Summary Ideomotor apraxia is a cognitive disorder in which the patient loses the ability to accurately perform learned, skilled actions. This is despite normal limb power and coordination. It has long been known that left supramarginal gyrus lesions cause bilateral upper limb apraxia and it was proposed that this area stored a visualkinaesthetic image of the skilled action, which was translated elsewhere in the brain into the pre-requisite movement formula. We hypothesise that, rather than these two functions occurring (...) separately, both are complementary functions of chains of ‘‘mirror neurons’’ within the left inferior parietal lobe. We go on to propose that this neural mechanism in the supramarginal gyrus and its projection zones, which originally evolved to allow the creation of a direct map between vision and movement, was subsequently exapted to allow other sorts of cross-domain mapping and in particular those sorts of abstract re-conceptualisation, such as metaphor, that make mankind unique. (shrink)

La présente étude a deux objectifs. Le premier est d’examiner les différentes formulations de l’objection de l’ἀπραξία telle qu’elle fut soulevée contre le scepticisme académicien et le pyrrhonisme, ainsi que les réponses à cette objection proposées par Arcésilas et Sextus Empiricus. Le second objectif consiste à évaluer la force de la version de l’objection de l’ἀπραξία selon laquelle le sceptique ne peut réaliser les actions rationnelles propres à l’être humain.

According to the objection of inactivity (apraxia), the skeptics cannot live their skepticism, since any attempt to apply it to everyday life would result in total inactivity, while any action they would perform qua skeptics would be a sign that they abandoned their skepticism. In this paper I discuss the ancient Pyrrhonists’ response to the objection as is presented in the writings of Sextus Empiricus. Sextus argues that the Pyrrhonists are immune to the apraxia objection because it is (...) based on the misunderstanding of their position, that is, on the wrong assumption that they live in accordance with philosophical logos. To live in accordance with philosophical logos includes two things. First, it includes the idea that one should apply one’s philosophical tenets, concepts and recommendations to ordinary human life and use it as a practical guide. However, the only item that survives skeptical philosophy, appearance, is not used in this way: its role as criterion of action is different. Second, it includes the idea that ordinary human life can be, and should be, described in philosophical terms. However, the skeptics refuse to describe their actions in philosophical terms. More specifically, they refuse to describe their actions in terms of beliefs: from the Pyrrhonists’ point of view, the question “Do you have beliefs?” is misplaced, since any answer to it, affirmative or negative, is as credible as any other, since it is about something non-evident. (shrink)

Borrett, Kelly and Kwan [ Phenomenology, dynamical neural networks and brain function, Philosophical Psychology, 13, 000-000] claim that unbiased, self-evident, direct description is possible, and may supply the data that brain theories account for. Merleau-Ponty's [ Phenomenology of perception, London: Routledge] description of Schneider's apraxia is offered as a case in point. According to the authors, Schneider's apraxia justifies brain components of predicative and pre-predicative experience. The description derives from a bias, however, that parallels modularity's morphological reduction. The (...) presence of biasing presuppositions contradicts the goal of direct description. Moreover, the authors' brain account is not necessary to explain Schneider's apraxia, and morphological reduction is not sufficient to explain emergent phenomena of motor control. (shrink)

