The tondo and "The Power of the Center".

The tondo, a circular work of art, comprises a geometry that is said to increase the visual concentration on the picture's centre, a concentration that is enhanced by a picture frame. The present contribution discusses these observations from the perspective of the psychologist and the art historian, notes the perceptual differences between circular and other shapes of pictures, and refers to studies including eye-tracking methods, neurophysiological experiments on the visual cortex in man and macaques, and consideration of ocular factors. These studies provide considerable support for the "Power of the Center" when viewing tondi.

Symmetry and Artistic Elongation of the Human Form: Exploring the Attainment of Aesthetic Appeal.

Although typically associated with the Mannerist artistic style of the Renaissance, artists throughout history have created pictures and sculptures of humans depicted in an unrealistic and abnormally elongated form. The scientific basis for adopting this form of distortion is discussed here. First, probably subconsciously, artists have appreciated that the human form displays a symmetry which is often aesthetically pleasing. Second, perceived beauty is enhanced when the symmetrical image is elongated. There is evidence that the appeal of artworks which feature these characteristics can be attributed to their ease of cerebral processing, a view supported by functional MRI studies indicating there is an overlap between regions of the brain devoted to processing of symmetry and those devoted to appreciation of beauty.

Drawing and Ignoring: The Perception of the Pictorial Line.

For over 2000 years, the pictorial line has been recognized as being fundamental to drawing and several other art forms. Yet pictorial lines present intriguing issues, three of which are considered here: lines very rarely exist in the natural world; there is no known part of the brain which "processes" lines; and, paradoxically, we often pay very little attention to the lines themselves, and they have even been viewed as "an imaginary idea".

Whence 'zoster'? The convoluted classical origins of a sometimes illogical term.

The term 'zoster' is nowadays associated with 'herpes zoster', the condition resulting from reactivation of the latent varicella-zoster virus which causes shingles. But in antiquity the meaning of 'zoster', a Latin word originating from the Greek for a belt or girdle, was variously associated in men with a form of body armour which could enclose just one half of the body; in women with a garment worn around the waist and sometimes called a 'zona'; and with a place, Zoster, linked mythologically then with the goddess Leto and her zona. Around 48 AD, the Roman physician Scribonius Largus became the first to associate 'zona' with 'herpes', and to attribute a medical meaning to 'zona', here an abbreviation of 'zona ignea' ('fiery girdle'). Although in the past the terms 'zoster' and 'zona' were sometimes used interchangeably, today only 'zoster' remains-even when etymologically illogical in those patients whose zoster rash occurs in body areas other than the trunk.

Pictures of pain: their contribution to the neuroscience of empathy.

The study of empathy, a translation of the term 'Einfühlung', originated in 19th century Germany in the sphere of aesthetics, and was followed by studies in psychology and then neuroscience. During the past decade the links between empathy and art have started to be investigated, but now from the neuroscientific perspective, and two different approaches have emerged. Recently, the primacy of the mirror neuron system and its association with automaticity and imitative, simulated movement has been envisaged. But earlier, a number of eminent art historians had pointed to the importance of cognitive responses to art; these responses might plausibly be subserved by alternative neural networks. Focusing here mainly on pictures depicting pain and evoking empathy, both approaches are considered by summarizing the evidence that either supports the involvement of the mirror neuron system, or alternatively suggests other neural networks are likely to be implicated. The use of such pictures in experimental studies exploring the underlying neural processes, however, raises a number of concerns, and suggests caution is exercised in drawing conclusions concerning the networks that might be engaged. These various networks are discussed next, taking into account the affective and sensory components of the pain experience, before concluding that both mirror neuron and alternative neural networks are likelyto be enlisted in the empathetic response to images of pain. A somewhat similar duality of spontaneous and cognitive processes may perhaps also be paralleled in the creation of such images. While noting that some have repudiated the neuroscientific approach to the subject, pictures are nevertheless shown here to represent an unusual but invaluable tool in the study of pain and empathy.

Revealing the invisible: the paradox of picturing a phantom limb.

Illustrations of phantom limbs are intriguing as they depict an invisible perception. But such illustrations are also important: they provide a form of objectivity to phenomena, which particularly in the past, have often stretched credulity. Acknowledging the paradox of using images to reveal an absent though sensate body part, depictions of phantom limbs are discussed from the neurological perspective, starting with medieval pictures that showed the miraculous restoration of limbs, and which possibly represented pictorial metaphors for a phantom limb. Centuries later, phantom limbs-whether resulting from amputation or deafferentation-became illustrated, and some reasons for their illustration are considered. Although often depicted by others, the most precise and perhaps revealing illustrations of these phantoms have been those made when patients guide the artist, or draw the phantom themselves. In the case of phantom pains, the painful component too is sometimes illustrated, again, as with the miraculous, in metaphorical terms. More recently, depictions of phantoms have also been revealing in studies of some underlying mechanisms of phantom phenomena, notably in demonstrating novel patterns of referred sensations after amputation and attributable to cortical plasticity. Mention is made of photographs of phantom hands visualized using a mirror box, such visualization recalling full circle the miraculous restoration of limbs pictured in the past. The nature of the outline of the phantom is included in a discussion of demarcation of an invisible body part, before concluding that images of phantom limbs provide an invaluable background to understanding and studying these remarkable sensory phenomena.

