Intelligible speakers achieve specific vocal tract constrictions in rapid sequence. These constrictions are associated in theory with speech motor goals. Adult-focused models of speech production assume that discrete phonological representations, sequenced into word-length plans for output, define these goals. This assumption introduces a serial order problem for speech. It is also at odds with children's speech. In particular, child phonology and timing control suggest holistic speech plans, and so the hypothesis of whole word production. This hypothesis solves the serial (...) order problem by avoiding it. When the same solution is applied to adult speech the problem becomes how to explain the development of highly intelligible speech. This is the problem addressed here. A modeling approach is used to demonstrate how perceptual-motor units of production emerge over developmental time with the perceptual-motor integration of holistic speech plans that are also phonological representations; the specific argument is that perceptual-motor units are a product of trajectories (nearly) crossing in motor space. The model, which focuses on the integration process, defines the perceptual-motor map as a set of linked pairs of experienced perceptual and motor trajectories. The trajectories are time-based excursions through speaker-defined perceptual and motor spaces. By hypothesis, junctures appear where motor trajectories near or overlap one another in motor space when the shared (or extremely similar) articulatory configurations in these regions are exploited to combine perceptually-linked motor paths along different trajectories. Junctures form in clusters in motor space. These clusters, along with their corresponding (linked) perceptual points, represent perceptual-motor units of production, albeit at the level of speech motor control only. The units serve as pivots in motor space during speaking; they are points of transition from one motor trajectory to another along perceptually-linked paths that are selected to produce best approximations of whole word targets. (shrink)

We offer a critique of the role of the parallel fiber beam as the unit of cerebellar computation, with the as its mode of operation. Instead we see the microcomplex linking cerebellar cortex and nuclei as the unit, with parallel fibers providing the means to coordinate the effects of microcomplexes in modulating various motor pattern generators (MPGs).

Is the assessment of motor milestones valid and scaled equivalently for all infants? It is not only important to understand if the way we use gross and fine motor scores are appropriate for monitoring motor milestones but also to determine if these scores are confounded by specific infant characteristics. Therefore, the aim of the study is to investigate the latent structure underlying motor milestone assessment in infancy and measurement invariance across sex, birth weight, and gestational age. (...) For this study, the birth cohort data from the United Kingdom Millennium Cohort Study was used, which includes the assessment of eight motor milestone tasks from the Denver Developmental Screening Test in 9-month-old infants, depicting early motor development of the first children of generation Z. Confirmatory factor analyses showed a better model fit for a two-factor structure compared to a one-factor structure, and multiple indicators multiple causes modeling revealed no differential item functioning related to sex, birth weight, and gestational age. The study provides support for the use of gross and fine motor scores when assessing motor milestones in infants—both boys and girls with different birth weights and of varying gestational ages. Further investigation into widely adopted assessment tools is recommended to support the use of valid composite scores in early childhood research and practice. (shrink)

The human masticatory system is a complex functional unit characterized by a multitude of skeletal components, muscles, soft tissues, and teeth. Muscle activation dynamics cannot be directly measured on live human subjects due to ethical, safety, and accessibility limitations. Therefore, estimation of muscle activations and their resultant forces is a longstanding and active area of research. Reinforcement learning (RL) is an adaptive learning strategy which is inspired by the behavioral psychology and enables an agent to learn the dynamics of an (...) unknown system via policy-driven explorations. The RL framework is a well-formulated closed-loop system where high capacity neural networks are trained with the feedback mechanism of rewards to learn relatively complex actuation patterns. In this work, we are building on a deep RL algorithm, known as the Soft Actor-Critic, to learn the inverse dynamics of a simulated masticatory system, i.e., learn the activation patterns that drive the jaw to its desired location. The outcome of the proposed training procedure is a parametric neural model which acts as the brain of the biomechanical system. We demonstrate the model’s ability to navigate the feasible three-dimensional (3D) envelope of motion with sub-millimeter accuracies. We also introduce a performance analysis platform consisting of a set of quantitative metrics to assess the functionalities of a given simulated masticatory system. This platform assesses the range of motion, metabolic efficiency, the agility of motion, the symmetry of activations, and the accuracy of reaching the desired target positions. We demonstrate how the model learns more metabolically efficient policies by integrating a force regularization term in the RL reward. We also demonstrate the inverse correlation between the metabolic efficiency of the models and their agility and range of motion. The presented masticatory model and the proposed RL training mechanism are valuable tools for the analysis of mastication and other biomechanical systems. We see this framework’s potential in facilitating the functional analyses aspects of surgical treatment planning and predicting the rehabilitation performance in post-operative subjects. (shrink)

