Logothetis, N.K.: Single units and conscious vision. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 353, 1801-1818 (1998) Abstract.

Traditional explanations of multistable visual phenomena (e.g. ambiguous figures, perceptual rivalry) suggest that the basis for spontaneous reversals in perception lies in antagonistic connectivity within the visual system. In this review, we suggest an alternative, albeit speculative, explanation for visual multistability – that spontaneous alternations reflect responses to active, programmed events initiated by brain areas that integrate sensory and non-sensory information to coordinate a diversity of behaviors. Much evidence suggests that perceptual reversals are themselves more closely related to the expression (...) of a behavior than to passive sensory responses: (1) they are initiated spontaneously, often voluntarily, and are influenced by subjective variables such as attention and mood; (2) the alternation process is greatly facilitated with practice and compromised by lesions in non-visual cortical areas; (3) the alternation process has temporal dynamics similar to those of spontaneously initiated behaviors; (4) functional imaging reveals that brain areas associated with a variety of cognitive behaviors are specifically activated when vision becomes unstable. In this scheme, reorganizations of activity throughout the visual cortex, concurrent with perceptual reversals, are initiated by higher, largely non-sensory brain centers. Such direct intervention in the processing of the sensory input by brain structures associated with planning and motor programming might serve an important role in perceptual organization, particularly in aspects related to selective attention. (shrink)

Asif A. Ghazanfar,1,3,* Hjalmar K. Turesson,1,3 statistical pattern recognition [16, 17] and psychophys- Joost X. Maier,1 Ralph van Dinther,2 ics [13, 18–23] have suggested that formants are signif- Roy D. Patterson,2 and Nikos K. Logothetis1 icant contributors to these indexical cues. It is likely, 1Max Planck Institute for Biological Cybernetics then, that detecting formants could have provided 72076 Tuebingen ancestral primates with indexical cues necessary for Germany navigating the complex social interactions that are the 2Centre for the Neural Basis (...) of Hearing essence of primate societies. One important indexical Department of Physiology cue is body size. Formant cues related to body size University of Cambridge could be used by monkeys to determine the sex (in sex- CB2 3EG Cambridge ually dimorphic species), degree of potential threat (e.g., United Kingdom whether a competitor is larger or smaller), and/or age of an individual, as such cues do for human listeners [13, 18, 20, 21]. Summary Formants are the result of acoustic filtering by the supralaryngeal vocal tract—the nasal and oral cavities Vocal-tract resonances (or formants) are acoustic sigabove the vocal folds. During vocal production, pulses natures in the voice and are related to the shape and of air generated by the rapid movement of the vocal length of the vocal tract. Formants play an important folds produce an acoustic signal. The frequency of these role in human communication, helping us not only to pulses—the glottal-pulse rate—determines the fundadistinguish several different speech sounds [1], but mental frequency of the signal, which in turn is perceived also to extract important information related to the as pitch. As the signal passes through the supralaryngphysical characteristics of the speaker, so-called ineal vocal tract, it excites resonances, resulting in the dexical cues. How did formants come to play such an enhancement of particular frequency bands; these are important role in human vocal communication? One the formants.. (shrink)

Despite considerable evidence that neural activity in monkeys reflects various aspects of face perception, relatively little is known about monkeys’ face processing abilities. Two characteristics of face processing observed in humans are a subordinate-level entry point, here, the default recognition of faces at the subordinate, rather than basic, level of categorization, and holistic effects, i.e. perception of facial displays as an integrated whole. The present study used an adaptation paradigm to test whether untrained rhesus macaques (Macaca mulatta) display these hallmarks (...) of face processing. In experiments 1 and 2, macaques showed greater rebound from adaptation to conspecific faces than to other animals at the individual or subordinate level. In experiment 3, exchanging only the bottom half of a monkey face produced greater rebound in aligned than in misaligned composites, indicating that for normal, aligned faces, the new bottom half may have influenced the perception of the whole face. Scan path analysis supported this assertion: during rebound, fixation to the unchanged eye region was renewed, but only for aligned stimuli. These experiments show that macaques naturally display the distinguishing characteristics of face processing seen in humans and provide the first clear demonstration that holistic information guides scan paths for conspecific faces. (shrink)

manganese (Mn2+) enhanced MRI (MEMRI) to study neuronal connectivity in vivo opens the possibility to these studies. However, several drawbacks exist that challenge its applicability. High Mn2+ concentrations produce cytotoxic effects that can perturb the circuits under study. In the other hand, the MR signal is..

