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RETT’S SYNDROME
a pervasive developmental disorder affecting the gray matter of the brain, occurring exclusively in females and present from birth. Characterized by autistic behavior, ataxia, dementia, seizures, and loss of purposeful movements of the hands.
 
QUADRANTANOPIA
defective vision or blindness in one fourth of the visual field.
 
ACCOMMODATION REFLEX
the coordinated changes that occur when the eye adapts itself for near vision; the changes are constriction of the pupil, convergence of the eyes, and increased convexity of the lens.
 
KYPHOSCOLIOSIS
the combination of kyphosis (backward curvature of the spine) and scoliosis (lateral curvature), as seen in Scheuermann disease.
 
KERNIG SIGN
a sign of meningitis: in the supine position the patient can easily and completely extend the leg, whereas in the sitting posture or when lying with the thigh flexed upon the abdomen the leg cannot be completely extended without pain.
 
JAMAIS VU
the sensation that familiar surroundings are strangely unfamiliar; the illusion that one has never seen anything like that before.
 
OBTUNDATION
mental blunting with mild to moderate reduction in alertness and a diminished sensation of pain.
 
LUMBAR PUNCTURE HEADACHE
headache in the erect position, and relieved by recumbency, following lumbar puncture, due to lowering of intracranial pressure by leakage of cerebrospinal fluid through the needle tract.
 
LEPTOMENINGES
the two more delicate components of the meninges: the pia mater and arachnoid considered together; the pia-arachnoid
 
EATON-LAMBERT SYNDROME
a myasthenia-like syndrome in which the weakness usually affects the limbs but ocular and bulbar muscles are spared; often associated with oat-cell carcinoma of the lung.
 
HEMIBALLISMUS
violent motor restlessness of half of the body, most marked in the upper limbs
 
HEIDENHAIN SYNDROME
a rapidly progressive degenerative disease manifested by cortical blindness, presenile dementia, dysarthria, ataxia, athetoid movements, and generalized rigidity
 
EFFERENT NEURON
a neuron that conducts nerve impulses that originated at the center and are proceeding towards the periphery
 
EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO)
a technique of providing respiratory support; the blood is circulated through an artificial lung consisting of two compartments separated by a gas-permeable membrane, with the blood on one side and the ventilating gas on the other. It was originally used exclusively in newborns but is now being used more and more in adults.
 
CHEYNE-STOKES RESPIRATION
breathing characterized by rhythmic waxing and waning of the depth of respiration; the patient breathes deeply for a short time and then breathes very slightly or stops breathing altogether. The pattern occurs over and over, every 45 seconds to 3 minutes. Periodic breathing of this type is caused by disease affecting the respiratory centers, usually heart failure or brain damage.
 
CEREBELLOPONTINE ANGLE SYNDROME
a syndrome caused by a tumor of the cerebellopontine angle or an acoustic tumor, characterized by hearing loss, subjective noises, ipsilateral cerebellar ataxia, and eventually ipsilateral impairment of function of the sixth and seventh cranial nerves accompanied by elevated intracranial pressure.
 
CEREBRAL PERFUSION PRESSURE
the mean arterial pressure minus the intracranial pressure, a measure of the adequacy of cerebral blood flow
 
CARDIOVERSION
the delivery of a direct current countershock synchronized with the QRS complex to the myocardium in order to end tachydysrhythmias and restore sinoatrial control of the heart rhythm through depolarization of the entire myocardium. The depolarization interrupts reentry circuits, thus ending myocardial fibrillation and some other types of dysrhythmias. The electric shock can be delivered directly to the myocardium in an open chest procedure, or through externally applied paddles placed on the chest.
 
VERTEBRAL LAMINA
either of the pair of broad plates of bone flaring out from the pedicles of the vertebral arches and fusing together at the midline to complete the dorsal part of the arch and provide a base for the spinous process of the vertebra.
 
VERNIX CASEOSA
the thick white substance composed of sebum and desquamated epithelial cells that provides a protective covering for the skin of the fetus. In the full-term newborn, during the first two or three days of life there is a small amount of vernix caseosa in body creases and the hair.
 
SLEEP PARALYSIS
paralysis occurring at awakening or sleep onset; it represents extension of the atonia of REM sleep into the waking state and is often seen in those suffering from narcolepsy or sleep apnea.
 