This work is descriptive observational, with transversal design, was to analyze the time of motor commitment in Physical Education classes in three subsystems of Venezuelan education. The analysis unit consisted of a discretionary sample of 6 Physical Education classes between initial education, basic education and secondary education, at the rate of 2 classes for each subsystem. The number of students participating was 192. For the observation and registration, was used, the temporal variables were recorded, and in the second instance, (...) the classes were recorded considering variables associated with: organization of groups, activities, disposition of materials, use and distribution of physical space. The results confirm the little use of the Physical Education class to favor the motor development; none of the observed classes managed to accumulate 50% of the time of motor commitment, thus confirming the trend of other investigations. (shrink)

Concepts are the elementary units of reason and linguistic meaning. They are conventional and relatively stable. As such, they must somehow be the result of neural activity in the brain. The questions are: Where? and How? A common philosophical position is that all concepts—even concepts about action and perception—are symbolic and abstract, and therefore must be implemented outside the brain’s sensory-motor system. We will argue against this position using (1) neuroscientific evidence; (2) results from neural computation; and (3) (...) results about the nature of concepts from cognitive linguistics. We will propose that the sensory-motor system has the right kind of structure to characterise both sensory-motor and more abstract concepts. Central to this picture are the neural theory of language and the theory of cogs, according to which, brain structures in the sensory-motor regions are exploited to characterise the so-called “abstract” concepts that constitute the meanings of grammatical constructions and general inference patterns. (shrink)

Studies have shown that in the mammalian neuromuscular system stretch reflexes are localized within individual muscles. Neuromuscular compartmentalization, the partitioning of sensory output from muscles, and the partitioning of segmental pathways to motor nuclei have also been demonstrated. This evidence indicates that individual motor nuclei and the muscles they innervate are not homogeneous functional units. An analysis of the functional significance of reflex localization and partitioning suggests that segmental control mechanisms are based on subdivisions of motor (...) nuclei–muscle complexes. A partitioned organization of segmental control mechanisms could utilize (1) the potential functional diversity of muscle fiber types, (2) the variety of mechanical actions of individual muscles arising from their distributed origins and insertions, and (3) diverse architectural features such as intramuscular variations in pinnation and complex in-series and in-parallel arrangements of muscle fibers. The differentiated activity observed in some muscles during natural movements also calls for localized segmental control mechanisms. Partitioning may also play a role in mechanical interactions between contracting motor units and in increasing the stability of neuromuscular systems. The functional advantages of reflex localization and partitioning suggest they are probably common features of segmental systems, whose organization reflects the structure and function of their associated neuromuscular systems. (shrink)

Experimental studies of speech production involving compensations for auditory and somatosensory perturbations and adaptation after training suggest that both types of sensory information are considered to plan and monitor speech production. Interestingly, individual sensory preferences have been observed in this context: subjects who compensate less for somatosensory perturbations compensate more for auditory perturbations, and \textit{vice versa}. We propose to integrate this sensory preference phenomenon in a model of speech motor planning using a probabilistic model in which speech units (...) are characterized both in auditory and somatosensory terms. Sensory preference is implemented in the model according to two approaches. In the first approach, which is often used in motor control models accounting for sensory integration, sensory preference is attributed to the relative precision (i.e., inverse of the variance) of the sensory characterization of the speech motor goals associated with phonological units (which are phonemes in the context of this paper). In the second, ``more original’’ variant, sensory preference is implemented by modulating the sensitivity of the comparison between the predicted sensory consequences of motor commands and the sensory characterizations of the phonemes. We present simulation results using these two variants, in the context of the adaptation to an auditory perturbation, implemented in a 2-dimensional biomechanical model of the tongue. Simulation results show that both variants lead to qualitatively similar results. Distinguishing them experimentally would require precise analyses of partial compensation patterns. However, the second proposed variant implements sensory preference without changing the sensory characterizations of the phonemes. This dissociates sensory preference and sensory characterizations of the phonemes, and makes the account of sensory preference more flexible. Indeed, in the second variant the sensory characterizations of the phonemes can remain stable, when sensory preference varies as a response to cognitive or attentional control. This opens new perspectives for capturing speech production variability associated with aging, disorders and speaking conditions. (shrink)

