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Aphasia: A cognitive disorder marked by an impaired ability to comprehend or express language in its written or spoken form. This condition is caused by diseases which affect the language areas of the dominant hemisphere. Clinical features are used to classify the various subtypes of this condition. General categories include receptive, expressive, and mixed forms of aphasia.Aphasia, Primary Progressive: A progressive form of dementia characterized by the global loss of language abilities and initial preservation of other cognitive functions. Fluent and nonfluent subtypes have been described. Eventually a pattern of global cognitive dysfunction, similar to ALZHEIMER DISEASE, emerges. Pathologically, there are no Alzheimer or PICK DISEASE like changes, however, spongiform changes of cortical layers II and III are present in the TEMPORAL LOBE and FRONTAL LOBE. (From Brain 1998 Jan;121(Pt 1):115-26)Neural Conduction: The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.Heart Conduction System: An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.Aphasia, Conduction: A type of fluent aphasia characterized by an impaired ability to repeat one and two word phrases, despite retained comprehension. This condition is associated with dominant hemisphere lesions involving the arcuate fasciculus (a white matter projection between Broca's and Wernicke's areas) and adjacent structures. Like patients with Wernicke aphasia (APHASIA, WERNICKE), patients with conduction aphasia are fluent but commit paraphasic errors during attempts at written and oral forms of communication. (From Adams et al., Principles of Neurology, 6th ed, p482; Brain & Bannister, Clinical Neurology, 7th ed, p142; Kandel et al., Principles of Neural Science, 3d ed, p848)Anomia: A language dysfunction characterized by the inability to name people and objects that are correctly perceived. The individual is able to describe the object in question, but cannot provide the name. This condition is associated with lesions of the dominant hemisphere involving the language areas, in particular the TEMPORAL LOBE. (From Adams et al., Principles of Neurology, 6th ed, p484)Primary Progressive Nonfluent Aphasia: A form of frontotemporal lobar degeneration and a progressive form of dementia characterized by motor speech impairment and AGRAMMATISM, with relative sparing of single word comprehension and semantic memory.Language Tests: Tests designed to assess language behavior and abilities. They include tests of vocabulary, comprehension, grammar and functional use of language, e.g., Development Sentence Scoring, Receptive-Expressive Emergent Language Scale, Parsons Language Sample, Utah Test of Language Development, Michigan Language Inventory and Verbal Language Development Scale, Illinois Test of Psycholinguistic Abilities, Northwestern Syntax Screening Test, Peabody Picture Vocabulary Test, Ammons Full-Range Picture Vocabulary Test, and Assessment of Children's Language Comprehension.Speech Therapy: Treatment for individuals with speech defects and disorders that involves counseling and use of various exercises and aids to help the development of new speech habits.Language Therapy: Rehabilitation of persons with language disorders or training of children with language development disorders.Atrioventricular Node: A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.Agraphia: Loss or impairment of the ability to write (letters, syllables, words, or phrases) due to an injury to a specific cerebral area or occasionally due to emotional factors. This condition rarely occurs in isolation, and often accompanies APHASIA. (From Adams et al., Principles of Neurology, 6th ed, p485; APA, Thesaurus of Psychological Index Terms, 1994)Apraxias: A group of cognitive disorders characterized by the inability to perform previously learned skills that cannot be attributed to deficits of motor or sensory function. The two major subtypes of this condition are ideomotor (see APRAXIA, IDEOMOTOR) and ideational apraxia, which refers to loss of the ability to mentally formulate the processes involved with performing an action. For example, dressing apraxia may result from an inability to mentally formulate the act of placing clothes on the body. Apraxias are generally associated with lesions of the dominant PARIETAL LOBE and supramarginal gyrus. (From Adams et al., Principles of Neurology, 6th ed, pp56-7)Semantics: The relationships between symbols and their meanings.Heart Block: Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.Language: A verbal or nonverbal means of communicating ideas or feelings.Speech: Communication through a system of conventional vocal symbols.Language Disorders: Conditions characterized by deficiencies of comprehension or expression of written and spoken forms of language. These include acquired and developmental disorders.Neuropsychological Tests: Tests designed to assess neurological function associated with certain behaviors. They are used in diagnosing brain dysfunction or damage and central nervous system disorders or injury.