The Neuroscience of Visual Hallucinations
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Foreword xi
Section 1: Background and Context 1
1 Visual hallucinations: history and context of current research 3
G.E. Berrios and Ivana S. Marková
1.1 Introduction 3
1.2 The construction of visual hallucinations 5
1.3 Epistemology: dichotomies 11
1.4 Research and its vicissitudes 15
1.5 Bringing the history of visual hallucinations and research together 17
1.6 Conclusions 18
1.7 References 19
2 Defining and measuring hallucinations and their consequences - what is really the difference between a veridical perception and a hallucination? Categories of hallucinatory experiences 23
Jan Dirk Blom
2.1 What every student knows 23
2.2 Suspended between realism and anti-realism 24
2.3 Faith 26
2.4 The philosophy of As If 28
2.5 Visual hallucinations 28
2.6 Visual illusions 30
2.7 Metamorphopsias (visual distortions) 34
2.8 Ways of measuring and quantifying positive disorders of vision 37
2.9 Concluding remarks 38
2.10 References 40
3 Hallucinatory aspects of normal vision 47
Geraint Rees
3.1 Introduction 47
3.2 Gregory's taxonomy 48
3.3 Blind spot and scotomas 49
3.4 After-images and after-effects 50
3.5 Perceptual ambiguity and multistable perception 51
3.6 Illusory contours and surfaces 52
3.7 Object perception and illusory vision 53
3.8 Conclusion 55
3.9 References 55
4 Non-pathological associations - sleep and dreams, deprivation and bereavement 59
Armando D'Agostino, Anna Castelnovo, and Silvio Scarone
4.1 Introduction 59
4.2 Visual hallucinations in the general population 60
4.3 Visual hallucinations during sleep and sleep/wake transitions 67
4.4 Trauma, grief and bereavement 74
4.5 Sensory deprivation 83
4.6 The Bayesian heuristic: a unifying model? 84
4.7 Conclusions: the psychosis continuum 85
4.8 References 86
5 The clinical associations of visual hallucinations 91
Marco Onofrj, Astrid Thomas, Giovanni Martinotti, Francesca Anzellotti, Massimo Di Giannantonio, Fausta Ciccocioppo, and Laura Bonanni
5.1 Introduction 91
5.2 Describing hallucinations 93
5.3 Visual hallucinations associated with visual loss 93
5.4 Visual hallucinations in acute vascular or neoplastic lesions 94
5.5 Visual hallucinations in neurodegenerative diseases 94
5.6 Visual hallucinations associated with dementia 99
5.7 Creutzfeldt-Jakob disease 101
5.8 Visual hallucinations in psychosis 102
5.9 Drug-induced hallucinations 104
5.10 Delirium 105
5.11 Epilepsy 105
5.12 Migraine 107
5.13 Inborn errors of metabolism 108
5.14 Commentary 108
5.15 References 110
Section 2: Investigations and Data 119
6 Hallucinogenic mechanisms: pathological and pharmacological insights 121
Simon J.G. Lewis, James M. Shine, Daniel Brooks, and Glenda M. Halliday
6.1 Introduction 121
6.2 Societal impact 122
6.3 Misperceptions and hallucinations 122
6.4 Pathological findings in clinical disorders with high levels of hallucinations 125
6.5 Role of neurotransmitters in hallucinations 130
6.6 A common neural mechanism 132
6.7 Conclusion 138
6.8 References 139
7 Imaging in visual hallucinations 151
Anne Marthe Meppelink
7.1 Introduction 151
7.2 Imaging the hallucinator 152
7.3 Imaging the hallucination 158
7.4 References 163
8 EEG and transcranial magnetic stimulation. Changing and recording the dynamic flow of visual perception 167
Nicholas Murphy, Sara Graziadio, and John-Paul Taylor
8.1 Introduction 167
8.2 Electroencephalography 168
8.3 Transcranial magnetic stimulation 179
8.4 Future directions for the study of visual hallucinations using neurophysiological approaches 184
8.5 References 186
9 Neuropsychological approaches to understanding visual hallucinations 193
Jim Barnes
9.1 Introduction 193
9.2 Perceptual impairments 195
9.3 Misidentifications of internal images 196
9.4 Executive function 199
9.5 Attention and vigilance 201
9.6 Questions and future directions 204
9.7 References 210
Section 3: Models and Theories 217
10 Geometric visual hallucinations and the structure of the visual cortex 219
Jack D. Cowan
10.1 Introduction 219
10.2 A new mathematical formulation of V1 circuitry 228
10.3 Conditions for the loss of stability of the homogeneous state 232
10.4 Extensions of the model 238
10.5 Summary and concluding remarks 248
10.6 References 250
11 Thalamic and brainstem regulatory systems - why disturbances external to the visual system can cause hallucinations 255
René M. Müri
11.1 Introduction 255
11.2 Overview of the cases published with peduncular hallucinations 257
11.3 Aetiology and lesion localization contributing to peduncular hallucinations 269
11.4 Origin and mechanisms of peduncular hallucinations 270
11.5 References 275
