Semir Zeki

Semir Zeki
UCL · Wellcome Laboratory of Neurobiology

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255
Publications
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Publications

Publications (255)
Preprint
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In the work reported here, we used the Land Color Mondrian experiments to test the degree to which subjects vary in their perception of color categories. Twenty subjects of different ethnic and cultural backgrounds, for all but one of whom English was not the primary language, viewed 8 patches of different color in two Mondrian displays; each patch...
Article
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Our past studies have led us to divide sensory experiences, including aesthetic ones derived from sensory sources, into two broad categories: biological and artifactual. The aesthetic experience of biological beauty is dictated by inherited brain concepts, which are resistant to change even in spite of extensive experience. The experience of artifa...
Preprint
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Through our past studies of the neurobiology of beauty, we have come to divide aesthetic experiences into two broad categories: biological and artifactual. The aesthetic experience of biological beauty is dictated by inherited brain concepts, which are resistant to change even in spite of extensive experience. The experience of artifactual beauty o...
Article
Efforts to parcellate the cortex into areas based on fine-scale anatomical signatures (e.g., cytoarchitectonics) date back to the early years of the last century. In the ensuing decades, rapidly growing knowledge of cortical connections encouraged neurobiologists to search for connectivity-based principles underlying the organization of the cerebra...
Preprint
Previous studies with the visual motion and form systems show that visual stimuli belonging to these categories trigger much earlier latency responses from the visual cortex than previously supposed and that the source of the earliest signals can be located in either the prestriate cortex or in both the striate (V1) and prestriate cortex. This is c...
Article
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We studied the neural mechanisms that are engaged during the experience of beauty derived from sorrow and from joy, two experiences that share a common denominator (beauty) but are linked to opposite emotional valences. Twenty subjects viewed and rerated, in a functional magnetic resonance imaging scanner, 120 images which each had classified into...
Article
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We undertook psychophysical experiments to determine whether the color of the after-image produced by viewing a colored patch which is part of a complex multi-colored scene depends on the wavelength-energy composition of the light reflected from that patch. Our results show that it does not. The after-image, just like the color itself, depends on t...
Article
Our previous studies with the visual motion and form systems show that visual stimuli belonging to these categories trigger much earlier latency responses from the visual cortex than previously supposed and that the source of the earliest signals can be located in either the prestriate cortex or in both the striate (V1) and prestriate cortex. This...
Article
Full-text available
We undertook psychophysical experiments to determine whether the color of the after-image produced by viewing a colored patch which is part of a complex multi-colored scene depends on the wavelength-energy composition of the light reflected from that patch. Our results show that, just as the color of a patch which is part of a complex scene is inde...
Article
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When, to silent sessions devoted to brain thought, We summon up formulations from endeavours past, And sigh the lack of many a principle that we sought, Because those principles were, in our mind, mis-cast, Lo, for all priors should not be tied in a single Bayesian knot For biological and artefactual priors each have a separate slot A (poster...
Article
Results from a variety of sources, some many years old, lead ineluctably to a re-appraisal of the twin strategies of hierarchical and parallel processing used by the brain to construct an image of the visual world. Contrary to common supposition, there are at least three "feed-forward" anatomical hierarchies that reach the primary visual cortex (V1...
Article
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Area V5 of the visual brain, first identified anatomically in 1969 as a separate visual area, is critical for the perception of visual motion. As one of the most intensively studied parts of the visual brain, it has yielded many insights into how the visual brain operates. Among these are: the diversity of signals that determine the functional capa...
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Using [(11)C]raclopride, a dopamine D2/D3 receptor antagonist, we undertook a positron emission tomography (PET) study to investigate the involvement of the dopaminergic neurotransmitter system when subjects viewed the pictures of partners to whom they were romantically attached. Ten subjects viewed pictures of their romantic partners and, as a con...
Article
Area V5 of the visual brain, first identified anatomically in 1969 as a separate visual area, is critical for the perception of visual motion. As one of the most intensively studied parts of the visual brain, it has yielded many insights into how the visual brain operates. Among these are: the diversity of signals that determine the functional capa...
