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Perturbational Complexity Index
Perturbational Complexity Index (PCI) is a quantitative measure used in neuroscience to assess the level of consciousness based on the complexity of brain responses to external perturbations, typically induced via transcranial magnetic stimulation (TMS). It was introduced in 2013 by Italian M.D.–Ph.D. Marcello Massimini and colleagues as a practical application of principles from Integrated Information Theory (IIT), which posits that conscious systems must exhibit both high integration and differentiation of information. Concept PCI quantifies the algorithmic complexity of the brain’s response to a controlled perturbation. In a typical protocol, a brief TMS pulse is delivered to the cortex, and the resulting electrical activity is recorded with electroencephalography (EEG). The recorded spatiotemporal EEG response is then binarized and compressed using a lossless algorithm to estimate its algorithmic complexity. The PCI value is normalized to control for signal length and amp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measurement
Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared to a basic reference quantity of the same kind. The scope and application of measurement are dependent on the context and discipline. In natural sciences and engineering, measurements do not apply to nominal properties of objects or events, which is consistent with the guidelines of the International Vocabulary of Metrology (VIM) published by the International Bureau of Weights and Measures (BIPM). However, in other fields such as statistics as well as the social and behavioural sciences, measurements can have multiple levels, which would include nominal, ordinal, interval and ratio scales. Measurement is a cornerstone of trade, science, technology and quantitative research in many disciplines. Historically, many measurement syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coma
A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to Nociception, respond normally to Pain, painful stimuli, light, or sound, lacks a normal Circadian rhythm, sleep-wake cycle and does not initiate voluntary actions. The person may experience respiratory and circulatory problems due to the body's inability to maintain normal bodily functions. People in a coma often require extensive medical care to maintain their health and prevent complications such as pneumonia or blood clots. Coma patients exhibit a complete absence of wakefulness and are unable to consciously feel, speak or move. Comas can be the result of natural causes, or can be Induced coma, medically induced, for example, during General anaesthesia, general anesthesia. Clinically, a coma can be defined as the consistent inability to follow a one-step command. For a patient to maintain consciousness, the components of ''wakefulness'' and ''awareness'' must be maintained. Wak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parietal Lobe
The parietal lobe is one of the four Lobes of the brain, major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory information among various sensory modality, modalities, including spatial sense and navigation (proprioception), the main sensory receptive area for the sense of touch in the somatosensory cortex which is just posterior to the central sulcus in the postcentral gyrus, and the two-streams hypothesis#Dorsal stream, dorsal stream of the visual system. The major sensory inputs from the skin (mechanoreceptor, touch, thermoreceptor, temperature, and nociceptor, pain receptors), relay through the thalamus to the parietal lobe. Several areas of the parietal lobe are important in language processing in the brain, language processing. The somatosensory cortex can be illustrated as a distorted figure – the cortical homunculus (Latin: "li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motor Cortex
The motor cortex is the region of the cerebral cortex involved in the planning, motor control, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus. Components The motor cortex can be divided into three areas: 1. The primary motor cortex is the main contributor to generating neural impulses that pass down to the spinal cord and control the execution of movement. However, some of the other motor areas in the brain also play a role in this function. It is located on the anterior paracentral lobule on the medial surface. 2. The premotor cortex is responsible for some aspects of motor control, possibly including the preparation for movement, the sensory guidance of movement, the spatial guidance of reaching, or the direct control of some movements with an emphasis on control of proximal and trunk muscles of the body. Located anterior to the primary mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premotor Cortex
The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks. Different subregions of the premotor cortex have different properties and presumably emphasize different functions. Nerve signals generated in the premotor cortex cause much more complex patterns of movement than the discrete patterns generated in the primary motor cortex. Structure The pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Information Theory