Single units that are not related to the desired task can become related to the task by conditioning their firing rates. We theorized that, during conditioning of firing rates to a tone, (a) unrelated single units would be recruited to the task; (b) the recruitment would depend on the phase of the task; (c) tones of different frequencies would produce different patterns of single unit recruitment. In our mute locked-in participant, we conditioned single units using tones of (...) different frequencies emitted from a tone generator. The conditioning task had three phases: Listen to the tone for 20 s, then silently sing the tone for 10 s, with a prior control period of resting for 10 s. Twenty single units were recorded simultaneously while feedback of one of the twenty single units was made audible to the mute locked-in participant. The results indicate that (a) some of the non-audible single units were recruited during conditioning, (b) some were recruited differentially depending on the phase of the paradigm (listen, rest, or silent sing), and (c) single unit firing patterns were specific for different tone frequencies such that the tone could be recognized from the pattern of single unit firings. These data are important when conditioning single unit firings in brain-computer interfacing tasks because they provide evidence that increased numbers of previously unrelated single units can be incorporated into the task. This incorporation expands the bandwidth of the recorded single unit population and thus enhances the brain-computer interface. This is the first report of conditioning of single unit firings in a human participant with a brain to computer implant. (shrink)

The motivation of someone who is locked-in, that is, paralyzed and mute, is to find relief for their loss of function. The data presented in this report is part of an attempt to restore one of those lost functions, namely, speech. An essential feature of the development of a speech prosthesis is optimal decoding of patterns of recorded neural signals during silent or covert speech, that is, speaking “inside the head” with output that is inaudible due to the paralysis of (...) the articulators. The aim of this paper is to illustrate the importance of both fast and slow single unit firings recorded from an individual with locked-in syndrome and from an intact participant speaking silently. Long duration electrodes were implanted in the motor speech cortex for up to 13 years in the locked-in participant. The data herein provide evidence that slow firing single units are essential for optimal decoding accuracy. Additional evidence indicates that slow firing single units can be conditioned in the locked-in participant 5 years after implantation, further supporting their role in decoding. (shrink)

A review of the scanty Gestaltist literature on motor behaviour indicates that a genuine Gestalt theoretic approach to motor behaviour can be characterized by three research questions: (1) What are the natural units of motor behaviour? (2) What characterizes the self-organization in motor behaviour? (3) What are the conditions for invariance in motor behaviour? Tentative answers to these questions can be found by analysing the parallels between Gestalt theory and Bernstein's theory of motor (...) actions and by showing that Gestalt theory can be regarded as a specific approach to non-linear dynamics as exemplified by synergetics (Haken, 1991). The congruence between the Gestalt theoretic approach and synergetics becomes apparent in the analysis of how a complex motor task is learned [1]. (shrink)

The processing of time intervals in the sub- to supra-second range by the brain is critical for the interaction of primates with their surroundings in activities, such as foraging and hunting. For an accurate processing of time intervals by the brain, representation of physical time within neuronal circuits is necessary. I propose that time dimension of the physical surrounding is represented in the brain by different types of neuronal oscillators, generating spikes or spike bursts at regular intervals. The proposed oscillators (...) include the pacemaker neurons, tonic inputs, and synchronized excitation and inhibition of inter-connected neurons. Oscillators, which are built inside various circuits of brain, help to form modular clocks, processing time intervals or other temporal characteristics specific to functions of a circuit. Relative or absolute duration is represented within neuronal oscillators by “neural temporal unit,” defined as the interval between regularly occurring spikes or spike bursts. Oscillator output is processed to produce changes in activities of neurons, named frequency modulator neuron, wired within a separate module, represented by the rate of change in frequency, and frequency of activities, proposed to encode time intervals. Inbuilt oscillators are calibrated by (a) feedback processes, (b) input of time intervals resulting from rhythmic external sensory stimulation, and (c) synchronous effects of feedback processes and evoked sensory activity. A single active clock is proposed per circuit, which is calibrated by one or more mechanisms. Multiple calibration mechanisms, inbuilt oscillators, and the presence of modular connections prevent a complete loss of interval timing functions of the brain. (shrink)

A broad sketch for a model of speech production is outlined which describes developmental aspects of its cognitive-linguistic and sensorimotor components. A description of the emergence of phonological knowledge is a central point in our model sketch. It will be shown that the phonological form level emerges during speech acquisition and becomes an important representation at the interface between cognitive-linguistic and sensorimotor processes. Motor planning as well as motor programming are defined as separate processes in our model sketch (...) and it will be shown that both processes revert to the phonological information. Two computational simulation experiments based on quantitative implementations are undertaken to show proof of principle of key ideas of the model sketch: the emergence of phonological information over developmental stages, the adaptation process for generating new motor programs, and the importance of various forms of phonological representation in that process. Based on the ideas developed within our sketch of a production model and its quantitative spell-out within the simulation models, motor planning can be defined here as the process of identifying a succession of executable chunks from a currently activated phoneme sequence and of coding them as raw gesture scores. Motor programming can be defined as the process of building up the complete set of motor commands by specifying all gestures in detail. This full specification of gesture scores is achieved in our model by adapting motor information from phonologically similar syllables or by assembling motor programs from sub-syllabic units. (shrink)