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Whether the visual brain uses a parallel or a serial, hierarchical, strategy to process visual signals, the end result appears to be that different attributes of the visual scene are perceived asynchronously—with colour leading form (orientation) by 40 ms and direction of motion by about 80 ms. Whatever the neural root of this asynchrony, it create...
Article
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Philosophies of aesthetics have posited that experience of the sublime—commonly but not exclusively derived from scenes of natural grandeur—is distinct from that of beauty and is a counterpoint to it. We wanted to chart the pattern of brain activity which correlates with the declared intensity of experience of the sublime, and to learn whether it d...
Article
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We used easily distinguishable stimuli of faces and houses constituted from straight lines, with the aim of learning whether they activate V1 on the one hand, and the specialized areas that are critical for the processing of faces and houses on the other, with similar latencies. Eighteen subjects took part in the experiment, which used magnetoencep...
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The answer as to how visual attributes processed in different brain loci at different speeds are bound together to give us our unitary experience of the visual world remains unknown. In this study we investigated whether bound representations arise, as commonly assumed, through physiological interactions between cells in the visual areas. In a foca...
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Can the arts and humanities contribute significantly to the study of the brain? Similar brain processes are involved in humanistic and scientific inference, and in this essay, I argue that conclusions reached by one are relevant to the other.
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We here extend and complement our earlier time-based, magneto-encephalographic (MEG), study of the processing of forms by the visual brain (Shigihara and Zeki, 2013) with a functional magnetic resonance imaging (fMRI) study, in order to better localize the activity produced in early visual areas when subjects view simple geometric stimuli of increa...
Article
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Imaging evidence shows that separate subdivisions of parietal cortex, in and around the intraparietal sulcus (IPS), are engaged when stimuli are grouped according to color and to motion (Zeki and Stutters, 2013). Since grouping is an essential step in the formation of concepts, we wanted to learn whether parietal cortex is also engaged in the forma...
Article
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It is generally supposed that there is a single, hierarchically organized pathway dedicated to form processing, in which complex forms are elaborated from simpler ones, beginning with the orientation-selective cells of V1. In this psychophysical study, we undertook to test another hypothesis, namely that the brain's visual form system consists of m...
Article
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Psychophysical experiments show that two different visual attributes, color and motion, processed in different areas of the visual brain, are perceived at different times relative to each other (Moutoussis and Zeki, 1997a). Here we demonstrate psychophysically that two variants of the same attribute, motion, which have the same temporal structure a...
Article
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Many have written of the experience of mathematical beauty as being comparable to that derived from the greatest art. This makes it interesting to learn whether the experience of beauty derived from such a highly intellectual and abstract source as mathematics correlates with activity in the same part of the emotional brain as that derived from mor...
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We report experiments designed to learn whether different kinds of perceptually unstable visual images engage different neural mechanisms. 21 subjects viewed two types of bi-stable images while we scanned the activity in their brains with functional magnetic resonance imaging (fMRI); in one (intra-categorical type) the two percepts remained within...
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In this paper we discuss the work of Francis Bacon in the context of his declared aim of giving a "visual shock."We explore what this means in terms of brain activity and what insights into the brain's visual perceptive system his work gives. We do so especially with reference to the representation of faces and bodies in the human visual brain. We...
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Though first published almost one century ago, and though its premise has been disputed, Clive Bell's essay on aesthetics in his book Art still provides fertile ground for discussing problems in aesthetics, especially as they relate to neuroesthetics. In this essay, I begin with a brief account of Bell's ideas on aesthetics, and describe how they f...
Article
Though first published almost one century ago, and though its premise has been disputed, Clive Bell's essay on aesthetics in his book Art still provides fertile ground for discussing problems in aesthetics, especially as they relate to neuroesthetics. In this essay, I begin with a brief account of Bell's ideas on aesthetics, and describe how they f...
Article
Full-text available
We used magnetoencephalography (MEG) to determine whether increasingly complex forms constituted from the same elements (lines) activate visual cortex with the same or different latencies. Twenty right-handed healthy adult volunteers viewed two different forms, lines and rhomboids, representing two levels of complexity. Our results showed that the...
Data
Absolute amplitude time course of event related magnetic fields for rhomboid stimuli in individual subjects.
