A novel simplistic fabrication technique for cranial epidural electrodes for chronic recording and stimulation in rats.

BACKGROUND: The demand for neuromodulatory and recording tools has resulted in a surge of publications describing techniques for fabricating devices and accessories in-house suitable for neurological recordings. However, many of these fabrication protocols use equipment which are not common to biological laboratories, thus limiting researchers to the use of commercial alternatives. New method:We have developed a simple yet robust implantable stimulating surface electrode which can be fabricated in all wet-bench laboratories. RESULTS: Female Sprague-Dawley rats received epidural implantation of the electrodes over the fore and hind limb areas of their motor cortex. Stimulation of the motor cortex successfully evoked fore- and hind limb motor outputs. The device was also able to record surface potentials of the motor cortex following epidural stimulation of the spinal cord. Comparisons with existing methods:For stimulation of the motor cortex, often stiff stainless or copper wires are roughly tucked underneath the skull, with little accuracy of localization. While, commercially available devices utilize burr holes and screw electrodes. Our new electrode design provides us stereotaxic accuracy that was not previously available. CONCLUSION: We developed a chronic implantable electrode capable of being fabricated in all wet-labs, are robust, versatile and electrically sensitive enough for long-term chronic use. The simple and versatile electrode design provides scientific, economical and ethical benefits.

Neurophysiological studies on atypical parkinsonian syndromes.

There have been a relatively large number of experimental investigations using neurophysiological techniques in patients with atypical parkinsonian syndromes (APs), including progressive supranuclear palsy, cortico-basal syndrome and multiple system atrophy. Earlier studies focused on the startle, blink and trigemino-cervical reflexes and showed several brainstem abnormalities. Studies using transcranial magnetic stimulation have revealed a number of abnormalities in primary motor cortex and inter-hemispheric connectivity. More recent studies have highlighted the role of cerebellar dysfunction and have reported altered movement kinematics. Neurophysiological abnormalities in APs reflect degeneration or functional changes at multiple brain levels. In the majority of cases, APs share common abnormalities even though some neurophysiological changes differ among the various APs. Evidence of a correlation between neurophysiological abnormalities and clinical signs and symptoms in APs is limited. This paper provides an update on the results of experimental investigations using neurophysiological techniques in APs and also reviews similarities and differences between APs and Parkinson's disease. The potential role of neurophysiological abnormalities in the clinical context of APs is also discussed.

Neurocognitive dysfunction in children with ß thalassemia major: psychometric, neurophysiologic and radiologic evaluation.

OBJECTIVE: To evaluate the impact of iron chelating drugs and serum ferritin on the neurocognitive functions of patients with ß thalassemia major (ß-TM), using psychometric, neurophysiologic and radiologic tests. METHODS: Eighty children with ß-TM were enrolled into the study and were compared to 40 healthy controls. All participants were evaluated by measuring serum ferritin, neurocognitive assessment by Benton Visual Retention Test, Wechsler Intelligence Scale for Children, Wisconsin Card Sort Test, P300 and magnetic resonance spectroscopy (MRS). RESULTS: WISC in our study showed that 40% of cases were borderline mental function as regards total IQ. Neurophysiologic tests were significantly impaired in patients compared to control group, with significant impairment in those receiving desferrioxamine (DFO). P300 amplitude was significantly lower in cases compared to controls (2.24 and 4.66 uv, respectively), recording the shortest amplitude in patients receiving DFO. Altered metabolic markers in the brain were detected by MRS in the form of reduced N-acetylaspartate to creatine ratio in 78.3% of our cases. There were significant correlations between psychometric tests and both neurophysiologic (P300) and radiologic (MRS) tests. CONCLUSION: ß-TM is associated with neurocognitive impairment that can be assessed by psychometric, neurophysiologic and radiologic tests. The role of hemosiderosis and iron chelation therapy on cognitive functioning still need more research. ABBREVIATIONS: ß-TM: beta thalassemia major; DFO: Dysferal; DFP: Deferiprone; DFX: Deferasirox; WISC: Wechsler Intelligence Scale for Children; VIQ: verbal IQ; PIQ: performance IQ; TIQ: total IQ; BVRT: Benton Visual Retention Test; WCST: Wisconsin Card Sort Test; MRS: Magnetic resonant spectroscopy; NAA/Cr ratio: N-acetylaspartate to creatine ratio.