In 1936, the journalist Hannah Lees published “Two Million Tightrope Walkers,” drawing attention to the significant number of people in the United States estimated to have diabetes. Focusing on how people with diabetes should live, she emphasized the importance of recording the exact values of everything they ate and avoiding all “riotous living” lest they be unable to keep careful measurements of calories, insulin, and sleep. Employing two meanings of measured – as counted and as moderate – Lees was doing (...) more than communicating how someone might control their disease; she was also calling for a “controlled and self-reliant citizenry.” Indeed, Lees insisted that diabetics who followed a regime of measurement “make a good deal better citizens than the average.” Drawing on the writings of Lees and other social commentators, I explore the link between biometrics, citizenship, and diabetes in the United States in the interwar years. In particular, I look at how this disease came to symbolize both the regimes of discipline thought to be necessary in a society moving to consumption as its economic motor, and the fears of what could happen if consumption ran amok. Biometrics, I argue, offered clinicians and patients a potent tool for measuring deviance and, potentially, for restoring a person to the “norm.”. (shrink)

The aim of this study was to analyse the relationship between the following three assessments: the Neonatal Behavioral Assessment Scale, the Alberta Infant Motor Scale, and the General Movement Assessment. 29 patients from the neonatal unit of the Gynecology and Obstetrics Clinical Hospital were examined. The study was conducted between feedings by a person properly trained in the use of the NBAS, the AIMS, and the GMA. The average postmenstrual age of the examined newborns was 35.6 weeks. The average (...) week of gestation was the 29th, the average birth weight was 1469 g, and the Median Apgar score in the fifth minute of life was 7. A relationship was found between the AIMS and the NBAS. It was concluded that the Neonatal Behavioral Assessment Scale and the Alberta Infant Motor Scale may be used to determine the motor development of preterm infants. Moreover, it is advisable to use more than one assessment method in order to adjust the intervention. (shrink)

Background: The new human coronavirus that leads to COVID-19 has spread rapidly around the world and has a high degree of lethality. In more severe cases, patients remain hospitalized for several days under treatment of the health team. Thus, it is important to develop and use technologies with the aim to strengthen conventional therapy by encouraging movement, physical activity, and improving cardiorespiratory fitness for patients. In this sense, therapies for exposure to virtual reality are promising and have been shown to (...) be an adequate and equivalent alternative to conventional exercise programs.Aim: This is a study protocol with the aim of comparing the conventional physical therapy intervention with the use of a non-immersive VR software during COVID-19 hospitalization.Methods: Fifty patients hospitalized with confirmed diagnosis of COVID-19 will be divided in two groups under physiotherapy treatment using conventional or VR intervention: Group A: participants with COVID-19 will start the first day of the protocol with VR tasks in the morning and then in the second period, in the afternoon, will perform the conventional exercises and Group B: participants with COVID-19 will start the first day with conventional exercises in the morning and in the second period, in the afternoon, will perform activity with VR. All participants will be evaluated with different motor and physiologic scales before and after the treatment to measure improvements.Conclusion: Considering the importance of benefits from physical activity during hospitalization, VR software shows promise as a potential mechanism for improving physical activity. The results of this study may provide new insights into hospital rehabilitation.Trial Registration:ClinicalTrials.gov, identifier: NCT04537858. Registered on 01 September 2020. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 8.4 (2001) 323-326 [Access article in PDF] The Tacit Dimension Thomas Fuchs Thirty years after its appearance, Blankenburg's "Psychopathology of common sense" has not lost its relevance. In my commentary I will try to illustrate the fruitfulness of his approach by pointing to some connections with the phenomenology of the body as well as with recent memory and infant research.As Blankenburg himself indicates, the notion (...) of common sense developed by a shift of meaning from the classical sensus communis and thus has its original basis in the sensual-bodily experience. By the koinè aísthesis, Aristoteles meant a central sense organ integrating all single modalities of sensation (which he localized in the heart). In German physiology and psychiatry of the nineteenth century, the sensus communis was still translated as "Gemeingefühl" ("common feeling") or "cenesthesia" (Fuchs 1995). This term denoted the inner, proprioceptive bodily sensations, but also an original unity of the senses, which has been rediscovered by recent infant research as intermodal sensory perception. The affection of the body was thus regarded as the common basis of all sensation.Looking on this track for a bodily basis of the common sense, we find it in the habitual structure of the lived-body as analysed by Merleau-Ponty (1945). The body is the primary "matter-of-course," namely, the tacitly functioning medium of our everyday being-in-the-world prior to any subject-object split. The body schema, in Merleau-Ponty's view, is not only a system of familiar units of movement or "kinetic melodies," it also incorporates the surrounding things, tools, and spaces that are familiar to us and that we "inhabit." Thus, the musician "does not only manipulate the instrument like a separate object, but lives in it like a limb and inhabits the expressive musical space it opens" (Behnke 1997). But for Merleau-Ponty, the body schema is also the basis of "intercorporeity," i.e., a prepersonal sphere of reciprocal comportment and understanding prior to any explicit consensus and symbolic communication. In this sphere of elementary contact, the "atmospheric" senses play a major role: The sense of smell (as shown, e.g., by the expression "to scent treason" or in German, "jemand nicht riechen können" [not be able to "smell" or stand someone]) as well as the sense of taste whose ambiguous meaning, mentioned by Blankenburg, points to the bodily basis of the feeling for what is suitable, decent, or aesthetically pleasing. Even the designation of homo sapiens that we give to ourselves is derived from the latin sapere (to taste/to know), and thus shows that the knowledge characteristic for man is not an explicit one, but an intuitive, implicit knowing or "feel" for his surroundings, or as Kant says, an "aesthetic rather than intellectual judgment" (cited by Blankenburg).Polanyi (1967) has analysed this knowledge at the roots of common sense as "tacit knowledge." It is based on processes of Gestalt formation that enable us to grasp unified wholes through their constituting elements without still being aware of the latter. Thus, we understand the facial expression of others immediately but cannot tell from which details. Or we know how [End Page 323] to waltz without knowing the single movements or being able to explain it. Tacit knowledge implies all the taken-for-granted that we have forgotten once it has become our second nature and part of our bodily habits. It is mainly based on the neuronal coupling of single sensori-motor units by repeated perception or action. This unconscious knowing has only recently come to be explored by psychology under the heading of "implicit" or "procedural memory" (Schacter 1987, 1996). It contains familiar styles or "melodies" of moving, perceiving, and being-with-others in which our whole bodily and emotional experience is engaged. There is an atmospheric, "felt" quality about them that cannot be analysed into single elements. Implicit knowledge may, therefore, never be wholly expressed by words—it is only realized in the concrete situation. It may only be circumscribed by expressions such as "how it feels...," "how it is...," e.g., how it is... (shrink)

