Publications

In Press

Bio, B. J., Guterstam, A., Pinsk, M., Wilterson, A. I., & Graziano, M. S. A. Right Temporoparietal Junction Encodes Inferred Mental Experience of Others. Neuropsychologia.

2022

Graziano, M. S. A. (2022). Consciousness is already solved: The continued debate is not about science. Behavioral and Brain Sciences, 45, E50.

Why do we leak lubricant from the eyes to solicit comfort from others? Why do we bare our teeth and crinkle our faces to express nonaggression? The defensive mimic theory proposes that a broad range of human emotional expressions evolved originally as exaggerated, temporally extended mimics of the fast, defensive reflexes that normally protect the body surface. Defensive reflexes are so important to survival that they cannot be safely suppressed; yet they also broadcast information about an animal’s internal state, information that can potentially be exploited by other animals. Once others can observe and exploit an animal’s defensive reflexes, it may be advantageous to the animal to run interference by creating mimic defensive actions, thereby manipulating the behavior of others. Through this interaction over millions of years, many human emotional expressions may have evolved. Here, human social signals including smiling, laughing, and crying, are compared component-by-component to the known, well-studied features of primate defensive reflexes. It is suggested that the defensive mimic theory can adequately account for the physical form of not all, but a large range of human emotional expression.

Graziano, . (2022). A conceptual framework for consciousness. Proceedings of the National Academy of Sciences USA, 119, Article e2116933119. Referenced from doi.org: A conceptual framework for consciousness
This article argues that consciousness has a logically sound, explanatory framework, different from typical accounts that suffer from hidden mysticism. The article has three main parts. The first describes background principles concerning information processing in the brain, from which one can deduce a general, rational framework for explaining consciousness. The second part describes a specific theory that embodies those background principles, the Attention Schema Theory. In the past several years, a growing body of experimental evidence—behavioral evidence, brain imaging evidence, and computational modeling—has addressed aspects of the theory. The final part discusses the evolution of consciousness. By emphasizing the specific role of consciousness in cognition and behavior, the present approach leads to a proposed account of how consciousness may have evolved over millions of years, from fish to humans. The goal of this article is to present a comprehensive, overarching framework in which we can understand scientifically what consciousness is and what key adaptive roles it plays in brain function.

Surprisingly little is known about how the general public understands consciousness, yet information on common intuitions is crucial to discussions and theories of consciousness. We asked 202 members of the general public, “In your own words, what is consciousness?” and analyzed the frequencies with which different perspectives on consciousness were represented. Almost all people (89%) described consciousness as fundamentally receptive – possessing, knowing, perceiving, being aware, or experiencing. In contrast, the perspective that consciousness is agentic (actively making decisions, driving output, or controlling behavior) appeared in only 33% of responses. Consciousness as a social phenomenon was represented by 24% of people. Consciousness as being awake or alert was mentioned by 19%. Consciousness as mystical, transcending the physical world, was mentioned by only 10%. Consciousness in relation to memory was mentioned by 6%. Consciousness as an inner voice or inner being – the homunculus view – was represented by 5%. Finally, only three people (1.5%) mentioned a specific, scholarly theory about consciousness, suggesting that we successfully sampled the opinions of the general public rather than capturing an academic construct. We found little difference between men and women, young and old, or US and non-US participants, except for one possible generation shift. Young, non-US participants were more likely to associate consciousness with moral decision-making. These findings show a snapshot of the public understanding of consciousness – a network of associated concepts, represented at varying strengths, such that some are more likely to emerge when people are asked an open-ended question about it.

Graziano, M. (2022). Conscious intention: New data on where and how in the brain. Current Biology, 32, R414–R432.

How do we decide to act, and how do those decisions relate to conscious choice? A new study helps dissociate the neuronal mechanisms that choose, prepare, and trigger movement from our explicit reports of conscious intention.

