Neurotechnology and Direct Brain Communication

New insights and responsibilities concerning speechless but communicative subjects

Michele Farisco, Kathinka Evers, Michele Farisco, Kathinka Evers

• Publisher: Routledge
• Year: 2016
• ISBN:
  9781317529583
• Edition: 1
• Topic: Philosophy
• Subtopic: Ethics & Moral Philosophy

Neurotechnology and Direct Brain Communication focuses on recent neuroscientific investigations of infant brains and of patients with disorders of consciousness (DOC), both of which are at the forefront of contemporary neuroscience. The prospective use of neurotechnology to access mental states in these subjects, including neuroimaging, brain simulation, and brain computer interfaces, offers new opportunities for clinicians and researchers, but has also received specific attention from philosophical, scientific, ethical, and legal points of view. This book offers the first systematic assessment of these issues, investigating the tools neurotechnology offers to care for verbally non-communicative subjects and suggesting a multidisciplinary approach to the ethical and legal implications of ordinary and experimental practices.

The book is divided into three parts: the first and second focus on the scientific and clinical implications of neurological tools for DOC patient and infant care. With reference to these developments, the third and final part presents the case for re-evaluating classical ethical and legal concepts, such as authority, informed consent, and privacy.

Neurotechnology and Direct Brain Communication will appeal to researchers and postgraduate students in the fields of cognitive science, medical ethics, medical technology, and the philosophy of the mind. With implications for patient care, it will also be a useful resource for clinicians, medical centres, and health practitioners.

Part I

1The emergence of consciousness

From foetal to newborn life

Hugo Lagercrantz and Nelly Padilla

What is it like to be a baby?

What is it like to be a bat? This important question was evoked by Thomas Nagel in 1974 and has then been discussed by philosophers over and over again (Nagel, 1974). Nagel chose the bat as an example since it is so different from the human. It hangs upside-down and uses sonar to communicate, etc. But what is it like to be a human foetus or a baby? The foetus is also usually positioned upside-down and listens to the filtered voice of the mother. The newborn infant spends most of its time in horizontal position and starts to imitate the facial expressions of adults and absorbs phonemes, which actually begins before birth. To what extent the newborn infant is conscious and how new neurotechnologies can be used to measure infant consciousness is discussed in this updated version of previous reviews (Lagercrantz and Changeux, 2009; Lagercrantz, 2014). The emergence of consciousness is related to the neurobiological and psychological development of the brain (Lagercrantz et al., 2010). This question, which may be elusive, does have important clinical implications to predict neuropsychiatric disease like autistic spectrum disorder (ASD) using neuroimaging biomarkers early in life to identify infants at risk and provide targeted intervention at an early stage.

Definition of consciousness

According to Henri Bergson, the primary function of consciousness is to retain what no longer is and to anticipate what as yet is not (see Posner and Rothbart, 1998). This definition of consciousness is not applicable to the newborn baby. However, the baby seems to be conscious if this is defined as awareness of the body, oneself, and the outside world, at least at a minimal level (Zelazo, 2004). Thus the infant seems to be conscious of something and can react with avoidance or cry. In this regard, using functional magnetic resonance imaging (fMRI) it has been demonstrated that the newborn has activated brain networks oriented toward sensory systems (Fransson et al., 2011), which contribute to the sense of body ownership.

It is important to distinguish between the states of consciousness, i.e., wakefulness, sleep, coma, and general anaesthesia, versus the content of consciousness. There is some controversy concerning whether rapid-eye movement (REM) sleep with dreaming should be regarded as a conscious or non-conscious state. Since purposeful movements are usually not performed and cortex is not activated to the same extent as during wakefulness, it should be regarded as an essentially unconscious state. Furthermore, insight and self-reflection are absent during dreams.

Models

There are several theoretical models of consciousness. The Integrated Information Theory (IIT) has been proposed by Giulio Tononi (Laureys and Tononi, 2008). It postulates that one can be conscious of multiple things and that they are highly integrated. A number of neuronal circuits are involved in the integration of all the conscious experiences. This can be further estimated mathematically.

Another model has been proposed by Jean-Pierre Changeux and Stanislas Dehaene (Changeux and Dehaene, 1989; Dehaene, 2014). Whenever we become conscious about something it can be retained in the working memory. It can then be processed in the global neuronal workspace (GNW), a number of long neurons interconnecting various hubs in the brain. In this way the impression from any sense organ, such as a familiar face or voice, a taste or a smell, can be associated with old memories and integrated.

