In the property listing task (PLT), participants are asked to list properties for a concept (e.g., for the concept dog, “barks,” and “is a pet” may be produced). In conceptual property norming (CPNs) studies, participants are asked to list properties for large sets of concepts. Here, we use a mathematical model of the property listing process to explore two longstanding issues: characterizing the difference between concrete and abstract concepts, and characterizing semantic knowledge in the blind versus sighted population. When we (...) apply our mathematical model to a large CPN reporting properties listed by sighted and blind participants, the model uncovers significant differences between concrete and abstract concepts. Though we also find that blind individuals show many of the same processing differences between abstract and concrete concepts found in sighted individuals, our model shows that those differences are noticeably less pronounced than in sighted individuals. We discuss our results vis‐a‐vis theories attempting to characterize abstract concepts. (shrink)

Despite all methodological efforts made in the last three decades, Western instruction grounds on traditional principles. Most educational programs follow theories that are mentalistic, i.e., they separate the mind from the body. At school, learners sit, watch, listen, and write. The aim of this paper is to present embodied learning as an alternative to mentalistic education. Similarly, this paper wants to describe embodied learning from a neuroscientific perspective. After a brief historical overview, I will review studies highlighting the behavioral effectiveness (...) of embodied instruction in second language learning, mathematics and spatial thinking. On this base, I will discuss some of the brain mechanisms driving embodied learning and describe its advantages, clearly pleading in favor of instructional practice that reunites body and mind. (shrink)

Barsalou has recently argued against the strategy of identifying amodal neural representations by using their cross-modal responses (i.e., their responses to stimuli from different modalities). I agree that there are indeed modal structures that satisfy this “cross-modal response” criterion (CM), such as distributed and conjunctive modal representations. However, I argue that we can distinguish between modal and amodal structures by looking into differences in their cross-modal responses. A component of a distributed cell assembly can be considered unimodal because its responses (...) to stimuli from a given modality are stable, whereas its responses to stimuli from any other modality are not (i.e., these are lost within a short time, plausibly as a result of cell assembly dynamics). In turn, conjunctive modal representations, such as superior colliculus cells in charge of sensory integration, are multimodal because they have a stable response to stimuli from different modalities. Finally, some prefrontal cells constitute amodal representations because they exhibit what has been called ‘adaptive coding’. This implies that their responses to stimuli from any given modality can be lost when the context and task conditions are modified. We cannot assign them a modality because they have no stable relation with any input type. (shrink)

Vocabulary learning in a second language is enhanced if learners enrich the learning experience with self-performed iconic gestures. This learning strategy is called enactment. Here we explore how enacted words are functionally represented in the brain and which brain regions contribute to enhance retention. After an enactment training lasting 4 days, participants performed a word recognition task in the functional Magnetic Resonance Imaging (fMRI) scanner. Data analysis suggests the participation of different and partially intertwined networks that are engaged in higher (...) cognitive processes, i.e., enhanced attention and word recognition. Also, an experience-related network seems to map word representation. Besides core language regions, this latter network includes sensory and motor cortices, the basal ganglia, and the cerebellum. On the basis of its complexity and the involvement of the motor system, this sensorimotor network might explain superior retention for enactment. (shrink)

Foreign language education in the twenty-first century still teaches vocabulary mainly through reading and listening activities. This is due to the link between teaching practice and traditional philosophy of language, where language is considered to be an abstract phenomenon of the mind. However, a number of studies have shown that accompanying words or phrases of a foreign language with gestures leads to better memory results. In this paper, I review behavioral research on the positive effects of gestures on memory. Then (...) I move to the factors that have been addressed as contributing to the effect, and I embed the reviewed evidence in the theoretical framework of embodiment. Finally, I argue that gestures accompanying foreign language vocabulary learning create embodied representations of those words. I conclude by advocating the use of gestures in future language education as a learning tool that enhances the mind. (shrink)