Schurger, A., & Graziano, M. S. (2022). Consciousness explained or described?. Neuroscience of Consciousness, 7, 1-9. Referenced from doi.org: Consciousness explained or described?
Consciousness is an unusual phenomenon to study scientifically. It is defined as a subjective, first-person phenomenon, and science is an objective, third-person endeavor. This misalignment between the means-science-and the end-explaining consciousness-gave rise to what has become a productive workaround: the search for 'neural correlates of consciousness' (NCCs). Science can sidestep trying to explain consciousness and instead focus on characterizing the kind(s) of neural activity that are reliably correlated with consciousness. However, while we have learned a lot about consciousness in the bargain, the NCC approach was not originally intended as the foundation for a true explanation of consciousness. Indeed, it was proposed precisely to sidestep the, arguably futile, attempt to find one. So how can an account, couched in terms of neural correlates, do the work that a theory is supposed to do: explain consciousness? The answer is that it cannot, and in fact most modern accounts of consciousness do not pretend to. Thus, here, we challenge whether or not any modern accounts of consciousness are in fact theories at all. Instead we argue that they are (competing) laws of consciousness. They describe what they cannot explain, just as Newton described gravity long before a true explanation was ever offered. We lay out our argument using a variety of modern accounts as examples and go on to argue that at least one modern account of consciousness, attention schema theory, goes beyond describing consciousness-related brain activity and qualifies as an explanatory theory.

2021

Graziano, M. S. A. (2021). Understanding Consciousness. Brain, 144, 1281-1283.
Graziano, M. S. A. (2021). Human emotional expression and the peripersonal margin of safety. In The world at our fingertips: A multidisciplinary exploration of peripersonal space.
Guterstam, A., Bio, B. J., Wilterson, A. I., & Graziano, M. S. A. (2021). Temporo-parietal cortex involved in modeling one’s own and others’ attention. Elife , 10.
Wilterson, ., & Graziano, M. S. A. (2021). The Attention Schema Theory in a Neural Network Agent: Controlling Visuospatial Attention Using a Descriptive Model of Attention. Proceedings of the National Academy of Sciences USA, 118.
Wilterson, A. I., Nastase, S. A., Bio, B. J., Guterstam, A., & Graziano, M. S. A. (2021). Attention, awareness, and the right temporoparietal junction. Proceedings of the National Academy of Sciences USA , 118.

2020

Graziano, M. S. (2020). Human emotional expression and the peripersonal margin of safety. In The World at Our Fingertips: A Multidisciplinary Exploration of Peripersonal Space. Oxford University Press.
The brain evolved to give special representation to the space immediately around the body. One of the most obvious adaptive uses of that peripersonal space is self-protection. It is a safety buffer zone, and intrusions can trigger a suite of protective behaviors. Perhaps less obvious is the possible relationship between that complex protective mechanism and social signaling. Standing tall, cringing, power poses and hand shakes, even coquettish tilts of the head that expose the neck, may all relate in some manner to that safety buffer, signaling to others that one’s protective mechanisms are heightened (when anxious) or reduced (when confident). Here I propose that some of our most fundamental human emotional expressions such as smiling, laughing, and crying may also have a specific evolutionary relationship to the buffer zone around the body, deriving ultimately from the reflexive actions that protect us.
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Graziano, M. S., & Morsella, E. (2020). A new motor approach to consciousness: Implications for the simulation of future behavior. Journal of Consciousness Studies, 27, 88-103.
Graziano, M. S. A. (2020). What makes us so certain that we’re conscious?. Cognitive Neuroscience, 12, 67-68.
Guterstam, A., Wilterson, A. I., Wachtell, D., & Graziano, M. S. A. (2020). Other people’s gaze encoded as implied motion in the human brain. Proceedings of the National Academy of Sciences, USA, 117, 13162-13167. Referenced from doi.org: Other people’s gaze encoded as implied motion in the human brain.
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Guterstam, A., & Graziano, M. S. A. (2020). Reply to Görner et al.: Encoding gaze as implied motion. Proceedings of the National Academy of Sciences USA, 117, 20377. Referenced from doi.org: Reply to Görner et al.: Encoding gaze as implied motion.
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Guterstam, A., & Graziano, M. S. A. (2020). Visual motion assists in social cognition. Proceedings of the National Academy of Sciences USA, 117, 32165-32168.
Wilterson, A. I., Kemper, C. M., Kim, N., Webb, T. W., Reblando, A. M. W., & Graziano, M. S. A. (2020). Attention control and the attention schema theory of consciousness. Progress in Neurobiology, 195, Article 101844. Referenced from doi.org: Attention control and the attention schema theory of consciousness
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2019

