Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.
Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to cause electric current at a specific area of the brain through electromagnetic induction. An electric pulse generator, or stimulator, is connected to a magnetic coil, which in turn is connected to the scalp. The stimulator generates a changing electric current within the coil which induces a magnetic field; this field then causes a second inductance of inverted electric charge within the brain itself.
Lipolysis is the metabolic pathway through which lipid triglycerides are hydrolyzed into a glycerol and three fatty acids. It is used to mobilize stored energy during fasting or exercise, and usually occurs in fat adipocytes. The most important regulatory hormone in lipolysis is insulin; lipolysis can only occur when insulin action falls to low levels, as occurs during fasting. Other hormones that affect lipolysis include glucagon, epinephrine, norepinephrine, growth hormone, atrial natriuretic peptide, brain natriuretic peptide, and cortisol.
Bioacoustics is a cross-disciplinary science that combines biology and acoustics. Usually it refers to the investigation of sound production, dispersion and reception in animals. This involves neurophysiological and anatomical basis of sound production and detection, and relation of acoustic signals to the medium they disperse through. The findings provide clues about the evolution of acoustic mechanisms, and from that, the evolution of animals that employ them.
A brain–computer interface (BCI), sometimes called a neural control interface (NCI), mind–machine interface (MMI), direct neural interface (DNI), or brain–machine interface (BMI), is a direct communication pathway between an enhanced or wired brain and an external device. BCIs are often directed at researching, mapping, assisting, augmenting, or repairing human cognitive or sensory-motor functions.
Channelrhodopsins are a subfamily of retinylidene proteins (rhodopsins) that function as light-gated ion channels. They serve as sensory photoreceptors in unicellular green algae, controlling phototaxis: movement in response to light. Expressed in cells of other organisms, they enable light to control electrical excitability, intracellular acidity, calcium influx, and other cellular processes. Channelrhodopsin-1 (ChR1) and Channelrhodopsin-2 (ChR2) from the model organism Chlamydomonas reinhardtii are the first discovered channelrhodopsins. Variants have been cloned from other algal species, and more are expected.
Remote control animals are animals that are controlled remotely by humans. Some applications require electrodes to be implanted in the animal's nervous system connected to a receiver which is usually carried on the animal's back. The animals are controlled by the use of radio signals. The electrodes do not move the animal directly, as if controlling a robot; rather, they signal a direction or action desired by the human operator and then stimulate the animal's reward centres if the animal complies. These are sometimes called bio-robots or robo-animals. They can be considered to be cyborgs as they combine electronic devices with an organic life form. Because of the surgery required, and the moral and ethical issues involved, there has been criticism aimed at the use of remote control animals, especially regarding animal welfare and animal rights. A similar, non-invasive application has been reported which stimulates the brain with ultrasound to control the animal. Some applications use vibrations or sound to control the movements of the animals.
Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electromagnetic fields produced by living cells, tissues or organisms, the effects of man-made sources of electromagnetic fields like mobile phones, and the application of electromagnetic radiation toward therapies for the treatment of various conditions.
Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography that measure the velocity of blood flow through the brain's blood vessels by measuring the echoes of ultrasound waves moving transcranially. These modes of medical imaging conduct a spectral analysis of the acoustic signals they receive and can therefore be classified as methods of active acoustocerebrography. They are used as tests to help diagnose emboli, stenosis, vasospasm from a subarachnoid hemorrhage, and other problems. These relatively quick and inexpensive tests are growing in popularity. The tests are effective for detecting sickle cell disease, ischemic cerebrovascular disease, subarachnoid hemorrhage, arteriovenous malformations, and cerebral circulatory arrest. The tests are possibly useful for perioperative monitoring and meningeal infection. The equipment used for these tests is becoming increasingly portable, making it possible for a clinician to travel to a hospital, to a doctor's office, or to a nursing home for both inpatient and outpatient studies. The tests are often used in conjunction with other tests such as MRI, MRA, carotid duplex ultrasound and CT scans. The tests are also used for research in cognitive neuroscience.
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.
Low-intensity pulsed ultrasound (LIPUS) is a technology that can be used for therapeutic purposes. It exploits low intensity and pulsed mechanical waves in order to induce regenerative and anti-inflammatory effects on biological tissues, such as bone, cartilage, and tendon. Even if the real mechanism underlying its effectiveness has not been understood yet, it is plausible that the treatment relies on non-thermal phenomena, such as microbubbles and microjets induced by cavitation, acoustic streaming, and mechanical stimulation.
Therapeutic ultrasound refers generally to any type of ultrasonic procedure that uses ultrasound for therapeutic benefit. Physiotherapeutic ultrasound was introduced into clinical practice in the 1950s, with lithotripsy introduced in the 1980s. Others are at various stages in transitioning from research to clinical use: HIFU, targeted ultrasound drug delivery, trans-dermal ultrasound drug delivery, ultrasound hemostasis, cancer therapy, and ultrasound assisted thrombolysis It may use focused ultrasound (FUS) or unfocused ultrasound.
Optogenetics is a biological technique that involves the use of light to control neurons that have been genetically modified to express light-sensitive ion channels. As such, optogenetics is a neuromodulation method that uses a combination of techniques from optics and genetics to control the activities of individual neurons in living tissue — even within freely-moving animals. In some usages, optogenetics also refers to optical monitoring of neuronal activity or control of other biochemical pathways in non-neuronal cells, although these research activities preceded the use of light-sensitive ion channels in neurons. As optogenetics is used by some authors to refer to only optical control of the activity of genetically defined neurons and not these additional research approaches, the term optogenetics is an example of polysemy.
Microbubbles (MBs) are bubbles smaller than one hundredth of a millimetre in diameter, but larger than one micrometre. They have widespread application in industry, life science, and medicine. The composition of the bubble shell and filling material determine important design features such as buoyancy, crush strength, thermal conductivity, and acoustic properties.
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.
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.
Burst suppression is an electroencephalography (EEG) pattern that is characterized by periods of high-voltage electrical activity alternating with periods of no activity in the brain. The pattern is found in patients with inactivated brain states, such as from general anesthesia, coma, or hypothermia. This pattern can be physiological, as during early development, or pathological, as in diseases such as Ohtahara syndrome.
Sharp waves and ripples (SWRs) are oscillatory patterns in the mammalian brain hippocampus seen on an EEG during immobility and sleep. There are three major network oscillation patterns in the hippocampus: theta waves, SWRs and gamma waves. Gamma oscillations are found in all major brain structures, whereas theta and sharp waves are specific to the hippocampus and its neighbouring areas. SWRs are composed of large amplitude sharp waves in local field potential and associated fast field oscillations known as ripples. SWRs are shown to be involved in memory consolidation and the replay of wakefulness-acquired memory. These network oscillations are the most synchronous patterns in the brain, making them susceptible to pathological patterns such as epilepsy.
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.