STENOSIS
an abnormal narrowing or contraction of a body passage or opening; called also arctation, coarctation, and stricture
 
RECEPTIVE APHASIA
inability to understand written, spoken, or tactile speech symbols; also called sensory aphasia or Wernicke's aphasia
 
EMBOLIZATION
therapeutic introduction of a substance into a vessel in order to occlude it
 
ELECTROCONVULSIVE THERAPY (ECT)
a treatment for mental disorders in which an electric current is used to produce convulsions. It is used primarily to treat depression or the depressive phase of bipolar disorder; it has also been used to treat some forms of schizophrenia and acute mania.
 
BRADYKINESIA
slowing down of a movement; gradual loss of spontaneous movement. This is a major symptom of Parkinson’s disease
 
INHIBITORY POST-SYNAPTIC POTENTIAL (IPSP) 
a hyperpolarizing potential recorded in a post-synaptic neuron when activated by an inhibitory neurotransmitter
 
SULCUS
anatomic nomenclature for a groove, trench, or furrow
 
CATAPLEXY
a condition, associated with narcolepsy; marked by abrupt attacks of muscular weakness and hypotonia triggered by an emotional stimulus, such as mirth, anger, or fear
 
WALLERIAN DEGENERATION
fatty degeneration of a nerve fiber that has been severed from its nutritive source
 
CONDUCTIVE HEARING LOSS 
hearing loss caused by impaired transmission of sound waves through the external ear canal to the bones of the middle ear, usually because of a blockage of the external ear or dysfunction of the middle ear. Common causes include obstruction of the ear canal by earwax or a foreign object; perforation of the eardrum; otitis media; otosclerosis; and congenital malformations of the outer or middle ear.
 
CHRONIC 
persisting for a long time; applied to a morbid state, designating one showing little change or extremely slow progression over a long period
 
IN VITRO
within a glass; phenomena that are observed in a test tub or artificial environment
 
CHOREA 
a type of dyskinesia (abnormal movement) characterized by continuing, rapid, dance-like movements
 
EXCITATORY POST-SYNAPTIC POTENTIAL (EPSP) 
a depolarizing potential recorded in a post-synaptic neuron when activated by an excitatory neurotransmitter
 
VERTEBROBASILAR INSUFFICIENCY
transient or intermittent ischemia of the brain stem and cerebellum due to stenosis, thrombosis, or other obstruction of the vertebral or basilar artery; this results in symptoms such as vertigo, diplopia, nystagmus, muscle weakness, and dysarthria
 
COPROLALIA
involuntary utterances of vulgar or obscene words; seen in Tourette’s syndrome
 
VENTRICULAR TACHYCARDIA 
an abnormally rapid ventricular rhythm with aberrant ventricular excitation, characterized by at least three consecutive ventricular complexes of more than 100 beats per minute
 
MAGNETOENCEPHALOGRAPHY (MEG) 
a noninvasive imaging technique that measures the magnetic fields produced by electrical currents in the brain; MEG uses superconducting quantum interference devices (SQUIDs)
 
AUTOSOMAL RECESSIVE
two copies of an abnormal gene must be present for the disease or trait to develop
 
ACETABULUM
the cup-shaped cavity on the lateral surface of the hip bone. It holds the round head of the femur (thigh bone)
 
EPIDURAL HEMATOMA
a hematoma between the dura mater and the skull, usually caused by a heavy blow to the head that damages the upper surface of the dura mater. This type of hematoma is the result of rupture of a relatively large meningeal artery, with rapid leakage of blood that increases intracranial pressure, which can be fatal in a short period of time. Symptoms occur within a few hours after injury and may include sudden or gradual loss of consciousness, partial or full paralysis on the side opposite the injury, and dilation of the pupil of the eye on the same side as the injury.
 
ANTAGONIST
a substance that tends to modify the action of another; a drug that binds to a cellular receptor for a neurotransmitter or a drug blocking the action of a substance without producing any physiological effect itself
 
DEPOLARIZATION
changing the resting potential of a neuron to less negative, moving toward threshold
 
HIPPOS
abnormal exaggeration of the rhythmic contraction and dilation of the pupil; independent of changes in illumination or in fixation of the eyes
 
HETEROTOPIA
displacement of parts; displacement of gray matter, typically into the deep cerebral white matter
 
AKINESIA
absence or difficulty in producing body movements
 
IN VIVO
within the body; phenomena that are observable in a living organism
 
NEUROBLASTOMA
a malignant tumor derived from primitive ganglion cells usually arising in the autonomic nervous system or the adrenal medulla; affects mostly infants and children up to 10 years of age.
 
