Déjà vu and involuntary autobiographical memories (IAM) can be induced by intracranial electric brain stimulation in epileptic patients, sometimes in the same individual. We suggest that there may be different types of IAM which should be taken into account and provide several ideas to test the hypothesis of a continuity between IAM and déjà vu phenomena.

Libet demonstrated that a substantial duration (>0.5-1.0 s) of direct electrical stimulation of the surface of a sensory cortex at a threshold or liminal current is required before a subject can experience a percept. Libet and his co-workers originally proposed that the result could be due either to spatial and temporal facilitation of the underlying neurons or additionally to a prolonged central processing time. However, over the next four decades, Libet chose to attribute the prolonged latency for evoking conscious (...) experience to a prolonged central processing time. In my view, Libet has not provided any convincing evidence, either on the basis of his own past work or in his critique of my paper, for his hypothesis of a central processing time exceeding 0.5s before conscious experience emerges following direct electrical threshold stimulation of the cortical surface. I stand by my original results and conclusion that such prolonged latencies are largely the consequence of a dynamically increasing cortical facilitatory process that begins hundreds of milliseconds before there is a sustained neuronal activation. In some cases, the facilitatory process must overcome an initial stimulus-induced inhibition before neuronal firing commences. (shrink)

People suffering from Obsessive-Compulsive Disorder (OCD) do things they do not want to do, and/or they think things they do not want to think. In about 10 percent of OCD patients, none of the available treatment options is effective. A small group of these patients is currently being treated with deep brain stimulation (DBS). Deep brain stimulation involves the implantation of electrodes in the brain. These electrodes give a continuous electrical pulse to the brain (...) area in which they are implanted. It turns out that patients may experience profound changes as a result of DBS treatment. It is not just the symptoms that change; patients rather seem to experience a different way of being in the world. These global effects are insufficiently captured by traditional psychiatric scales, which mainly consist of behavioural measures of the severity of the symptoms. In this article we aim to capture the changes in the patients’ phenomenology and make sense of the broad range of changes they report. For that we introduce an enactive, affordance-based model that fleshes out the dynamic interactions between person and world in four aspects. The first aspect is the patients’ experience of the world. We propose to specify the patients’ world in terms of a field of affordances, with the three dimensions of broadness of scope (‘width’ of the field), temporal horizon (‘depth’), and relevance of the perceived affordances (‘height’). The second aspect is the person-side of the interaction, that is, the patients’ self-experience, notably their moods and feelings. Thirdly, we point to the different characteristics of the way in which patients relate to the world. And lastly, the existential stance refers to the stance that patients take towards the changes they experience: the second-order evaluative relation to their interactions and themselves. With our model we intend to specify the notion of being in the world in order to do justice to the phenomenological effects of DBS treatment. (shrink)

Libet discovered that a substantial duration (> 0.5-1.0 s) of direct electrical stimulation of the surface of the somatosensory cortex at threshold currents is required before human subjects can report that a conscious somatosensory experience had occurred. Using a reaction time method we confirm that a similarly long stimulation duration at threshold currents is required for activation of elementary visual experiences (phosphenes) in human subjects following stimulation of the surface of the striate cortex. However, the reaction times (...) for the subject to respond to the cessation of the visual experience after the end of electrical stimulation could be as brief as 225-242 ms. We also carried out extensive studies in cats under a variety of anesthetic conditions using the same electrodes and parameters of stimulation employed in the human studies to study the patterns of neuronal activity beneath the stimulating surface electrode. Whereas sufficiently strong currents can activate neurons within milliseconds, stimulating currents close to threshold activate sustained neural activity only after at least 350-500 ms. When currents are close to threshold, some neurons are inhibited for several hundreds of millisecond before the balance between inhibition and excitation shifts towards excitation. These results suggest that the prolonged latencies, i.e., latencies beyond 200-250 ms, for the emergence of conscious experience following direct cortical stimulation result from a delay in the sustained activation of underlying cortical neurons at threshold currents rather than being due to any unusually long duration in central processing time. Intracellular records from cortical neurological cells during repetitive electrical stimulation of the surface of the feline striate cortex demonstrate that such stimulation induces a profound depolarizing shift in membrane potential that may persist after each stimulus train. Such a depolarization is evidence that extracellular K+ concentrations have increased during electrical stimulation. Such an increase in extracellular K+ progressively increases cortical excitability until the threshold for sustained activation of cortical neurons is reached and then exceeded. Consequently, the long latency for threshold activation of cortical neurons depends upon a dynamically increasing cortical facilatory process that begins hundreds of milliseconds before there is sustained activation of such neurons. In some cases, this facilatory process must overcome an initial stimulus-induced inhibition before neuronal firing commences. (shrink)