Terapia autógena: técnicas, fundamentos, aplicaciones en la salud y clínica y apoyo empírico / Autogenic therapy: techniques, foundations, health and clinical applications, and empirical support

La terapia autógena se origina en el entrenamiento autógeno de Schultz y en su desarrollo incorpora diferentes métodos terapéuticos de orientación psicofisiológica creados para promover procesos cerebrales homeostáticos autorregulatorios. Los objetivos de este artículo son describir y analizar los diferentes métodos autógenos, los procesos psicofisiológicos y neurofisiológicos implicados y sus aplicaciones eficaces en la salud y la clínica. Para ello, además de revisar los primeros trabajos de Schultz y Luthe, se ha hecho una búsqueda electrónica de estudios para encontrar contribuciones relevantes sobre estos temas. Los resultados muestran un gran desarrollo de los métodos autógenos hasta los años 80, con una ingente cantidad de aplicaciones y estudios sobre los cambios psicofisiológicos y neurofisiológicos concomitantes. Sin embargo, su expansión durante los últimos 25 años ha sido mucho menor en comparación con métodos como el mindfulness o la hipnosis. Se discuten posibles causas y se plantean retos futuros para la terapia autógena

Autogenic therapy emerges from the "autogenic training" method created by Schultz, and its development incorporates different therapeutic methods based on a psychophysiological approach. All these methods promote homeostatic self-regulatory brain processes. The aims of this paper are to describe and analyse the autogenic methods, the psychophysiological and neurophysiological processes involved, and their effective applications in both health and clinical fields. For these purposes, beside reviewing the earlier work by Schultz and Luthe, an electronic search of literature was conducted in order to find relevant contributions on these topics. Results show a big development of autogenic methods until the 80s, with an enormous amount of applications and studies on the psychophysiological and neurophysiological changes related to the practice of autogenic training. However, their expansion during the last 25 years has been much lower in comparison with other methods such as mindfulness and hypnosis. Possible causes are discussed and new challenges are suggested

Anorgasmia masculina como síntoma inicial de mielitis transversa / Male anorgasmia as initial symptom of transverse myelitis

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Predicting Mental Imagery-Based BCI Performance from Personality, Cognitive Profile and Neurophysiological Patterns.

Mental-Imagery based Brain-Computer Interfaces (MI-BCIs) allow their users to send commands to a computer using their brain-activity alone (typically measured by ElectroEncephaloGraphy-EEG), which is processed while they perform specific mental tasks. While very promising, MI-BCIs remain barely used outside laboratories because of the difficulty encountered by users to control them. Indeed, although some users obtain good control performances after training, a substantial proportion remains unable to reliably control an MI-BCI. This huge variability in user-performance led the community to look for predictors of MI-BCI control ability. However, these predictors were only explored for motor-imagery based BCIs, and mostly for a single training session per subject. In this study, 18 participants were instructed to learn to control an EEG-based MI-BCI by performing 3 MI-tasks, 2 of which were non-motor tasks, across 6 training sessions, on 6 different days. Relationships between the participants' BCI control performances and their personality, cognitive profile and neurophysiological markers were explored. While no relevant relationships with neurophysiological markers were found, strong correlations between MI-BCI performances and mental-rotation scores (reflecting spatial abilities) were revealed. Also, a predictive model of MI-BCI performance based on psychometric questionnaire scores was proposed. A leave-one-subject-out cross validation process revealed the stability and reliability of this model: it enabled to predict participants' performance with a mean error of less than 3 points. This study determined how users' profiles impact their MI-BCI control ability and thus clears the way for designing novel MI-BCI training protocols, adapted to the profile of each user.

Measurement of Neurophysiological Signals of Ignoring and Attending Processes in Attention Control.

Attention control is the ability to selectively attend to some sensory signals while ignoring others. This ability is thought to involve two processes: enhancement of sensory signals that are to be attended and the attenuation of sensory signals that are to be ignored. The overall strength of attentional modulation is often measured by comparing the amplitude of a sensory neural response to an external input when attended versus when ignored. This method is robust for detecting attentional modulation, but precludes the ability to assess the separate dynamics of attending and ignoring processes. Here, we describe methodology to measure independently the neurophysiological signals of attending and ignoring using the intermodal attention task (IMAT). This task, when combined with electroencephalography, isolates neurophysiological sensory responses in auditory and visual modalities, when either attending or ignoring, with respect to a passive control. As a result, independent dynamics of attending and of a ignoring can be assessed in either modality. Our results using this task indicate that the timing and cortical sources of attending and ignoring effects differ, as do their contributions to the attention modulation effect, pointing to unique neural trajectories and demonstrating sample utility of measuring them separately.

