observed at higher concentrations. Thiopental did not affect the frequency of ripple oscillation at any of the concentrations tested (10–200 μM). Furthermore, the drug significantly prolonged single SPWs at concentrations ≥50 μM (it increased the half-width and the duration of SPWs by 35–90 %). Thiopental did not affect evoked excitatory synaptic potentials and its results on SPW-R complexes were also observed under blockade of NMDA receptors. Phenobarbital significantly accelerated SPWs at 50 and 100 μM whereas it reduced their rate at 200 and 400 μM. Furthermore, it significantly prolonged SPWs, reduced their synchrony and reduced the quantity of ripples only at the clinically very high concentration of 400 μM, reported to affect memory.</p> <p>Conclusion</p> <p>We hypothesize that thiopental, by interfering with SPW-R activity, through enhancement of the GABA_Areceptor-mediated transmission, affects memory processes which involve hippocampal circuit activation. The quantity but not the frequency of ripple oscillation was affected by the drug.</p

Wandering in Contemporary Literature: A Narrative Theory of Cognition

This study offers a theory of wandering cognition as an animating feature of western literature, in general, and of contemporary literature, in particular. Unlike existing theories of peripatetic bodies and minds in fiction that focus primarily on political critiques, cultural practices, or pleasures of digression, this theory of wandering offers an aesthetic philosophy and ethical critique of representing cognition, memory, and narrative identity that finds affinities in the political, phenomenological, and ethical thought of Walter Benjamin, Emmanuel Levinas, and Giorgio Agamben. Unlike existing cognitive theories of literature that apply cognitive theory to literary study (or vice versa), this study develops an aesthetic and phenomenological theory of consciousness that emerges from within the representation of perception, attentiveness, and memory in literatures of wandering minds. Wandering generates narrative identity apart from conventional and normative narrativity, a narrative consciousness that accounts for the cognitive motion (and blindspots) in remembering selves and that illuminates cognitive mimeses of amnesic, episodic, and disabled consciousness. Finally, while this study focuses primarily on the contemporary literary experiments of wandering in the works of Kazuo Ishiguro, W.G. Sebald, Ben Lerner, and Maud Casey, it has a wider reach in its retrospective and prospective rethinking of the function of peripatetic fiction. Wandering is built into the narrative motion and aesthetic technique of narrated and remembering identities in the early Romantic autobiography of Rousseau, Wordsworth, and De Quincey; and wandering underlies the conscious identities narrated absent memory in the emerging genre of the amnesic memoir

Brain Learning, Attention, and Consciousness

The processes whereby our brains continue to learn about a changing world in a stable fashion throughout life are proposed to lead to conscious experiences. These processes include the learning of top-down expectations, the matching of these expectations against bottom-up data, the focusing of attention upon the expected clusters of information, and the development of resonant states between bottom-up and top-down processes as they reach an attentive consensus between what is expected and what is there in the outside world. It is suggested that all conscious states in the brain are resonant states, and that these resonant states trigger learning of sensory and cognitive representations. The model which summarize these concepts are therefore called Adaptive Resonance Theory, or ART, models. Psychophysical and neurobiological data in support of ART are presented from early vision, visual object recognition, auditory streaming, variable-rate speech perception, somatosensory perception, and cognitive-emotional interactions, among others. It is noted that ART mechanisms seem to be operative at all levels of the visual system, and it is proposed how these mechanisms are realized by known laminar circuits of visual cortex. It is predicted that the same circuit realization of ART mechanisms will be found in the laminar circuits of all sensory and cognitive neocortex. Concepts and data are summarized concerning how some visual percepts may be visibly, or modally, perceived, whereas amoral percepts may be consciously recognized even though they are perceptually invisible. It is also suggested that sensory and cognitive processing in the What processing stream of the brain obey top-down matching and learning laws that arc often complementary to those used for spatial and motor processing in the brain's Where processing stream. This enables our sensory and cognitive representations to maintain their stability a.s we learn more about the world, while allowing spatial and motor representations to forget learned maps and gains that are no longer appropriate as our bodies develop and grow from infanthood to adulthood. Procedural memories are proposed to be unconscious because the inhibitory matching process that supports these spatial and motor processes cannot lead to resonance.Defense Advance Research Projects Agency; Office of Naval Research (N00014-95-1-0409, N00014-95-1-0657); National Science Foundation (IRI-97-20333

