Diagnosis
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Intermittent rhythmic delta activity (IRDA) is a type of brain wave abnormality found in electroencephalograms (EEG). [1]
It can be classified based on the area of brain it originates from:
It can also be
It can be caused by a number of different reasons, some benign, unknown reasons, but also are commonly associated with lesions, tumors, and encephalopathies. [3] Association with periventricular white matter disease and cortical atrophy has been documented and they are more likely to show up during acute metabolic derangements such as uremia and hyperglycemia. [4]
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Magnetoencephalography (MEG) is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers. Arrays of SQUIDs are currently the most common magnetometer, while the SERF magnetometer is being investigated for future machines. Applications of MEG include basic research into perceptual and cognitive brain processes, localizing regions affected by pathology before surgical removal, determining the function of various parts of the brain, and neurofeedback. This can be applied in a clinical setting to find locations of abnormalities as well as in an experimental setting to simply measure brain activity.
Hypergraphia is a behavioral condition characterized by the intense desire to write or draw. Forms of hypergraphia can vary in writing style and content. It is a symptom associated with temporal lobe changes in epilepsy and in Geschwind syndrome. Structures that may have an effect on hypergraphia when damaged due to temporal lobe epilepsy are the hippocampus and Wernicke's area. Aside from temporal lobe epilepsy, chemical causes may be responsible for inducing hypergraphia.
Delta waves are high amplitude neural oscillations with a frequency between 0.5 and 4 hertz. Delta waves, like other brain waves, can be recorded with electroencephalography (EEG) and are usually associated with the deep stage 3 of NREM sleep, also known as slow-wave sleep (SWS), and aid in characterizing the depth of sleep.
A gamma wave or gamma Rhythm is a pattern of neural oscillation in humans with a frequency between 25 and 140 Hz, the 40-Hz point being of particular interest. Gamma rhythms are correlated with large scale brain network activity and cognitive phenomena such as working memory, attention, and perceptual grouping, and can be increased in amplitude via meditation or neurostimulation. Altered gamma activity has been observed in many mood and cognitive disorders such as Alzheimer's disease, epilepsy, and schizophrenia.
Language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same grammatical understanding or systematicity in even human's closest primate relatives.
The sensorimotor rhythm (SMR) is a brain wave. It is an oscillatory idle rhythm of synchronized electric brain activity. It appears in spindles in recordings of EEG, MEG, and ECoG over the sensorimotor cortex. For most individuals, the frequency of the SMR is in the range of 13 to 15 Hz.
Alpha waves or Alpha rhythm are macroscopic neural oscillations in the frequency range of 8–12 Hz likely originating from the synchronous and coherent electrical activity of thalamic pacemaker cells in humans. Historically, they are also called "Berger's waves" after Hans Berger, who first described them when he invented the EEG in 1924.
Brainwave entrainment, also referred to as brainwave synchronization and neural entrainment, refers to the hypothesized capacity of the brain to naturally synchronize its brainwave frequencies with the rhythm of periodic external stimuli, most commonly auditory, visual, or tactile.
Hippocampal sclerosis (HS) is a neuropathological condition with severe neuronal cell loss and gliosis in the hippocampus, specifically in the CA-1 and subiculum of the hippocampus. It was first described in 1880 by Wilhelm Sommer. Hippocampal sclerosis is a frequent pathologic finding in community-based dementia. Hippocampal sclerosis can be detected with autopsy or MRI. In MRI, a decrease in signal is observed at T1 and an increase in signal at T2. Positron emission tomography is also used as an aid for diagnosis. In PET examination, glucose uptake is lower than in the normal part. The reason for this is that the sclerotic part works at a lower level than the normal part and needs less energy. Individuals with hippocampal sclerosis have similar initial symptoms and rates of dementia progression to those with Alzheimer's disease (AD) and therefore are frequently misclassified as having Alzheimer's Disease. But clinical and pathologic findings suggest that hippocampal sclerosis has characteristics of a progressive disorder although the underlying cause remains elusive. A diagnosis of hippocampal sclerosis has a significant effect on the life of patients because of the notable mortality, morbidity and social impact related to epilepsy, as well as side effects associated with antiepileptic treatments.