The role of gesture in music has been widely investigated in different disciplines, from experimental psychology to aesthetics, from musicology to anthropology. What seems to drive the different researches is the question about the relationship arising between gestures and sound, and how this relationship affects the experience of music. In this article, I focus on the role of the hand in the production, listening and expression of music. After briefly referring to the influence of body development on language, I consider (...) some typical responses to listening to music that involve the hand, suggesting that musical experience relies on the ability of the listener-performer to transform sound perceptions into motor units. In the conclusion, I delve deeper into the topic in a phenomenological direction, proposing that gestures can be configured as a bodily continuation of the musical material rather than mere motor reactions or conventional responses to sound perception. (shrink)

Pathological tremor is a common but highly complex movement disorder, affecting ~5% of population older than 65 years. Different methodologies have been proposed for its quantification. Nevertheless, the discrimination between Parkinson’s disease tremor and essential tremor remains a daunting clinical challenge, greatly impacting patient treatment and basic research. Here, we propose and compare several movement-based and electromyography-based tremor quantification metrics. For the latter, we identified individual motor unit discharge patterns from high-density surface electromyograms and characterized the neural drive to (...) a single muscle and how it relates to other affected muscles in 27 Parkinson’s disease and 27 essential tremor patients. We also computed several metrics from the literature. The most discriminative metrics were the symmetry of the neural drive to muscles, motor unit synchronization, and the mean log power of the tremor harmonics in movement recordings. Noteworthily, the first two most discriminative metrics were proposed in this study. We then used decision tree modelling to find the most discriminative combinations of individual metrics, which increased the accuracy of tremor type discrimination to 94%. In summary, the proposed neural drive-based metrics were the most accurate at discriminating and characterizing the two most common pathological tremor types. (shrink)