Deep brain stimulation (DBS) of the globus pallidus interna and subthalamic nucleus has restored some degree of motor control in many patients in advanced stages of Parkinson’s disease. DBS has also been used to treat dystonia, essential tremor (progressive neurological condition causing trembling), chronic pain, obsessive-compulsive disorder, Tourette’s syndrome, major depressive disorder, obesity, cerebral palsy, and the minimally conscious state. Although the underlying mechanisms of the technique are still not clear, DBS can modulate underactive or overactive neural circuits (...) and restore disrupted communication between and among groups of neurons in interacting regions of the brain. This can control and relieve many symptoms associated with a range of neurological and psychiatric disorders.But the procedures of implanting and stimulating the electrodes are brain-invasive and entail significant risks. Some patients receiving DBS have experienced intracerebral hemorrhage, infection, cognitive disturbances such as impulsive behavior, and affective disturbances such as mania. It is not known whether continuous electrical stimulation of the brain would reshape synaptic connectivity and permanently alter neural circuits in ways that may not be salutary. The risk of these effects indicates that DBS should be used only when a patient’s condition is refractory to all other interventions and when there is a high probability that the technique will benefit the patient and improve his or her quality of life. If a patient’s quality of life is poor and all other treatment options have been exhausted, then the likelihood of benefit can justify physicians’ exposing patients to some risk. The clinical and ethical significance of the risk in DBS underscores the obligation of physicians to obtain fully informed consent from patients undergoing the procedure. (shrink)

Deep Brain Stimulation (DBS) is an invasive therapeutic method involving the implantation of electrodes and the electrical stimulation of specific areas of the brain to modulate their activity. DBS brings therapeutic benefits, but can also have adverse side effects. Recently, neuroethicists have recognized that DBS poses a threat to the very fabric of human existence, namely, to the selves of patients. This article provides a review of the neuroethical literature examining this issue, and identifies the crucial (...) dimensions related to the self which DBS may endanger—personal identity, authenticity, and autonomy. The most influential theories accounting for these dimensions are analyzed herein, and it is argued that most of these theories require further refinement. This paper also demonstrates the interrelation between personal identity, authenticity, and autonomy, and concludes that one can only fully understand the impact of DBS on the self when all of these factors are taken into account. (shrink)

Despite technological and interpretative advances, the non-invasive modalities used for pre-surgical evaluation of patients with drug-resistant epilepsy, fail to generate a concordant anatomo-electroclinical hypothesis for the location of the seizure onset zone in many patients. This requires chronic monitoring with intracranial electroencephalography, which facilitates better localization of the seizure onset zone, and allows evaluation of the functional significance of cortical regions-of-interest by electrical stimulation mapping. There are two principal modalities for intracranial EEG, namely subdural electrodes and stereotactic depth electrodes. (...) Although ESM is considered the gold standard for functional mapping with subdural electrodes, there have been concerns about its utility with stereo-EEG. This is mainly because subdural electrodes allow contiguous sampling of the dorsolateral convexity of cerebral hemispheres, and permit delineation of the extent of eloquent functional areas on the cortical surface. Stereo-EEG, while having relatively sparse sampling on the cortical surface, offers the ability to access the depth of sulci, mesial and basal surfaces of cerebral hemispheres, and deep structures such as the insula, which are largely inaccessible to subdural electrodes. As stereo-EEG is increasingly the preferred modality for intracranial monitoring, we find it opportune to summarize the literature for ESM with stereo-EEG in this narrative review. Emerging evidence shows that ESM for defining functional neuroanatomy is feasible with stereo-EEG, but probably requires a different approach for interpretation and clinical decision making compared to ESM with subdural electrodes. We have also compared ESM with stereo-EEG and subdural electrodes, for current thresholds required to evoke desired functional responses vs. unwanted after-discharges. In this regard, there is preliminary evidence that ESM with stereo-EEG may be safer than ESM with subdural grids. Finally, we have highlighted important unanswered clinical and scientific questions for ESM with stereo-EEG in the hope to encourage future research and collaborative efforts. (shrink)

Deep brain stimulation is a clinical intervention for the treatment of movement disorders. It has also been applied to the treatment of psychiatric disorders such as depression, anorexia nervosa, obsessive-compulsive disorder, and schizophrenia. Psychiatric disorders including schizophrenia, bipolar disorder, and major depression can lead to psychosis, which can cause patients to lose touch with reality. The ventral tegmental area, located near the midline of the midbrain, is an important region involved in psychosis. However, the clinical application of electrical (...) stimulation of the VTA to treat psychotic diseases has been limited, and related mechanisms have not been thoroughly studied. In the present study, hyperlocomotion and stereotyped behaviors of the mice were employed to mimic and evaluate the positive-psychotic-like behaviors. We attempted to treat positive psychotic-like behaviors by electrically stimulating the VTA in mice and exploring the neural mechanisms behind behavioral effects. Local field potential recording and in vivo fiber photometry to observe the behavioral effects and changes in neural activities caused by DBS in the VTA of mice. Optogenetic techniques were used to verify the neural mechanisms underlying the behavioral effects induced by DBS. Our results showed that electrical stimulation of the VTA activates local gamma-aminobutyric acid neurons, and dopamine neurons, reduces hyperlocomotion, and relieves stereotyped behaviors induced by MK-801 injection. The results of optogenetic manipulation showed that the activation of the VTA GABA neurons, but not DA neurons, is involved in the alleviation of hyperlocomotion and stereotyped behaviors. We visualized changes in the activity of specific types in specific brain areas induced by DBS, and explored the neural mechanism of DBS in alleviating positive psychotic-like behaviors. This preclinical study not only proposes new technical means of exploring the mechanism of DBS, but also provides experimental justification for the clinical treatment of psychotic diseases by electrical stimulation of the VTA. (shrink)