12 The pathology of hallucinations: one or several points of processing breakdown? 281
Nico J. Diederich, Christopher G. Goetz, and Glenn T. Stebbins
12.1 Introduction 281
12.2 Requirements for an ideal model 282
12.3 Phenomenology - a clue to pathogenesis? 282
12.4 Early unimodal models of pathogenesis 283
12.5 Neuropathological findings 287
12.6 Interactive, multifactorial models 290
12.7 Conclusions and outlook 299
12.8 References 301
Section 4: New Directions 307
13 Future directions for research 309
Daniel Collerton, Urs Peter Mosimann, and Elaine Perry
13.1 Introduction 309
13.2 References 318
14 The treatment of visual hallucinations at present and in the future 321
Elaine Perry, Urs Peter Mosimann, and Daniel Collerton
14.1 Introduction 321
14.2 Excluding drugs that induce visual hallucinations 323
14.3 Drug treatment of visual hallucinations 327
14.4 Psychological interventions 332
14.5 Unexplored issues and other potential therapies 334
14.6 References 336
Index 343
Chapter 1
Visual hallucinations: history and context of current research
G.E. Berrios1 and Ivana S. Marková2
1Department of Psychiatry, University of Cambridge, Cambridge, UK
2Centre for Health and Population Sciences, Hull York Medical School, University of Hull, Hull, UK
1.1 Introduction
'Visual hallucination' is the name of a class of heterogeneous phenomena which share as a common feature the report that a subject (the 'hallucinator') is entertaining a putative 'visual' image of something placed in the public space that others cannot see. Hence 'absence of an object to be seen' has become part of its conventional definition. 'Images' may range from simple dots to complex forms in movement. This chapter will deal only with the latter. The hallucinator's report can be interpreted as meaning that he is entertaining a visual image or that he only believes that he is so doing, as it might well be the case with psychotic or obsessional hallucinations (Castilla del Pino, 1984; Gimenez, 2000; Fuentenebro and Berrios, 2000).
Disambiguating such reports is not always straightforward. On occasions, it can be reasonably claimed that proxy representations of the image in question can be ascertained by technical means (e.g. neuroimaging) as may well be the case in regard to so-called 'organic' or 'provoked' visual hallucinations (Berrios, 1985; Manford and Andermann, 1998; ffytche, 2007). However, when the proxy representations are counter-intuitive and merely correlational, that is, when changes do not seem to be related to those brain regions obviously associated with visual perception (as it seems to be the case with some visual obsessional or psychotic hallucinations) (Boksa, 2009) then disambiguation becomes problematic. The possibility that the hallucinator is only expressing the belief that he is entertaining a visual image cannot be easily dismissed (Castilla del Pino, 1984; Gimenez, 2000).
Therefore, it is likely that the class 'visual hallucinations' is but a mixture of clinical phenomena which are different from each other, both from the phenomenological and aetiological point of view. Indeed, this was the way they were perceived until the 'unitary' view was first proposed during the early nineteenth century (Berrios, 1996). Historical accuracy requires that two 'unitary views' are distinguished: UV1 refers to the view that ALL hallucinations, regardless of their sense modality, are structurally the same phenomenon; and UV2 refers to the view that all visual hallucinations, regardless of the disease in which they appear, are the same phenomenon. Ever since UV1 and UV2 became the official view, voices have been raised against them (for a detailed analysis of this literature see: Ey, 1957, 1973; Lanteri-Laura, 1991).
Before the nineteenth century there was no unitarian view of visual hallucinations (UV2). Visions, apparitions, phantoms, fantasies, imaginings, contemplations, supernatural insights and so on were all conceptualized as different phenomena in their own right (Tyrrell, 1943; Green and McCreery, 1975; Berrios, 2007). Some of them were considered to be pregnant with meaning to represent forms of communication between god, unknown forces and man or between men themselves. By the early nineteenth century, in what became the scientific approach to hallucinations, these experiences were shelled out of all semantic content, lumped together and treated as mechanical 'disorders' of the brain. Although the semantic view of hallucinations still lingers on, both in folkloric Western psychology and in some non-Western cultures, it cannot be said to have the force of the scientific view.
