The Merging Tracks of Anosognosia and Neglect.

Anosognosia and hemineglect are among the most startling neurological phenomena identified during the 20th century. Though both are associated with right hemisphere cerebral dysfunction, notably stroke, each disorder had its own distinct literature. Anosognosia, as coined by Babinski in 1914, describes patients who seem to have no idea of their paralysis, despite general cognitive preservation. Certain patients seem more than unaware, with apparent resistance to awareness. More extreme, and qualitatively distinct, is denial of hemiplegia. Various interpretations of pathogenesis are still deliberated. As accounts of its captivating manifestations grew, anosognosia was established as a prominent symbol of neurological and psychic disturbance accompanying (right-hemisphere) stroke. Although reports of specific neglect-related symptomatology appeared earlier, not until nearly 2 decades after anosognosia's inaugural definition was neglect formally defined by Brain, paving a path spanning some years, to depict a class of disorder with heterogeneous variants. Disordered awareness of body and extrapersonal space with right parietal lesions, and other symptom variations, were gathered under the canopy of neglect. Viewed as a disorder of corporeal awareness, explanatory interpretations involve mechanisms of extinction and perceptual processing, disturbance of spatial attention, and others. Odd alterations involving apparent concern, attitudes, or belief characterize many right hemisphere conditions. Anosognosia and neglect are re-examined, from the perspective of unawareness, the nature of belief, and its baffling distortions. Conceptual parallels between these 2 distinct disorders emerge, as the major role of the right hemisphere in mental representation of self is highlighted by its most fascinating syndromes of altered awareness.

History of Anosognosia.

Even if Babinski (1914) is usually considered as the discoverer of anosognosia, other authors before him contributed to the development of this construct. Von Monakow (1885) and Dejerine and Vialet (1893) gave the first descriptions of patients with cortical blindness who were unaware of their disability, but did not distinguish this unawareness from the rest of the clinical description. Anton (1999) described patients with cortical deafness and cortical blindness, considering these defects of awareness as a symptom independent from the neurological dysfunction. He conceptualized them as a phenomenon in its own right and tried to link this unawareness of a disability with specific neuro-anatomical changes. Finally, Babinski (1914) coined the term "anosognosia" to designate the clinical entity conceptualized by Anton (1899) and extended this concept from the unawareness of cortical deafness and blindness to the unawareness of hemiplegia. The choice of the term "anosognosia" to denote the observed phenomenon was important, because referring to "lack of knowledge of the disease" (anosognosia), he not only emphasized the separation between "lack of knowledge" and "disease, " but also suggested a general use of this term, because disease can refer to many other disabilities besides hemiplegia. Further investigations have shown that: (a) brain-damaged patients may be unaware of different kinds of disabilities; (b) anosognosia can be selective, in that an affected person with multiple impairments may be unaware of only one handicap, while appearing fully aware of any others; and (c) lack of acknowledgment of a disease may not necessarily be due to a defective awareness, but must sometimes be considered as an extreme but understable pattern of adaptation to stress. For this condition, the term "Denial of Illness" seems preferable to that of anosognosia. Anosognosia must perhaps be viewed as a multifaceted phenomenon, resulting from both cognitive and motivational factors.

Hemineglect and Attentional Dysfunction.