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Bone Conduction: Transmission of sound waves through vibration of bones in the SKULL to the inner ear (COCHLEA). By using bone conduction stimulation and by bypassing any OUTER EAR or MIDDLE EAR abnormalities, hearing thresholds of the cochlea can be determined. Bone conduction hearing differs from normal hearing which is based on air conduction stimulation via the EAR CANAL and the TYMPANIC MEMBRANE.Electrocardiography: Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.Dyslexia, Acquired: A receptive visual aphasia characterized by the loss of a previously possessed ability to comprehend the meaning or significance of handwritten words, despite intact vision. This condition may be associated with posterior cerebral artery infarction (INFARCTION, POSTERIOR CEREBRAL ARTERY) and other BRAIN DISEASES.Median Nerve: A major nerve of the upper extremity. In humans, the fibers of the median nerve originate in the lower cervical and upper thoracic spinal cord (usually C6 to T1), travel via the brachial plexus, and supply sensory and motor innervation to parts of the forearm and hand.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Speech Production Measurement: Measurement of parameters of the speech product such as vocal tone, loudness, pitch, voice quality, articulation, resonance, phonation, phonetic structure and prosody.Linguistics: The science of language, including phonetics, phonology, morphology, syntax, semantics, pragmatics, and historical linguistics. (Random House Unabridged Dictionary, 2d ed)Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Stroke: A group of pathological conditions characterized by sudden, non-convulsive loss of neurological function due to BRAIN ISCHEMIA or INTRACRANIAL HEMORRHAGES. Stroke is classified by the type of tissue NECROSIS, such as the anatomic location, vasculature involved, etiology, age of the affected individual, and hemorrhagic vs. non-hemorrhagic nature. (From Adams et al., Principles of Neurology, 6th ed, pp777-810)Apraxia, Ideomotor: A form of apraxia characterized by an acquired inability to carry out a complex motor activity despite the ability to mentally formulate the action. This condition has been attributed to a disruption of connections between the dominant parietal cortex and supplementary and premotor cortical regions in both hemispheres. (From Adams et al., Principles of Neurology, 6th ed, p57)Arrhythmias, Cardiac: Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.Refractory Period, Electrophysiological: The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.Names: Personal names, given or surname, as cultural characteristics, as ethnological or religious patterns, as indications of the geographic distribution of families and inbreeding, etc. Analysis of isonymy, the quality of having the same or similar names, is useful in the study of population genetics. NAMES is used also for the history of names or name changes of corporate bodies, such as medical societies, universities, hospitals, government agencies, etc.Ulnar Nerve: A major nerve of the upper extremity. In humans, the fibers of the ulnar nerve originate in the lower cervical and upper thoracic spinal cord (usually C7 to T1), travel via the medial cord of the brachial plexus, and supply sensory and motor innervation to parts of the hand and forearm.Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Verbal Behavior: Includes both producing and responding to words, either written or spoken.Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.Electrophysiologic Techniques, Cardiac: Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Atrophy: Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes.Speech Disorders: Acquired or developmental conditions marked by an impaired ability to comprehend or generate spoken forms of language.Speech-Language Pathology: The study of speech or language disorders and their diagnosis and correction.Atrioventricular Block: Impaired impulse conduction from HEART ATRIA to HEART VENTRICLES. AV block can mean delayed or completely blocked impulse conduction.Comprehension: The act or fact of grasping the meaning, nature, or importance of; understanding. (American Heritage Dictionary, 4th ed) Includes understanding by a patient or research subject of information disclosed orally or in writing.Frontotemporal Lobar Degeneration: Heterogeneous group of neurodegenerative disorders characterized by frontal and temporal lobe atrophy associated with neuronal loss, gliosis, and dementia. Patients exhibit progressive changes in social, behavioral, and/or language function. Multiple subtypes or forms are recognized based on presence or absence of TAU PROTEIN inclusions. FTLD includes three clinical syndromes: FRONTOTEMPORAL DEMENTIA, semantic dementia, and PRIMARY PROGRESSIVE NONFLUENT APHASIA.Frontotemporal Dementia: The most common clinical form of FRONTOTEMPORAL LOBAR DEGENERATION, this dementia presents with personality and behavioral changes often associated with disinhibition, apathy, and lack of insight.Tibial Nerve: The medial terminal branch of the sciatic nerve. The tibial nerve fibers originate in lumbar and sacral spinal segments (L4 to S2). They supply motor and sensory innervation to parts of the calf and foot.Functional Laterality: Behavioral manifestations of cerebral dominance in which there is preferential use and superior functioning of either the left or the right side, as in the preferred use of the right hand or right foot.Atrial Flutter: Rapid, irregular atrial contractions caused by a block of electrical impulse conduction in the right atrium and a reentrant wave front traveling up the inter-atrial septum and down the right atrial free wall or vice versa. Unlike ATRIAL FIBRILLATION which is caused by abnormal impulse generation, typical atrial flutter is caused by abnormal impulse conduction. As in atrial fibrillation, patients with atrial flutter cannot effectively pump blood into the lower chambers of the heart (HEART VENTRICLES).Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Electrodiagnosis: Diagnosis of disease states by recording the spontaneous electrical activity of tissues or organs or by the response to stimulation of electrically excitable tissue.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Temporal Lobe: Lower lateral part of the cerebral hemisphere responsible for auditory, olfactory, and semantic processing. It is located inferior to the lateral fissure and anterior to the OCCIPITAL LOBE.Psycholinguistics: A discipline concerned with relations between messages and the characteristics of individuals who select and interpret them; it deals directly with the processes of encoding (phonetics) and decoding (psychoacoustics) as they relate states of messages to states of communicators.Dysarthria: Disorders of speech articulation caused by imperfect coordination of pharynx, larynx, tongue, or face muscles. This may result from CRANIAL NERVE DISEASES; NEUROMUSCULAR DISEASES; CEREBELLAR DISEASES; BASAL GANGLIA DISEASES; BRAIN STEM diseases; or diseases of the corticobulbar tracts (see PYRAMIDAL TRACTS). The cortical language centers are intact in this condition. (From Adams et al., Principles of Neurology, 6th ed, p489)Dominance, Cerebral: Dominance of one cerebral hemisphere over the other in cerebral functions.Sural Nerve: A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Brain Mapping: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.Frontal Lobe: The part of the cerebral hemisphere anterior to the central sulcus, and anterior and superior to the lateral sulcus.Sinoatrial Node: The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).Catheter Ablation: Removal of tissue with electrical current delivered via electrodes positioned at the distal end of a catheter. Energy sources are commonly direct current (DC-shock) or alternating current at radiofrequencies (usually 750 kHz). The technique is used most often to ablate the AV junction and/or accessory pathways in order to interrupt AV conduction and produce AV block in the treatment of various tachyarrhythmias.Peripheral Nervous System Diseases: Diseases of the peripheral nerves external to the brain and spinal cord, which includes diseases of the nerve roots, ganglia, plexi, autonomic nerves, sensory nerves, and motor nerves.Wolff-Parkinson-White Syndrome: A form of ventricular pre-excitation