In-vivo phenotyping of genetically engineered mouse models for amyotrophic lateral sclerosis is established by combining BT-MRI and CASL G. Vanhoutte1, E. Storkebaum2, P. Carmeliet2, A. Van der Linden1.

We report and compare the performance of different learning algorithms based on data from cortical recordings. The task is to predict the orientation of visual stimuli from the activity of a population of simultaneously recorded neurons. We compare several ways of improving the coding of the input (i.e., the spike data) as well as of the output (i.e., the orientation), and report the results obtained using different kernel algorithms.

c Ralph Mason -- 199. A New Frontier for Proton MRI: Quantitative Tissue Oximetry g f e d c Ralph P. Mason -- 200. S-GalTM, a Novel 1H MRI Reporter for b-Galactosidase g f e d c John Chen -- 201. Myeloperoxidase-mediated activation of paramagnetic imaging g f e d.

Background: Continuous viewing of ambiguous patterns is characterized by wavering perception that alternates between two or more equally valid visual solutions. However, when such patterns are viewed intermittently, either by repetitive presentation or by periodic closing of the eyes, perception can become locked or "frozen" in one configuration for several minutes at a time. One aspect of this stabilization is the possible existence of a perceptual memory that persists during periods in which the ambiguous stimulus is absent. Here, we use (...) a novel paradgim of temporally interleaved ambiguous stimuli to explore the nature of this memory, with particular regard to its potential impact on perceptual organization. Results: We found that the persistence of a perceptual configuration was robust to interposed visual patterns and, further, that at least three ambiguous patterns, when interleaved in time, could undergo parallel, stable time courses. Then, using an interleaved presentation paradigm, we established that the occasional reversal in one pattern could be coupled with that of its interleaved counterpart, and that this coupling was a function of the structural similarity between the patterns. Conclusions: We postulate that the stabilization observed with repetitive presentation of ambiguous patterns can be at least partially accounted for by processes that retain a recent perceptual interpretation, and we speculate that such memory may be important in natural vision. We further propose tha the interleaved paradigm introduced here may be of great value to gauge aspects of stimulus similarity that appeal to particular mechanisms of perceptual organization. (shrink)

Correspondence should be addressed to David A. Leopold [email protected] the viewing of certain patterns, widely known as ambiguous or puzzle figures, perception lapses into a sequence of spontaneous alternations, switching every few seconds between two or more visual interpretations of the stimulus. Although their nature and origin remain topics of debate, these stochastic switches are generally thought to be the automatic and inevitable consequence of viewing a pattern without a unique solution. We report here that in humans such perceptual alternations (...) can be slowed, and even brought to a standstill, if the visual stimulus is periodically removed from view. We also show, with a visual illusion, that this stabilizing effect hinges on perceptual disappearance rather than on actual removal of the stimulus. These findings indicate that uninterrupted subjective perception of an ambiguous pattern is required for the initiation of the brain-state changes underlying multistable vision.Visual perception involves coordination between sensory sampling of the world and active interpretation of the sensory data. Human perception of objects and scenes is normally stable and robust, but it falters when one is presented with patterns that are inherently ambiguous or contradictory. Under such conditions, vision lapses into a chain of continually alternating percepts, whereby a viable visual interpretation dominates for a few seconds and is then replaced by a rival interpretation. This multistable vision, or 'multistability', is thought to result from destabilization of fundamental visual mechanisms, and has offered valuable insights into how sensory patterns are actively organized and interpreted in the brain1, 2. Despite a great deal of recent research and interest in multistable perception, however, its neurophysiological underpinnings remain poorly understood. Physiological studies have suggested that disambiguation of ambiguous patterns. (shrink)