Tracing the history of neglect is intriguing, as diverse terminologies have been used to characterize a multi-factorial disorder with rather startling manifestations. In part, heterogeneous terms may have hinted at distinct subtypes. Thus, different variants of hemi-inattention and neglect relate conceptually, but may be functionally dissociable. Patients with neglect, acting as if the world-space they perceive is full, do not phenomenally experience the omissions or absences so patently obvious to an observer. From the late 19th century, hemi-inattention was described according to its prominent manifestations, visual, bodily or spatial. Since then, diverse terms including imperception, inattention, unilateral visual inattention, unilateral spatial agnosia, and neglect, among others, reflected proposed underlying mechanisms. Major theories presented to account for this curious, even astonishing, neurological disorder, included disruption of body-scheme, perceptual rivalry and extinction, forgetting or amnesia for half the body, and highly nuanced models of distribution of directed spatial attention, and of disrupted perceptual processes. Unlike neurological counterparts, already designated as hemi-syndromes by the first part of the 20th century, not until about 1970 did neglect become so broadly recognized as a syndrome. Earlier, commonalities were identified, features conceptually clustered, and then subtypes were distinguished. Neglect was designated as an overarching term for a class of disorder with distinct subtypes, including visual, motor, extrapersonal, bodily or personal, other somatosensory, and representational. Specificity for modality, chronology, material, and symptom severity was noted. Remarkable clinical, neuropsychological, and behavioral manifestations of hemi-inattention and neglect may involve varying proposed mechanisms of higher cognitive functions, all within a spectrum of clinical disorder. Concepts of connectivity and interaction, neural networks, and functional integration enhance understanding of dysfunction, recovery, and compensation in neglect and inattention. Focus on distinct manifestations clustered under the umbrella of neglect offers a vantage point for examining historical trends in approach to the phenomenon.

Damasio's error - Prosopagnosia with intact within-category object recognition.

The sudden inability to recognize individual faces following brain damage was first reported in a scientific journal 150 years ago and termed 'prosopagnosia' 70 years ago. While the term originally identified a face-selective neurological condition, it is now obscured by a sequence of imprecisions. First, prosopagnosia is routinely used to define symptoms of individual face recognition (IFR) difficulties in the context of visual object agnosia or other neurological conditions, or even in the normal population. Second, this over-expansive definition has lent support to a long-standing within-category recognition account of prosopagnosia, that is, that the impairment of IFR reflects a general impairment in recognizing within-category objects. However, stringent experimental studies of classical cases of prosopagnosia following brain damage show that their core impairment is not in recognizing physically similar exemplars within non-face object categories. Instead, the impairment presents specifically for recognizing exemplars of the category of faces. Moreover, compared to typical observers, the impairment appears even more severe for recognizing individual faces against physically dissimilar than similar distractors. Here, I argue that we need to limit accordingly our definition of prosopagnosia to a clinical (i.e., neurological) condition in which there is no basic-level object recognition impairment. Other criteria for prosopagnosia are proposed, with the hope that this conservative definition enables the study of human IFR processes in isolation, and supports progress in understanding the nature of these processes.

Perceptual deficits of object identification: apperceptive agnosia.

It is argued here that apperceptive object agnosia (generally now known as visual form agnosia) is in reality not a kind of agnosia, but rather a form of "imperception" (to use the term coined by Hughlings Jackson). We further argue that its proximate cause is a bilateral loss (or functional loss) of the visual form processing systems embodied in the human lateral occipital cortex (area LO). According to the dual-system model of cortical visual processing elaborated by Milner and Goodale (2006), area LO constitutes a crucial component of the ventral stream, and indeed is essential for providing the figural qualities inherent in our normal visual perception of the world. According to this account, the functional loss of area LO would leave only spared visual areas within the occipito-parietal dorsal stream - dedicated to the control of visually-guided actions - potentially able to provide some aspects of visual shape processing in patients with apperceptive agnosia. We review the relevant evidence from such individuals, concentrating particularly on the well-researched patient D.F. We conclude that studies of this kind can provide useful pointers to an understanding of the processing characteristics of parietal-lobe visual mechanisms and their interactions with occipitotemporal perceptual systems in the guidance of action.

"With a smile through tears": the uprooted career of the man behind Gerstmann syndrome.