Mass media campaigns are widely and successfully used to change health decisions and behaviors for better or for worse in society. In the United States, media campaigns have been launched at local offices of the states’ department of motor vehicles to promote citizens’ willingness to organ donation and donor registration. We analyze interventional studies of multimedia communication campaigns to encourage organ-donor registration at local offices of states’ department of motor vehicles. The media campaigns include the use of multifaceted (...) communication tools and provide training to desk clerks in the use of scripted messages for the purpose of optimizing enrollment in organ-donor registries. Scripted messages are communicated to customers through mass audiovisual entertainment media, print materials and interpersonal interaction at the offices of departments of motor vehicles. These campaigns give rise to three serious concerns: (1) bias in communicating information with scripted messages without verification of the scientific accuracy of information, (2) the provision of misinformation to future donors that may result in them suffering unintended consequences from consenting to medical procedures before death (e.g, organ preservation and suitability for transplantation), and (3) the unmanaged conflict of interests for organizations charged with implementing these campaigns, (i.e, dual advocacy for transplant recipients and donors). We conclude the following: (1) media campaigns about healthcare should communicate accurate information to the general public and disclose factual materials with the least amount of bias; (2) conflicting interests in media campaigns should be managed with full public transparency; (3) media campaigns should disclose the practical implications of procurement as well as acknowledge the medical, legal, and religious controversies of determining death in organ donation; (4) organ-donor registration must satisfy the criteria of informed consent; (5) media campaigns should serve as a means of public education about organ donation and should not be a form of propaganda. (shrink)

Posterior parietal cortex has traditionally been considered to be a sensory association area in which higher-order processing and intermodal integration of incoming sensory information occurs. In this paper, evidence from clinical reports and from lesion and behavioral-electrophysiological experiments using monkeys is reviewed and discussed in relation to the overall functional organization of posterior parietal association cortex, and particularly with respect to a proposed posterior parietal mechanism concerned with the initiation and control of certain classes of eye and limb movements. Preliminary (...) data from studies of the effects of posterior parietal lesions on oculomotor control in monkeys are reported.The behavioral effects of lesions of posterior parietal cortex in monkeys have been found to be similar to those which follow analogous damage of the minor hemisphere in humans, while behavioral-electrophysiological experiments have disclosed classes of neurons in this area which have functional properties closely related to the behavioral acts that are disrupted by lesions of the area. On the basis of current data from these areas of study, it is proposed that the sensory association model of posterior parietal function is inadequate to account for the complexities of the present evidence. Instead, it now appears that many diverse neural mechanisms are locatedin partin parietal cortex, that some of these mechanisms are involved in sensory processing and perceptual functions, but that others participate in motor control, and that still others are involved in attentional, motivational, or emotional processes. It is further proposed that the elementary units of these various neural mechanisms are distributed within posterior parietal cortex according to the columnar hypothesis of Mountcastle. (shrink)

A growing body of evidence in cognitive psychology and neuroscience suggests a deep interconnection between sensory-motor and language systems in the brain. Based on recent neurophysiological findings on the anatomo-functional organization of the fronto-parietal network, we present a computational model showing that language processing may have reused or co-developed organizing principles, functionality, and learning mechanisms typical of premotor circuit. The proposed model combines principles of Hebbian topological self-organization and prediction learning. Trained on sequences of either motor or linguistic (...) units, the network develops independent neuronal chains, formed by dedicated nodes encoding only context-specific stimuli. Moreover, neurons responding to the same stimulus or class of stimuli tend to cluster together to form topologically connected areas similar to those observed in the brain cortex. Simulations support a unitary explanatory framework reconciling neurophysiological motor data with established behavioral evidence on lexical acquisition, access, and recall. (shrink)

Intermediate constructs are required as bridges between complex behaviors and realistic models of neural circuitry. For cognitive scientists in general, schemas are the appropriate functional units; brain theorists can work with neural layers as units intermediate between structures subserving schemas and small neural circuits.After an account of different levels of analysis, we describe visuomotor coordination in terms of perceptual schemas and motor schemas. The interest of schemas to cognitive science in general is illustrated with the example of (...) perceptual schemas in high-level vision and motor schemas in the control of dextrous hands.Rana computatrix, the computational frog, is introduced to show how one constructs an evolving set of model families to mediate flexible cooperation between theory and experiment. Rana computatrix may be able to do for the study of the organizational principles of neural circuitry what Aplysia has done for the study of subcellular mechanisms of learning. Approach, avoidance, and detour behavior in frogs and toads are analyzed in terms of interacting schemas. Facilitation and prey recognition are implemented as tectal-pretectal interactions, with the tectum modeled by an array of tectal columns. We show how layered neural computation enters into models of stereopsis and how depth schemas may involve the interaction of accommodation and binocular cues in anurans. (shrink)