The attention schema theory provides a single coherent framework for understanding three seemingly unrelated phenomena. The first is our ability to control our own attention through predictive modeling. The second is a fundamental part of social cognition, or theory of mind – our ability to reconstruct the attention of others, and to use that model of attention to help make behavioral predictions about others. The third is our claim to have a subjective consciousness – not merely information inside us, but something else in addition that is non-physical – and to believe that others have the same property. In the attention schema theory, all three phenomena stem from the same source. The brain constructs a useful internal model of attention. This article summarizes the theory and discusses one aspect of it in greater detail: how an attention schema may be useful for predicting the behavior of others. The article outlines a hypothetical, artificial system that can make time-varying behavioral predictions about other people, and concludes that attributing some form of awareness to others is a useful computational part of the prediction engine.
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Graziano, M. S. (2019). We are machines that claim to be conscious. Journal of Consciousness Studies, 26, 94-104.
Guterstam, A., Kean, H., Webb, T., Kean, F., & Graziano, M. S. (2019). Implicit model of other people’s visual attention as an invisible, force-carrying beam projecting from the eyes. Proceedings of the National Academy of Sciences U. S. A., 116(1), 328-333. https://doi.org/10.1073/pnas.1816581115
As a part of social cognition, people automatically construct rich models of other people's vision. Here we show that when people judge the mechanical forces acting on an object, their judgments are biased by another person gazing at the object. The bias is consistent with an implicit perception that gaze adds a gentle force, pushing on the object. The bias was present even though the participants were not explicitly aware of it and claimed that they did not believe in an extramission view of vision (a common folk view of vision in which the eyes emit an invisible energy). A similar result was not obtained on control trials when participants saw a blindfolded face turned toward the object, or a face with open eyes turned away from the object. The findings suggest that people automatically and implicitly generate a model of other people's vision that uses the simplifying construct of beams coming out of the eyes. This implicit model of active gaze may be a hidden, yet fundamental, part of the rich process of social cognition, contributing to how we perceive visual agency. It may also help explain the extraordinary cultural persistence of the extramission myth of vision.
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2018

Bio, B., Webb, T., & Graziano, M. S. (2018). Projecting one’s own spatial bias onto others during a theory-of-mind task. Proceedings of the National Academy of Sciences U. S. A., 115(7), E1684-E1689. https://doi.org/10.1073/pnas.1718493115
Many people show a left-right bias in visual processing. We measured spatial bias in neurotypical participants using a variant of the line bisection task. In the same participants, we measured performance in a social cognition task. This theory-of-mind task measured whether each participant had a processing-speed bias toward the right of, or left of, a cartoon agent about which the participant was thinking. Crucially, the cartoon was rotated such that what was left and right with respect to the cartoon was up and down with respect to the participant. Thus, a person's own left-right bias could not align directly onto left and right with respect to the cartoon head. Performance on the two tasks was significantly correlated. People who had a natural bias toward processing their own left side of space were quicker to process how the cartoon might think about objects to the left side of its face, and likewise for a rightward bias. One possible interpretation of these results is that the act of processing one's own personal space shares some of the same underlying mechanisms as the social cognitive act of reconstructing someone else's processing of their space.
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Graziano, M. S. (2018). The temporoparietal junction and awareness. Neuroscience of Consciousness, 4(1). https://doi.org/10.1093/nc/niy005
Visual attention and awareness can be experimentally separated. In a recent study (Webb , Cortical networks involved in visual awareness independently of visual attention. 2016a;113:13923-8), we suggested that awareness was associated with activity in a set of cortical networks that overlap the temporoparietal junction. In a comment, Morales (Measuring away an attentional confound? 2017;3:doi:10.1093/nc/nix018) suggested that we had imperfectly controlled attention thereby jeopardizing the experimental logic. Though we agree that attention behaves differently in the presence and absence of awareness, we argue it is still possible to roughly equate the level of attention between aware and unaware conditions, and that an imbalance in attention probably does not explain our experimental results.
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Graziano, M. S., Webb, T., & Jacquette, . (2018). Understanding consciousness by building it. In Bloomsbury Companion to Philosophy of Consciousness (pp. 187-210). Bloomsbury.