The current general concept of hallucination and that of visual hallucination were both constructed during the early nineteenth century (Ey, 1939; Berrios, 1996). Although there have since been debates on their aetiology, the conventional assumption remains that hallucinations in general are a disorder of perception (Berrios and Marková, 2012), and the same applies, mutatis mutandi, to visual hallucinations. This has made debates on the nature of visual hallucination dependent upon changing theories of visual perception (Hamlyn, 1961).
It remains to be seen whether UV2 should be considered epistemologically superior to earlier views, that is, whether it is more helpful both to the understanding and management of these phenomena. This can only be decided by empirical research. Unfortunately, no one seems interested in carrying out studies comparing UV2 against earlier taxonomic and aetiological views of visual hallucinations.
By the end of the nineteenth century, the current 'operational' definition had been put together (Berrios, 2005). Visual hallucinations: (i) were to be defined as reports of real visual images of unascertainable public objects - not of the belief that the person was experiencing an image and (ii) which regardless of their phenomenology or clinical associations resulted from pathological changes in the visual system. Agencies external to the body (such as spirits or ghosts) were no longer to be considered as part of the explanatory model. 'Personality' and 'culture' were allowed within the explanatory model but only to account for the 'content' of the visual hallucination (i.e. thus according to their 'culture', hallucinators may see a devil, a dragon or whatever).
From the above, at least three conclusions can be drawn:
- The phenomena currently called 'visual hallucinations' do not seem to be ontologically stable 'natural kinds' but will-o'-the-wisp phenomena, which in each historical period have been configured in a different way.
- To 'understand' these phenomena properly (and hence to manage them) a set of tools is required, which may be more complex than any offered by the neurosciences and,
- To discharge their brief, we will need to sketch the history and epistemology of: (i) visual hallucinations and (ii) the social activity called 'research' and explore their historical interactions.
Historical analysis shows that UV2 has become a hindrance to the understanding of visual hallucinations. Exploring their neuro-mechanics or mapping them in the current language of cognitive neuropsychology is bound to be insufficient. Per contra, this chapter will put forward the view that: (i) before empirical research starts in earnest much work on the clinical phenomenology and taxonomy of visual hallucinations needs to be done and (ii) a new taxonomic approach will show that 'visual hallucinations' names a rag bag of heterogeneous phenomena, each of which will require a different aetiological account. Lastly, because subjects suffering from these clinical afflictions may need direct clinical intervention, conceptual and ethical auditing become particularly important in this type of research.
1.2 The construction of visual hallucinations
1.2.1 History
The history of visual hallucinations can be broken up into four periods. The first period extends from Classical times to the beginning of the nineteenth century (Berrios, 1996). At that point, a physiological period started in the work of Johannes Müller (Berrios, 2005). A hermeneutic period developed after the 1850s and is characterized by work on dreams, parapsychology and the reappearance of the moot question of 'hallucinations in the sane' (James, 1995). The organicist period starts with the work of Tamburini (Berrios, 1990a, 1990b) and can be said to continue to this day. To some extent, these four periods run into each other (Géraud, 1989).
1.2.2 Classical period
Reports of visions and apparitions can be found very early in history (Calmet, 1641; Dufresnoy, 1752; Amat, 1885). Often considered as epiphanic occurrences, that is, as divine revelations, these phenomena were explored with tools borrowed from the theological analysis of the soul and its relationship with the deity (Bona, 1676). The resulting taxonomy, metalanguage and hermeneutic approach provided the model for the later philosophical analysis of visual hallucinations.
St. Augustine wrote: "Three kinds of visions take place; one with the eyes, when you see the actual letters; another with the human spirit, by which you think of your neighbour even though he is not there; a third with the attention of the mind, by which you understand and look at love itself . let is call the first vision 'bodily' . the second 'spiritual' . the third one, finally, 'intellectual'" (Lit. Meaning. Genesis. 6. Book XII, 6.15,16). This analysis was to be repeated many times in the history of Christian theology until its culmination in the great works of Calmet (1641) and Bona (1672).
That apparitions and other 'visual' experiences could be empirically studied was first suggested by Augustin Calmet (1641), a Benedictine monk who proposed that: (i) apparitions of angels, demons and souls were real enough, (ii) the mechanisms involved remained obscure and (iii) God had left to humans the task of finding out the said mechanisms.
Cardinal Bona (1676) in turn differentiated visions from apparitions: the former were images of subjects known, the latter of subjects unknown. There were three types of...