Neural oscillations, or brainwaves, are rhythmic or repetitive patterns of neural activity in the central nervous system. Neural tissue can generate oscillatory activity in many ways, driven either by mechanisms within individual neurons or by interactions between neurons. In individual neurons, oscillations can appear either as oscillations in membrane potential or as rhythmic patterns of action potentials, which then produce oscillatory activation of post-synaptic neurons. At the level of neural ensembles, synchronized activity of large numbers of neurons can give rise to macroscopic oscillations, which can be observed in an electroencephalogram. Oscillatory activity in groups of neurons generally arises from feedback connections between the neurons that result in the synchronization of their firing patterns. The interaction between neurons can give rise to oscillations at a different frequency than the firing frequency of individual neurons. A well-known example of macroscopic neural oscillations is alpha activity.
Temporal lobe epilepsy (TLE) is a chronic disorder of the nervous system characterized by recurrent, unprovoked focal seizures that originate in the temporal lobe of the brain and last about one or two minutes. TLE is the most common form of epilepsy with focal seizures. A focal seizure in the temporal lobe may spread to other areas in the brain when it may become a focal to bilateral seizure.
Electrocorticography (ECoG), or intracranial electroencephalography (iEEG), is a type of electrophysiological monitoring that uses electrodes placed directly on the exposed surface of the brain to record electrical activity from the cerebral cortex. In contrast, conventional electroencephalography (EEG) electrodes monitor this activity from outside the skull. ECoG may be performed either in the operating room during surgery or outside of surgery. Because a craniotomy is required to implant the electrode grid, ECoG is an invasive procedure.
Electroencephalography (EEG) is an electrophysiological monitoring method to record electrical activity on the scalp that has been shown to represent the macroscopic activity of the surface layer of the brain underneath. It is typically non-invasive, with the electrodes placed along the scalp. Electrocorticography, involving invasive electrodes, is sometimes called intracranial EEG.
The neuroscience of music is the scientific study of brain-based mechanisms involved in the cognitive processes underlying music. These behaviours include music listening, performing, composing, reading, writing, and ancillary activities. It also is increasingly concerned with the brain basis for musical aesthetics and musical emotion. Scientists working in this field may have training in cognitive neuroscience, neurology, neuroanatomy, psychology, music theory, computer science, and other relevant fields.
EEG microstates are transient, patterned, quasi-stable states or patterns of an electroencephalogram. These tend to last anywhere from milliseconds to seconds and are hypothesized to be the most basic instantiations of human neurological tasks, and are thus nicknamed "the atoms of thought". Microstate estimation and analysis was originally done using alpha band activity, though broader bandwidth EEG bands are now typically used. The quasi-stability of microstates means that the "global [EEG] topography is fixed, but strength might vary and polarity invert."
Meditation and its effect on brain activity and the central nervous system became a focus of collaborative research in neuroscience, psychology and neurobiology during the latter half of the 20th century. Research on meditation sought to define and characterize various practices. Meditation's effect on the brain can be broken up into two categories: state changes and trait changes, respectively alterations in brain activities during the act of meditating and changes that are the outcome of long-term practice.
The temporal dynamics of music and language describes how the brain coordinates its different regions to process musical and vocal sounds. Both music and language feature rhythmic and melodic structure. Both employ a finite set of basic elements that are combined in ordered ways to create complete musical or lingual ideas.
Drug-resistant epilepsy (DRE), also known as refractory epilepsy or pharmacoresistant epilepsy, is defined as failure of adequate trials of two tolerated and appropriately chosen and used antiepileptic drugs to achieve sustained seizure freedom. The probability that the next medication will achieve seizure freedom drops with every failed AED. For example, after two failed AEDs, the probability that the third will achieve seizure freedom is around 4%. Drug-resistant epilepsy is commonly diagnosed after several years of uncontrolled seizures, however, in most cases, it is evident much earlier. Approximately 30% of people with epilepsy have a drug-resistant form.
High frequency oscillations (HFO) are brain waves of the frequency faster than ~80 Hz, generated by neuronal cell population. High frequency oscillations can be recorded during an electroencephalagram (EEG), local field potential (LFP) or electrocorticogram (ECoG) electrophysiology recordings. They are present in physiological state during sharp waves and ripples - oscillatory patterns involved in memory consolidation processes. HFOs are associated with pathophysiology of the brain like epileptic seizure and are often recorded during seizure onset. It makes a promising biomarker for the identification of the epileptogenic zone. Other studies points to the HFO role in psychiatric disorders and possible implications to psychotic episodes in schizophrenia.
Computational models in epilepsy mainly focus on describing an electrophysiological manifestation associated with epilepsy called seizures. For this purpose, computational neurosciences use differential equations to reproduce the temporal evolution of the signals recorded experimentally. A book published in 2008, Computational Neuroscience in Epilepsy,. summarizes different works done up to this time. The goals of using its models are diverse, from prediction to comprehension of underlying mechanisms.
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