SUBARACHNOID SPACE
space between the arachnoid and pia mater (under the arachnoid and above the pia) in which cerebrospinal fluid (CSF) circulates
 
CAPACITANCE
the ability to store a charge. Capacitors block direct current but pass alternating current. The unit of capacitance is the farad
 
ANTIDROMIC
conduction of action potentials in the opposite direction, e.g., conduction of potentials toward the periphery in a sensory axon
 
ACTION TREMOR 
rhythmic, involuntary movement of a limb when movement is initiated, e.g., when writing or lifting a cup
 
REM REBOUND
the phenomenon in which a person deprived of rapid eye movement (REM) sleep for a prolonged period will when permitted to sleep undisturbed compensate by having increased REM sleep
 
GLASGOW COMA SCALE
a clinical tool used to assess the degree of consciousness and neurological functioning - and therefore severity of brain injury - by testing motor responsiveness, verbal acuity, and eye opening
 
SCHWANN CELLS
cells that produce the myelin sheath around axons in the peripheral nervous system
 
SALT BRIDGE
when the conductive medium (paste, salt jelly…) between two electrodes has smeared and joined making the two electrodes record as one big electrode
 
PROXIMAL
closer to the center of the body; opposite of distal
 
ANEURYSM
a balloon-like sac in the wall of an artery, vein, or heart caused by a weakening of the wall by injury, disease, or abnormality present at birth
 
ANASTOMOSIS
a connection between two vessels; on opening created by surgical, traumatic, or pathological means between two normally separate spaces or organs
 
HYPOCAPNIA
a state in which the level of carbon dioxide in the blood is lower than normal; can result from deep or rapid breathing
 
BONE CONDUCTION
transmission of sound to inner ear is mediated by mechanical vibration of the cranial bones
 
TEMPORAL DISPERSION
signals traveling at different rates in different portions of a nerve creating a “bumpy” looking picture on the EP or NCS computer screen
 
CATHODE
the negative terminal of an electrolytic cell
 
NEUROFIBROMATOSIS
a familial disorder characterized by developmental changes in the nervous system, muscles, bones, and skin
 
GLIOBLASTOMA MULTIFORME
rapidly growing malignant glioma usually occurring in adults
 
METASTATIC
spreading from other primary carcinomas within the body
 
OCULOMOTOR
related to or causing movements of the eyeball
 
CLUSTER HEADACHES
vascular headaches that occur in clusters, i.e., daily headaches for weeks or months before disappearing for months or years characterized by unilateral excruciating pain in and around one eye; more common in males than females
 
APOPTOSIS
programmed cell death induced by specialized biochemical pathways, often serving a specific purpose in the development of the animal
 
NECROSIS
cell death due to external factors, such as lack of oxygen or physical damage, that disrupt the normal biochemical processes in the cell
 
GAMMA-AMINO BITYRIC ACID – GABA
an amino acid neurotransmitter whose primary function is to inhibit the firing of neurons
 
MANIA
a mental disorder characterized by excessive excitement, exalted feelings, elevated mood, psychomotor overactivity, and overproduction of ideas
 
HIPPOCAMPUS
a seahorse-shaped structure located within the brain and is part of the limbic system. Learning and memory formation are its major known functions
 
RAREFACTION
the first major acoustic wave applies a negative pressure in front of the diaphragm and air goes away from the eardrum 
 
ECTODERM
outermost embryonic layer from which skin, hair, nails, nerve, and brain tissue arise
 
REFLEX EPILEPSY 
seizures triggered by something in the environment, such as flashing lights, certain types of music, or particular odors. Also known as environmental epilepsy
 
INHIBITORY POSTSYNAPTIC POTENTIALS – IPSP
change in the membrane voltage of a postsynaptic neuron that makes it more difficult to fire an action potential
 
RESTLESS LEG SYNDROME
condition that occurs shortly after bedtime in which the legs feel uncomfortable unless moved
 
NODES OF RANVIER
regularly spaced, about one micrometer gap in the myelin sheath around an axon
 