There is growing evidence that words that are acquired early in life are processed faster and more accurately than words acquired later, even by adults. As neuropsychological and neuroimaging studies have implicated different brain networks in the processing of action verbs and concrete nouns, the present study was aimed at contrasting reaction times to early and later-acquired action verbs and concrete nouns, in order to determine whether effects of word learning age express differently for the two types of words. Our (...) results show that while word frequency affected both types of words in the same way, distinct learning age effects were observed for action verbs and concrete nouns. A further experiment specified that this difference was observed for verbs describing actions belonging to the human motor repertoire, but not for verbs denoting actions past this repertoire (e.g., to neigh). We interpret these data within a recently emerging framework according to which language processing is associated with sensory motor programs. (shrink)

The Complex-First Paradox consists in a set of collectively incompatible but individually well-confirmed propositions that regard the evolution, development, and cortical realization of the meanings of concrete nouns. Although these meanings are acquired earlier than those of other word classes, they are semantically more complex and their cortical realizations more widely distributed. For a neurally implemented syntaxsemantics interface, it should thus take more effort to establish a link between a concept and its lexical expression. However, in ontogeny and phylogeny, capabilities (...) demanding more effort, ceteris paribus, develop and evolve later than those demanding less effort. The paradox points to an explanatory deficit in linguistic theory. (shrink)

In this paper we discuss an approach called grounded action cognition, which aims to provide a theory of the interdependencies between motor control and action-related cognitive processes, like perceiving an action or thinking about an action. The theory contrasts with traditional views in cognitive science in that it motivates an understanding of cognition as embodied, through application of Barsalou’s general idea of grounded cognition. To guide further research towards an appropriate theory of grounded action cognition we distinguish between grounding qua (...) acquisition and grounding qua constitution. On this basis, we distinguish three possible theoretical conceptions of grounded action cognition. In addition to these methodological and conceptual analyses, we draw on recent empirical evidence to motivate our inclination towards a particular theory. According to this theory certain representations are involved in action cognition and action perception that are not modality-specific as usually proposed by advocates of grounded cognition. Further, the evidence is in favor of our more specific theory stating that for some cognitive abilities, some motor abilites are constitutive. (shrink)

Impairments in cognitive coordination in schizophrenia are supported by phenomenological data that suggest deficits in the processing of visual context. Although the target article is sympathetic to such a phenomenological perspective, we argue that the relevance of phenomenological data for a wider understanding of consciousness in schizophrenia is not sufficiently addressed by the authors.

The concept of locally specialized functions dominates research on higher brain function and its disorders. Locally specialized functions must be complemented by processes that coordinate those functions, however, and impairment of coordinating processes may be central to some psychotic conditions. Evidence for processes that coordinate activity is provided by neurobiological and psychological studies of contextual disambiguation and dynamic grouping. Mechanisms by which this important class of cognitive functions could be achieved include those long-range connections within and between cortical regions that (...) activate synaptic channels via NMDA-receptors, and which control gain through their voltage-dependent mode of operation. An impairment of these mechanisms is central to PCP-psychosis, and the cognitive capabilities that they could provide are impaired in some forms of schizophrenia. We conclude that impaired cognitive coordination due to reduced ion flow through NMDA-channels is involved in schizophrenia, and we suggest that it may also be involved in other disorders. This perspective suggests several ways in which further research could enhance our understanding of cognitive coordination, its neural basis, and its relevance to psychopathology. Key Words: attention; cerebral cortex; cognitive coordination; cognitive neuropsychiatry; cognitive neuropsychology; context disorganization; Gamma rhythms; Gestalt theory; glutamate; grouping; memory; NMDA-receptors; PCP-psychosis; perceptual organization; schizophrenia. (shrink)

Information management systems improve the retention of information in large collections. As such they act as memory prostheses, implying an ideal basis in human memory models. Since humans process information by association, and situate it in the context of space and time, systems should maximize their effectiveness by mimicking these functions. Since human attentional capacity is limited, systems should scaffold cognitive efforts in a comprehensible manner. We propose the Principles of Mnemonic Associative Knowledge (P-MAK), which describes a framework for semantically (...) identifying, organizing, and retrieving information, and for encoding episodic events by time and stimuli. Inspired by prominent human memory models, we propose associative networks as a preferred representation. Networks are ideal for their parsimony, flexibility, and ease of inspection. Networks also possess topological properties—such as clusters, hubs, and the small world—that aid analysis and navigation in an information space. Our cognitive perspective addresses fundamental problems faced by information management systems, in particular the retrieval of related items and the representation of context. We present evidence from neuroscience and memory research in support of this approach, and discuss the implications of systems design within the constraints of P-MAK’s principles, using text documents as an illustrative semantic domain. (shrink)