Austrian neuroscientist Josef Gerstmann, well known for describing Gerstmann syndrome and for pioneering works on tactile agnosia, also co-described the familial prion disorder later known as Gerstmann-Sträussler-Scheinker disease. In 1938, Nazi Germany annexed Austria (the "Anschluss") and the three-time decorated war veteran Gerstmann was dismissed from his professorship in Vienna because of his "race." In 1942, he unknowingly had his doctorate stripped, only to have it returned in 1955. The Gerstmann properties were seized in Vienna, resulting in a bitter postwar reclamation battle. Gerstmann immigrated to the United States quickly after the annexation and had some success in exile but never again directed a hospital. He maintained a private practice throughout his exile and, in the 1940s, had some research and consulting positions in New York. More than 75 years after the Anschluss, many questions remain unanswered about Gerstmann's forced exile and the impact of becoming a refugee on his life and career.

The construction of anosognosia: history and implications.

The construction of anosognosia as a clinical 'disorder' resulted from the convergence (in the work of various writers and culminating in Babinski) of a name, a concept, and a clinical phenomenon. During the early stages of this convergence, unawareness of neurological dysfunction was not considered as an independent clinical phenomenon. Started in the work of Anton, the process of separating it as a differentiable clinical state is completed by Babinski who reaffirmed the semiological independence of 'unawareness'. The history of the construction of 'anosognosia' parallels the late 19th century debate on the nature and brain inscription of the concept of 'consciousness'.

Mindblindness: metaphor and neuroaesthetics in the works of Silas Weir Mitchell and Simon Baron-Cohen.

Silas Weir Mitchell's novel, When All the Woods are Green (1894), acknowledges the medical use of mindblindness (agnosia) but also casts it as a developmental disorder, bringing it provocatively close to how current neuropsychologist, Simon Baron-Cohen and his followers use the term in relation to autism. This chapter traces the mindblindess metaphor in the works of Mitchell and Baron-Cohen to show how mindblindness informs the larger paradigms by which they theorize the brain. This analysis suggests that Baron-Cohen, and thus much current thinking about autism spectrum conditions, is influenced by Victorian-era cultural assumptions and neurosexism, a connection that calls for scrutiny of Baron-Cohen's current models of the brain and theories of autism. This chapter also demonstrates the extent to which Mitchell used fiction and advocated writing as neuroaesthetic tools and thus bridged in his work cognitive science and aesthetics--a connection that current scholars of neuroaesthetics are now theorizing.

Psychic blindness or visual agnosia: early descriptions of a nervous disorder.

This article briefly reports on three early contributions to the understanding of visual agnosia as a syndrome sui generis. The authors of the respective papers worked in different fields such as physiology, ophthalmology, and neurology, and, although they were not in direct contact with each other, their results converged upon a consistent view of a nervous disorder that they called psychic blindness.

Christfried Jakob's 1921 Theory of the Gnoses and Praxes as fundamental factors in cerebral cortical dynamics.

This study aims at reviving an important contribution by the pioneer neurobiologist and neurophilosopher Christfried Jakob (1866-1956) to the understanding of higher cortical functions. Jakob studied cortical dynamics at multiple levels by comparing gnoses and praxes and their corresponding pathological states, i.e. the agnosias and the apraxias. We herein provide a complete English translation of Jakob's original Spanish article dating to 1921, and further consider some key points under the scope of the neuropsychological knowledge available then, and the research evidence available 90 years later.

Babinski's anosognosia for hemiplegia in early twentieth-century French neurology.

In 1914, Babinski first described "anosognosia"; a term he coined for a phenomenon involving unawareness of disability in hemiplegia. Historical roots of contemporary perspectives on anosognosia after stroke may be found in early discussions among French neurologists. Current notions and debate regarding the roles played by cognition, emotional factors, sensory loss and somatosensory neglect in anosognosia, and the distinctness of anosognosia as a symptom echo the theoretical dilemmas of an earlier past. Historical overview of the development of perspectives on anosognosia enriches our understanding of unawareness of disability.

Lovis Corinth: integrating hemineglect and spatial distortions.