ORTHODROMIC RECORDING
the stimulus is distal and the recording site is proximal so the impulses travel in the same direction as naturally arising sensory impulses
 
SOMNAMBULISM
a sleep disorder, a parasomnia, where the person rises out of bed and walks about or performs other complex motor behavior while asleep
 
ICP – INTRACRANIAL PRESSURE
the amount of pressure exerted inside the skull by brain tissue, blood, and cerebrospinal fluid
 
DELIRIUM 
syndrome with the clinical picture of clouding of consciousness; changes in psychomotor activity; alterations in sleep, speech, and perception; and disorientation and memory impairment
 
FIBRILLATIONS 
low amplitude, brief biphasic or triphasic potentials that result from the spontaneous activity of single muscle fibers that have lost their innervation.
 
PET – POSITRON EMISSION TOMOGRAPHY
imaging scan during which a small amount of radioactive glucose is injected and the scanner measures the activity or functional level of the brain by measuring its glucose
 
SARS - SEVERE ACQUIRED RESPIRATORY SYNDROME
severe form of pneumonia characterized by fever, coughing, difficulty breathing, and hypoxia caused by the SARS coronavirus
 
EMBOLISM
the sudden blocking of an artery by a clot or foreign material which has been brought to the site of the obstruction by the blood current
 
PAPILLEDEMA
edema (swelling) of the optic disk most commonly due to increased intracranial pressure; also called choked disk
 
SUBDURAL HEMATOMA 
a collection of blood under the dura mater (the outermost meningeal covering of the brain and spinal cord)
 
DYSPHONIA
difficulty in speaking
 
SIGNAL-TO-NOISE RATIO
S/N ratio – the amplitude of the signal divided by the amplitude of the noise
 
LOGOCLONIA 
spasmodic repetition of words or parts of words, particularly the end syllables, often occurring in Alzheimer’s disease
 
STEREOGNOSIS
the ability to have knowledge (gnosis) of the solidness (stereo) of an object using the sense of touch
 
MONTAGE 
an organized combination of electrode derivations recording at the same time
 
GANGLION
a group of nerve cell bodies usually located outside the central nervous system; occasionally applied to certain nuclear groups within the brain or spinal cord such as the basal ganglia
 
WERNICKE’S APHASIA
Language disorder caused by damage to Wernicke’s area located in the temporal lobe of the dominant hemisphere. The disorder is characterized by fluent but meaningless speech and severe impairment of the ability to understand spoken or written words.
 
POLYMORPHIC
multiple frequencies that together create complex waveforms
 
MRSA 
Methicillin-resistant Staphylococcus aureus – strain of Staphylococcus aureus that has become resistant to certain antibiotics
 
GAMMA FREQUENCY
above 30 Hz (unlimited in upper range); exact width of the gamma range is still being debated
 
HYPOTONIA
a condition of diminished tone of the skeletal muscles; diminished resistance of muscle to passive stretching
 
POSTICTAL
after a seizure. The EEG shows postictal slowing. The patient has postictal confusion

 

PLEDs - Periodic Lateralized Epileptiform Discharges
an EEG pattern that occurs in a variety of acute neurologic conditions, most often cerebral infarctions
 
HYPNAGOGIC HALLUCINATIONS
vivid often frightening, dreamlike experiences that occur while dozing, falling asleep or upon awakening
 
EPILEPTOGENSIS
the production or development of epilepsy
 
BATTLE’S SIGN
discoloration over the skin of the mastoid region of the skull seen with factures of the base of the skull

 

DEMENTIA

a general loss of cognitive abilities, including impairment of memory as well as one or more of the following: aphasia, apraxia, agnosia, or disturbed planning, organizing, and abstract thinking abilities

 

PERIODICITY 

the distribution of patterns or elements in time; the appearance of a particular EEG activity at more or less regular intervals

 
INTERNEURON 
any neuron in a chain of neurons that is situated between a primary sensory neuron and the final motor neuron
 
PATHOPHYSIOLOGY
the functional changes that accompany a particular syndrome or disease

 

TODD’S PARESIS
also known as Todd’s paralysis – focal motor weakness that occurs after an epileptic seizure

 

CEREBRUM 
the main portion of the brain occupying the upper part of the cranial cavity; its two hemispheres form the largest part of the central nervous system in humans.
 