Precision targeting of specific white matter bundles that traverse the subcallosal cingulate has been linked to efficacy of deep brain stimulation for treatment resistant depression. Methods to confirm optimal target engagement in this heterogenous region are now critical to establish an objective treatment protocol. As yet unexamined are the time-frequency features of the SCC evoked potential, including spectral power and phase-clustering. We examined these spectral features—evoked power and phase clustering—in a sample of TRD patients with implanted SCC stimulators. (...) Electroencephalogram was recorded during wakeful rest. Location of electrical stimulation in the SCC target region was the experimental manipulation. EEG was analyzed at the surface level with an average reference for a cluster of frontal sensors and at a time window identified by prior study. Morlet wavelets generated indices of evoked power and inter-trial phase clustering. Enhanced phase clustering at theta frequency was observed in every subject and was significantly correlated with SCC-EP magnitude, but only during left SCC stimulation. Stimulation to dorsal SCC evinced stronger phase clustering than ventral SCC. There was a weak correlation between phase clustering and white matter density. An increase in evoked delta power was also coincident with SCC-EP, but was less consistent across participants. DBS evoked time-frequency features index mm-scale changes to the location of stimulation in the SCC target region and correlate with structural characteristics implicated in treatment optimization. Results also imply a shared generative mechanism between evoked potentials evinced by electrical stimulation and evoked potentials evinced by auditory/visual stimuli and behavioral tasks. Understanding how current injection impacts downstream cortical activity is essential to building new technologies that adapt treatment parameters to individual differences in neurophysiology. (shrink)

Non‐invasive brain stimulation is used to modulate brain excitation and inhibition and to improve cognitive functioning. The effectiveness of the enhancement due to transcranial direct current stimulation (tDCS) is still controversial, but the technique seems to have large potential for improvement and more specific applications. In particular, it has recently been used by athletes, both beginners and professionals. This paper analyses the ethical issues related to tDCS enhancement, which depend on its specific features: ease of use, (...) immediate effect, non‐detectability and great variability of effects. If tDCS were to become widespread, there could be some potential side effects, especially the rise of inequality in many selective competitive contexts. I discuss two possible scenarios to counter this effect: that of prohibition and that of compensation, each supported by reasons and arguments that seem plausible and worthy of consideration. In conclusion, I show why I think the scenario of compensation is the preferable one. (shrink)

A central debate in philosophy and neuroscience pertains to whether PFC activity plays an essential role in the neural basis of consciousness. Neuroimaging and electrophysiology studies have revealed that the contents of conscious perceptual experience can be successfully decoded from PFC activity, but these findings might be confounded by post- perceptual cognitive processes, such as thinking, reasoning, and decision-making, that are not necessary for con- sciousness. To clarify the involvement of the PFC in consciousness, we present a synthesis of research (...) that has used intracranial electrical stimulation (iES) for the causal modulation of neural activity in the human PFC. This research provides compelling evidence that iES of only certain prefrontal regions (i.e., orbitofrontal cortex and anterior cingu- late cortex) reliably perturbs conscious experience. Conversely, stimulation of anterolateral prefrontal sites, often con- sidered crucial in higher-order and global workspace theories of consciousness, seldom elicits any reportable alterations in consciousness. Furthermore, the wide variety of iES-elicited effects in the PFC (e.g., emotions, thoughts, and olfactory and visual hallucinations) exhibits no clear relation to the immediate environment. Therefore, there is no evidence for the kinds of alterations in ongoing perceptual experience that would be predicted by higher-order or global workspace theories. Nevertheless, effects in the orbitofrontal and anterior cingulate cortices suggest a specific role for these PFC subregions in supporting emotional aspects of conscious experience. Overall, this evidence presents a challenge for higher-order and global workspace theories, which commonly point to the PFC as the basis for con- scious perception based on correlative and possibly confounded information. (shrink)

Cranial electrical stimulation has been applied at various current levels in both adults and children with neurological conditions with seemingly promising but somewhat inconsistent results. Stimulation-induced spatial electric fields within a specific brain region are likely a significant contributing factor for the biological effects. Although several simulation models have been used to predict EF distributions in the brain, these models actually have not been validated by in vivo CES-induced EF measurements in the live human brain. (...) This study directly measured the CES-induced voltage changes with implanted stereotactic-electroencephalographic electrodes in twenty-one epilepsy participants and then compared these measured values with the simulated ones obtained from the personalized models. In addition, we further investigated the influence of stimulation frequency, intensity, electrode montage and age on EFs in parts of participants. We found both measured voltages and EFs obtained in vivo are highly correlated with the predicted ones in our cohort. In white matter and gray matter, the measured voltages linearly increased when the stimulation intensity increased from 5 to 500 μA but showed no significant changes with changing stimulation frequency from 0.5 to 200 Hz. Electrode montage, but not age, significantly affects the distribution of the EFs. Our in vivo measurements demonstrate that the individualized simulation model can reliably predict the CES-induced EFs in both adults and children. It also confirms that the CES-induced EFs highly depend on the electrode montages and individual anatomical features. (shrink)