Sustratos psiconeurobiológicos de la meditación y la conciencia plena / Neuropsychological substrates for mindfulness and meditation

El presente estudio se propone contribuir a esclarecer en el momento actual los sustratos neurales y psicofisiológicos subyacentes a la meditación y la conciencia plena o mindfulness con arreglo a la mejor información científica disponible de calidad. El trabajo es una revisión narrativa, no sistemática, de tipo cualitativo, basada principalmente en una búsqueda en PubMed e ISI Web of Knowledge hasta final de 2013. El conocimiento de los efectos de la meditación en la fisiología del cerebro es aún limitado, pero hay pruebas de que afecta a la función del sistema nervioso central y autónomo, activa las estructuras neuronales involucradas en la atención y regula las emociones. La práctica meditativa se asocia con cambios en la neuroplasticidad de la corteza cingulada anterior, ínsula, unión temporoparietal, red neuronal frontolímbica y otras, cambios que pueden operar en conjunto estableciendo una mayor autorregulación. La conciencia plena proporciona una metacognición emocional más adaptativa y mejores índices fisiológicos de regulación autonómica. Especialmente en el largo plazo, los meditadores detentan diferencias estructurales en la materia cerebral gris y blanca debidas a la plasticidad neuronal (AU)

This study intends to help elucidate the current psycho-physiological and neural basis underlying meditation and mindfulness, according to the best good-quality available scientific information. The work is a qualitative, non-systematic, narrative review, which is mainly based on the search in PubMed and ISI Web of Knowledge until the end of 2013. Knowledge of the effects of meditation on the brain physiology is limited, but there is evidence showing that it affects the function of the autonomous and central nervous system, activates the neuronal cells involved in attention, and regulates emotions. Meditative practice is associated with changes in the neuroplasticity of the anterior cingulate cortex, insula, temporoparietal junction, frontolimbic neural networks, and others. These changes can work together to produce better self-regulation. Mindfulness provides more adaptive emotional metacognition and better physiological rates of self-regulation. Meditators show structural differences in grey and white brain matter due to neuronal plasticity, particularly in the long term (AU)

Arousal vs. relaxation: a comparison of the neurophysiological and cognitive correlates of Vajrayana and Theravada meditative practices.

Based on evidence of parasympathetic activation, early studies defined meditation as a relaxation response. Later research attempted to categorize meditation as either involving focused or distributed attentional systems. Neither of these hypotheses received strong empirical support, and most of the studies investigated Theravada style meditative practices. In this study, we compared neurophysiological (EEG, EKG) and cognitive correlates of meditative practices that are thought to utilize either focused or distributed attention, from both Theravada and Vajrayana traditions. The results of Study 1 show that both focused (Shamatha) and distributed (Vipassana) attention meditations of the Theravada tradition produced enhanced parasympathetic activation indicative of a relaxation response. In contrast, both focused (Deity) and distributed (Rig-pa) meditations of the Vajrayana tradition produced sympathetic activation, indicative of arousal. Additionally, the results of Study 2 demonstrated an immediate dramatic increase in performance on cognitive tasks following only Vajrayana styles of meditation, indicating enhanced phasic alertness due to arousal. Furthermore, our EEG results showed qualitatively different patterns of activation between Theravada and Vajrayana meditations, albeit highly similar activity between meditations within the same tradition. In conclusion, consistent with Tibetan scriptures that described Shamatha and Vipassana techniques as those that calm and relax the mind, and Vajrayana techniques as those that require 'an awake quality' of the mind, we show that Theravada and Vajrayana meditations are based on different neurophysiological mechanisms, which give rise to either a relaxation or arousal response. Hence, it may be more appropriate to categorize meditations in terms of relaxation vs. arousal, whereas classification methods that rely on the focused vs. distributed attention dichotomy may need to be reexamined.