Patients with apraxia perform poorly when demonstrating how an object is used, particularly when pantomiming the action. However, these patients are able to accurately identify, and to pick up and move objects, demonstrating intact ventral and dorsal stream visuomotor processing. Appropriate object manipulation for skilled use is thought to rely on integration of known and visible object properties associated with ‘ventro-dorsal’ stream neural processes. In apraxia, it has been suggested that stored object knowledge from the ventral stream may (...) be less readily available to incorporate into the action plan, leading to an over-reliance on the objects’ visual affordances in object-directed motor behaviour. The current study examined grasping performance in left hemisphere stroke patients with (N = 3) and without (N = 9) apraxia, and in age-matched healthy control participants (N = 14), where participants repeatedly grasped novel cylindrical objects of varying weight distribution. Across two conditions, object weight distribution was indicated by either a memory-associated cue (object colour) or visual-spatial cue (visible dot over the weighted end). Participants were required to incorporate object-weight associations to effectively grasp and balance each object. Control groups appropriately adjusted their grasp according to each object’s weight distribution across each condition, whereas throughout the task two of the three apraxic patients performed poorly on both the memory-associated and visual-spatial cue conditions. A third apraxic patient seemed to compensate for these difficulties but still performed differently to control groups. Patients with apraxia performed normally on the neutral control condition when grasping the evenly weighted version. The pattern of behaviour in apraxic patients suggests impaired integration of visible and known object properties attributed to the ventro-dorsal stream: in learning to grasp the weighted object accurately, apraxic patients applied neither pure knowledge-based information (the memory-associated condition) nor higher-level information given in the visual-spatial cue condition. Disruption to ventro-dorsal stream predicts that apraxic patients will have difficulty learning to manipulate new objects on the basis of information other than low-level visual cues such as shape and size. (shrink)

In the haptic domain, a double dissociation can be proposed on the basis of neurological deficits between tactile information for action, represented by tactile apraxia, and tactile information for perception, represented by tactile agnosia. We suggest that this dissociation comes from different networks, both involving the anterior intraparietal area of the posterior parietal cortex.

En este artículo reconstruyo y analizo las respuestas de los escépticos académicos a la objeción de apraxia. Esta objeción afirma que el escepticismo es una doctrina imposible de practicar puesto que sus tesis conducen a la apraxia, esta es, un estado de privación o imposibilidad de acción. Las respuestas a la objeción se dividen en dos clases. La primera prueba que el asentimiento no es una condición necesaria para realizar acciones, por lo que la recomendación escéptica de suspender (...) global y permanentemente el asentimiento no conduciría a la apraxia. La segunda prueba que es posible deliberar y orientar racionalmente nuestras acciones sin impresiones aprehensivas, por lo que la tesis escéptica de que no existen impresiones aprehensivas tampoco conduciría a la apraxia. Tras unas breves consideraciones generales, en la primera parte de este artículo presento las respuestas de Arcesilao y en la segunda parte las repuestas de Carnéades. (shrink)

The study of signed languages has inspired scientific' speculation regarding foundations of human language. Relationships between the acquisition of sign language in apes and man are discounted on logical grounds. Evidence from the differential hreakdown of sign language and manual pantomime places limits on the degree of overlap between language and nonlanguage motor systems. Evidence from functional magnetic resonance imaging reveals neural areas of convergence and divergence underlying signed and spoken languages.

Evidence for a dichotomy between the planning of an action and its on-line control in humans is reviewed. This evidence suggests that planning and control each serve a specialized purpose utilizing distinct visual representations. Evidence from behavioral studies suggests that planning is influenced by a large array of visual and cognitive information, whereas control is influenced solely by the spatial characteristics of the target, including such things as its size, shape, orientation, and so forth. Evidence from brain imaging and neuropsychology (...) suggests that planning and control are subserved by separate visual centers in the posterior parietal lobes, each constituting part of a larger network for planning and control. Planning appears to rely on phylogenetically newer regions in the inferior parietal lobe, along with the frontal lobes and basal ganglia, whereas control appears to rely on older regions in the superior parietal lobe, along with the cerebellum. Key Words: action; apraxia; control; illusions; optic ataxia; PET; planning; reaching;. (shrink)

This paper presents the case of a 17-year-old right-handed Belgian boy with developmental FAS and comorbid developmental apraxia of speech (DAS). Extensive neuropsychological and neurolinguistic investigations demonstrated a normal IQ but impaired planning (visuo-constructional dyspraxia). A Tc-99m-ECD SPECT revealed a significant hypoperfusion in the prefrontal and medial frontal regions, as well as in the lateral temporal regions. Hypoperfusion in the right cerebellum almost reached significance. It is hypothesized that these clinical findings support the view that FAS and DAS are (...) related phenomena following impairment of the cerebro-cerebellar network. (shrink)

In this paper, I critically engage with Casey Perin's interpretation of Sextan Pyrrhonism in his book, The Demands of Reason: An Essay on Pyrrhonian Scepticism. From an approach that is both exegetical and systematic, I explore a number of issues concerning the Pyrrhonist's inquiry into truth, his alleged commitment to the canons of rationality, and his response to the apraxia objection.

