The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals—that is, all multicellular animals except sponges and jellyfish. It is a structure composed of nervous tissue positioned along the rostral to caudal axis of the body and may have an enlarged section at the rostral end which is a brain. Not all animals with a central nervous system have a brain, although the large majority do.
A brain–computer interface (BCI), sometimes called a brain–machine interface (BMI), is a direct communication pathway between the brain's electrical activity and an external device, most commonly a computer or robotic limb. BCIs are often directed at researching, mapping, assisting, augmenting, or repairing human cognitive or sensory-motor functions. Implementations of BCIs range from non-invasive and partially invasive to invasive, based on how close electrodes get to brain tissue.
Functional electrical stimulation (FES) is a technique that uses low-energy electrical pulses to artificially generate body movements in individuals who have been paralyzed due to injury to the central nervous system. More specifically, FES can be used to generate muscle contraction in otherwise paralyzed limbs to produce functions such as grasping, walking, bladder voiding and standing. This technology was originally used to develop neuroprostheses that were implemented to permanently substitute impaired functions in individuals with spinal cord injury (SCI), head injury, stroke and other neurological disorders. In other words, a person would use the device each time he or she wanted to generate a desired function. FES is sometimes also referred to as neuromuscular electrical stimulation (NMES).
Neurotechnology encompasses any method or device in which electronics interface with the nervous system to monitor or modulate neural activity.
Neuroprosthetics is a discipline related to neuroscience and biomedical engineering concerned with developing neural prostheses. They are sometimes contrasted with a brain–computer interface, which connects the brain to a computer rather than a device meant to replace missing biological functionality.
Neural engineering is a discipline within biomedical engineering that uses engineering techniques to understand, repair, replace, or enhance neural systems. Neural engineers are uniquely qualified to solve design problems at the interface of living neural tissue and non-living constructs.
Neurohacking is a subclass of biohacking, focused specifically on the brain. Neurohackers seek to better themselves or others by “hacking the brain” to improve reflexes, learn faster, or treat psychological disorders. The modern neurohacking movement has been around since the 1980s. However, herbal supplements have been used to increase brain function for hundreds of years. After a brief period marked by a lack of research in the area, neurohacking started regaining interest in the early 2000s. Currently, most neurohacking is performed via do-it-yourself (DIY) methods by in-home users.
Monoplegia is paralysis of a single limb, usually an arm. Common symptoms associated with monoplegic patients are weakness, numbness, and pain in the affected limb. Monoplegia is a type of paralysis that falls under hemiplegia. While hemiplegia is paralysis of half of the body, monoplegia is localized to a single limb or to a specific region of the body. Monoplegia of the upper limb is sometimes referred to as brachial monoplegia, and that of the lower limb is called crural monoplegia. Monoplegia in the lower extremities is not as common of an occurrence as in the upper extremities. Monoparesis is a similar, but less severe, condition because one limb is very weak, not paralyzed. For more information, see paresis.
Transcranial direct current stimulation (tDCS) is a form of neuromodulation that uses constant, low direct current delivered via electrodes on the head. It was originally developed to help patients with brain injuries or neuropsychiatric conditions such as major depressive disorder. It can be contrasted with cranial electrotherapy stimulation, which generally uses alternating current the same way, as well as transcranial magnetic stimulation.
The supplementary motor area (SMA) is a part of the primate cerebral cortex that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of the primary motor cortex leg representation. In monkeys the SMA contains a rough map of the body. In humans the body map is not apparent. Neurons in the SMA project directly to the spinal cord and may play a role in the direct control of movement. Possible functions attributed to the SMA include the postural stabilization of the body, the coordination of both sides of the body such as during bimanual action, the control of movements that are internally generated rather than triggered by sensory events, and the control of sequences of movements. All of these proposed functions remain hypotheses. The precise role or roles of the SMA is not yet known.
Neurorobotics, a combined study of neuroscience, robotics, and artificial intelligence, is the science and technology of embodied autonomous neural systems. Neural systems include brain-inspired algorithms, computational models of biological neural networks and actual biological systems. Such neural systems can be embodied in machines with mechanic or any other forms of physical actuation. This includes robots, prosthetic or wearable systems but also, at smaller scale, micro-machines and, at the larger scales, furniture and infrastructures.