In the attention schema theory, awareness is an impossible, physically incoherent property that is described by a packet of information in the brain. That packet of information is an internal model and its function is to provide a continuously updated account of attention. It describes attention in a manner that is accurate enough to be useful but not so accurate or detailed as to waste time or resources. In effect, subjective awareness is a caricature of attention. One advantage of this theory of awareness is that it is buildable. No part of it requires a metaphysical leap from chemistry to qualia. In this article we consider how to build a conscious machine as a way to introduce the attention schema theory.

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Graziano, M. S. (2018). The Spaces Between Us: A Story of Neuroscience, Evolution, and Human Nature. Oxford University Press.

2017

Graziano, M. S., & Gennaro, . (2017). The Attention Schema Theory of Consciousness. In Routledge Handbook of Consciousness (pp. 174-187). Routledge.
The attention schema theory of consciousness describes how an information-processing machine can make the claim that it has a consciousness of something. In the theory, the brain is an information processor that is captive to the information constructed within it. The challenge of explaining consciousness is not, “How does the brain produce an ineffable internal experience,” but rather, “How does the brain construct a quirky self description, and what is the useful cognitive role of that self model?”
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The purpose of the attention schema theory is to explain how an information-processing device, the brain, arrives at the claim that it possesses a non-physical, subjective awareness, and assigns a high degree of certainty to that extraordinary claim. The theory does not address how the brain might actually possess a non-physical essence. It is not a theory that deals in the non-physical. It is about the computations that cause a machine to make a claim and to assign a high degree of certainty to the claim. The theory is offered as a possible starting point for building artificial consciousness. Given current technology, it should be possible to build a machine that contains a rich internal model of what consciousness is, attributes that property of consciousness to itself and to the people it interacts with, and uses that attribution to make predictions about human behavior. Such a machine would “believe” it is conscious and act like it is conscious, in the same sense that the human machine believes and acts.