Theories of binding have recently come into the focus of the consciousness debate. In this review, we discuss the potential relevance of temporal binding mechanisms for sensory awareness. Specifically, we suggest that neural synchrony with a precision in the millisecond range may be crucial for conscious processing, and may be involved in arousal, perceptual integration, attentional selection and working memory. Recent evidence from both animal and human studies demonstrates that specific changes in neuronal synchrony occur during all of these processes (...) and that they are distinguished by the emergence of fast oscillations with frequencies in the gamma-range. (shrink)

This paper investigates how "representation" is actually used in some areas in cognitive neuroscience. It is argued that recent philosophy has largely ignored an important kind of representation that differs in interesting ways from the representations that are standardly recognized in philosophy of mind. This overlooked kind of representation does not represent by having intentional contents; rather members of the kind represent by displaying or instantiating features. The investigation is not simply an ethnographic study of the discourse of neuroscientists. If (...) there are indeed two different kinds of representations, and the non-standard ones are the ones referred to in some areas of cognitive neuroscience, then we will have to give up the idea that appealing to inner representations with intentional contents is the defining distinction between cognitive neuroscience and behaviorist psychology (Montgomery, 1995). Further, if the conclusions of this paper are correct, many general accounts of how neural states represent are either false or theoretically ill-motivated. (shrink)

Digital communication has generated forms of written speech that may deviate from standard ones, such as Greeklish (a Latin-alphabet-based script) vs. Greek. The question of interest is how different orthographic representations of the same referent (e.g. petaloyda, “butterfly”, in Greeklish vs. πϵταλούδα “butterfly” in Greek) may influence word processing, particularly visual word recognition and access to affective connotations. 120 Greek native speakers were tested on a lexical decision task, in which script (Greeklish vs. Greek) and valence (positive vs. negative vs. (...) neutral) were manipulated within participants. Words were matched for word class, frequency, concreteness, length, number of syllables and orthographic neighbourhood. Emotional words differed from neutral ones in valence and arousal. Results yielded faster response times for words written in the standard script (Greek) than the non-standard script (Greeklish). Moreover, regardless of script, response times were negatively correlated with the words’ valence, with slowest responses for negative words and fastest for positive ones, suggesting that positive content accelerates lexical access, whereas negative content slows it down. To sum up, although script type was found to affect word recognition, activation of and access to emotional content seemed to resist non-standard characteristics of visual word processing. (shrink)

The aim of this paper is to give an account of what it is to internalize a rule. I claim that internalization is the process of redistributing the burden of instruction from the teacher to the student. The process is complete when instruction is no longer needed, and the rule has reshaped perceptual classification of the circumstances in which it applies. Teaching a rule is the initiation of this process. We internalize rules by simulating instruction coming from someone else. Running (...) these simulations enables us to toggle between the perspective of the instructor and our own perspective. By doing this we coordinate our perspectives with that of the teacher. The account given here provides a deeper explanation of why internalizing a rule involves the dispositions and reactive attitudes proponents of Rule Consequentialism often say it does, why moral reflection is variably demanding, how intergenerational moral progress is made possible by our cognitive architectures, and why the adoption of a rule should be understood in terms of teaching that rule. (shrink)