ATTENUATION
reduction of amplitude of EEG activity resulting from decreased voltage; may be seen during painful stimulation while recording an EEG on a patient in coma

 

RETROGRADE AMNESIA 

inability to recall events that occurred before the actual onset or cause (e.g., head trauma) of memory loss

 

ACTIVE SLEEP

sleep stage in a neonate characterized by rapid eye movement (REM), irregular respirations, loss of muscle tone, and a continuous EEG pattern

 
GYRUS 

one of the convolutions of the cerebral hemispheres caused by infolding of the cortex

 

SHORT TERM MEMORY 

memory that is lost within a brief period (from a few seconds to a maximum of about 30 minutes) unless reinforced

 

VERTEBRECTOMY

excision of a vertebra

 

BRADYCARDIA 

slowness of the heartbeat as evidenced by slowing of the pulse rate to less than 60 beats per minute

 

PROGNOSIS

a forecast as to the probable outcome of an attack of disease

 
ROSTRAL 
in human anatomy, toward the oral and nasal region 

 

CONCEPTUAL AGE (CA)

time in utero (gestational age) plus time since birth; infant born at 34 weeks gestational age who is 2 weeks old has a CA of 36 weeks.

ALIASING
signal distortion that occurs when too low sample rates are used to digitize analog signals.

SPHENOIDAL ELECTRODES
electrodes inserted (by a physician) between the zygoma and the sigmoid notch in the mandible until they are in contact with the base of the skull lateral to the foramen ovale to gain closer access to the temporal lobe and to portions of the temporal lobe not examined with scalp electrodes.

AGORAPHOBIA
intense, irrational fear of open places

SUBDURAL HEMATOMA
accumulation of blood and possibly cerebrospinal fluid in the space under the dura mater and above the arachnoid.

NEUROCYSTICERCOSIS
infection of the central nervous system with the larval form of Taenia solium. Manifestations are highly variable depending on the location and number of cysts and include seizures, hydrocephalus, and a variety of neurological dysfunctions.

MALIGNANT
tending to become progressively worse and to result in death

TRIGEMINAL NEURALGIA
excruciating episodic pain in the area supplied by the trigeminal nerve, often precipitated by stimulation of well-defined trigger points.

FLACCID
weak or soft

THROMBOSIS
the formation or development of a stationary blood clot along the wall of a blood vessel.

RETICULAR ACTIVATING SYSTEM (RAS)
the system of cells of the reticular formation of the medulla that receive collaterals from the ascending sensory pathways and project to higher centers; they control the overall degree of central nervous system activity including wakefulness, attentiveness, and sleep.

NEUROPSYCHOLOGY
a discipline combining neurology and psychology to study the relationship between the functioning of the brain and cognitive processes or behavior using psychological testing and assessment to assay central nervous system function and diagnose specific behavioral or cognitive deficits or disorders.

ENCEPHALOMALACIA
softening of the brain, especially that caused by an infarct.

SETTING SUN SIGN
downward deviation of the eyes, so that each iris resembles a sun setting beneath the lower lid, with the sclera exposed between it and the upper lid; this indicates increased intracranial pressure, hydrocephalus, or a pineal gland tumor.

ANGIOGRAPHY
the radiographic visualization of blood vessels following introduction of a contrast material.

BURST SUPPRESSION
EEG activity characterized by bursts of slow activity (theta or delta) with spikes and/or sharp waves intermixed with relatively long intervening periods of very low voltage activity.

BABINSKI’S REFLEX
dorsiflexion (upward flexion) of the big toe on stimulating the sole of the foot; normal in infants but in others a sign of a lesion in the central nervous system, particularly in the pyramidal tract.

HEMIPLEGIA
paralysis of one side of the body.

OHM
the unit of electrical resistance being equivalent to the resistance of a circuit in which a current of one ampere is maintained by an electromotive force of one volt.

ANOSMIA
absence of the sense of smell. 

AXON
the process of a neuron by which impulses travel away from the cell body; at the terminal end of the axon impulses are transmitted to other neurons or to effector organs.

PHOTOPAROXYSMAL RESPONSE
response to intermittent photic stimulation characterized by spike and wave and multiple spike and wave complexes that are bilaterally synchronous and symmetrical.  

BLEPHAROSPASM 
tonic spasm of the orbicularis oculi muscle producing more or less complete closure of the eyelids.

