Publications by authors named "Gerhard M Friehs"

Patients with amyotrophic lateral sclerosis (ALS) can lose all muscle-based routes of communication as motor neuron degeneration progresses, and ultimately, they may be left without any means of communication. While others have evaluated communication in people with remaining muscle control, to the best of our knowledge, it is not known whether neural-based communication remains possible in a completely locked-in state. Here, we implanted two 64 microelectrode arrays in the supplementary and primary motor cortex of a patient in a completely locked-in state with ALS.

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Hypophosphatasia (HPT) and cleidocranial dysplasia (CCD) are rare genetic disorders characterized by both defective ossification and bone mineralization. Patients usually present with craniosynostosis and cranial defects which in many cases require surgical repair. There is only 1 reported case of combined HPT and CCD in the literature.

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Planning and performing volitional movement engages widespread networks in the human brain, with motor cortex considered critical to the performance of skilled limb actions. Motor cortex is also engaged when actions are observed or imagined, but the manner in which ensembles of neurons represent these volitional states (VoSs) is unknown. Here we provide direct demonstration that observing, imagining or attempting action activates shared neural ensembles in human motor cortex.

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We present a point-and-click intracortical neural interface system (NIS) that enables humans with tetraplegia to volitionally move a 2-D computer cursor in any desired direction on a computer screen, hold it still, and click on the area of interest. This direct brain-computer interface extracts both discrete (click) and continuous (cursor velocity) signals from a single small population of neurons in human motor cortex. A key component of this system is a multi-state probabilistic decoding algorithm that simultaneously decodes neural spiking activity of a small population of neurons and outputs either a click signal or the velocity of the cursor.

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Background: We investigated the use of deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) for treatment refractory depression.

Methods: Fifteen patients with chronic, severe, highly refractory depression received open-label DBS at three collaborating clinical sites. Electrodes were implanted bilaterally in the VC/VS region.

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The relationship between spiking activities in motor cortex and movement kinematics has been well studied in neurologically intact nonhuman primates. We examined the relationship between spiking activities in primary motor cortex (M1) and intended movement kinematics (position and velocity) using 96-microelectrode arrays chronically implanted in two humans with tetraplegia. Study participants were asked to perform two different tasks: imagined pursuit tracking of a cursor moving on a computer screen and a "neural cursor center-out" task in which cursor position was controlled by the participant's neural activity.

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Stereotactic radiosurgery (SRS) with the Gamma Knife and linear accelerator has revolutionized neurosurgery over the past 20 years. The most common indications for radiosurgery today are tumors and arteriovenous malformations of the brain. Functional indications such as treatment of movement disorders or intractable pain only contribute a small percentage of treated patients.

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Background/aims: The 'precentral knob', a cortical representation of the motor hand function, can be identified and localized consistently using magnetic resonance imaging (MRI) and functional MRI. We present a method of indirectly identifying and localizing the Omega-shaped precentral knob using the anatomical landmarks on computed tomography (CT).

Methods: CT and MRI obtained within 24 h from 10 patients undergoing a headache workup and found to be negative for any anatomical abnormalities were studied.

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Primary motor cortex (M1), a key region for voluntary motor control, has been considered a first choice as the source of neural signals to control prosthetic devices for humans with paralysis. Less is known about the potential for other areas of frontal cortex as prosthesis signal sources. The frontal cortex is widely engaged in voluntary behavior.

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Deep brain stimulation (DBS) of the anterior limb of the internal capsule has been shown to be beneficial in the short term for obsessive-compulsive disorder (OCD) patients who exhaust conventional therapies. Nuttin et al, who published the first DBS for OCD series, found promising results using a capsule target immediately rostral to the anterior commissure extending into adjacent ventral capsule/ventral striatum (VC/VS). Published long-term outcome data are limited to four patients.

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Neuromotor prostheses (NMPs) aim to replace or restore lost motor functions in paralysed humans by routeing movement-related signals from the brain, around damaged parts of the nervous system, to external effectors. To translate preclinical results from intact animals to a clinically useful NMP, movement signals must persist in cortex after spinal cord injury and be engaged by movement intent when sensory inputs and limb movement are long absent. Furthermore, NMPs would require that intention-driven neuronal activity be converted into a control signal that enables useful tasks.

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Neurostimulation techniques are potentially useful options for severely depressed patients who have failed trial after trial of medication and psychotherapy. Cervical VNS therapy for chronic or recurrent depression which does not resolve with pharmacotherapy was recently approved by the FDA. DBS for severe intractable depression has been studied in two pilot studies with very few patients to date.

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Object: The authors undertook a study to identify magnetic resonance (MR) imaging techniques that can be used reliably during gamma knife surgery (GKS) to identify the trigeminal nerve, surrounding vasculature, and areas of compression.

Methods: Preoperative visualization of the trigeminal nerve and surrounding vasculature as well as targeting the area of vascular compression may increase the effectiveness of GKS for trigeminal neuralgia. During the past years our gamma knife centers have researched different MR imaging sequences with regard to their ability to visualize cranial nerves and vascular structures.

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The idea of connecting the human brain to a computer or machine directly is not novel and its potential has been explored in science fiction. With the rapid advances in the areas of information technology, miniaturization and neurosciences there has been a surge of interest in turning fiction into reality. In this paper the authors review the current state-of-the-art of brain-computer and brain-machine interfaces including neuroprostheses.

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Therapeutic brain stimulation through left cervical VNS now has established safety and efficacy as a long-term adjunct treatment for medication-resistant epilepsy. There is considerable evidence from both animal and human studies that the vagus nerve carries afferent signals to limbic and higher cortical brain regions, providing a rationale for its possible role in the treatment of psychiatric disorders. Open-label studies in patients with treatment-resistant depression have produced promising results, especially when response rates at longer term (1 year and 2 years) follow-up time points are considered.

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