Pictures as a neurological tool: lessons from enhanced and emergent artistry in brain disease.

Pictures created spontaneously by patients with brain disease often display impaired or diminished artistry, reflecting the patient's cerebral damage. This article explores the opposite: those pictures created in the face of brain disease that show enhanced or enduring artistry, and those that emerge for the first time in artistically naïve patients. After comments on background issues relating to the patient and the viewer, the paintings and drawings are considered in relation to the heterogeneous conditions in which this artistic creativity is seen. These conditions include various dementias-most notably frontotemporal lobar dementia, stroke, Parkinson's disease, autism and related disorders and psychiatric disease, epilepsy, migraine and trauma. In the discussion, it is argued that evidence of underlying brain dysfunction revealed by these pictures often rests on the abnormal context in which the pictures are created, or on changes in artistry demonstrated by a sequence of pictures. In the former, the compulsive element and sensory and emotional accompaniments are often important features; in the latter, evolving changes are evident, and have included depiction of increasing menace in portrayal of faces. The occurrence of synaesthesia, and its relation to creativity, are briefly discussed in respect of two unusual patients, followed by considering the role of the anterior and frontal lobes, mesolimbic connections and the right hemisphere. In at least some patients, impaired inhibition leading to paradoxical functional facilitation, with compensatory changes particularly in the right posterior hemisphere, is likely to be pivotal in enabling unusual artistry to emerge; preservation of language, however, is not a prerequisite. Many patients studied have been artists, and it appears possible that some of those with an artistic predisposition may be more likely to experience pathologically obsessive creativity. The discussion concludes that occasionally pictures created by these rare individuals unexpectedly prove to be an invaluable but little studied tool for investigating the dysfunctioning brain.

Exploring the visual hallucinations of migraine aura: the tacit contribution of illustration.

The visual aura of migraine is a subjective phenomenon, and what the migraineur experiences is necessarily inaccessible to others. Fortunately, however, the sufferer can occasionally reveal what is being seen by means of graphic representation, enabling an otherwise closed 'window' to be opened on the transiently dysfunctioning brain. This article explores the unique contribution that illustration has made to understanding mechanisms subserving the visual aura. The most revealing illustrations are those made by the very few scientists who have recorded and analysed the scotomas, and in particular the expanding fortification spectra, experienced during their migraine attacks. It is solely through illustrations such as these that the uniform nature of many of these hallucinations has been demonstrated. As a result, it follows that there is likely to be a similarly uniform repertoire of processes that generate the hallucinations in the occipital cortex. The precise form of the zigzags that comprise the fortification spectrum, their shimmering appearance, and in particular the speed of the peripheral spread, all of which are entirely dependent on graphic display for their elucidation, enable conclusions to be reached about a number of the underlying pathophysiological mechanisms, including the involvement of spreading cortical depression, that likely occur. Illustration has been pivotal too in revealing uncommon and sometimes curious, if not bizarre, visual hallucinations, the forms of which suggest that extrastriate and temporal lobe involvement contributes to migraine aura in some instances. Illustration can also be valuable in differential diagnosis, depicting other forms of visual hallucination which result from a variety of non-migrainous causes. Illustration, particularly when made during the attack, provides an unusual, little used but powerful tool which uniquely allows the sufferer's subjective visual experiences to inform objective analysis. In turn, this analysis leads to insights into some of the cerebral disturbances which subserve migraine aura.

Mirror writing: neurological reflections on an unusual phenomenon.

Mirror writing is an unusual script, in which the writing runs in the opposite direction to normal, with individual letters reversed, so that it is most easily read using a mirror. This writing is seen in healthy individuals; it is also associated with various focal lesions that most commonly involve the left hemisphere, as well as with certain diffuse cerebral disorders. Mirror writing is nearly always undertaken with the left hand, and left-handers, and those whose languages are written leftwards, have an unusual facility for this writing. Concerning possible underlying processes, the implications of using the left hand when writing are considered first. Motor pathways that may be important, the surrogate model of bimanual mirror movements and the contribution of the corpus callosum are then discussed. The reasons why left-handed writing is mirrored, and the factors that tend to inhibit mirroring, are outlined. After commenting on mirrored motor and visual engrams, the possibility that the right hemisphere may play an important part is entertained, and Leonardo da Vinci's unique, habitual mirror writing proves to be of unexpected relevance. Further investigations, ranging from epidemiological to functional imaging studies, may provide valuable insights into mirror writing.