Summary

We perceive the world by means of an elaborate set of distinct, modality-specific receptor systems. It is hardly conceivable that losing or lacking a sensory modality would not, in some fashion, alter the capacities of processing, understanding or interacting with the world. Therefore, if lack or loss of a sensory modality leads to a compensatory enhancement of other senses, ultimately resulting in minimal functional loss or even functional gains, these would represent instances of paradoxical functional facilitation. In fact, enhancement of functioning in people with chronic or recent sensory loss has been one of the more widely studied and reliable forms of paradoxical functional facilitation. Individuals with visual loss have been found to show enhanced auditory function, tactile function and even verbal memory performance. Analogously, long-term auditory loss has been associated with enhanced cognitive performance, evident on tactile and visual tasks. Functional brain imaging and transcranial magnetic stimulation studies have pointed to a major reorganization of cerebral function in blind or deaf individuals, and these plastic changes are associated with functional adaptations and gains.

Introduction

In his novel Blindness, Jose Saramago (1998) uses blindness as a metaphor for both personal misfortune and social catastrophe. A man suddenly loses his vision. Within a few days, people who had contact with him also go blind, and blindness spreads like an epidemic. In the context of practically universal blindness, society breaks down, nothing functions, food and resources become scarce, and lives are threatened. Ultimately, only one character in the novel miraculously avoids blindness.

Summary

Paradoxes abound in nature and in the realm of the human condition. Paradoxes have been evident in fields of science – from plant biology to human biology to physics – and in areas of human endeavour, ranging through political, literary and social activities. Paradoxes often represent instances where current knowledge may be deficient, and thus predictions based on such knowledge may be inconsistent with actual events or findings. At the level of scientific methodology, paradoxical phenomena offer powerful opportunities to test models and conceptual frameworks, and to enable true ‘paradigm shifts’ in certain areas of scientific inquiry. Insights from paradoxical phenomena in clinical sciences not only help us to understand mechanisms of function and dysfunction, they also provide clues as to therapeutic strategies, which may alleviate impairment and disability resulting from disease and injury. In addition, they may contribute towards a more positive, humanistic view of diverse states of the human condition.

Introduction

The word paradox is derived from the Greek: the prefix para means contrary or opposed, and doxos means opinion. The Shorter Oxford English Dictionary (2002) includes amongst its definitions of paradox ‘a seemingly absurd or self-contradictory statement or proposition which, when investigated or explained, may prove to be well-founded or true’. In his philosophical treatise on paradoxes, Sainsbury (2009) has highlighted the paradoxical nature of paradoxes themselves: ‘Paradoxes are fun.

Summary

Noninvasive brain stimulation with transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) is valuable in research and has potential therapeutic applications in cognitive neuroscience, neurophysiology, psychiatry, neurology and neurorehabilitation. TMS and tDCS allow diagnostic and interventional neurophysiology applications, targeted neuropharmacology delivery and systematic exploration of local cortical plasticity and brain network dynamics. Repetitive TMS or tDCS can modulate cortical excitability of the directly targeted brain region beyond the duration of the brain stimulation train by the induction of phenomena similar to long-term potentiation (LTP) or long-term depression (LTD), which may increase or decrease cortical excitability respectively. The effects of TMS or tDCS do not remain limited to the targeted brain region, and thus disruption of brain activity by TMS or tDCS can result in behavioural facilitation via distant cortical or subcortical structures. In addition, state-dependent effects of noninvasive brain stimulation condition the impact of TMS and tDCS and may result in paradoxical behavioural effects of the stimulation. Greater understanding of the neurobiological mechanisms involved in such intances may allow us to systematically use TMS or tDCS to leverage paradoxical functional facilitation for therapeutic applications.

Introduction

In the past decades, neuroimaging techniques such as computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), magnetoencephalography (MEG) and electro-encephalography (EEG) have shaped the ways in which we model behaviour. Anatomical neuroimaging techniques produce ever more detailed descriptions of the extent of lesions produced by brain injury.

Summary

Paradoxical findings relating to the human brain have implications for our understanding of the workings of the normal brain, and for how normal functioning may be enhanced. Paradoxical findings may also have implications for how we can prevent and detect brain disease, and how we may best repair and rehabilitate the damaged brain. The brain may best be modelled as a nonlinear device, which relies on dynamic synchrony and balance between neural systems. Damage to the brain may upset this dynamic state, and repair may often entail interventions that restore a degree of synchrony and balance. In this final chapter, we propose 10 principles of brain function that can help accommodate paradoxical phenomena, and we also speculate on paradoxical therapeutic interventions that may be beneficial to human brain functioning.

Introduction

If we can be forgiven a degree of owner's pride, the human brain is quite extraordinary. A three-pound mass of jelly-like material is the only entity in the universe (that we know of) which can form and test theories about that universe. It can also speculate about structures much smaller or larger than it can possibly see. It might be thought that, when it comes to studying itself, the brain would have a number of inherent advantages, being on home turf, as it were. It is certainly true that we are very familiar with what the brain can achieve.