Lovis Corinth suffered a right-hemispheric stroke at the age of 53 years, but died only 14 years later. The huge number of artworks that he produced after this life-threatening disease allows a detailed analysis of his poststroke artwork in comparison to his prestroke artwork. When performing this analysis as a neurologist, an enormous diversity of subtle stroke sequelae can be discovered, which can mostly be explained by a left-sided hemineglect. These findings clearly go far beyond pure psychological processes. Moreover, Corinth is a good and motivating example for patients suffering disability after a stroke, because he was able to produce great artwork after his stroke. Lovis Corinth was struggling against motor disability that admittedly was not severely affecting his artistic production but he also had to fight against severe neuropsychological deficits that did have clear consequences for his artistic production. Corinth's credo was 'true art means to use unreality'. Taken together with the often cited phrase of 'drawing means to [details]', there will be a clear-cut interpretation for the neurologist that can be derived from the understanding of a right-hemisphere lesion and subsequent left-sided neglect.

Visconti and Fellini: from left social neorealism to right-hemisphere stroke.

The acclaimed Italian directors Luchino Visconti and Federico Fellini had very different life trajectories that led them to become major figures in the history of cinema. Similarities, however, can be found in their debuts with the neorealist genre, their personalities, creative styles and politicocultural involvement, and ultimately in the neurological disease that struck them at the end of their careers. Both suffered a right-hemispheric stroke that left them hemiplegic on the left side. We review their life and career to put that event into perspective, and then discuss its aftermath for both artists in the light of our current knowledge of right-hemispheric functions. Visconti showed a tremendous resilience following the accident and managed to direct several films and plays as an infirm, whereas Fellini had to put an end to his career but still was able to display his talents to the neuropsychologists that treated him. A speculative account is given of the links between right-hemispheric symptomatology and the premorbid personality of these highly prolific patients.

[The Juliane Hochriehser case--a classical case of anosognosia]. / Der Fall Juliane Hochriehser: Ein klassischer Fall von Anosognosie.

Still today anosognosia as a phenomenon attracts the attention of both clinicians and researchers. Patients affected by this syndrome deny an obvious neurological dysfunction caused by a defined damage in their brains. This lack of awareness of their impairment is the most interesting feature of this syndrome. In the neuropsychiatric literature case studies have played an important role, among them four contributions by Gabriel Anton (1858-1933) at the end of the 19th century. The phenomenon described by him in these case studies was later referred to as anosognosia by Josef François Babinski (1857-1932). Recognising his achievements in the description of this phenomenon one kind of anosognosia, namely cortical blindness, is still referred to in the scientific literature as the Anton-Syndrome (also Anton Symptom). Using the recently discovered original files of 1895/96 our study substantiates one case described by Anton. The case in question is that of Juliane Hochriehser, a 69-year old dairymaid who showed anosognosia with cortical deafness due to bilateral lesion of the temporal lobes. Other cases of his are also included. The study concludes with an overview of the current state of research and the different approaches to this syndrome. Yet it is still not clear which areas and structures in the brain are responsible for the development of anosognosia. It may well be that dextral or bilateral damage of several areas of the brain plays a major role.

"I could see, and yet, mon, I could na' see": William Macewen, the agnosias, and brain surgery.

Two little noticed cases in which William Macewen used symptoms of visual agnosia to plan brain surgery on the angular gyrus are reviewed and evaluated. Following a head injury, Macewen's first patient had an immediate and severe visual object agnosia that lasted for about 2 weeks. After that he gradually became homicidal and depressed and it was for those symptoms that Macewen first saw him, some 11 months after the accident. From his examination, Macewen concluded that the agnosia clearly indicated a lesion in "the posterior portion of the operculum or in the angular gyrus." When he removed parts of the internal table that had penetrated those structures the homicidal impulses disappeared. Macewen's second patient was seen for a chronic middle ear infection and, although neither aphasic nor deaf, was 'word deaf.' Slightly later he became 'psychically blind' as well. Macewen suspected a cerebral abscess pressing on both the angular gyrus and the first temporal convolution. A large subdural abscess was found there and the symptoms disappeared after it was treated. The patients are discussed and Macewen's positive results analysed in the historical context of the dispute over the proposed role of the angular gyrus as the visual centre.