Craneotomía en el paciente consciente. Consideraciones en situaciones especiales / Awake craniotomy. Considerations in special situations

La craneotomía con el paciente despierto es un procedimiento ancestral, que vuelve a estar de actualidad. Confinada durante mucho tiempo a la cirugía de la epilepsia, sus indicaciones se han ampliado, siendo una técnica ampliamente reconocida para la resección de lesiones próximas a regiones corticales fundamentales, y en neurocirugía funcional. Es un procedimiento seguro, que además de proporcionar excelentes resultados, ahorra dinero y recursos. El anestesiólogo ha de estar familiarizado con los fundamentos de la neuroanestesia, conocer la técnica concreta de infiltración, así como los protocolos de sedación, y manejarse cómodamente con la vía aérea. El objetivo principal es que el paciente colabore en los momentos en que el cirujano lo precise (anestesia basada en la analgesia). Esta revisión pretende sintetizar lo publicado hasta la fecha, pues cada vez son más los procedimientos de esta naturaleza que se van a realizar, sobre todo en la población pediátrica(AU)

Awake craniotomy was the earliest surgical procedure known, and it has become fashionable again. In the past it was used for the surgical management of intractable epilepsy, but nowadays, its indications are increasing, and it is a widely recognized technique for the resection of mass lesions involving the eloquent cortex, and for deep brain stimulation. The procedure is safe, provides excellent results, and saves money and resources. The anesthesiologist should know the principles underlying neuroanesthesia, the technique of scalp blockade, and the sedation protocols, as well as feeling comfortable with advanced airway management. The main anesthetic aim is to keep patients cooperating when required (analgesia-based anesthesia). This review attempts to summarize the most recent evidence from the clinical literature, a long as the number of patients undergoing craniotomies in the awake state are increasing, specifically in the pediatric population(AU)

Dissociation of detection and discrimination of pure tones following bilateral lesions of auditory cortex.

It is well known that damage to the peripheral auditory system causes deficits in tone detection as well as pitch and loudness perception across a wide range of frequencies. However, the extent to which to which the auditory cortex plays a critical role in these basic aspects of spectral processing, especially with regard to speech, music, and environmental sound perception, remains unclear. Recent experiments indicate that primary auditory cortex is necessary for the normally-high perceptual acuity exhibited by humans in pure-tone frequency discrimination. The present study assessed whether the auditory cortex plays a similar role in the intensity domain and contrasted its contribution to sensory versus discriminative aspects of intensity processing. We measured intensity thresholds for pure-tone detection and pure-tone loudness discrimination in a population of healthy adults and a middle-aged man with complete or near-complete lesions of the auditory cortex bilaterally. Detection thresholds in his left and right ears were 16 and 7 dB HL, respectively, within clinically-defined normal limits. In contrast, the intensity threshold for monaural loudness discrimination at 1 kHz was 6.5 ± 2.1 dB in the left ear and 6.5 ± 1.9 dB in the right ear at 40 dB sensation level, well above the means of the control population (left ear: 1.6 ± 0.22 dB; right ear: 1.7 ± 0.19 dB). The results indicate that auditory cortex lowers just-noticeable differences for loudness discrimination by approximately 5 dB but is not necessary for tone detection in quiet. Previous human and Old-world monkey experiments employing lesion-effect, neurophysiology, and neuroimaging methods to investigate the role of auditory cortex in intensity processing are reviewed.

A novel phase portrait for neuronal excitability.

Fifty years ago, FitzHugh introduced a phase portrait that became famous for a twofold reason: it captured in a physiological way the qualitative behavior of Hodgkin-Huxley model and it revealed the power of simple dynamical models to unfold complex firing patterns. To date, in spite of the enormous progresses in qualitative and quantitative neural modeling, this phase portrait has remained a core picture of neuronal excitability. Yet, a major difference between the neurophysiology of 1961 and of 2011 is the recognition of the prominent role of calcium channels in firing mechanisms. We show that including this extra current in Hodgkin-Huxley dynamics leads to a revision of FitzHugh-Nagumo phase portrait that affects in a fundamental way the reduced modeling of neural excitability. The revisited model considerably enlarges the modeling power of the original one. In particular, it captures essential electrophysiological signatures that otherwise require non-physiological alteration or considerable complexification of the classical model. As a basic illustration, the new model is shown to highlight a core dynamical mechanism by which calcium channels control the two distinct firing modes of thalamocortical neurons.

Synaptic plasticity in neurodegenerative diseases evaluated and modulated by in vivo neurophysiological techniques.

Several studies demonstrated in experimental models and in humans synaptic plasticity impairment in some neurodegenerative and neuropsychiatric diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and schizophrenia. Recently new neurophysiological tools, such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation, have been introduced in experimental and clinical settings for studying physiology of the brain and modulating cortical activity. These techniques use noninvasive transcranial electrical or magnetic stimulation to modulate neurons activity in the human brain. Cortical stimulation might enhance or inhibit the activity of cortico-subcortical networks, depending on stimulus frequency and intensity, current polarity, and other stimulation parameters such as the configuration of the induced electric field and stimulation protocols. On this basis, in the last two decades, these techniques have rapidly become valuable tools to investigate physiology of the human brain and have been applied to treat drug-resistant neurological and psychiatric diseases. Here we describe these techniques and discuss the mechanisms that may explain these effects.