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Igelström, K., & Graziano, M. S. (2017). The inferior parietal lobule and temporoparietal junction: A network perspective. Neuropsychologia, 105, 70-83. https://doi.org/10.1016/j.neuropsychologia.2017.01.001
Information processing in specialized, spatially distributed brain networks underlies the diversity and complexity of our cognitive and behavioral repertoire. Networks converge at a small number of hubs - highly connected regions that are central for multimodal integration and higher-order cognition. We review one major network hub of the human brain: the inferior parietal lobule and the overlapping temporoparietal junction (IPL/TPJ). The IPL is greatly expanded in humans compared to other primates and matures late in human development, consistent with its importance in higher-order functions. Evidence from neuroimaging studies suggests that the IPL/TPJ participates in a broad range of behaviors and functions, from bottom-up perception to cognitive capacities that are uniquely human. The organization of the IPL/TPJ is challenging to study due to the complex anatomy and high inter-individual variability of this cortical region. In this review we aimed to synthesize findings from anatomical and functional studies of the IPL/TPJ that used neuroimaging at rest and during a wide range of tasks. The first half of the review describes subdivisions of the IPL/TPJ identified using cytoarchitectonics, resting-state functional connectivity analysis and structural connectivity methods. The second half of the article reviews IPL/TPJ activations and network participation in bottom-up attention, lower-order self-perception, undirected thinking, episodic memory and social cognition. The central theme of this review is to discuss how network nodes within the IPL/TPJ are organized and how they participate in human perception and cognition.
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Igelström, K., Webb, T., & Graziano, M. S. (2017). Functional Connectivity Between the Temporoparietal Cortex and Cerebellum in Autism Spectrum Disorder. Cerebral Cortex, 27(4), 2617-2627. https://doi.org/10.1093/cercor/bhw079
The neural basis of autism spectrum disorder (ASD) is not yet understood. ASD is marked by social deficits and is strongly associated with cerebellar abnormalities. We studied the organization and cerebellar connectivity of the temporoparietal junction (TPJ), an area that plays a crucial role in social cognition. We applied localized independent component analysis to resting-state fMRI data from autistic and neurotypical adolescents to yield an unbiased parcellation of the bilateral TPJ into 11 independent components (ICs). A comparison between neurotypical and autistic adolescents showed that the organization of the TPJ was not significantly altered in ASD. Second, we used the time courses of the TPJ ICs as spatially unbiased "seeds" for a functional connectivity analysis applied to voxels within the cerebellum. We found that the cerebellum contained a fine-grained, lateralized map of the TPJ. The connectivity of the TPJ subdivisions with cerebellar zones showed one striking difference in ASD. The right dorsal TPJ showed markedly less connectivity with the left Crus II. Disturbed cerebellar input to this key region for cognition and multimodal integration may contribute to social deficits in ASD. The findings might also suggest that the right TPJ and/or left Crus II are potential targets for noninvasive brain stimulation therapies.
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2016

Graziano, M. S. (2016). Ethological Action Maps: A Paradigm Shift for the Motor Cortex. Trends in Cognitive Sciences, 20(2), 121-132. https://doi.org/10.1016/j.tics.2015.10.008
The map of the body in the motor cortex is one of the most iconic images in neuroscience. The map, however, is not perfect. It contains overlaps, reversals, and fractures. The complex pattern suggests that a body plan is not the only organizing principle. Recently a second organizing principle was discovered: an action map. The motor cortex appears to contain functional zones, each of which emphasizes an ethologically relevant category of behavior. Some of these complex actions can be evoked by cortical stimulation. Although the findings were initially controversial, interest in the ethological action map has grown. Experiments on primates, mice, and rats have now confirmed and extended the earlier findings with a range of new methods.
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Graziano, M. S., Webb, T., & Kaas, . (2016). From sponge to human: The evolution of consciousness. In Evolution of Nervous Systems (2nd ed., Vols. 2, pp. 547–554). Elsevier.

The attention schema theory is a proposed explanation for the brain basis of conscious experience. The theory is mechanistic, testable, and supported by at least some preliminary experiments. In the theory, subjective awareness is an internal model of attention that serves several adaptive functions. This chapter discusses the evolution of consciousness in the context of the attention schema theory, beginning with the evolution of attentional mechanisms that emerged more than half a billion years ago and extending to human consciousness and the social attribution of conscious states to others.

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Graziano, M. S. (2016). Consciousness engineered. Journal of Consciousness Studies, 23(11-12), 98-115. Referenced from www.ingentaconnect.com: Consciousness engineered

The attention schema theory offers one possible account for how we claim to have consciousness. The theory begins with attention, a mechanistic method of handling data in which some signals are enhanced at the expense of other signals and are more deeply processed. In the theory, the brain does more than just use attention. It also constructs an internal model, or representation, of attention. That internal model contains incomplete, schematic information about what attention is, what the consequences of attention are, and what its own attention is doing at any moment. This “attention schema” is used to help control attention, much like the “body schema,” the brain’s internal simulation of the body, is used to help control the body. Subjective awareness – consciousness – is the caricature of attention depicted by that internal model. This article summarizes the theory and discusses its relationship to the approach to consciousness that is called “illusionism.”