We respond to Morgan and Feeley’s critique on our article “Mass Media in Organ Donation: Managing Conflicting Messages and Interests.” We noted that Morgan and Feeley agree with the position that the primary aims of media campaigns are: “to educate the general public about organ donation process” and “help individuals make informed decisions” about organ donation. For those reasons, the educational messages in media campaigns should not be restricted to “information from pilot work or focus groups” but should include evidence-based (...) facts resulting from a comprehensive literature research. We consider the controversial aspects about organ donation to be relevant, if not necessary, educational materials that must be disclosed in media campaigns to comply with the legal and moral requirements of informed consent. With that perspective in mind, we address the validity of Morgan and Feeley’s claim that media campaigns have no need for informing the public about the controversial nature of death determination in organ donation. Scientific evidence has proven that the criteria for death determination are inconsistent with the Uniform Determination of Death Act and therefore potentially harmful to donors. The decision by campaign designers to use the statutory definition of death without disclosing the current controversies surrounding that definition does not contribute to improved informed decision making. We argue that if Morgan and Feeley accept the important role of media campaigns to enhance informed decision making, then critical controversies should be disclosed. In support of that premise, we will outline: (1) the wide-spread scientific challenges to brain death as a concept of death; (2) the influence of the donor registry and team-huddling on the medical care of potential donors; (3) the use of authorization rather than informed consent for donor registration; (4) the contemporary religious controversy; and (5) the effects of training desk clerks as organ requestors at the Department of Motor Vehicles offices. We conclude that organ donation is a medical procedure subject to all the ethical obligations that the medical profession must uphold including that of transparency and truthfulness. (shrink)

People coordinate body postures and gaze patterns during conversation. We review literature showing that (1) action embodies cognition, (2) postural coordination emerges spontaneously when two people converse, (3) gaze patterns influence postural coordination, (4) gaze coordination is a function of common ground knowledge and visual information that conversants believe they share, and (5) gaze coordination is causally related to mutual understanding. We then consider how coordination, generally, can be understood as temporarily coupled neuromuscular components that function as a collective unit (...) known as a coordinative structure in the motor control literature. We speculate that the coordination of gaze and body sway found in conversation may be understood as a cross‐person coordinative structure that embodies the goals of the joint action system. (shrink)

If the cortex is an associative memory, strongly connected cell assemblies will form when neurons in different cortical areas are frequently active at the same time. The cortical distributions of these assemblies must be a consequence of where in the cortex correlated neuronal activity occurred during learning. An assembly can be considered a functional unit exhibiting activity states such as full activation (“ignition”) after appropriate sensory stimulation (possibly related to perception) and continuous reverberation of excitation within the assembly (a putative (...) memory process). This has implications for cortical topographies and activity dynamics of cell assemblies forming during language acquisition, in particular for those representing words. Cortical topographies of assemblies should be related to aspects of the meaning of the words they represent, and physiological signs of cell assembly ignition should be followed by possible indicators of reverberation. The following postulates are discussed in detail: (1) assemblies representing phonological word forms are strongly lateralized and distributed over perisylvian cortices; (2) assemblies representing highly abstract words such as grammatical function words are also strongly lateralized and restricted to these perisylvian regions; (3) assemblies representing concrete content words include additional neurons in both hemispheres; (4) assemblies representing words referring to visual stimuli include neurons in visual cortices; and (5) assemblies representing words referring to actions include neurons in motor cortices. Two main sources of evidence are used to evaluate these proposals: (a) imaging studies focusing on localizing word processing in the brain, based on stimulus-triggered event-related potentials (ERPs), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI), and (b) studies of the temporal dynamics of fast activity changes in the brain, as revealed by high-frequency responses recorded in the electroencephalogram (EEG) and magnetoencephalogram (MEG). These data provide evidence for processing differences between words and matched meaningless pseudowords, and between word classes, such as concrete content and abstract function words, and words evoking visual or motor associations. There is evidence for early word class-specific spreading of neuronal activity and for equally specific high-frequency responses occurring later. These results support a neurobiological model of language in the Hebbian tradition. Competing large-scale neuronal theories of language are discussed in light of the data summarized. Neurobiological perspectives on the problem of serial order of words in syntactic strings are considered in closing. Key Words: associative learning; cell assembly; cognition; cortex; ERP; EEG; fMRI; language; lexicon; MEG; PET; word category. (shrink)