Electrical brain stimulation (EBS), also referred to as focal brain stimulation (FBS), is a form of electrotherapy and technique used in research and clinical neurobiology to stimulate a neuron or neural network in the brain through the direct or indirect excitation of its cell membrane by using an electric current. It is used for research or for therapeutic purposes.
Spinal locomotion results from intricate dynamic interactions between a central program in lower thoracolumbar spine and proprioceptive feedback from body in the absence of central control by brain as in complete spinal cord injury (SCI). Following SCI, the spinal circuitry below the lesion site does not become silent rather it continues to maintain active and functional neuronal properties although in a modified manner.
Neurostimulation is the purposeful modulation of the nervous system's activity using invasive or non-invasive means. Neurostimulation usually refers to the electromagnetic approaches to neuromodulation.
In September 2018, the Center for Sensorimotor Neural Engineering (CSNE) changed its name to the Center for Neurotechnology (CNT) to highlight the role of neurotechnologies in healing the brain and spinal cord.
Neuromodulation is "the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body". It is carried out to normalize – or modulate – nervous tissue function. Neuromodulation is an evolving therapy that can involve a range of electromagnetic stimuli such as a magnetic field (rTMS), an electric current, or a drug instilled directly in the subdural space. Emerging applications involve targeted introduction of genes or gene regulators and light (optogenetics), and by 2014, these had been at minimum demonstrated in mammalian models, or first-in-human data had been acquired. The most clinical experience has been with electrical stimulation.
Transcranial pulsed ultrasound (TPU) uses low intensity, low frequency ultrasound (LILFU) to stimulate the brain. In 2002, Dr. Alexander Bystritsky first proposed the idea that this methodology contained therapeutic benefits. Beginning in 2008, Dr. William Tyler and his research team from Arizona State University began an investigation and development of this alternative neuromodulation without the harmful effects and risks of invasive surgery. They discovered that this low-power ultrasound is able to stimulate high neuron activity which allows for the manipulation of the brain waves through an external source. Unlike deep brain stimulation or Vagus nerve stimulation, which use implants and electrical impulses, TPU is a noninvasive and focused procedure that does not require the implantation of electrodes that could damage the nervous tissue. Its use is applicable in the various fields including but not limited to medical and military science. Although this technology holds great potential to introducing new and beneficial alternatives to conventional brain manipulation, it is a relatively young science and has certain obstructions to its full development such as a lack of complete understanding and control of every safety measure.
A peripheral nerve interface is the bridge between the peripheral nervous system and a computer interface which serves as a bi‐directional information transducer recording and sending signals between the human body and a machine processor. Interfaces to the nervous system usually take the form of electrodes for stimulation and recording, though chemical stimulation and sensing are possible. Research in this area is focused on developing peripheral nerve interfaces for the restoration of function following disease or injury to minimize associated losses. Peripheral nerve interfaces also enable electrical stimulation and recording of the peripheral nervous system to study the form and function of the peripheral nervous system. For example, recent animal studies have demonstrated high accuracy in tracking physiological meaningful measures, like joint angle. Many researchers also focus in the area of neuroprosthesis, linking the human nervous system to bionics in order to mimic natural sensorimotor control and function. Successful implantation of peripheral nerve interfaces depend on a number of factors which include appropriate indication, perioperative testing, differentiated planning, and functional training. Typically microelectrode devices are implanted adjacent to, around or within the nerve trunk to establish contact with the peripheral nervous system. Different approaches may be used depending on the type of signal desired and attainable.
Transcranial random noise stimulation (tRNS) is a non-invasive brain stimulation technique and a form of transcranial electrical stimulation (tES). Terney et al from Göttingen University was the first group to apply tRNS in humans in 2008. They showed that by using an alternate current along with random amplitude and frequency in healthy subjects, the motor cortex excitability increased for up to 60 minutes after 10 minutes of stimulation. The study included all the frequencies up to half of the sampling rate i.e. 640 Hz, however the positive effect was limited only to higher frequencies. Although tRNS has shown positive effects in various studies the optimal parameters, as well as the potential clinical effects of this technique, remain unclear.
Gait variability seen in Parkinson's Disorders arise due to cortical changes induced by pathophysiology of the disease process. Gait rehabilitation is focused to harness the adapted connections involved actively to control these variations during the disease progression. Gait variabilities seen are attributed to the defective inputs from the Basal Ganglia. However, there is altered activation of other cortical areas that support the deficient control to bring about a movement and maintain some functional mobility.