Understanding how activity in the brain leads to a subjective percept is of great interest to philosophers and neuroscientists alike. In the last years, neurophysiological experiments have approached this problem directly by measuring neural signals in animals as they experience well-defined visual percepts. Stimuli in these studies are often inherently ambiguous, and thus rely upon the subjective report, generally from trained monkeys, to provide a measure of perception. By correlating activity levels in the brain to this report, one can speculate (...) on the role of individual neurons and groups of neurons in the formation and maintenance of a particular percept. However, in order to draw valid conclusions from such experiments, it is critical that the responses accurately and reliably reflect what is perceived. For this reason, a number of behavioural paradigms have been developed to control and evaluate the truthfulness of responses from behaving animals. Here we describe several approaches to optimizing the reliability of a monkey's perceptual report, and argue that their combination provides an invaluable approach in the study of subjective visual perception. (shrink)

Moutoussis, K., A. Maier, S. Zeki and N. K. Logothetis: Seeing invisible motion: responses of area V5 neurons in the awake-behaving macaque. Soc. for Neurosci. Abstr. 390.11, 1.

Our political thinking is driven, far more than philosophers recognize, by a concern for social equality and, more specifically, a concern to avoid relations of inferiority. Niko Kolodny argues that, in order to make sense of the most familiar ideas in our political thought and discourse - the justification of the state, democracy, and rule of law, as well as objections to paternalism and corruption - we cannot merely appeal to freedom (as libertarians like Nozick do) or to distributive fairness (...) (as liberals like Rawls do). We must, instead, appeal directly to claims against inferiority, that no one stands above or below. (shrink)

Often our reason for doing something is an "instrumental reason": that doing that is a means to doing something else that we have reason to do. What principles govern this "instrumental transmission" of reasons from ends to means? Negatively, I argue against principles often invoked in the literature, which focus on necessary or sufficient means. Positively, I propose a principle, "General Transmission," which answers to two intuitive desiderata: that reason transmits to means that are "probabilizing" and "nonsuperfluous" with respect to (...) the relevant end. I then apply General Transmission to the debate over "detachment": whether "wide-scope" reason for a material conditional or disjunction implies "narrow-scope" reason for the consequent or disjuncts. (shrink)

My subject is what I will call the “Myth of Formal Coherence.” In its normative telling, the Myth is that there are “requirements of formal coherence as such,” which demand just that our beliefs and intentions be formally coherent.1 Some examples are.

Quel rapport entretenait Marx avec la culture, l'histoire et la philosophie de la Grèce antique? Pourquoi le jeune Marx s'était-il intéressé à la pensée d'Epicure? Que représentait pour lui la philosophie enseignée par le fondateur de l'École du Jardin? A part l'aspect purement philosophique du rapport de l'auteur du Capital à la Grèce antique, on se donnera également pour tâche de mettre en perspective la contribution que les notions marxiennes de classe, de lutte des classes et d'exploitation peuvent apporter à (...) une compréhension féconde de l'histoire des formations sociales grecques, en partant de l'oeuvre majeure de l'historien britannique G. E. M. de Ste Croix. (shrink)

In this paper we will try to find resemblances of the operation of human consciousness with systems with the intention to simulate it mathematically. Also we will try to do the same for the non-conscious operations and try to synthesize the human mind in form of system with subsystems.