The use of transcranial Electrical Stimulation in the modulation of cognitive brain functions to improve neuropsychiatric conditions has extensively increased over the decades. tES techniques have also raised new challenges associated with study design, stimulation protocol, functional specificity, and dose-response relationship. In this paper, we addressed challenges through the emerging methodology to investigate the dose-response relationship of High Definition-transcranial Direct Current Stimulation, identifying the role of negative valence in tinnitus perception. In light of the neurofunctional testable (...) framework and tES application, hypotheses were formulated to measure clinical and surrogate endpoints. We posited that conscious pairing adequately pleasant stimuli with tinnitus perception results in correction of the loudness misperception and would be reinforced by concurrent active HD-tDCS on the left Dorsolateral Prefrontal Cortex. The dose-response relationship between HD-tDCS specificity and the loudness perception is also modeled. We conducted a double-blind, randomized crossover pilot study with six recruited tinnitus patients. Accrued data was utilized to design a well-controlled adaptive seamless Bayesian dose-response study. The sample size and optimum interims were anticipated for adaptive decision-making about efficacy, safety, and single session dose parameters. Furthermore, preliminary pilot study results were sufficient to show a significant difference within the longitudinally detected self-report tinnitus loudness between before and under positive emotion induction. This study demonstrated a research methodology used to improve emotion regulation in tinnitus patients. In the projected method, positive emotion induction is essential for promoting functional targeting under HD-tDCS anatomical specificity to indicate the efficacy and facilitate the dose-finding process. The continuous updating of prior knowledge about efficacy and dose during the exploratory stage adapts the anticipated dose-response model. Consequently, the effective dose range to make superiority neuromodulation in correcting loudness misperception of tinnitus will be redefined. Highly effective dose adapts the study to a standard randomized trial and transforms it into the confirmatory stage in which active HD-tDCS protocol is compared with a sham trial. Establishing the HD-tDCS intervention protocols relying on this novel method provides reliable evidence for regulatory agencies to approve or reject the efficacy and safety. Furthermore, this paper supports a technical report for designing multimodality data-driven complementary investigations in emotion regulation, including EEG-driven neuro markers, Stroop-driven attention biases, and neuroimaging-driven brain network dynamics. (shrink)

Enhancing brain activity and function is a very ancient practice which is usually accomplished by taking illegal drugs. Prescription medication is becoming more commonly used as a means of enhancing mood, and recently, it has become possible to modulate mood by applying magnetic or electrical current to the brain or by training the brain to work at predetermined oscillations. A summary of the available neuromodulation techniques will be presented associated with data from human subjects implanted with cortical (...) and/or subcutaneous electrodes that demonstrate the potential for electrical neuro-enhancement. (shrink)

Direct electrical stimulation has been widely applied in both guidance of lesion resection and scientific research; however, the design and selection of intraoperative cognitive mapping tasks have not been updated in a very long time. We introduce updated mapping tasks for language and non-language functions and provide recommendations for optimal design and selection of intraoperative mapping tasks. In addition, with DES becoming more critical in current neuroscientific research, a task design that has not been widely used in DES yet (...) was introduced for more delicate mapping of brain functions especially for research purposes. We also illustrate the importance of designing a common task series for DES and other non-invasive mapping techniques. This review gives practical updated guidelines for advanced application of DES in clinical and neuroscientific research. (shrink)

This paper proposed a novel tactile-stimuli P300 paradigm for Brain-Computer Interface, which potentially targeted at people with less learning ability or difficulty in maintaining attention. The new paradigm using only two types of stimuli was designed, and different targets were distinguished by frequency and spatial information. The classification algorithm was developed by introducing filters for frequency bands selection and conducting optimization with common spatial pattern on the tactile evoked EEG signals. It features a combination of spatial and frequency information, (...) with the spatial information distinguishing the sites of stimuli and frequency information identifying target stimuli and disturbances. We investigated both electrical stimuli and vibration stimuli, in which only one target site was stimulated in each block. The results demonstrated an average accuracy of 94.88% for electrical stimuli and 95.21% for vibration stimuli, respectively. (shrink)

Due to the individual differences controlling brain-computer interfaces, the applicability and accuracy of BCIs based on motor imagery are limited. To improve the performance of BCIs, this article examined the effect of transcranial electrical stimulation on brain activity during MI. This article designed an experimental paradigm that combines tES and MI and examined the effects of tES based on the measurements of electroencephalogram features in MI processing, including the power spectral density and dynamic event-related desynchronization. Finally, we (...) investigated the effect of tES on the accuracy of MI classification using linear discriminant analysis. The results showed that the ERD of the μ and β rhythms in the left-hand MI task was enhanced after electrical stimulation with a significant effect in the tDCS group. The average classification accuracy of the transcranial alternating current stimulation group and transcranial direct current stimulation group were improved significantly compared to the pre-and pseudo stimulation groups. These findings indicated that tES can improve the performance and applicability of BCI and that tDCS was a potential approach in regulating brain activity and enhancing valid features during noninvasive MI-BCI processing. (shrink)

In order to make an attempt at grouping the various aspects of brain functional imaging (fMRI, MRS, EEG-MEG, ...) within a coherent frame, we implemented a model consisting of a system of differential equations, that includes: (1) sodium membrane transport, (2) Na/K ATPase, (3) neuronal energy metabolism (i.e. glycolysis, buffering effect of phosphocreatine, and mitochondrial respiration), (4) blood-brain barrier exchanges and (5) brain hemodynamics, all the processes which are involved in the activation of brain areas. We (...) assumed that the correlation between brain activation and metabolism could be due to either changes in the concentrations of ATP and ADP following activation of Na/K ATPase that result from the changes in ion concentrations, or the involvement, in different phases of metabolism, of a second messenger such as calcium. In this article, we show how this type of model enables interpretation of MRS and fMRI published data that were obtained during prolonged stimulations. (shrink)