The embodiment approach has shown that motor neural networks are involved in the processing of action verbs. There is developmental evidence that embodied effects on verb processing are already present in early years. Yet, the ontogenetic origin of this motor reuse in action verbs remains unknown. This longitudinal study investigates the co-occurrence of manual verbs and actions during mother-child daily routines when children were 1 to 2 and 2 to 3 years old. Eight mother-child dyads were video-recorded in 3-month intervals (...) across 12 months, and the timing of verbs and manual actions were coded by independent observers. Results showed that the probability of matched verb-action co-occurrences were much higher than that of random co-occurrences for Group 1 and Group 2, respectively. The distributions of the verb-action temporal intervals in both groups were quite symmetrical and skewed with the peak corresponding to both 0.00 s synchronic intervals and the shortest +5 s interval. Mother-led instances occurred in both groups whereas child-led instances were restricted to Group 2. Mothers pragmatically aligned their verbal productions, since they repeatedly used those verbs they shared with their children’s repertoire. In conclusion, the early multisensory communicative and manipulative scene affords grounding of verb meanings on the ongoing actions, facilitating verb-action pairing in the realm of social interactions, providing a new dimension to the prevailing solipsistic approach to embodiment. (shrink)

According to embodied theories of language (ETLs), word meaning relies on sensorimotor brain areas, generally dedicated to acting and perceiving in the real world. More specifically, words denoting actions are postulated to make use of neural motor areas, while words denoting visual properties draw on the resources of visual brain areas. Therefore, there is a direct correspondence between word meaning and the experience a listener has had with a word's referent on the brain level. Behavioral and neuroimaging studies have provided (...) evidence in favor of ETLs; however, recent studies have also shown that sensorimotor information is recruited in a flexible manner during language comprehension (e.g., Raposo et al. ; Van Dam et al., ), leaving open the question as to what level of language processing sensorimotor activations contribute. In this study, we investigated the time course of modality‐specific contributions (i.e., the contribution of action information) as to word processing by manipulating both (a) the linguistic and (b) the action context in which target words were presented. Our results demonstrate that processes reflecting sensorimotor information play a role early in word processing (i.e., within 200 ms of word presentation), but that they are sensitive to the linguistic context in which a word is presented. In other words, when sensorimotor information is activated, it is activated quickly; however, specific words do not reliably activate a consistent sensorimotor pattern. (shrink)

The debate between the amodal and the grounded views of cognition seems to be stuck. Their only substantial disagreement is about the vehicle or format of concepts. Amodal theorists reject the grounded claim that concepts are couched in the same modality-specific format as representations in sensory systems. The problem is that there is no clear characterization of format or its neural correlate. In order to make the disagreement empirically meaningful and move forward in the discussion we need a neurocognitive criterion (...) for representational format. I argue that efficient coding models in computational neuroscience can be used to characterize modal codes: These are codes which satisfy special informational demands imposed by sensory tasks. Additionally, I examine recent studies on neural coding and argue that although they do not provide conclusive evidence for either the grounded or the amodal views, they can be used to determine what predictions these approaches can make and what experimental and theoretical developments would be required to settle the debate. (shrink)

Recent experiments have shown that when individuals with a substance use disorder are confronted with drug-related cues, they exhibit an automatically activated tendency to approach these cues. The strength of the drug approach bias has been associated with clinically relevant measures, such as increased drug craving and relapse, and activations in brain reward areas. Retraining the approach bias by means of cognitive bias modification has been demonstrated to decrease relapse rates in patients with an alcohol use disorder and to reduce (...) alcohol cue-evoked limbic activity. Here, we review empirical and theoretical literature on the drug approach bias and explore two distinct models of how the drug approach bias may be embodied. First, we consider the “biological meaning” hypothesis, which grounds the automatic approach bias in the natural meaning of the body. Second, we consider the “sensorimotor hypothesis,” which appeals to the specific sensorimotor loops involved in the instantiation of addictive behaviors as the basis of the automatic approach bias. In order to differentiate between the adequacies of these competing explanations, we present specific, predictions that each model should make. (shrink)

We propose a view of embodied representations that is alternative to both symbolic/linguistic approaches and purely sensorimotor views of cognition, and can account for procedural and declarative knowledge manipulation. In accordance with recent evidence in cognitive neuroscience and psychology, we argue that anticipatory and simulative mechanisms, which arose during evolution for action control and not for cognition, determined the first form of representational content and were exapted for increasingly sophisticated cognitive uses. In particular, procedural and declarative forms of knowledge can (...) be explained, respectively, in terms of on-line sensorimotor anticipation and off-line simulations of potential actions, which can give access to tacit knowledge and make it explicit. That is, mechanisms that evolved for the on-line prediction of the consequences of one's own actions (i.e. forward models) determine a (procedural) form of representation, and became exapted for off-line use. They can therefore be used to produce (declarative) knowledge of the world, by running a simulation of the action that would produce the relevant information. We conclude by discussing how embodied representations afford a form of internal manipulation that can be described as internalized situated action. (shrink)