A third model of consciousness is proposed from the neuroanthropology approach (Northoff, 2010), which emphasizes the huge importance of cultural circuits in the formation of individual consciousness (Bartra, 2014). Brain circuits may use symbolic resources from the cultural networks in their different conscious operations constituting bidirectional traffic between subjects and environment that is reflected in the brain’s neuronal activity (Han and Northoff, 2008). In infants, for example, the development of spoken language begins as a social activity, and then it acquires a self-centred character to finally generate inner speech. Instead, in autism, the dysfunctional connection of the brain with the sociocultural circuits results in difficulties establishing social relations and verbal and non-verbal communication. Hence, structural and functional brain development will require extending networks from the brain through the body into the sensorimotor environment (Byrge et al., 2014). Thus, in order to reach a high-level consciousness (or self-consciousness) the individual and their internal sensations must be exposed to the external world (Bartra, 2014).

Neurotechnological assessment

The hard problem (Chalmers, 1996) is whether it is possible to bridge the hump from what is going on at a neurophysiological level to subjective feeling. This is particularly difficult in infants who cannot report what they are conscious about. By magnetic resonance imaging (fMRI) the difference between oxygenated and deoxygenated blood can be monitored. This blood oxygen level-dependent signal (BOLD) is assumed to correlate with neuronal activity, particularly the slow cortical potentials (SCP) (He and Raichle, 2009), which has been proposed to correspond to “the stream of consciousness”. However, there is an inverse-signal response in infants probably due to a lower increase of perfusion as compared with oxygen consumption (Born et al., 1996).

The problem with fMRI particularly when monitoring infants is that the head has to be immobilized. Furthermore, there is considerable noise. To overcome these difficulties fast acquisitions and advanced MRI sequences have been developed. fMRI is used to study normal and abnormal patterns of brain activations and also to evaluate the activity of the brain in its resting state. This methodology has been successfully applied to examine neonatal populations (Doria et al., 2010) defining patterns of neural networks development in the maturing brain. Recently, the application of an advanced processing method to evaluate fMRI (dynamic functional connectivity) has demonstrated that wakefulness is characterized by a great diversity of brain states, which may constitute a signature of consciousness (Barttfeld et al., 2015). This promising methodology may provide unique insight into early functional brain development related to consciousness in infants.

A simpler method to assess the hemodynamic response is to use Near Infrared spectroscopy (NIRS). The NIRS device produces near infrared light at different wavelengths. This is reflected by natural chromophores like oxygenated and deoxygenated haemoglobin. The signals are picked up by receiver probes and correlate to the blood flow which is assumed to correspond to the neuronal activity in areas of interest. By this way the somatosensory response to painful procedures has been recorded in preterm infants as an indication of awareness of pain (Bartocci et al., 2006). NIRS is less sophisticated than fMRI, but can be used bedside and is a fairly silent method.

Electroencephalography (EEG) can also be used, particularly to monitor event-related potentials (ERP) in response to sound and visual impressions. ERP was monitored in 5- to 15-month-old infants by showing them faces that were masked to render them visible or non-visible (Kouider et al., 2013). A late ignition in the ERP response was found already at 5 months assumed to reflect conscious perception. However, the response was fairly weak as compared with the older infants. ERP is also useful to study how speech and language are processed in the infant brain (Kuhl, 2010).

EEG can also be used to monitor the resting-state activity, by modelling the frequency power spectrum with a power-law function (Fransson et al., 2013). Similar patterns of connectivity in the infant brain have been observed with this method as by using fMRI.

Magnetoencephalography (MEG) measures the magnetic fields associated with electrophysiological brain activity which is a more direct method than analyzing the hemodynamic response with fMRI. It may disturb the infant less than fMRI, since it is less noisy and can be performed more rapidly. It can be used both for human foetuses and neonates (Schleger et al., 2014).

Neural correlates of consciousness

Human consciousness is assumed to be related with neural activity in the brain and particularly in the neocortex (Koch, 2004). According to Sporns (Heuvel and Sporns, 2011), “the collective actions of individual nerve cells linked by a dense web of intricate connectivity guide behaviour, shape thoughts, from and retrieve memories, and create consciousness”. The “atoms” of consciousness, i.e., the neurons, prolipherate mainly between the tenth to the twentieth gestational week (see Lagercrantz et al., 2010). There does not seem to be any neurogenesis in the cortex after birth (Nowakowsky, 2006). The neurons begin to sprout, develop dendritic spines during the third trimester. Synaptogenesis is also ignited during this period to peak at about one year after birth (Bourgeiois, 2010). The “synaptic crosstalk” between the neurons is of course essential for consciousness. In this way, single neurons are interconnected into coherent population and integrated into systems that enable local regions to participate of dynamic events providing the functional bases for consciousness.