To preserve postoperative brain function, it is important for neurosurgeons to fully understand the brain's structure, vasculature, and function. Intraoperative high-frequency electrical stimulation during awake craniotomy is the gold standard for mapping the function of the cortices and white matter; however, this method can only map the “focal” functions and cannot monitor large-scale cortical networks in real-time. Recently, an in vivo electrophysiological method using cortico-cortical evoked potentials induced by single-pulse electrical cortical stimulation has been developed in (...) an extraoperative setting. By using the CCEP connectivity pattern intraoperatively, mapping and real-time monitoring of the dorsal language pathway is available. This intraoperative CCEP method also allows for mapping of the frontal aslant tract, another language pathway, and detection of connectivity between the primary and supplementary motor areas in the frontal lobe network. Intraoperative CCEP mapping has also demonstrated connectivity between the frontal and temporal lobes, likely via the ventral language pathway. Establishing intraoperative electrophysiological monitoring is clinically useful for preserving brain function, even under general anesthesia. This CCEP technique demonstrates potential clinical applications for mapping and monitoring large-scale cortical networks. (shrink)

It is hypothesized that repeated, non‐invasive stimulation of the vestibular (balance) system, via a small electrical current to the skin behind the ears, will cause the brain centers that control energy homeostasis to shift the body toward a leaner physique. This is because these centers integrate multiple inputs to, in effect, fix a set‐point for body fat, which though difficult to alter is not immutable. They will interpret repeated stimulation of the parts of the vestibular system that (...) detect acceleration as a state of chronic activity. During such a physiologically challenging time it is preferable, from an energy homeostasis viewpoint, to both utilize fat reserves, and reduce the volume of these reserves and thus the energy cost of carrying them around. Hence, this type of vestibular stimulation could potentially be a therapeutic option for metabolic syndrome disorders such as obesity. This hypothesis is eminently testable via a clinical trial. (shrink)

Deep brain stimulation has been of considerable interest to bioethicists, in large part because of the effects that the intervention can occasionally have on central features of the recipient’s personality. These effects raise questions regarding the philosophical concept of authenticity. In this article, we expand on our earlier work on the concept of authenticity in the context of deep brain stimulation by developing a diachronic, value-based account of authenticity. Our account draws on both existentialist and essentialist (...) approaches to authenticity, and Laura Waddell Ekstrom’s coherentist approach to personal autonomy. In developing our account, we respond to Sven Nyholm and Elizabeth O’Neill’s synchronic approach to authenticity, and explain how the diachronic approach we defend can have practical utility, contrary to Alexandre Erler and Tony Hope’s criticism of autonomy-based approaches to authenticity. Having drawn a distinction between the authenticity of an individual’s traits and the authenticity of that person’s values, we consider how our conception of authenticity applies to the context of anorexia nervosa in comparison to other prominent accounts of authenticity. We conclude with some reflections on the prudential value of authenticity, and by highlighting how the language of authenticity can be invoked to justify covert forms of paternalism that run contrary to the value of individuality that seems to be at the heart of authenticity. (shrink)

Building upon an earlier critique of the Food and Drug Adminstration (FDA) granting of a humanitarian device exemption for deep brain stimulation in treatment-resistant obsessive compulsive disorder, this article considers how we regulate and finance DBS. It suggests that these devices are mosaic in nature: both potentially therapeutic and probative and that their dual roles need to be appreciated to maximize their therapeutic and investigational potential.

One of the topics that often comes up in ethical discussions of deep brain stimulation (DBS) is the question of what impact DBS has, or might have, on the patient’s self. This is often understood as a question of whether DBS poses a “threat” to personal identity, which is typically understood as having to do with psychological and/or narrative continuity over time. In this article, we argue that the discussion of whether DBS is a “threat” to continuity over (...) time is too narrow. There are other questions concerning DBS and the self that are overlooked in discussions exclusively focusing on psychological and/or narrative continuity. For example, it is also important to investigate whether DBS might sometimes have a positive (e.g. a rehabilitating) effect on the patient’s self. To widen the discussion of DBS, so as to make it encompass a broader range of considerations that bear on DBS’s impact on the self, we identify six features of the commonly used concept of a person’s “true self”. We apply these six features to the relation between DBS and the self. And we end with a brief discussion of the role DBS might play in treating otherwise treatment-refractory anorexia nervosa. This further highlights the importance of discussing both continuity over time and the notion of the true self. (shrink)

Ethical evaluation of deep brain stimulation as a treatment for Parkinson’s disease is complicated by results that can be described as involving changes in the patient’s identity. The risk of becoming another person following surgery is alarming for patients, caregivers and clinicians alike. It is one of the most urgent conceptual and ethical problems facing deep brain stimulation in Parkinson’s disease at this time. In our paper we take issue with this problem on two accounts. First, (...) we elucidate what is meant by “becoming another person” from a conceptual point of view. After critically discussing two broad approaches we concentrate on the notion of “individual identity” which centers on the idea of “core attitudes”. Subsequently we discuss several approaches to determine what distinguishes core attitudes from those that are more peripheral. We argue for a “foundational-function model” highlighting the importance of specific dependency relations between these attitudes. Our second aim is to comment on the possibility to empirically measure changes in individual identity and argue that many of the instruments now commonly used in selecting and monitoring DBS-patients are inappropriate for this purpose. Future research in this area is advised combining a conceptual and an empirical approach as a basis of sound ethical appraisal. (shrink)