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Igelström, K., Webb, T., Kelly, Y., & Graziano, M. S. (2016). Topographical Organization of Attentional, Social, and Memory Processes in the Human Temporoparietal Cortex. ENeuro, 3(2). https://doi.org/10.1523/ENEURO.0060-16.2016
The temporoparietal junction (TPJ) is activated in association with a large range of functions, including social cognition, episodic memory retrieval, and attentional reorienting. An ongoing debate is whether the TPJ performs an overarching, domain-general computation, or whether functions reside in domain-specific subdivisions. We scanned subjects with fMRI during five tasks known to activate the TPJ, probing social, attentional, and memory functions, and used data-driven parcellation (independent component analysis) to isolate task-related functional processes in the bilateral TPJ. We found that one dorsal component in the right TPJ, which was connected with the frontoparietal control network, was activated in all of the tasks. Other TPJ subregions were specific for attentional reorienting, oddball target detection, or social attribution of belief. The TPJ components that participated in attentional reorienting and oddball target detection appeared spatially separated, but both were connected with the ventral attention network. The TPJ component that participated in the theory-of-mind task was part of the default-mode network. Further, we found that the BOLD response in the domain-general dorsal component had a longer latency than responses in the domain-specific components, suggesting an involvement in distinct, perhaps postperceptual, computations. These findings suggest that the TPJ performs both domain-general and domain-specific computations that reside within spatially distinct functional components.
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Webb, T., Kean, H., & Graziano, M. S. (2016). Effects of Awareness on the Control of Attention. Journal of Cognitive Neuroscience, 28(6), 842-851. https://doi.org/10.1162/jocn_a_00931
Previous studies show that it is possible to attend to a stimulus without awareness of it. Whether attention and awareness are independent or have a specific relationship, however, remains debated. Here, we tested three aspects of visual attention with and without awareness of the visual stimulus. Metacontrast masking rendered participants either subjectively aware or not aware of the stimulus. Attention drawn to the stimulus was measured by using the stimulus as a cue in a spatial attention task. We found that attention was drawn to the stimulus regardless of whether or not people were aware of it. However, attention changed significantly in the absence of awareness in at least three ways. First, attention to a task-relevant stimulus was less stable over time. Second, inhibition of return, the automatic suppression of attention to a task-irrelevant stimulus, was reduced. Third, attention was more driven by the luminance contrast of the stimulus. These findings add to the growing information on the behavior of attention with and without awareness. The findings are also consistent with our recently proposed account of the relationship between attention and awareness. In the attention schema theory, awareness is the internal model of attention. Just as the brain contains a body schema that models the body and helps control the body, so it contains an attention schema that helps control attention. In that theory, in the absence of awareness, the control of attention should suffer in basic ways predictable from dynamical systems theory. The present results confirm some of those predictions.
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Webb, T., Igelström, K., Schurger, A., & Graziano, M. S. (2016). Cortical networks involved in visual awareness independent of visual attention. Proceedings of the National Academy of Sciences U. S. A., 113(48), 13923-13928. https://doi.org/10.1073/pnas.1611505113
It is now well established that visual attention, as measured with standard spatial attention tasks, and visual awareness, as measured by report, can be dissociated. It is possible to attend to a stimulus with no reported awareness of the stimulus. We used a behavioral paradigm in which people were aware of a stimulus in one condition and unaware of it in another condition, but the stimulus drew a similar amount of spatial attention in both conditions. The paradigm allowed us to test for brain regions active in association with awareness independent of level of attention. Participants performed the task in an MRI scanner. We looked for brain regions that were more active in the aware than the unaware trials. The largest cluster of activity was obtained in the temporoparietal junction (TPJ) bilaterally. Local independent component analysis (ICA) revealed that this activity contained three distinct, but overlapping, components: a bilateral, anterior component; a left dorsal component; and a right dorsal component. These components had brain-wide functional connectivity that partially overlapped the ventral attention network and the frontoparietal control network. In contrast, no significant activity in association with awareness was found in the banks of the intraparietal sulcus, a region connected to the dorsal attention network and traditionally associated with attention control. These results show the importance of separating awareness and attention when testing for cortical substrates. They are also consistent with a recent proposal that awareness is associated with ventral attention areas, especially in the TPJ.
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2015

Graziano, M. S., Obhi, S., & Cross, E. (2015). A new view of the motor cortex and its relation to social behavior. In Shared Representations: Sensorimotor Foundations of Social Life (pp. 38-58). Cambridge University Press.