Article
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This study was undertaken to learn whether the principle of functional specialization that is evident at the level of the prestriate visual cortex extends to areas that are involved in grouping visual stimuli according to attribute, and specifically according to colour and motion. Subjects viewed, in an fMRI scanner, visual stimuli composed of movi...
Article
We recorded brain activity when 21 subjects judged the beauty (aesthetic or affective judgment) and brightness (perceptual or cognitive judgment) of simultaneously presented paintings. Aesthetic judgments engaged medial and lateral subdivisions of the orbitofrontal cortex as well as subcortical stations associated with affective motor planning (glo...
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We here address the question of whether there is any correlation between subjective preference for simple configurations within a specific visual domain such as motion and strength of activity in visual areas in which that domain is emphasized. We prepared several distinctive patterns of dots in motion with various characteristics and asked humans...
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Empirical and theoretical studies suggest that human knowledge is partly based on innate concepts that are experience-independent. We can, therefore, consider concepts underlying our knowledge as being broadly divided into inherited and acquired ones. Using fMRI, we studied the brain reaction in 20 subjects to violation of face, space (inherited),...
Article
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Visual masking can result from the interference of perceptual signals. According to the principle of functional specialization, interference should be greatest when signal and mask belong to the same visual attribute (e.g., color or motion) and least when they belong to different ones. We provide evidence to support this view and show that the time...
Data
Behavioral data collected in preliminary behavioral test. Distribution of behavioral ratings during preliminary test by stimulus modality, averaged over all subjects. Range shows maximum and minimum percentages among subjects. (DOCX)
Article
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We wanted to learn whether activity in the same area(s) of the brain correlate with the experience of beauty derived from different sources. 21 subjects took part in a brain-scanning experiment using functional magnetic resonance imaging. Prior to the experiment, they viewed pictures of paintings and listened to musical excerpts, both of which they...
Article
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Perception entails interactions between activated brain visual areas and the records of previous sensations, allowing for processes like figure-ground segregation and object recognition. The aim of this study was to characterize top-down effects that originate in the visual cortex and that are involved in the generation and perception of form. We p...
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A compelling single case report of visual awareness (visual qualia) without primary visual cortex would be sufficient to refute the hypothesis that the primary visual cortex and the back-projections to it are necessary for conscious visual experience. In a previous study, we emphasized the presence of crude visual awareness in Patient G.Y., with a...
Data
Supplementary detail for the following topics: physiological noise correction, processing of face images, putamen activation and correlations with relationship length. (DOC)
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We pursued our functional magnetic resonance imaging (fMRI) studies of the neural correlates of romantic love in 24 subjects, half of whom were female (6 heterosexual and 6 homosexual) and half male (6 heterosexual and 6 homosexual). We compared the pattern of activity produced in their brains when they viewed the faces of their loved partners with...
Article
'To determine orientation we occasionally used a PDP-12 computer to produce a graph of average response vs orientation, generating the slit electronically on a television screen. This method took much longer, and the usual minute-to-minute variations in responsiveness of the cell tended to make the curves broader and noisier. We concluded that for...
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The visual features of an object are processed by multiple, functionally specialized areas of cerebral cortex. When several objects are seen simultaneously, what mechanism preserves the association of features that belong to a single item? We address this question-known as the "binding problem"-by examining combinatorial feature selectivity of neur...
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Several human and monkey studies have demonstrated a close relationship between motion perception and activation of area V5, leading to the general view that activity in this area correlates with the subjective experience of motion. In the present study, we investigate whether the responses of this area are still governed by the motion percept when...
Article
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Aesthetic judgments, like most judgments, depend on context. Whether an object or image is seen in daily life or in an art gallery can significantly modulate the aesthetic value humans attach to it. We investigated the neural system supporting this modulation by presenting human subjects with artworks under different contexts whilst acquiring fMRI...
Article
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Most experiments on the "neural correlates of consciousness" employ stimulus reportability as an operational definition of what is consciously perceived. The interpretation of such experiments therefore depends critically on understanding the neural basis of stimulus reportability. Using a high volume of fMRI data, we investigated the neural correl...
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In an event-related fMRI study, we scanned eighteen normal human subjects while they viewed three categories of pictures (events, objects and persons) which they classified according to desirability (desirable, indifferent or undesirable). Each category produced activity in a distinct part of the visual brain, thus reflecting its functional special...