Cranial electrotherapy stimulation is a neuromodulation tool used for treating several clinical disorders, including insomnia, anxiety, and depression. More recently, a limited number of studies have examined CES for altering affect, physiology, and behavior in healthy, non-clinical samples. The physiological, neurochemical, and metabolic mechanisms underlying CES effects are currently unknown. Computational modeling suggests that electrical current administered with CES at the earlobes can reach cortical and subcortical regions at very low intensities associated with subthreshold neuromodulatory effects, and studies using (...) electroencephalography and functional magnetic resonance imaging show some effects on alpha band EEG activity, and modulation of the default mode network during CES administration. One theory suggests that CES modulates brain stem, limbic, and cortical regions and increases relative parasympathetic to sympathetic drive in the autonomic nervous system. There is no direct evidence supporting this theory, but one of its assumptions is that CES may induce its effects by stimulating afferent projections of the vagus nerve, which provides parasympathetic signals to the cardiorespiratory and digestive systems. In our critical review of studies using CES in clinical and non-clinical populations, we found severe methodological concerns, including potential conflicts of interest, risk of methodological and analytic biases, issues with sham credibility, lack of blinding, and a severe heterogeneity of CES parameters selected and employed across scientists, laboratories, institutions, and studies. These limitations make it difficult to derive consistent or compelling insights from the extant literature, tempering enthusiasm for CES and its potential to alter nervous system activity or behavior in meaningful or reliable ways. The lack of compelling evidence also motivates well-designed and relatively high-powered experiments to assess how CES might modulate the physiological, affective, and cognitive responses to stress. Establishing reliable empirical links between CES administration and human performance is critical for supporting its prospective use during occupational training, operations, or recovery, ensuring reliability and robustness of effects, characterizing if, when, and in whom such effects might arise, and ensuring that any benefits of CES outweigh the risks of adverse events. (shrink)

continent. 1.2 (2011): 76-77. Please click to listen to the mp3 files of deep brain recordings of individual brain cells, the smallest unit of the brain, in a whole, intact living brain. Each brain region’s cells possess an electrical signature. During recordings electrical signals are transformed into sound to facilitate auditory identification of cells during a process called “mapping.” Subthalamic nucleus by continent Cortex by continent Mapping is an important step in successfully identifying and localizing (...) the appropriate target site in the brain for an experimental therapeutic procedure called deep brain stimulation which has been used for patients with movement disorders and, more recently, for patients with psychiatric disorders. Thalamus by continent I have pursued a career as a neuroscientist for the past decade because I wanted to learn about the mind. In my most recent research, I record electrical activity from individual cells in the brain, and look at individual brain cells with a high resolution, electron microscope. Globus Pallidus (internal segment) by continent Globus Pallidus (external segment) by continent The closer I examine the brain, the less I learn about the mind. Rather, what has been most informative about the mind is how people—neuroscientists and non-neuroscientists alike—interpret neuroscience data. Some cognitive neuroscientists have proposed the qualities we hold most precious as humans, like morality and free will, exist only in the context of human interaction. Likewise, I propose that the mind does not exist in a vacuum and one’s mind only necessitates distinction in a social context, and the mind’s existence may only be relevant due to its relative relationships. In sum, bodies have brains. People have minds. Striatum by continent I invite readers to reflect on and/or refute these statements after listening to these recordings of the brain in action. These regions are part of the cortico-basal ganglia-thalamo-cortical circuit, which is thought to possess parallel, functionally segregated loops including a motor-movement circuit and limbic-emotional circuit which work together to generate behavior (e.g. motivated movements) and have been researched for their role in Parkinson’s disease as well as Obsessive Compulsive Disorder. EDITOR'S SUGGESTED RESOURCES Michael Gazzaniga's lecture, “Free Yet Determined and Constrained” at Edinburgh University Gifford Lectures in 19 October, 2009 is an excellent discussion of the field. It can be viewed on Edinburgh University's Youtube channel . The Cognitive Neuroscience of the Mind . Eds. Patricia A. Reuter-Lorenz, Kathleen Baynes, George R. Mangun, and Elizabeth A. Phelps. Cambridge: MIT Press. 2010. Print. (shrink)

The goal of this article is to shed light on Deep Brain Stimulation (DBS) postoperative suicidality risk factors within Treatment Resistant Depression (TRD) patients, in particular by focusing on the ethical concern of enrolling patient with history of self-estrangement, suicide attempts and impulsive–aggressive inclinations. In order to illustrate these ethical issues we report and review a clinical case associated with postoperative feelings of self-estrangement, self-harm behaviours and suicide attempt leading to the removal of DBS devices. Could prospectively identifying (...) and excluding patients with suicidality risk factors from DBS experimental trials—such as history of self-estrangement, suicide attempts and impulsive–aggressive inclinations—lead to minimizing the risk of suicidality harm? (shrink)