This paper analyzes the apraxia argument in Cicero’s Academica. It proposes that the argument assumes two modes: the evidential mode maintains that skepticism is false, while the pragmatic claims that it is disadvantageous. The paper then develops a tension between the two modes, and concludes by exploring some differences between ancient and contemporary skepticism.

Tool-use behavior is currently one of the most intriguing and widely debated topics in cognitive neuroscience. Different accounts of our ability to use tools have been proposed. In the first part of the paper we review the most prominent interpretations and suggest that none of these accounts, considered in itself, is sufficient to explain tool use. In the second part of the paper we disentangle three different types of reasoning on tools, characterized by a different distribution of motor and cognitive (...) ingredients. At the conceptual level, these types of reasoning reflect the distinction between three types of abductive inference as they are described in semiotic studies. At the functional level, we suggest that these types of reasoning on tools may correspond to different mental processes, possibly implemented in different regions of the left inferior parietal lobe. This proposal can account for the different interpretations commonly associated with the role of the left parietal cortex in tool use. (shrink)

This chapter presents an account of Merleau-Ponty’s interpretation of the body schema as an operative intentionality that is not only opposed to, but also complexly intermingled with, the representation-like grasp of the world and one’s own body, or the body image. The chapter reconstructs Merleau-Ponty’s position primarily based on his preparatory notes for his 1953 lecture ‘The Sensible World and the World of Expression’. Here, Merleau-Ponty elaborates his earlier efforts to show that the body schema is a perceptual ground against (...) which the perceived world stands out as a complex of perceptual figures. The chapter clarifies how Merleau-Ponty’s renewed interpretation of the figure-ground structure makes it possible for him to describe the relationship between body schema and perceptual (body) image as a strictly systematic phenomenon. Subsequently, the chapter shows how Merleau-Ponty understands apraxia, sleep, and perceptual orientation as examples of dedifferentiation and subtler differentiation of the body-schematic system. The last section clarifies how such body-schematic differentiating processes give rise to relatively independent superstructures of vision and symbolic cognition which constitute our body image. It, moreover, explains how, according to Merleau-Ponty, the cognitive superstructures always need to be supported by praxic operative intentionality to maintain their full sense, even though, in some cases, they have the power to compensate for praxic deficiencies. (shrink)

The "width" of the mind is an important topic in contemporary philosophical psychology. Support for active externalism derives from theoretical, engineering, and observational perspectives. Given the history of psychology, psychopathology is notable in its absence from the list of avenues of support for the idea that some cognitive processes extend beyond the physical bounds of the organism in question. The current project is to defend the possibility, plausibility, and desirability of externalist psychopathology. Doing so both adds to the case for (...) externalism and suggests ways of improving our study of cognitive dysfunction. I establish the possibility of externalist psychopathology through the development of models of wide cognitive processing, and, by implication, failure of such processing, from the work of S.L. Hurley and Robert Wilson. The plausibility of wide conceptualization and explanation of cognitive disorders is shown through an examination of apraxia, disorders of learned, skilled movements. The desirability of externalist psychopathology is suggested through a look at theoretical and therapeutic virtues, again drawing on Wilson's work. (shrink)

Por séculos, o ceticismo pirrônico vem sendo atacado por argumentações dogmáticas que propõem fazer dele uma escola que, inevitavelmente, provoca um estado de apraxia, isto é, de inércia, bem como de neutralidade, diante da vida comum e das investigações científicas que, diuturnamente, vêm sendo desenvolvidas. Mas seria o pirronismo culpado de tal acusação? Como pretendemos demonstrar no presente artigo, não. Para demonstrar tal inocência, voltamo-nos sobre alguns dos escritos de Oswaldo Porchat Pereira sobre seu Neopirronismo, dividindo este texto em (...) duas partes. Na primeira, faz-se necessário, seguindo a argumentação do autor, distinguir dois momentos do ceticismo pirrônico: (1) o primeiro negativo e que tem como escopo o alcance da epokhé e o embate com o dogmatismo; (2) o segundo positivo e que nos leva a pensar o campo da filosofia prática a partir de uma reflexão acerca da ação e da vida comum. Desse modo, o caminho se abre para que, na segunda parte de nosso texto, possamos então concluir com o autor o porquê de que ainda é necessário, bem como possível, ser cético nos embates filosóficos e científicos contemporâneos, haja vista as contribuições que o ceticismo ainda hoje pode nos fornecer. (shrink)