Thirty years ago, grounded cognition had roots in philosophy, perception, cognitive linguistics, psycholinguistics, cognitive psychology, and cognitive neuropsychology. During the next 20 years, grounded cognition continued developing in these areas, and it also took new forms in robotics, cognitive ecology, cognitive neuroscience, and developmental psychology. In the past 10 years, research on grounded cognition has grown rapidly, especially in cognitive neuroscience, social neuroscience, cognitive psychology, social psychology, and developmental psychology. Currently, grounded cognition appears to be achieving increased acceptance throughout cognitive (...) science, shifting from relatively minor status to increasing importance. Nevertheless, researchers wonder whether grounded mechanisms lie at the heart of the cognitive system or are peripheral to classic symbolic mechanisms. Although grounded cognition is currently dominated by demonstration experiments in the absence of well-developed theories, the area is likely to become increasingly theory driven over the next 30 years. Another likely development is the increased incorporation of grounding mechanisms into cognitive architectures and into accounts of classic cognitive phenomena. As this incorporation occurs, much functionality of these architectures and phenomena is likely to remain, along with many original mechanisms. Future theories of grounded cognition are likely to be heavily influenced by both cognitive neuroscience and social neuroscience, and also by developmental science and robotics. Aspects from the three major perspectives in cognitive science—classic symbolic architectures, statistical/dynamical systems, and grounded cognition—will probably be integrated increasingly in future theories, each capturing indispensable aspects of intelligence. (shrink)

The purpose of this paper is to defend a conception of language that does not rely on linguistic meanings, and use it to address the Sorites and Liar paradoxes.

In chronic schizophrenic patients with both positive and negative symptoms (see Table 1), interhemispheric connections at the high frequency beta2-rhythm are absent during cognitive tasks, in contrast to normal controls, who have many interhemispheric connections at this frequency in the same situation. Connectivity is a fundamental brain feature, evidently greatly promoted by the NMDA system. It is a more reliable measure of brain function than the spectral power of this rhythm.

To understand schizophrenia, a linking hypothesis is needed that shows how brain mechanisms lead to behavioral functions in normals, and also how breakdowns in these mechanisms lead to behavioral symptoms of schizophrenia. Such a linking hypothesis is now available that complements the discussion offered by Phillips & Silverstein (P&S).

The Phillips & Silverstein model of NMDA-mediated coordination deficits provides a useful heuristic for the study of schizophrenic cognition. However, the model does not specifically account for the development of schizophrenia-spectrum disorders. The P&S model is compared to Meehl's seminal model of schizotaxia, schizotypy, and schizophrenia, as well as the model of schizophrenic cognitive dysfunction posited by McCarley and colleagues.

Mechanisms that contribute to perceptual processing dysfunction in schizophrenia were examined by Phillips & Silverstein, and formulated as involving disruptions in both local and higher-level coordination of signals. We agree that dysfunction in the coordination of cognitive functions (disconnection) is also indicated for many of the linguistic processing deficits documented for schizophrenia. We suggest, however, that it may be necessary to add a timing mechanism to the theoretical account.