Three main views of the primate motor cortex have been proposed over the 140 years of its study. These views are not necessarily incompatible. In the homunculus view, the motor cortex functions as a rough map of the body’s musculature. In the population-code view, populations of broadly tuned neurons combine to specify hand direction or some other parameter of movement. In the recently proposed action map view, common actions in the movement repertoire are emphasized in different regions of cortex. In the action map view, to fully understand the organization of the motor cortex, it is necessary to study the structure and complexity of the movement repertoire and understand how that statistical structure is mapped onto the cortical surface. This chapter discusses the action map in the primate brain and how some of the complex actions represented there may play a role in social behavior.

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Graziano, ., & Toga, A. (2015). Cortical action representations. In Brain Mapping: An Encyclopedic Reference (Vols. 2). Elsevier.

The organization of the motor cortex has been studied and debated for more than 130 years. Although it contains a map of the body, the map is overlapping and fractured and therefore additional principles of organization may be needed to explain the topography. Recently, a growing body of evidence suggests one such principle. The motor cortex appears to be partly organized as a map of complex, behaviorally useful actions that compose the animal’s movement repertoire. In the action-map perspective, the statistical complexity of the movement repertoire leads to the complexity of the cortical map.

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Igelström, K., Webb, T., & Graziano, M. S. (2015). Neural Processes in the Human Temporoparietal Cortex Separated by Localized Independent Component Analysis. Journal of Neuroscience, 35(25), 9432-9445. https://doi.org/10.1523/JNEUROSCI.0551-15.2015
The human temporoparietal junction (TPJ) is a topic of intense research. Imaging studies have identified TPJ activation in association with many higher-order functions such as theory-of-mind, episodic memory, and attention, causing debate about the distribution of different processes. One major challenge is the lack of consensus about the anatomical location and extent of the TPJ. Here, we address this problem using data-driven analysis to test the hypothesis that the bilateral TPJ can be parcellated into subregions. We applied independent component analysis (ICA) to task-free fMRI data within a local region around the bilateral TPJ, iterating the ICA at multiple model orders and in several datasets. The localized analysis allowed finer separation of processes and the use of multiple dimensionalities provided qualitative information about lateralization. We identified four subdivisions that were bilaterally symmetrical and one that was right biased. To test whether the independent components (ICs) reflected true subdivisions, we performed functional connectivity analysis using the IC coordinates as seeds. This confirmed that the subdivisions belonged to distinct networks. The right-biased IC was connected with a network often associated with attentional processing. One bilateral subdivision was connected to sensorimotor regions and another was connected to auditory regions. One subdivision that presented as distinct left- and right-biased ICs was connected to frontoparietal regions. Another subdivision that also had left- and right-biased ICs was connected to social or default mode networks. Our results show that the TPJ in both hemispheres hosts multiple neural processes with connectivity patterns consistent with well developed specialization and lateralization.
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Webb, T., & Graziano, M. S. (2015). The attention schema theory: a mechanistic account of subjective awareness. Frontiers in Psychology, 6. https://doi.org/10.3389/fpsyg.2015.00500
We recently proposed the attention schema theory, a novel way to explain the brain basis of subjective awareness in a mechanistic and scientifically testable manner. The theory begins with attention, the process by which signals compete for the brain's limited computing resources. This internal signal competition is partly under a bottom-up influence and partly under top-down control. We propose that the top-down control of attention is improved when the brain has access to a simplified model of attention itself. The brain therefore constructs a schematic model of the process of attention, the 'attention schema,' in much the same way that it constructs a schematic model of the body, the 'body schema.' The content of this internal model leads a brain to conclude that it has a subjective experience. One advantage of this theory is that it explains how awareness and attention can sometimes become dissociated; the brain's internal models are never perfect, and sometimes a model becomes dissociated from the object being modeled. A second advantage of this theory is that it explains how we can be aware of both internal and external events. The brain can apply attention to many types of information including external sensory information and internal information about emotions and cognitive states. If awareness is a model of attention, then this model should pertain to the same domains of information to which attention pertains. A third advantage of this theory is that it provides testable predictions. If awareness is the internal model of attention, used to help control attention, then without awareness, attention should still be possible but should suffer deficits in control. In this article, we review the existing literature on the relationship between attention and awareness, and suggest that at least some of the predictions of the theory are borne out by the evidence.
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2014