A prerequisite for the emergence of consciousness is also that the thalamocortical connections have developed (Kostovic and Judas, 2010). The neurons from the sensory organs (except olfaction) terminate in the subplate of the cortex before about 25 weeks of gestational age. The subplate may be up to four times thicker than the cortical plate and serves as a waiting zone and a guidance hub for the afferents from the thalamus and other areas of the brain. After that the ingrowth of thalamocortical axons in the somatosensory, auditory, visual, and frontal cortex commences. However, most of the corticocortical neuronal circuits develop later during infancy. In summary, the development of connections between the thalamus and the cortex as early as 25 weeks of gestation creates the structural substrate for various sensory experiences in the newborn.

The immature brain circuitries are reflected by the pattern of the EEG. This has been found to be discontinuous in preterm infants interrupted by so called spontaneous activity transients (SATs) or spindle bursts, which can be observed at about 23 to 24 weeks of gestation (Vanhatalo and Kaila, 2006). They may be generated by immature neurons establishing their connectivity. This is also reflected by the patterns of the somatosensory evoked potentials (Vanhatalo and Lauronen, 2006). With the emergence of consciousness, the characteristic activity pattern of the EEG during wakefulness is generated by the corticothalamic system. In addition, groups of cells in the brainstem and hypothalamus provide neuromodulatory input to the cortex that promotes arousal (Deco et al., 2014).

Spontaneous resting state activity

Even without any task performance there is a low frequency spontaneous intrinsic brain activity called the resting state activity. It generates patterns of functional connectivity involving different regions of the brain exhibiting a spatial organization into functional networks very well described in adults. Resting-state networks have also been found in the foetal brain (Schöpf et al., 2012), the preterm infants at term age (Fransson et al., 2007), and full-term infants soon after birth (Fransson et al., 2009). Thus, the newborn brain cannot be regarded as a blank slate as previously believed.

The topology of structural and functional networks change throughout development driving behaviour which in turn can change pattern of connectivity modulating future behaviour (Byrge et al., 2014). In this way, consciousness as the waking state, as experience, and as mind is not a static product but an evolving characteristic. An atypical organization of functional networks and its extension into the world is related with many developmental disorders (Byrge et al., 2014). For example, an atypical neural representation of the self is a key mechanism of both self-referential and social impairments in autism (Lombardo et al., 2010).

Default mode network

The default mode network, a set of regions that participate in internal modes of cognition, may subserve the mechanisms for maintaining and promoting consciousness (Demertzi et al., 2014). This network shows specific connectivity changes as the level of consciousness diminishes, thus connectivity strength could be an indicator of the level of consciousness under different conditions (Vanhaudenhuyse et al., 2010).

In infants, the default mode network shows a temporal evolution with an immature and incomplete network in neonates (Fransson et al., 2009; Doria et al., 2010), and a more complex and intensively connected network at one year of life. By two years, the default mode network shows similar structural characteristics as the adult network. Despite the different structures composing the default mode network during infancy, the posterior cingulate cortex/retrosplenial represents one of the main hubs of the default mode network as in adults (Gao et al., 2009). Indeed, the posterior cingulate cortex supports a central role in the development of functional brain networks already during foetal life when negative correlations between this structure and other parts of the brain become more negative with advancing gestational age (Thomason et al., 2014). Such negative correlations are absent in the anesthetized brain and are a genuine characteristic in the awake brain (Barttfeld et al., 2015).

It has been proposed that the structural organization of the default mode network may predate its functional specialization (Gao et al., 2009), even though the temporal and spatial evolution of the default mode network seems to be correlated with the evolving trajectory of self-consciousness in infants before two years of life.

Psychological criteria of consciousness

Sensory awareness is a crucial component of consciousness (Koch, 2004) which is also amenable to investigate even in the infant. This involves the ability to be awake and aware of visual, auditory, olfactory, and sensory factors including painful impressions. Other important components are memory and social communication. All these criteria can be mimicked by a virtual baby (Cotterill, 2003). To achieve consciousness a subjective component is also required. Emotional feelings like joy (Kringelbach and Berridge, 2012), love, hatred, and sadness are also important components of consciousness.

Awakefulness

A common-sense definition of consciousness, according to John Searle, is those states of sentience and awareness that typically begin when we awake from a dreamless sleep and continue until we go to sleep again, or fall into coma or die or otherwise become “unconscious” (Searle, 2000). With this definition the foetus and the preterm infant born before 24 weeks are never conscious, although the foetus and newborn infant...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Acknowledgments
• List of contributors
• Introduction: exploring a speechless world
• Part I
• Part II
• Part III
• Conclusion
• Index