Ancient sceptics, unlike their modern counterparts, claim to live their scepticism. Nowadays scepticism, whether epistemological, moral, or of any other variety, is seen as a purely theoretical position, with no direct bearing on the actual living of one’s life; this is because philosophical theories and everyday attitudes are taken to be in some way “insulated” from one another. Serious questions may be raised about the character of this alleged “insulation,” but these are not my present concern; the fact is that (...) no such split between “the philosophical” and “the ordinary” was entertained in the ancient world. It follows that the viability of scepticism as a way of life is a crucial issue for ancient sceptics. It is no accident that one of the most enduring objections to ancient scepticism is to the effect that the sceptical attitude—that is, the posture of universal suspension of judgement—is incompatible with any kind of normal human action; this was known in antiquity as the charge of apraxia, “inaction.” The sceptics for their part, were just as persistent in arguing that suspension of judgement had no such damaging consequences. In as much as the assessment of actual or imaginable types of human life is the province of ethics, I take this debate between ancient sceptics and their detractors to be, in a broad sense, an ethical debate. (shrink)

Anchoring his schema in the belief that nonorganic disorders are disturbances in _adaptation_ explicable within a depth-psychological framework, Gedo posits two broad categories of functional disorder: "apraxias" that represent any failure to learn adaptively essential skills, and disorders of what her terms "obligatory repetition." Within both categories of disorder, Gedo avers, the vicissitudes of mental functioning are understandable in terms of regression to relatively archaic modes of function and the reversal of regression and return to expectable modes of adult function. (...) It follwos from Gedo's understanding of how and why the mind becomes disordered, that diagnosis utilizing psychoanalytic principles can only be based on the succession of transference constellations encountered in treatment, since these constellations invariably pinpoint the developmental impasses in which maladaptive repetitive patterns and the failure to learn basic psychological skills are rooted. For purposes of understanding a variety of apraxic and repetitive disorders, Gedo equates such basic skills not only with the three major psychobiological attainments he has invoked in the past, but with the development of adequate perception, cognition, affectivity, and communication skills. Beautifullu organized, lucidly written, and richly illustrated with case vignettes, _The Mind in Disorder_ is not only the thoughtful yield of an outstanding clinician's three decades of experience. It is also the first psychoanalytic book since Otto Fenichel's masterwork of 1945, _The Psychoanalytic Theory of Neurosis_, to take the issue of how we conceptualize psychopathology as its central focus. (shrink)

O ceticismo antigo se concebia como um modo de vida. Para acadêmicos e pirrônicos, a suspensão do juízo era o único caminho para a felicidade e a sabedoria. Na Antiguidade, essa filosofia recebeu inúmeras críticas, como o argumento da apraxia, mas talvez a principal delas tenha sido a de Agostinho, que buscou reformular o conceito de sabedoria. Para Agostinho, a sabedoria não pode ser definida como mera abstenção do erro e a felicidade não é concebível sem a presença daquilo (...) que se deseja. De Cícero e Sexto Empírico a Agostinho, portanto, há uma transformação muito relevante na maneira de se avaliar a relação entre a verdade e o bem viver, que, quando compreendida, permite que se perceba com mais clareza as diferenças entre autores modernos como, por exemplo, Montaigne e Pascal. (shrink)