The term ‘locked-in’ syndrome (LIS) describes a medical condition in which persons concerned are severely paralyzed and at the same time fully conscious and awake. The resulting anarthria makes it impossible for these patients to naturally communicate, which results in diagnostic as well as serious practical and ethical problems. Therefore, developing alternative, muscle-independent communication means is of prime importance. Such communication means can be realized via brain–computer interfaces (BCIs) circumventing the muscular system by using brain signals associated with preserved cognitive, (...) sensory, and emotional brain functions. Primarily, BCIs based on electrophysiological measures have been developed and applied with remarkable success. Recently, also blood flow–based neuroimaging methods, such as functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS), have been explored in this context. After reviewing recent literature on the development of especially hemodynamically based BCIs, we introduce a highly reliable and easy-to-apply communication procedure that enables untrained participants to motor-independently and relatively effortlessly answer multiple-choice questions based on intentionally generated single-trial fMRI signals that can be decoded online. Our technique takes advantage of the participants’ capability to voluntarily influence certain spatio-temporal aspects of the blood oxygenation level–dependent (BOLD) signal: source location (by using different mental tasks), signal onset and offset. We show that healthy participants are capable of hemodynamically encoding at least four distinct information units on a single-trial level without extensive pretraining and with little effort. Moreover, realtime data analysis based on simple multi-filter correlations allows for automated answer decoding with a high accuracy (94.9%) demonstrating the robustness of the presented method.. (shrink)

1993: GE’s NBC News unit issues an on-air apology to General Motors for staging a misleading simulated crash test. NBC agrees to pay GM’s estimated $1 million legal and investigation expenses.February 1994: The Justice Department brought a criminal antitrust case against General Electric, accusing it of conspiring with an arm of the South African DeBeers diamond cartel to fix prices in the $600 million world market for industrial diamonds. General Electric denied wrongdoing...

Introduction There are some exceptions, which we shall see below, but virtually all theories in psychology and cognitive science make use of the notion of representation. Arguably, folk psychology also traffics in representations, or is at least strongly suggestive of their existence. There are many different types of things discussed in the psychological and philosophical literature that are candidates for representation-hood. First, there are the propositional attitudes – beliefs, judgments, desires, hopes etc. (see Chapters 9 and 17 of this volume). (...) If the propositional attitudes are representations, they are person-level representations – the judgment that the sun is bright pertains to John, not a subpersonal part of John. By contrast, the representations of edges in V1 of the cerebral cortex that neuroscientists talk about and David Marr’s symbolic representations of “zero-crossings” in early vision (Marr 1982) are at the “sub-personal” level – they apply to parts or states of a person (e.g. neural parts or computational states of the visual system). Another important distinction is often made among perceptual, cognitive, and action-oriented representations (e.g. motor commands). Another contrast lies between “stored representations” (e.g. memories) and “active representations” (e.g. a current perceptual state). Related to this is the distinction between “dispositional representations” and “occurrent representations.” Beliefs that are not currently being entertained are dispositional, e.g. your belief that the United States is in North America - no doubt you had this belief two minutes ago, but you were not consciously accessing it until you read this sentence. Occurrent representations, by contrast, are active, conscious thoughts or perceptions. Which leads us to another important distinction: 1 between conscious and non-conscious mental representations, once a bizarre-sounding distinction that has become familiar since Freud (see Chapter 4 of this volume). I mention these distinctions at the outset to give you some idea of the range of phenomena we will be considering, and to set the stage for our central “problem of representation”: what is a mental representation, exactly, and how do we go about deciding whether there are any? We know there are public representations of various kinds: words, maps, and pictures, among others.. (shrink)

Abstract“Sign stimuli” elicit specific patterns of behavior when an organism's motivation is appropriate. In the toad, visually released prey-catching involves orienting toward the prey, approaching, fixating, and snapping. For these action patterns to be selected and released, the prey must be recognized and localized in space. Toads discriminate prey from nonprey by certain spatiotemporal stimulus features. The stimulus-response relations are mediated by innate releasing mechanisms (RMs) with recognition properties partly modifiable by experience. Striato-pretecto-tectal connectivity determines the RM's recognition and localization (...) properties, whereas medialpallio-thalamo-tectal circuitry makes the system sensitive to changes in internal state and to prior history of exposure to stimuli. RMs encode the diverse stimulus conditions referring to the same prey object through different combinations of “specialized” tectal neurons, involving cells selectively tuned to prey features. The prey-selective neurons express the outcome of information processing in functional units consisting of interconnected cells. Excitatory and inhibitory interactions among feature-sensitive tectal and pretectal neurons specify the perceptual operations involved in distinguishing the prey from its background, selecting its features, and discriminating it from predators. Other connections indicate stimulus location. The results of these analyses are transmitted by specialized neurons projecting from the tectum to bulbar/spinal motor systems, providing a sensorimotor interface. Specific combinations of such projective neurons – mediating feature- and space-related messages – form “command releasing systems” that activate corresponding motor pattern generators for appropriate prey-catching action patterns. (shrink)