There are some complex experiences, such as the experiences that allow us to understand linguistic expressions and pictures respectively, which seem to be very similar. For they are stratified experiences in which, on top of grasping certain low-level properties, one also grasps some high-level semantic-like properties. Yet first of all, those similarities notwithstanding, a phenomenologically-based reflection shows that such experiences are different. For a meaning experience has a high-level fold, in which one grasps the relevant expression’s meaning, which is not (...) perceptual, but is only based on a low-level perceptual fold that merely grasps that expression in its acoustically relevant properties. While a pictorial experience, a seeing-in experience, has two folds, the configurational and the recognitional fold, in which one respectively grasps the physical basis of a picture, its vehicle, and what the picture presents, its subject, that are both perceptual, insofar as they are intimately connected. For unlike a meaning experience, in a seeing-in experience one can perceptually read off the picture’s subject from the picture’s vehicle. Moreover, this phenomenological difference is neurologically implemented. For not only the cerebral areas that respectively implement such experiences are different, at least as far as the access to those experiences’ respective high-level content is concerned. As is shown by the fact that one can selectively be impaired in the area respectively implementing the meaning vs. the seeing-in experience without losing one’s pictorial vs. semantic competence respectively. But also, unlike meaning experiences, the area implementing the seeing-in experiential folds is perceptual as a whole. For not only a picture’s subject can be accessed earlier than an expression’s meaning, but also the neural underpinnings of such folds are located in the perceptual areas of the brain. (shrink)

Cognitive-pragmatic approaches to how metaphors are understood view the activation of perceptual or motor effects as inferred. Crucially, inferences elicit conceptual representations, e.g. in the form of implicatures, and/or mental simulations, e.g. in the form of imagery, memory, an impression and other private elements. Emotional effects, being non-conceptual, must be left out of this picture. But evidence in neurolinguistics and psycholinguistics has shown that metaphors activate brain regions linked to emotions, and that in L2, in the absence of fully-propositional meaning, (...) metaphors yield meaningful interpretations by evoking imagery, impressions, emotions. Drawing on relevance-theoretic views, we would like to argue that metaphors are processed in not entirely propositional terms. Subjective experience heuristics allows making rapid responses by absorbing emotions, imagery, impressions, into the interpretation process, an ability which outweighs standard inferential reasoning processes. Such a position is likely to apply to non-metaphorical language, too and thus pervade linguistic processing in general. (shrink)

Vision is the main entrance for environmental input to the human brain. Even if vision is our most used sensory modality, its importance is not limited to environmental exploration. Rather it has strong links to motor competences, further extending to cognitive and social aspects of human life. These multifaceted relationships are particularly important in developmental age and become dramatically evident in presence of complex deficits originating from visual aberrancies. The present review summarizes the available neuropsychological evidence on the development of (...) visual competences, with a particular focus on the associated visuo-motor integration skills in health and disease. With the aim of supporting future research and interventional settings, the goal of the present review is to constitute a solid base to help the translation of neuropsychological hypotheses into straightforward empirical investigations and rehabilitation/training protocols. This approach will further increase the impact, ameliorate the acceptance, and ease the use and implementation of lab-derived intervention protocols in real-life situations. (shrink)

Embodied theories of grounded semantics postulate that, when word meaning is first acquired, a link is established between symbol and corresponding semantic information present in modality-specific—including primary—sensorimotor cortices of the brain. Direct experimental evidence documenting the emergence of such a link, however, is still missing. Here, we present new neuroimaging results that provide such evidence. We taught participants aspects of the referential meaning of previously unknown, senseless novel spoken words by associating them with either a familiar action or a familiar (...) object. After training, we used functional magnetic resonance imaging to analyze the participants’ brain responses to the new speech items. We found that hearing the newly learnt object-related word sounds selectively triggered activity in the primary visual cortex, as well as secondary and higher visual areas.These results for the first time directly document the formation of a link between the novel, previously meaningless spoken items and corresponding semantic information in primary sensory areas in a category-specific manner, providing experimental support for perceptual accounts of word-meaning acquisition in the brain. (shrink)

Neurons repeatedly exposed to similar perceptual experiences fire together and wire together to form ‘meaning kernels’ of concepts. Pulvermueller argues that abstract concepts may be devoid of meaning kernels, because the perceptual experiences that construct abstract concepts are subject to great variation and share few common features. Abstract concept are therefore grounded in the brain through features that belong to ‘meaning halos’, rather than to ‘meaning kernels’.