characterized by a short PR interval and a long QRS interval with a delta wave. In this syndrome, atrial impulses are abnormally conducted to the HEART VENTRICLES via an ACCESSORY CONDUCTING PATHWAY that is located between the wall of the right or left atria and the ventricles, also known as a BUNDLE OF KENT. The inherited form can be caused by mutation of PRKAG2 gene encoding a gamma-2 regulatory subunit of AMP-activated protein kinase.Communication Aids for Disabled: Equipment that provides mentally or physically disabled persons with a means of communication. The aids include display boards, typewriters, cathode ray tubes, computers, and speech synthesizers. The output of such aids includes written words, artificial speech, language signs, Morse code, and pictures.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Reaction Time: The time from the onset of a stimulus until a response is observed.Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Motor Neurons: Neurons which activate MUSCLE CELLS.Atrial Function: The hemodynamic and electrophysiological action of the HEART ATRIA.Diabetic Neuropathies: Peripheral, autonomic, and cranial nerve disorders that are associated with DIABETES MELLITUS. These conditions usually result from diabetic microvascular injury involving small blood vessels that supply nerves (VASA NERVORUM). Relatively common conditions which may be associated with diabetic neuropathy include third nerve palsy (see OCULOMOTOR NERVE DISEASES); MONONEUROPATHY; mononeuropathy multiplex; diabetic amyotrophy; a painful POLYNEUROPATHY; autonomic neuropathy; and thoracoabdominal neuropathy. (From Adams et al., Principles of Neurology, 6th ed, p1325)NAV1.5 Voltage-Gated Sodium Channel: A voltage-gated sodium channel subtype that mediates the sodium ion PERMEABILITY of CARDIOMYOCYTES. Defects in the SCN5A gene, which codes for the alpha subunit of this sodium channel, are associated with a variety of CARDIAC DISEASES that result from loss of sodium channel function.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Thalamic Diseases: Disorders of the centrally located thalamus, which integrates a wide range of cortical and subcortical information. Manifestations include sensory loss, MOVEMENT DISORDERS; ATAXIA, pain syndromes, visual disorders, a variety of neuropsychological conditions, and COMA. Relatively common etiologies include CEREBROVASCULAR DISORDERS; CRANIOCEREBRAL TRAUMA; BRAIN NEOPLASMS; BRAIN HYPOXIA; INTRACRANIAL HEMORRHAGES; and infectious processes.Ranvier's Nodes: Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.Agnosia: Loss of the ability to comprehend the meaning or recognize the importance of various forms of stimulation that cannot be attributed to impairment of a primary sensory modality. Tactile agnosia is characterized by an inability to perceive the shape and nature of an object by touch alone, despite unimpaired sensation to light touch, position, and other primary sensory modalities.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Connexin 43: A 43-kDa peptide which is a member of the connexin family of gap junction proteins. Connexin 43 is a product of a gene in the alpha class of connexin genes (the alpha-1 gene). It was first isolated from mammalian heart, but is widespread in the body including the brain.Tachycardia, Atrioventricular Nodal Reentry: Abnormally rapid heartbeats caused by reentry of atrial impulse into the dual (fast and slow) pathways of ATRIOVENTRICULAR NODE. The common type involves a blocked atrial impulse in the slow pathway which reenters the fast pathway in a retrograde direction and simultaneously conducts to the atria and the ventricles leading to rapid HEART RATE of 150-250 beats per minute.Peroneal Nerve: The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot.Atrial Fibrillation: Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.Carpal Tunnel Syndrome: Entrapment of the MEDIAN NERVE in the carpal tunnel, which is formed by the flexor retinaculum and the CARPAL BONES. This syndrome may be associated with repetitive occupational trauma (CUMULATIVE TRAUMA DISORDERS); wrist injuries; AMYLOID NEUROPATHIES; rheumatoid arthritis (see ARTHRITIS, RHEUMATOID); ACROMEGALY; PREGNANCY; and other conditions. Symptoms include burning pain and paresthesias involving the ventral surface of the hand and fingers which may radiate proximally. Impairment of sensation in the distribution of the median nerve and thenar muscle atrophy may occur. (Joynt, Clinical Neurology, 1995, Ch51, p45)