This chapter provides a brief overview of the history of behavioral neurology, dividing it roughly into six eras. In the ancient and classical eras, emphasis is placed on two transitions: firstly, from descriptions of head trauma and attempted neurosurgical treatments to the exploratory dissections during the Hellenistic period and the replacement of cardiocentrism; and secondly, to the more systematic investigations of Galenus and the rise of pneumatic ventricular theory. In the medieval through post-Renaissance eras, the scholastic consolidation of knowledge and (...) the role of compendia are emphasized, along with the use of new methods from within a mechanistic framework. With the discovery of electrical conductance and the rise of experimentalism, we frame the modern era as period of intense debate over localization, decomposition, and other mechanistic principles, and marked by rapid discovery about the brain. The chapter ends with a discussion of the contemporary era, focusing on the establishment of behavioral neurology research on aphasia, apraxia, and neuropsychiatric conditions. (shrink)

Encoding articulate speech is widely accepted as the principal (or sole) role of the frontal operculum. Clinical observations of speech apraxia have been confirmed by brain-imaging studies of speech production. We present evidence that the frontal operculum also programs limb movements. We argue that this area is a ventral counterpart of the dorsal premotor area. The two are functionally distinguished by specialization for somatic and visual space, respectively.

Understanding how conceptual structures inform stone tool production and use would help us resolve the issue of a pongid-hominid dichotomy in brain organisation and cognitive ability. Evidence from ideational apraxia suggests that the planning of linguistic and manipulative behaviours is not colocalized in homologous circuits. An alternative account in terms of the evolutionary expansion of the whole prefrontal-premotor area may be more plausible.

Skepticism is regularly a target for the _apraxia_ challenge, namely, that skepticism robs us of the cognitive means for life (or at least the life well-lived). Skeptics have replied to the _apraxia_ challenge in various manners, and anti-skeptics have then answered with objections to these skeptical replies. St. Augustine’s crossroads case in _Contra Academicos_ is one such second-stage pragmatic anti-skepticism, one targeting Academic probabilism in particular. This dialectical assessment challenges Augustine’s case as inappropriately comparing the possible errors and their costs (...) in the crossroads decision, but this assessment opens Academics to a potentially devastating dilemma for their probabilism. (shrink)

Despite the striking similarities between Pyrrhonian skepticism and Madhyamaka Buddhism, few lessons have been drawn from the parallels between the two traditions. Here, it is argued that Madhyamaka Buddhism verifies the livability of Pyrrhonian skepticism. After establishing that Pyrrhonism and Madhyamaka can be understood as undertaking the same project, it is shown that Madhyamaka philosophy is able to refute objections to the viability of Pyrrhonism. Finally, it is demonstrated that Madhyamaka is still a lived practice in Tibetan Buddhism, and it (...) is argued that this constitutes empirical support for the livability of Pyrrhonian skepticism. (shrink)

Current work in the evolution of language and communication is emphasising a close relationship between the evolution of speech, language and gestural action. This paper briefly explores some evolutionary implications of a range of closely related impairments of speech, language and gesture arising from left frontal brain lesions. I discuss aphasic lexical speech automatisms and their resolution with some recovery into agrammatism with apraxia of speech, an impairment of speech planning and programming. I focus attention on the most common (...) forms of LSAs, expletives and the pronoun+modal/aux subtype, and propose that further research into these phenomena can contribute to the debate. I briefly discuss recent studies of progressively degenerating neurological conditions resulting in progressive patterns of cognitive impairments that promises to provide insight into the evolutionary relationships between speech, language and gesture. (shrink)

What do the relationships observed in the occurrence of various limb, facial, and speech apraxias following left hemisphere damage mean for Corballis's theory? What does the right hemisphere's role in nonpropositional and automatic speech production tell us about the coevolution of right hand preference and speech; how could the possibility that the right hemisphere may be “dominant” for some aspects of speech be accommodated by his theory?