There is considerable evidence that language comprehenders derive lexical‐semantic meaning by mentally simulating perceptual and motor attributes of described events. However, the nature of these simulations—including the level of detail that is incorporated and contexts under which simulations occur—is not well understood. Here, we examine the effects of first‐ versus third‐person perspective on mental simulations during sentence comprehension. First‐person sentences describing physical transfer towards or away from the body (e.g., “You threw the microphone,” “You caught the microphone”) modulated response latencies (...) when responses were made along a front‐back axis, consistent with the action‐sentence compatibility effect (ACE). This effect was not observed for third‐person sentences (“He threw the microphone,” “He caught the microphone”). The ACE was observed when making responses along a left‐right axis for third‐person, but not first‐person sentences. Abstract sentences (e.g., “He heard the message”) did not show an ACE along either axis. These results show that perspective is a detail that is simulated during action sentence comprehension, and that motoric activations are flexible and affected by the pronominal perspective used in the sentence. (shrink)

Phillips & Silverstein's focus on schizophrenia as a failure of “cognitive coordination” is welcome. They note that a simple hypothesis of reduced Gamma synchronisation subserving impaired coordination does not fully account for recent observations. We suggest that schizophrenia reflects a dynamic compensation to a core deficit of coordination, expressed either as hyper- or hyposynchronisation, with neurotransmitter systems and arousal as modulatory mechanisms.

Although interesting, the hypotheses proposed by Phillips & Silverstein lack unifying structure both in specific mechanisms and in cited evidence. They provide little to support the notion that low-level sensory processing and high-level cognitive coordination share dynamic grouping by synchrony as a common processing mechanism. We suggest that more realistic large-scale modeling at multiple levels is needed to address these issues.

Phillips & Silverstein's ambitious link between receptor abnormalities and the symptoms of schizophrenia involves a certain amount of fuzziness: No detailed mechanism is suggested through which the proposed abnormality would lead to psychological traits. We propose that detailed simulation of brain regions, using model neural networks, can aid in understanding the relation between biological abnormality and psychological dysfunction in schizophrenia.

Numerous searches have failed to identify a single co-occurrence of total blindness and schizophrenia. Evidence that blindness causes loss of certain NMDA-receptor functions is balanced by reports of compensatory gains. Connections between visual and anterior cingulate NMDA-receptor systems may help to explain how blindness could protect against schizophrenia.

Phillips & Silverstein argue that schizophrenia is a result of a deficit of the contextual coordination of neuronal responses. The authors propose that NMDA-receptors control these modulatory effects. However, hallucinations, which are among the principle symptoms of schizophrenia, imply a flaw in the interactions between neurons that is more fundamental than just a general weakness of contextual modulation.

This commentary highlights methods for using scalp EEG to make inferences about contextual field interactions, which, in view of the target article, may be specially relevant to the study of schizophrenia. Although scalp EEG has limited spatial resolution, prior knowledge combined with experimental manipulations may be used to strengthen inferences about underlying brain processes. Both spatial and temporal context are discussed within the framework of nonlinear interactions. Finally, results from a visual contour integration EEG pilot study are summarized in view (...) of a hypothesis that relates receptive field and contextual field processing to evoked and induced activity, respectively. (shrink)

Although context-processing deficits may be core features of schizophrenia, context remains a poorly defined concept. To test Phillips & Silverstein's model, we need to operationalize context more precisely. We offer several useful ways of framing context and discuss enhancing or facilitating schizophrenic patients' performance under different contextual situations. Furthermore, creativity may be a byproduct of cognitive uncoordination.

Schizophrenics exhibit a deficit in theory of mind (ToM), but an intact theory of biology (ToB). One explanation is that ToM relies on an independent module that is selectively damaged. Phillips & Silverstein's analyses suggest an alternative: ToM requires the type of coordination that is impaired in schizophrenia, whereas ToB is spared because this type of coordination is not involved.

Neurophysiological investigations of the past two decades have consistently demonstrated a deficit in sensory gating associated with schizophrenia. Phillips & Silverstein interpret this impairment as being consistent with cognitive coordination dysfunction. However, the physiological mechanisms that underlie sensory gating have not been shown to involve gamma-band oscillations or NMDA-receptors, both of which are critical neural elements in the cognitive coordination model.