Graziano, M. S. (2014). Speculations on the evolution of awareness. Journal of Cognitive Neuroscience, 26(6), 1300-1304. https://doi.org/10.1162/jocn_a_00623
The "attention schema" theory provides one possible account of the biological basis of consciousness, tracing the evolution of awareness through steps from the advent of selective signal enhancement about half a billion years ago to the top-down control of attention, to an internal model of attention (which allows a brain, for the first time, to attribute to itself that it has a mind that is aware of something), to the ability to attribute awareness to other beings, and from there to the human attribution of a rich spirit world surrounding us. Humans have been known to attribute awareness to plants, rocks, rivers, empty space, and the universe as a whole. Deities, ghosts, souls--the spirit world swirling around us is arguably the exuberant attribution of awareness.
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Graziano, M. S., & Webb, T. (2014). A mechanistic theory of consciousness. International Journal of Machine Consciousness, 6, 163-176. Referenced from doi.org: A mechanistic theory of consciousness

Recently we proposed a theory of consciousness, the attention schema theory, based on findings in cognitive psychology and systems neuroscience. In that theory, consciousness is an internal model of attention or an ‘attention schema.’ Consciousness relates to attention the same way that the internal model of the body, the ‘body schema,’ relates to the physical body. The body schema is used to model and help control the body. The attention schema is used to model and help regulate attention, a data-handling process in the brain in which some signals are enhanced at the expense of other signals. We proposed that attention and the attention schema co-evolved over the past half billion years. Over that time span, the attention schema may have taken on additional functions such as promoting the integration of information across diverse domains and promoting social cognition. This article summarizes some of the main points of the attention schema theory, suggests how a brain with an attention schema might conclude that it has a subjective awareness, and speculates that the same basic properties can be engineered into machines.

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My son and I have a pet orangutan named Kevin. He talks to us almost every day and usually asks for a banana. All right, he’s not a pet, he’s a large hairy puppet, and I make him talk using the trick of ventriloquism. But it’s pretty fun anyway. When the puppet moves his mouth, a squeaky voice seems to come out of him, not me.

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Kelly, Y., Webb, T., Meier, J., Arcaro, M., & Graziano, M. S. (2014). Attributing awareness to oneself and to others. Proceedings of the National Academy of Sciences U. S. A., 111(13), 5012-5017. https://doi.org/10.1073/pnas.1401201111
This study tested the possible relationship between reported visual awareness ("I see a visual stimulus in front of me") and the social attribution of awareness to someone else ("That person is aware of an object next to him"). Subjects were tested in two steps. First, in an fMRI experiment, subjects were asked to attribute states of awareness to a cartoon face. Activity associated with this task was found bilaterally within the temporoparietal junction (TPJ) among other areas. Second, the TPJ was transiently disrupted using single-pulse transcranial magnetic stimulation (TMS). When the TMS was targeted to the same cortical sites that had become active during the social attribution task, the subjects showed symptoms of visual neglect in that their detection of visual stimuli was significantly affected. In control trials, when TMS was targeted to nearby cortical sites that had not become active during the social attribution task, no significant effect on visual detection was found. These results suggest that there may be at least some partial overlap in brain mechanisms that participate in the social attribution of sensory awareness to other people and in attributing sensory awareness to oneself.
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