In this paper I argue that Mill’s ‘Doctrine of Philosophical Necessity’ regarding the human will and action cannot apply on all cases, and that the human mind has potentially the capacity to create freely a will or action that, no matter what kind of knowledge we possess, cannot be predicted. More precisely, I argue against Mill’s attempt of conjunction between the freedom of the will and the ‘Doctrine of Philosophical Necessity’ while I attempt a comparison with the relevant Kantian approach. (...) I then claim that a will cannot be free and be predicted at the same time, as both the elements of freedom and unpredictability of the will are founded on the very process of its formulation as an outcome of genuine creativity. I, thus, attempt to propose a more substantially free view of free will and action than the ones presented by the prominent conceptions. (shrink)

Normativity involves two kinds of relation. On the one hand, there is the relation of being a reason for. This is a relation between a fact and an attitude. On the other hand, there are relations specified by requirements of rationality. These are relations among a person's attitudes, viewed in abstraction from the reasons for them. I ask how the normativity of rationality—the sense in which we ‘ought’ to comply with requirements of rationality—is related to the normativity of reasons—the sense (...) in which we ‘ought’ to have the attitudes what we have conclusive reason to have. The normativity of rationality is not straightforwardly that of reasons, I argue; there are no reasons to comply with rational requirements in general. First, this would lead to ‘bootstrapping’, because, contrary to the claims of John Broome, not all rational requirements have ‘wide scope’. Second, it is unclear what such reasons to be rational might be. Finally, we typically do not, and in many cases could not, treat rational requirements as reasons. Instead, I suggest, rationality is only apparently normative, and the normativity that it appears to have is that of reasons. According to this ‘Transparency Account’, rational requirements govern our responses to our beliefs about reasons. The normative ‘pressure’ that we feel, when rational requirements apply to us, derives from these beliefs: from the reasons that, as it seems to us, we have. (shrink)

It is argued that standard music notation pictures Aristotle’s time (time, as Aristotle conceived of it) in a number of important respects, which concern its micro-structure. It is then argued that this allows us to see some features of Aristotle’s time more clearly. Most importantly, Aristotelian instants can be pictured by bar-lines. This allows us to see as how radically devoid of any content Aristotelian instants should be interpreted. Thus, attention to music notation may show why Aristotle was not a (...) presentist. (shrink)

Comment le jeune Hegel définit-il la notion du positif, ainsi que le concept de positivité? Pour quelles raisons insiste-t-il tellement sur la critique du judaïsme et du christianisme dans ses écrits des années 1790-1800, en se fondant sur une conception novatrice de la positivité? Ce livre essaie de mettre en perspective à travers la lecture de certains textes, que la positivité est pour le jeune Hegel, la perte de la part de l'être humain de la maîtrise de sa propre vie, (...) la privation de l'autonomie du sujet au profit de l'autonomisation du monde des objets, aussi bien que l'asservissement des personnes à des lois et à des forces, lesquelles leur sont étrangères et hostiles. Ainsi cet ouvrage propose de comprendre la positivité, tantôt comme l'extension des rapports mutilés entre l'être humain, le monde et la nature, tantôt comme le prodrome du concept de l'aliénation. (shrink)

As prose dramatic texts Plato's dialogues would have been read by their original audience as an alternative type of theatrical composition. The 'paradox' of the dialogue form is explained by his appropriation of the discourse of theatre, the dominant public mode of communication of his time. The oral performance of his works is suggested both by the pragmatics of the publication of literary texts in the classical period and by his original role as a Sokratic dialogue-writer and the creator of (...) a fourth dramatic genre. Support comes from a number of pieces of evidence, from a statue of Sokrates in the Academy to a mosaic of Sokrates in Mytilene, which point to a centuries-old tradition of treating the dialogues in the context of performance literature and testify to the significance of the image of 'Plato the prose dramatist' for his original and subsequent audiences. (shrink)

We consider a paradox involving indicative conditionals (‘ifs’) and deontic modals (‘oughts’). After considering and rejecting several standard options for resolv- ing the paradox—including rejecting various premises, positing an ambiguity or hidden contextual sensitivity, and positing a non-obvious logical form—we offer a semantics for deontic modals and indicative conditionals that resolves the paradox by making modus ponens invalid. We argue that this is a result to be welcomed on independent grounds, and we show that rejecting the general validity of modus (...) ponens is compatible with vindicating most ordinary uses of modus ponens in reasoning. (shrink)