In this paper, we engage in dialogue with Jonathan Pugh, Hannah Maslen, and Julian Savulescu about how to best interpret the potential impacts of deep brain stimulation on the self. We consider whether ordinary people’s convictions about the true self should be interpreted in essentialist or existentialist ways. Like Pugh et al., we argue that it is useful to understand the notion of the true self as having both essentialist and existentialist components. We also consider two ideas from (...) existentialist philosophy – Jean-Paul Sartre and Simone de Beauvoir’s ideas about “bad faith” and “ambiguity” – to argue that there can be value to patients in regarding themselves as having a certain amount of freedom to choose what aspects of themselves should be considered representative of their true selves. Lastly, we consider the case of an anorexia nervosa-patient who shifts between conflicting mind-sets. We argue that mind-sets in which it is easier for the patient and his or her family to share values can plausibly be considered to be more representative of the patient’s true self, if this promotes a well-functioning relationship between the patient and the family. However, we also argue that families are well-advised to give patients room to figure out what such shared values mean to them, since it can be alienating for patients if they feel that others try to impose values on them from the outside. (shrink)

Although philosophers have explored several connections between neuroscience and moral responsibility, the issue of how real-world neurological modifications, such as Deep Brain Stimulation, impact moral responsibility has received little attention. In this article, we draw on debates about the relevance of history and manipulation to moral responsibility to argue that certain kinds of neurological modification can diminish the responsibility of the agents so modified. We argue for a historicist position - a version of the history-sensitive reflection view - (...) and defend that account against a rival, relational view of responsibility. We conclude that DBS can, under certain conditions, diminish responsibility, and explore the circumstances under which this might be so. We conclude by suggesting that philosophical debates about moral responsibility, manipulation, and history have greater practical relevance than is sometimes thought, and that attention to practical cases can help inform and deepen this body of scholarship. (shrink)

For about four decades data suggestive of correlations between functional states of two separated brains, not mediated by sensory or other known mechanisms, were reported, but the experimental evidence is still scarce and controversial. In this paper we briefly review studies in which one member of a pair of human subjects was physically stimulated and synchronous correlates were searched for in the brain electrical activity of the other, non-stimulated subject. We give a comprehensive account of our study of dyadic (...) EEG correlations, discussing pros and contras of its design, and we review parallel and follow-up studies on the same topic carried out elsewhere. Possible directions of future research are discussed and novel experimental paradigms are proposed. (shrink)

Traditional rehabilitation strategies become difficult in the chronic phase stage of stroke prognosis. Brain–computer interface combined with external devices may improve motor function in chronic stroke patients, but it lacks comprehensive assessments of neurological changes regarding functional rehabilitation. This study aimed to comprehensively and quantitatively investigate the changes in brain activity induced by BCI–FES training in patients with chronic stroke. We analyzed the EEG of two groups of patients with chronic stroke, one group received functional electrical stimulation (...) rehabilitation training and the other group received BCI combined with FES training. We constructed functional networks in both groups of patients based on direct directed transfer function and assessed the changes in brain activity using graph theory analysis. The results of this study can be summarized as follows: after rehabilitation training, the Fugl–Meyer assessment scale score was significantly improved in the BCI–FES group, and there was no significant difference in the FES group. Both the global and local graph theory measures of the brain network of patients with chronic stroke in the BCI–FES group were improved after rehabilitation training. The node strength in the contralesional hemisphere and central region of patients in the BCI–FES group was significantly higher than that in the FES group after the intervention, and a significant increase in the node strength of C4 in the contralesional sensorimotor cortex region could be observed in the BCI–FES group. These results suggest that BCI–FES rehabilitation training can induce clinically significant improvements in motor function of patients with chronic stroke. It can improve the functional integration and functional separation of brain networks and boost compensatory activity in the contralesional hemisphere to a certain extent. The findings of our study may provide new insights into understanding the plastic changes of brain activity in patients with chronic stroke induced by BCI–FES rehabilitation training. (shrink)

Functional human brain mapping is commonly performed during invasive monitoring with intracranial electroencephalographic electrodes prior to resective surgery for drug­ resistant epilepsy. The current gold standard, electrocortical stimulation mapping, is time ­consuming, sometimes elicits pain, and often induces after discharges or seizures. Moreover, there is a risk of overestimating eloquent areas due to propagation of the effects of stimulation to a broader network of language cortex. Passive iEEG spatial-temporal functional mapping has recently emerged as a potential alternative (...) to ESM. However, investigators have observed less correspondence between STFM and ESM maps of language than between their maps of motor function. We hypothesized that incongruities between ESM and STFM of language function may arise due to propagation of the effects of ESM to cortical areas having strong effective connectivity with the site of stimulation. We evaluated five patients who underwent invasive monitoring for seizure localization, whose language areas were identified using ESM. All patients performed a battery of language tasks during passive iEEG recordings. To estimate the effective connectivity of stimulation sites with a broader network of task-activated cortical sites, we measured cortico-cortical evoked potentials elicited across all recording sites by single-pulse electrical stimulation at sites where ESM was performed at other times. With the combination of high gamma power as well as CCEPs results, we trained a logistic regression model to predict ESM results at individual electrode pairs. The average accuracy of the classifier using both STFM and CCEPs results combined was 87.7%, significantly higher than the one using STFM alone, indicating that the correspondence between STFM and ESM results is greater when effective connectivity between ESM stimulation sites and task-activated sites is taken into consideration. These findings, though based on a small number of subjects to date, provide preliminary support for the hypothesis that incongruities between ESM and STFM may arise in part from propagation of stimulation effects to a broader network of cortical language sites activated by language tasks, and suggest that more studies, with larger numbers of patients, are needed to understand the utility of both mapping techniques in clinical practice. (shrink)

Under the current Mental Health Act of England and Wales, it is lawful to perform deep brain stimulation in the absence of consent and independent approval. We argue against the Care Quality Commission's preferred strategy of addressing this problematic issue, and offer recommendations for deep brain stimulation-specific provisions in a revised Mental Health Act.