Data
Supplementary data documenting response scores and response times for reacting to the patterns generated from the different submodalities. (0.08 MB DOC)
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Visual changes in feature movies, like in real-live, can be partitioned into global flow due to self/camera motion, local/differential flow due to object motion, and residuals, for example, due to illumination changes. We correlated these measures with brain responses of human volunteers viewing movies in an fMRI scanner. Early visual areas respond...
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In this work, we address an important but unexplored topic, namely the neural correlates of hate. In a block-design fMRI study, we scanned 17 normal human subjects while they viewed the face of a person they hated and also faces of acquaintances for whom they had neutral feelings. A hate score was obtained for the object of hate for each subject an...
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In the work reported here, we set out to study the neural systems that detect predictable temporal patterns and departures from them. We used functional magnetic resonance imaging (fMRI) to locate activity in the brains of subjects when they viewed temporally regular and irregular patterns produced by letters, numbers, colors and luminance. Activit...
Article
Consciousness is commonly considered to be a single entity, as expressed in the term "unity of consciousness", and neurobiologists are fond of believing that, sooner or later, they will be able to determine its neural correlate (rather than its neural correlates). Here I propose an alternative view, derived from compelling experimental and clinical...
Chapter
This chapter contains section titled: The Functional Specialization of the Visual BrainProcessing Sites in the Visual Brain Are also Perceptual SitesPerceptual Asynchrony and Temporal Hierarchies in Visual PerceptionThe Distribution of Micro- consciousnesses in Space and TimeTh ree Levels of Hierarchy in ConsciousnessThe Autonomy of the Processing-...
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Romantic and maternal love are highly rewarding experiences. Both are linked to the perpetuation of the species and therefore have a closely linked biological function of crucial evolutionary importance. The newly developed ability to study the neural correlates of subjective mental states with brain imaging techniques has allowed neurobiologists t...
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The relationship between neural activity and object perception has received considerable attention using stimulus manipulations such as masking or dichoptic presentation. Here we investigate the same problem by occluding objects with an opaque screen that acts to dissociate the direct perception of the object from the awareness of its presence. We...
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The mechanism of positional localization has recently been debated due to interest in the flash-lag effect, which occurs when a briefly flashed stationary stimulus is perceived to lag behind a spatially aligned moving stimulus. Here we report positional localization observed at motion offsets as well as at onsets. In the 'flash-lead' effect, a movi...
Article
The brain processes distinct attributes such as colour and motion in anatomically largely segregated systems. Moreover, these two attributes are perceived with different latencies. Here, we show that the time required to bind these two attributes differs too. In psychophysical experiments, we determined minimal presentation times required to percep...
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When objects are viewed in different illuminants, their color does not change or changes little in spite of significant changes in the wavelength composition of the light reflected from them. In previous studies, we have addressed the physiology underlying this color constancy by recording from cells in areas V1, V2, and V4 of the anesthetized monk...
Article
A common view about visual consciousness is that it could arise when and where activity reaches some higher level of processing along the cortical hierarchy. Reports showing that activity in striate cortex can be dissociated from awareness , whereas the latter modulates activity in higher areas , point in this direction. In the specific case of vis...
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Objects in the visual scene are defined by different cues such as colour and motion. Through the integration of these cues the visual system is able to utilize different sources of information, thus enhancing its ability to discriminate objects from their backgrounds. In the following experiments, we investigate the neural mechanisms of cue integra...
Article
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The visual brain consists of many different visual areas, which are functionally specialized to process and perceive different attributes of the visual scene. However, the time taken to process different attributes varies; consequently, we see some attributes before others. It follows that there is a perceptual asynchrony and hierarchy in visual pe...
Article
The visual brain consists of many different visual areas, which are functionally specialized to process and perceive different attributes of the visual scene. However, the time taken to process different attributes varies; consequently, we see some attributes before others. It follows that there is a perceptual asynchrony and hierarchy in visual pe...
Article
Full-text available
We review here a new approach to mapping the human cerebral cortex into distinct subdivisions. Unlike cytoarchitecture or traditional functional imaging, it does not rely on specific anatomical markers or functional hypotheses. Instead, we propose that the unique activity time course (ATC) of each cortical subdivision, elicited during natural condi...