Integrated information theory (IIT) proposes a mathematical model for the consciousness of a system. It comprises a framework ultimately intended to explain why some physical systems (such as human brains) are conscious, and to be capable of providing a concrete inference about whether any physical system is conscious, to what degree, and what particular experience it has; why they feel the particular way they do in particular states (e.g. why our visual field appears extended when we gaze out at the night sky), and what it would take for other physical systems to be conscious (Are other animals conscious? Might the whole universe be?). According to IIT, a system's consciousness (what it is like subjectively) is conjectured to be identical to its causal properties (what it is like objectively). Therefore, it should be possible to account for the conscious experience of a physical system by unfolding its complete causal powers. IIT was proposed by neuroscientist Giulio Tononi i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disorders Of Consciousness
Disorders of consciousness are medical conditions that inhibit consciousness. Some define disorders of consciousness as any change from complete self-awareness to inhibited or absent self-awareness and arousal. This category generally includes minimally conscious state and persistent vegetative state, but sometimes also includes the less severe locked-in syndrome and more severe but rare chronic coma. Differential diagnosis of these disorders is an active area of biomedical research. Finally, brain death results in an irreversible disruption of consciousness. While other conditions may cause a moderate deterioration (e.g., dementia and delirium) or transient interruption (e.g., grand mal and petit mal seizures) of consciousness, they are not included in this category. Classification Patients in such a dramatically altered state of consciousness present unique problems for diagnosis, prognosis and treatment. Assessment of cognitive functions remaining after a traumatic brai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locked-in Syndrome
Locked-in syndrome (LIS), also known as pseudocoma, is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in their body except for vertical eye movements and blinking. This is due to quadriplegia and bulbar palsy. The individual is conscious and sufficiently intact cognitively to be able to communicate with eye movements. Electroencephalography results are normal in locked-in syndrome as these individuals have retained brain activity such as sleep-wake cycles and attention that is detectable. Fred Plum and Jerome B. Posner coined the term for this disorder in 1966. Locked-in syndrome can be separated into different subcategories based on symptom severity. This consists of classic locked-in syndrome, characterized by the inability to move distal limbs and facial muscles, but retained ability to blink and move eyes vertically, with preserved cognition and consciousness. Incomplete locked-in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minimally Conscious State
A minimally conscious state (MCS) is a disorder of consciousness distinct from persistent vegetative state (PVS) and locked-in syndrome. Unlike PVS, patients with MCS have partial preservation of conscious awareness. MCS is a relatively new category of disorders of consciousness. The natural history and longer term outcome of MCS have not yet been thoroughly studied. The prevalence of MCS was estimated to be nine times of PVS cases (adult and pediatric), or between 112,000 and 280,000 in the US by year 2000. Pathophysiology Neuroimaging Because minimally conscious state is a relatively new criterion for diagnosis, there are very few functional imaging studies of patients with this condition. Preliminary data has shown that overall cerebral metabolism is less than in those with conscious awareness (20–40% of normal) and is slightly higher but comparable to those in vegetative states. Activation in the medial parietal cortex and adjacent posterior cingulate cortex are brain r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vegetative State
A vegetative state (VS) or post-coma unresponsiveness (PCU) is a disorder of consciousness in which patients with severe brain damage are in a state of partial arousal rather than true awareness. After four weeks in a vegetative state, the patient is classified as being in a persistent vegetative state (PVS). This diagnosis is classified as a permanent vegetative state some months (three in the US and six in the UK) after a non-traumatic brain injury or one year after a traumatic injury. The term unresponsive wakefulness syndrome may be used alternatively, as "vegetative state" has some negative connotations among the public. It is occasionally also called Apallic syndrome or Apallisches syndrome, borrowings from German, primarily in European or older sources. Definition There are several definitions that vary by technical versus layman's usage. There are different legal implications in different countries. Medical definition Per the definition of the British Royal College ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Anaesthesia
General anaesthesia (UK) or general anesthesia (US) is medically induced loss of consciousness that renders a patient unarousable even by painful stimuli. It is achieved through medications, which can be injected or inhaled, often with an analgesic and neuromuscular blocking agent. General anaesthesia is usually performed in an operating theatre to allow surgical procedures that would otherwise be intolerably painful for a patient, or in an intensive care unit or emergency department to facilitate endotracheal intubation and mechanical ventilation in critically ill patients. Depending on the procedure, general anaesthesia may be optional or required. No matter whether the patient prefers to be unconscious or not, certain pain stimuli can lead to involuntary responses from the patient, such as movement or muscle contractions, that make the operation extremely difficult. Thus, for many procedures, general anaesthesia is necessary from a practical point of view. The patient's n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