Every attempt to examine our consciousness’s passive life and its dynamic in its various forms inevitably intersects with our primal awareness of the future. Even though Husserl’s theory of time-consciousness enjoys a certain fame, his conception of our primordial relation to the future has not been adequately accounted for. The book at hand aims to offer a close study of Husserl’s view of protentional consciousness and to trace its unique contribution to our overall awareness of time. It offers an extensive (...) analysis of various aspects of protention by investigating its connection to different fields and levels of experience. To achieve such a task, the book stresses the need to enrich the familiar formal account of protention with a material one. Thus, alongside issues pertaining exclusively to the form of protention, such as its relation to fulfillment as well as its double-intentional structure, various other dimensions are discussed, such as the phenomena of disappointment and correction as well as the role hyle plays in both of them. In the same vein, special attention is given to the relation between protentional consciousness and affectivity, thus shedding light on the dynamic unity of our living-present. What this study purports to show is that Husserl’s phenomenology is equipped to offer a solid account of the thinnest and subtlest ways in which we are aware of the future in our experiential life. (shrink)

This study contributes substantially to research on Aristotelian logic in Byzantium. It includes a critical edition of the commentary by Leo Magentenos, the Metropolitan of Mytilene (twelfth c.?) on Book II of the Prior Analytics along with an edition of the syllogism diagram attributed to this work in the manuscript tradition of this work.

Dans la pensée de Rousseau, l'aliénation revêt plusieurs sens. Cette notion, qui avait principalement une origine théologique et fut par la suite associée aux théories du contractualisme, celle de Hobbes par exemple, ou à la théorie du droit de Grotius, subit alors une profonde transformation. En dépit de son rôle central dans la pensée politique de Rousseau, notamment dans son ouvrage Du contrat social, elle a été peu étudiée de façon systématique. Ce livre propose une lecture méthodique de Rousseau, afin (...) d'éclairer sa conception de l'aliénation et de comprendre sa dualité, fondement de l'auto-institution de la communauté politique."--Page 4 of cover. (shrink)

Cet ouvrage propose une lecture méthodique de la place centrale et des sens multiples de l'aliénation et de l'extériorisation dans la Phénoménlogoie de l'esprit de Hegel. Quelle est la place de ces notions dans l'oeuvre majeure du philosophe allemand? L'auteur tente ainsi de mettre l'accent tantôt sur l'aspect et l'enracinement profondément social-historique de ces deux notions.

The aim of this volume is to explore new approaches to the problem of the constitution of the various aspects of sociality and to confront these with received ideas. Therefore many of the contributions to this volume are devoted to a rather holistic and antireductionist conception of social objects, groups, joint actions and collective knowledge. The topics, that are dealt with are: a) the question of the ontological status of social objects and their relation to physical objects, b) collective agency (...) and c) the question whether there can be shared knowledge and shared beliefs - a rather new topic in the discussion of the social aspects of personal life. (shrink)

At first glance, love seems to be a psychological state for which there are normative reasons: a state that, if all goes well, is an appropriate or fitting response to something independent of itself. Love for one’s parent, child, or friend is fitting, one wants to say, if anything is. On reflection, however, it is elusive what reasons for love might be. It is natural to assume that they would be nonrelational features of the person one loves, something about her (...) in her own right. According to the “quality theory,” for example, reasons for love are the beloved’s personal attributes, such as her wit and beauty. In J. David Velleman’s provocative and ingeniously argued proposal, the reason for love is the beloved’s bare Kantian personhood, her capacity for rational choice and valuation.1 But no such nonrelational feature works. To appreciate just one difficulty, observe that whatever nonrelational feature one selects as the reason for love will be one that another person could, or actually does, possess. The claim that nonrelational features are reasons for love implies, absurdly, that insofar as one’s love for Jane is responsive to its reasons, it will accept any relevantly similar person as a replacement. (shrink)