HERTZ
the unit of frequency equal to one cycle per second; abbreviated Hz.

CORPUS CALLOSUM 
an arched mass of white matter found in the depths of the longitudinal fissure that connects the cerebral hemispheres.

AURA
a subjective sensation or motor phenomenon that sometimes gives warning of an approaching generalized or complex partial seizure. Formerly considered part of the prodrome (symptom indicating the onset) of a seizure, it is now known to be itself a type of simple partial seizure and may occur without progression to a more serious attack.

IDIOPATHIC
an unknown cause or origin

CREUTZFELDT-JAKOB DISEASE
a rare prion disease associated with a number of different mutations of the prion protein gene, existing in sporadic, familial, and infectious forms with onset usually in middle life.

PRION
any of several protease-resistant, insoluble, transmissible isoforms of the 27-30 kD core of the prion protein that cause a group of progressive neurodegenerative diseases in humans and animals.

GLOSSOKINETIC POTENTIALS
artifacts caused by tongue movement; the tip of the tongue is more negative than the root. Artifacts become prominent when the patient talks or swallows

TRENDELENBURG'S POSITION
the patient is supine on the table or bed; the head is tilted downward 30 to 40 degrees, and the table or bed is angulated beneath the knees

EPINEPHRINE
a catecholamine hormone secreted by the adrenal medulla and a neurotransmitter that is a potent stimulator of adrenergic receptors of the sympathetic nervous system and a powerful cardiac stimulant that accelerates the heart rate and increases cardiac output

AUTOMATISM
aimless and semi-purposeful behavior that is not under conscious control and is performed without conscious knowledge; seen in complex partial seizures, catatonic schizophrenia, dissociative fugue.

HYPOTHALAMUS
the ventral part of the diencephalon forming the floor and part of the lateral wall of the third ventricle. Activates, controls, and integrates the peripheral autonomic mechanisms, endocrine activity, and many somatic functions, such as general regulation of water balance, body temperature, sleep, and food intake

MYASTHENIA GRAVIS
a disorder of neuromuscular function due to the presence of antibodies to acetylcholine receptors at the neuromuscular junction. Characteristics include muscular fatigue and exhaustion

MU
7 to 11 hertz arch-shaped waveforms that occur unilaterally or bilaterally over the central regions maximal at the C3 and/or C4 electrodes; attenuated by fisting of the contralateral hand

PHOTOPHOBIA
dislike of the light that is a common complaint of patients with migraine headaches

CONCUSSION
an injury caused by a violent shaking of the brain

LOW VOLTAGE EEG
a waking EEG characterized by not more than 30 microvolts over all head regions

HYDROCEPHALUS
an increase in the accumulation of cerebrospinal fluid within the ventricles of the head

ACTIVATION PROCEDURES
methods such as hyperventilation, photic stimulation, sleep, eye opening and eye closing used to bring out abnormalities. These procedures are known to activate or stimulate EEG abnormalities in some patients

DIFFUSE
widespread, occurring over large areas of one or both hemispheres

REACTIVITY
a pattern that changes with stimulation such as eye opening that causes attenuation of the alpha activity in the occipital leads

FOCAL
in a clearly delineated area of the brain as in a focal temporal spike or focal slowing

ANEURYSM
a weak bulge in an artery wall prone to rupture causing a hemorrhage

BURST SUPPRESSION
a pattern characterized by bursts of theta and/or delta intermixed with faster frequencies with intervening periods of relative quiescence or flattening

VOLTAGE
an electrical potential or potential difference expressed in volts. In EEG a measurement of the output deflection in millimeters multiplied by the sensitivity will obtain the output voltage

IN PHASE
two channels of EEG recording one event of the same polarity causing like deflections with the same timing

NYSTAGMUS
rapid involuntary eye movements characterized by a slow drift in one direction and a rapid movement in the opposite direction

TIC
a recurrent spasm

POSITIVE OCCIPITAL SHARP TRANSIENTS of SLEEP (POSTS)
normal sleep pattern that has a positive polarity and sharp morphology and is seen in light sleep

ISCHEMIA
a restriction in the blood supply generally due to factors in the blood vessels with resultant damage or dysfunction of the tissue supplied by the blood vessel

FAST FOURIER TRANSFORM (FFT)
an algorithm used to process digital signals and display comparisons of power (voltage) in the various frequency bands