Este artigo se divide em duas partes. Na primeira seção, após a introdução, mapeamos as diversas ocorrências de “phýsis” ao longo das Hipotiposes Pirrônicas de Sexto Empírico, dividindo-as em 5 categorias: “natureza” como o real, em posição à “aparência”; o “natural” como aquilo que parece próprio, pertencente a algo ou alguém; a “Natureza”, como uma dimensão criadora e regente; o “natural” em oposição ao “antinatural”; a “natureza dos homens”. A forma como esses diversos usos aparecem na obra é invariavelmente crítica, (...) como elementos da argumentação contra os dogmáticos, especialmente os estoicos. Na segunda parte do trabalho, entretanto, mostramos como a “phýsis” aparece também de maneira positiva no início das Hipotiposes com a função de guia para a vida, como parte da resposta à célebre objeção da apraxía. Além disso, defendemos a hipótese de que a “natureza”, da perspectiva de Sexto, não se opõe nem ultrapassa as convenções e os costumes; pelo contrário, a natureza é o que é reconhecido por todos e é mesmo determinada pelas convenções e pelos costumes. (shrink)

Carnéades es un escéptico académico y un pragmático que quiere fundamentar la ética no en la idea de Bien o Valor, sino en la noción de bien útil, convincente y conveniente. Una noción basada no tanto en hacer algo grande que merezca la admiración o el elogio de las personas, sino en no hacer mal a nadie y extender el bienestar personal a la mayoría. Para ello creó una norma o guía, una regla de conducta probable o persuasiva que invitaba (...) a actuar sin pretensiones ni orgullo, decidiendo en cada momento lo que parece más probable o persuasivo en cada ocasión para evitar la apraxia en la acción moral. Además, fue el primero en distinguir entre seguir una acción moral con la pauta de la probabilidad, y la imposibilidad de asentir a ella con seguridad de no equivocarnos. (shrink)

Michael Hannon has recently given “a new apraxia” argument against skepticism. Hannon’s case is that skepticism depends on a theory of knowledge that makes the concept “useless and uninteresting.” Three arguments rebutting Hannon’s metaphilosophical pragmatism are given that show that the concept of knowledge that makes skepticism plausible is both interesting and useful.

This paper takes up two questions. Is there a sense in which the Sceptic as described by Sextus Empiricus is detached from himself? Does this self-detachment by itself make the Sceptic’s way of life undesirable? I sketch two conceptions of self-detachment, and then conclude that the Sceptic faces a dilemma: either he is more detached from himself than the non-Sceptic or he is vulnerable to a non-standard version of the apraxia objection.

K L Kahlbaum published in 1874 the first recorded description of catatonia. Akinetic catatonia is now defined as a neuropsychiatric syndrome principally characterised by akinesia, mutism, stupor, and catalepsy. 1 Even if some advances have been made in the recognition of catatonia, in particular by the development of different rating scales, 1 the pathophysiology of this syndrome is not clearly established. A right handed 14 year old girl presented with akinetic catatonia during an episode of depression in the context of (...) a bipolar type I disorder. Her catatonic status was characterised by akinesia with brief episodic spontaneous stereotyped movements, mutism, no spontaneous oral intake, catalepsy, waxy flexibility, and stupor with brief occasional eye contacts. This corresponded to a total score of 19 on the Northoff Catatonia Scale.1 Electroencephalogram performed one day after onset of symptoms showed diffuse theta activity with sporadic diffuse delta activity. Cerebral magnetic resonance imaging was normal. Brain positron emission tomographies (PET) were obtained on a CTI-Siemens HR+ tomograph. A first PET (PET1) using (18F(- fluorodeoxyglucose (FDG) was performed on day 2 in a drug free state. Thereafter, intramuscular injection of 2 mg of lorazepam induced rapid clinical remission of the akinetic phase. Oral lorazepam was then given (3.75 mg/day) during five days. On day 8, a second PET with FDG was performed while the patient was treated by olanzapine (15 mg/day) and presented hyperactivity, logorrhoea, and disinhibition characterised by uncontrolled social interactions and physical contacts. Neuropsychological testing performed some days after remission revealed no apraxia or language disturbances but dysfunction of executive tasks manifested in the revised Wisconsin card sorting, the Tower of London, Stroop, and Trailmaking tests. Voxel based analyses comparing patient’s cerebral glucose metabolism with that of 29 right handed healthy controls (16 women and 13 men, mean age 32) were performed using Statistical Parametric Mapping (SPM99) (Wellcome Department of Cognitive Neurology, London, UK).. (shrink)