Davis called for “extreme caution” in the use of non-invasive brain stimulation to treat neurological disorders in children, due to gaps in scientific knowledge. We are sympathetic to his position. However, we must also address the ethical implications of applying this technology to minors. Compensatory trade-offs associated with NIBS present a challenge to its use in children, insofar as these trade-offs have the effect of limiting the child’s future options. The distinction between treatment and enhancement has some normative (...) force here. As the intervention moves away from being a treatment toward being an enhancement—and thus toward a more uncertain weighing of the benefits, risks, and costs—considerations of the child’s best interests diminish, and the need to protect the child’s autonomy looms larger. NIBS for enhancement involving trade-offs should therefore be delayed, if possible, until the child reaches a state of maturity and can make an informed, personal decision. NIBS for treatment, by contrast, is permissible insofar as it can be shown to be at least as safe and effective as currently approved treatments, which are themselves justified on a best interests standard. (shrink)

This paper discusses the use of deep brain stimulation for the treatment of neurological and psychiatric disorders in children. At present, deep brain stimulation is used to treat movement disorders in children and a few cases of deep brain stimulation for psychiatric disorders in adolescents have been reported. Ethical guidelines on the use of deep brain stimulation in children are therefore urgently needed. This paper focuses on the decision-making process, and provides an (...) ethical framework for (future) treatment decisions in pediatric deep brain stimulation. I defend a shared decision-making model in case of deep brain stimulation for neurological and psychiatric disorders in children. To protect the vulnerable child patient, a dual consent process is needed where parents or parental guardians give their consent, and the child gives his/her assent. (shrink)

Deep brain stimulation (DBS) to different sites allows interfering with dysfunctional network function implicated in major depression. Because a prominent clinical feature of depression is anhedonia--the inability to experience pleasure from previously pleasurable activities--and because there is clear evidence of dysfunctions of the reward system in depression, DBS to the nucleus accumbens might offer a new possibility to target depressive symptomatology in otherwise treatment-resistant depression. Three patients suffering from extremely resistant forms of depression, who did not respond to (...) pharmacotherapy, psychotherapy, and electroconvulsive therapy, were implanted with bilateral DBS electrodes in the nucleus accumbens. Stimulation parameters were modified in a double-blind manner, and clinical ratings were assessed at each modification. Additionally, brain metabolism was assessed 1 week before and 1 week after stimulation onset. Clinical ratings improved in all three patients when the stimulator was on, and worsened in all three patients when the stimulator was turned off. Effects were observable immediately, and no side effects occurred in any of the patients. Using FDG-PET, significant changes in brain metabolism as a function of the stimulation in fronto-striatal networks were observed. No unwanted effects of DBS other than those directly related to the surgical procedure (eg pain at sites of implantation) were observed. Dysfunctions of the reward system--in which the nucleus accumbens is a key structure--are implicated in the neurobiology of major depression and might be responsible for impaired reward processing, as evidenced by the symptom of anhedonia. These preliminary findings suggest that DBS to the nucleus accumbens might be a hypothesis-guided approach for refractory major depression. (shrink)

This paper explores the impacts of neurological intervention on selfhood with reference to recipients’ claims about changes to their self-understanding following Deep Brain Stimulation for treatment of Parkinson’s Disease. In the neuroethics literature, patients’ claims such as: “I don’t feel like myself anymore” and “I feel like a machine”, are often understood as expressing threats to identity. In this paper I argue that framing debates in terms of a possible threat to identity—whether for or against the proposition, is (...) mistaken and occludes what is ethically salient in changes from DBS. Rather, by adopting a relational narrative approach to identity and autonomy, I show that the ethically salient issue from DBS is impacts on autonomous agency—whether one’s actions and beliefs are one’s own, and how DBS may hinder, or foster, embodied, relational autonomy competences. This approach recognizes that if sufficiently significant, impacts on autonomy competences may pose a threat to one’s ability to contribute to the process of authoring one’s own life and so pose a threat to identity formation. I argue this approach resolves the confusion in the literature about whether and how DBS threatens identity and provides a complex picture of how DBS may affect selfhood by disrupting narrative identity formation and revision, distorting agency and/or undermining autonomy. (shrink)

Despite growing evidence that a significant number of patients living with Parkison’s disease experience neuropsychiatric changes following Deep Brain Stimulation treatment, the phenomenon remains poorly understood and largely unexplored in the literature. To shed new light on this phenomenon, we used qualitative methods grounded in phenomenology to conduct in-depth, semi-structured interviews with 17 patients living with Parkinson’s Disease who had undergone DBS. Our study found that patients appear to experience postoperative DBS-induced changes in the form of self-estrangement. Using (...) the insights from patients’ subjective perceptions of postoperative self-change provides a potent explanation of potential DBS-induced self-estrangement. (shrink)