Clinical neurophysiology of visual and auditory processing in dyslexia: a review.

Neurophysiological studies on children and adults with dyslexia provide a deeper understanding of how visual and auditory processing in dyslexia might relate to reading deficits. The goal of this review is to provide an overview of research findings in the last two decades on motion related and contrast sensitivity visual evoked potentials and on auditory event related potentials to basic tone and speech sound processing in dyslexia. These results are particularly relevant for three important theories about causality in dyslexia: the magnocellular deficit hypothesis, the temporal processing deficit hypothesis and the phonological deficit hypothesis. Support for magnocellular deficits in dyslexia are primarily provided from evidence for altered visual evoked potentials to rapidly moving stimuli presented at low contrasts. Consistently ERP findings revealed altered neurophysiological processes in individuals with dyslexia to speech stimuli, but evidence for deficits processing certain general acoustic information relevant for speech perception, such as frequency changes and temporal patterns, are also apparent.

Tratamiento con acupuntura y moxibustión del síndrome poslaminectomía. Caso clínico / Treatment of post-laminectomy syndrome with acupuncture and moxibustion: a clinical case

El síndrome de la cirugía fallida de espalda es una complicación frecuente posquirúrgica que cursa con lumbalgia crónica con gran repercusión clínica y económica. Las posibilidades de tratamiento abarcan una gran variedad de técnicas y fármacos, siendo pese a ello una de las principales causas de dolor lumbar de más difícil tratamiento. Cada vez hay más pruebas sólidas de que la acupuntura puede ser un complemento útil al tratamiento convencional para el tratamiento de la lumbalgia. Se presenta el caso de un paciente de 37 años intervenido hace 2 años de artrodesis L4-L5,con reintervención posterior hace 1 año de retirada del material de osteosíntesis persistiendo con síndrome poslaminectomía no controlado con cicatriz disestésica pese a tratamiento con opiáceos débiles y anticonvulsivantes que se trató adecuadamente con sesiones de acupuntura y moxibustión. Como pruebas complementarias tenía una resonancia magnética en la que se aprecian además de cambios postquirúrgicos en la región lumbar posterior, deshidratación discal en L5-S1 y cambios degenerativos artrósicos de las pequeñas articulaciones interapofisarias a nivel de los últimos niveles lumbares, un estudio electroneurofisiológico en el que se observa una alteración en los potenciales evocados somestésicos realizados en el nervio fémorocutáneo lateral izquierdo, compatible con una neuropatía axonal de dicho nervio. El tratamiento se realizó en 10 sesiones durante 5 semanas, en cada una de las sesiones se hizo un tratamiento bifásico de 40min, tratando en primer lugar la zona cicatricial y a continuación la lumbalgia, en ambos se realizó moxibustión con puro de Artemisa con técnica de picoteo. El dolor fue controlándose pasando de una escala EAV inicial de 8 a una escala EAV al final del tratamiento de 0. Tras pasar revisión a los 6 meses continua con una escala EAV de 0 (AU)

Failed back surgery syndrome is a common post-surgical complication which leads to chronic low back pain with great clinical and financial repercussions. The treatment possibilities include a great variety of techniques and drugs, despite this being one of the main causes of a very difficult to treat lumbar pain. There is increasing solid evidence that acupuncture may be a useful complement to conventional treatment for treating low back pain. A case is presented of a 37 year-old patient surgically intervened 2 years ago for L4-L5 arthrodesis, with subsequent intervention 1 year ago to remove the osteosynthesis material. There was a persistent uncontrolled post-laminectomy syndrome with a dysesthetic scar despite treatment with weak opiates and anticonvulsants, which was treated adequately with sessions of acupuncture and moxibustion. A magnetic resonance imaging scan was performed as a complementary test, in which post-surgical changes could also be seen in the posterior lumbar region, disc dehydration in L5-S1, and degenerative arthrosis of the small interapophyseal lumbar joints. An electro-neurophysiological study showed a change in the somesthetic evoked potentials performed in the left lateral femoral-cutaneous nerve, compatible with an axonal neuropathy of that nerve. Treatment was given in 10 sessions over 5 weeks, in with a biphasic treatment of 40min being performed in each of them. The scar area was treated first and then the low back pain, moxibustion was performed on both with Artemis smoke and a pecking technique. The pain was controlled, going from a initial VAS score of 8 to 0 at the end of treatment. At the follow-up review at 6 months it was still 0 on the VAS scale (AU)

Chronic detachable headphones for acoustic stimulation in freely moving animals.