Individuals With Amnesia are not Stuck in Time: Evidence From Risky Decision-Making, Intertemporal Choice, and Scaffolded Narratives

This dissertation investigates the supposition that individuals with amnesia are cognitively stuck in time. In Experiment 1, I used a Galton-Crovitz cueing paradigm to test etiologically diverse amnesic cases on their ability to richly recollect autobiographical episodic memories and imagine future experiences. In Experiment 2, I use two behavioural economics tasks (a risky decision-making task and an intertemporal choice task) to examine whether amnesic cases judgment and decision-making reflects proneness to risky choices or steep disregard for the future. In Experiment 3, I examine the flexibility of amnesics intertemporal choice by testing whether cueing them with personal future events increases their value of future rewards as it does in healthy controls. In Experiment 4, I attempt to decrease the severity of amnesic cases episodic memory and prospection impairment by using structured and personally meaningful cues rather than the single cue words featured in the Galton-Crovitz paradigm. I replicated existing research showing that those with MTL damage have impaired ability to (re)construct rich and detailed narratives of past and future experiences, and I extended this finding for the first time to a lateral dorsal thalamic stroke case (Experiment 1). Despite this impairment in mental time travel, the same amnesic cases made financial decisions that a) systematically considered and valued the future and b) showed normal sensitivity to risk (Experiment 2). The normalcy of intertemporal choice in amnesia extends beyond basic rates of future reward discounting in intertemporal choice. In controls, cues to imagine future experiences can modulate decision-making by increasing the value one places on future rewards. Here, most amnesic cases also retain this modulatory effect, despite having impaired ability to generate detailed representations of future experiences (Experiment 3). Finally, I found that the severity of episodic prospection impairment in MTL amnesia is cue-dependent and likely overestimated in current research: specific, personally meaningful cues lead to an appreciable reduction of episodic prospection impairment over single cue words for those with mild-moderate amnesia (Experiment 4). Collectively, results challenge assumptions that amnesic populations are cognitively confined to the present and call for refinement to simple accounts of limited temporality in individuals with amnesia

Active Forgetting: Adaptation of Memory by Prefrontal Control.

Over the past century, psychologists have discussed whether forgetting might arise from active mechanisms that promote memory loss to achieve various functions, such as minimizing errors, facilitating learning, or regulating one's emotional state. The past decade has witnessed a great expansion in knowledge about the brain mechanisms underlying active forgetting in its varying forms. A core discovery concerns the role of the prefrontal cortex in exerting top-down control over mnemonic activity in the hippocampus and other brain structures, often via inhibitory control. New findings reveal that such processes not only induce forgetting of specific memories but also can suppress the operation of mnemonic processes more broadly, triggering windows of anterograde and retrograde amnesia in healthy people. Recent work extends active forgetting to nonhuman animals, presaging the development of a multilevel mechanistic account that spans the cognitive, systems, network, and even cellular levels. This work reveals how organisms adapt their memories to their cognitive and emotional goals and has implications for understanding vulnerability to psychiatric disorders

The multiplicity of self: neuropsychological evidence and its implications for the self as a construct in psychological research

This paper examines the issue ofwhat the self is by reviewing neuropsychological research,which converges on the idea that the selfmay be more complex and differentiated than previous treatments of the topic have suggested. Although some aspects of self-knowledge such as episodic recollection may be compromised in individuals, other aspects—for instance, semantic trait summaries—appear largely intact. Taken together, these findings support the idea that the self is not a single, unified entity. Rather, it is a set of interrelated, functionally independent systems. Implications for understanding the self in various areas of psychological research—e.g., neuroimaging, autism, amnesia, Alzheimer’s disease, and mirror self-recognition—are discussed in brief