A growing number of studies of auditory processing are being carried out in awake, behaving animals, creating a need for precisely controlled sound delivery without restricting head movements. We have designed a system for closed-field stimulus presentation in freely moving ferrets, which comprises lightweight, adjustable headphones that can be consistently positioned over the ears via a small, skull-mounted implant. The invasiveness of the implant was minimized by simplifying its construction and using dental adhesive only for attaching it to the skull, thereby reducing the surgery required and avoiding the use of screws or other anchoring devices. Attaching the headphones to a chronic implant also reduced the amount of contact they had with the head and ears, increasing the willingness of the animals to wear them. We validated sound stimulation via the headphones in ferrets trained previously in a free-field task to localize stimuli presented from one of two loudspeakers. Noise bursts were delivered binaurally over the headphones and interaural level differences (ILDs) were introduced to allow the sound to be lateralized. Animals rapidly transferred from the free-field task to indicate the perceived location of the stimulus presented over headphones. They showed near perfect lateralization with a 5 dB ILD, matching the scores achieved in the free-field task. As expected, the ferrets' performance declined when the ILD was reduced in value. This closed-field system can easily be adapted for use in other species, and provides a reliable means of presenting closed-field stimuli whilst monitoring behavioral responses in freely moving animals.

Assessing instantaneous synchrony of nonlinear nonstationary oscillators in the brain.

Neuronal populations throughout the brain achieve levels of synchronous electrophysiological activity as a consequence of both normal brain function as well as during pathological states such as in epileptic seizures. Understanding this synchrony and being able to quantitatively assess the dynamics with which neuronal oscillators across the brain couple their activity is a critical component toward decoding such complex behavior. Commonly applied techniques to resolve relationships between oscillators typically make assumptions of linearity and stationarity that are likely not to be valid for complex neural signals. In this study, intracranial electroencephalographic activity was recorded bilaterally in both hippocampi and in anteromedial thalamus of rat under normal conditions and during hypersynchronous seizure activity induced by focal injection of the epileptogenic agent kainic acid. Nonlinear oscillators were first extracted using empirical mode decomposition. The technique of eigenvalue decomposition was used to assess global phase synchrony of the highest energy oscillators. The Hilbert analytical technique was then used to measure instantaneous phase synchrony of these oscillators as they evolved in time. To test the reliability of this method, we first applied it to a system of two coupled Rössler attractors under varying levels of coupling with small frequency mismatch. The application of these analytical techniques to intracranially recorded brain signals provides a means for assessing how complex oscillatory behavior in the brain evolves and changes during both normal activity and as a consequence of diseased states without making restrictive and possibly erroneous assumptions of the linearity and stationarity of the underlying oscillatory activity.

Electrode contact configuration and energy consumption in spinal cord stimulation.

OBJECTIVE: To test the hypothesis that in spinal cord stimulation, an increase in the number of cathodes increases the energy per pulse, contrary to an increase in the number of anodes, which decreases energy consumption per pulse. METHODS: Patients with an Itrel III (7425; Medtronic, Inc., Minneapolis, MN) implantable pulse generator and a Pisces-Quad (3487A; Medtronic, Inc.) implantable quadripolar lead were selected for this study. A set of 7 standard contact configurations was used for each patient. Resistor network models mimicking these configurations were constructed. The University of Twente's Spinal Cord Stimulation software was used to simulate the effect of these contact configurations on large spinal nerve fibers. To allow a comparison of the measured and modeled energy per pulse, all values were normalized. RESULTS: Both the empirical and the modeling results showed an increase in energy consumption with an increasing number of cathodes. Although the patient data with 1 and 2 cathodes did not differ significantly, energy consumption was significantly higher when 3 cathodes were used instead of 1 or 2 cathodes. The average energy consumption was significantly higher when bipolar stimulation was used instead of monopolar cathodal stimulation. An increasing number of anodes caused a decrease in energy consumption. CONCLUSION: When the paresthesia area can be covered with several configurations, it will be beneficial for the patient to program a configuration with 1 cathode and either no or multiple anodes.