Conditioning, Classical: Learning that takes place when a conditioned stimulus is paired with an unconditioned stimulus.Conditioning (Psychology): A general term referring to the learning of some particular response.Conditioning, Eyelid: Reflex closure of the eyelid occurring as a result of classical conditioning.Transplantation Conditioning: Preparative treatment of transplant recipient with various conditioning regimens including radiation, immune sera, chemotherapy, and/or immunosuppressive agents, prior to transplantation. Transplantation conditioning is very common before bone marrow transplantation.Fear: The affective response to an actual current external danger which subsides with the elimination of the threatening condition.Conditioning, Operant: Learning situations in which the sequence responses of the subject are instrumental in producing reinforcement. When the correct response occurs, which involves the selection from among a repertoire of responses, the subject is immediately reinforced.Blinking: Brief closing of the eyelids by involuntary normal periodic closing, as a protective measure, or by voluntary action.Association Learning: The principle that items experienced together enter into a connection, so that one tends to reinstate the other.Electroshock: Induction of a stress reaction in experimental subjects by means of an electrical shock; applies to either convulsive or non-convulsive states.Freezing Reaction, Cataleptic: An induced response to threatening stimuli characterized by the cessation of body movements, except for those that are involved with BREATHING, and the maintenance of an immobile POSTURE.Air Conditioning: The maintenance of certain aspects of the environment within a defined space to facilitate the function of that space; aspects controlled include air temperature and motion, radiant heat level, moisture, and concentration of pollutants such as dust, microorganisms, and gases. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Amygdala: Almond-shaped group of basal nuclei anterior to the INFERIOR HORN OF THE LATERAL VENTRICLE of the TEMPORAL LOBE. The amygdala is part of the limbic system.Extinction, Psychological: The procedure of presenting the conditioned stimulus without REINFORCEMENT to an organism previously conditioned. It refers also to the diminution of a conditioned response resulting from this procedure.Avoidance Learning: A response to a cue that is instrumental in avoiding a noxious experience.Busulfan: An alkylating agent having a selective immunosuppressive effect on BONE MARROW. It has been used in the palliative treatment of chronic myeloid leukemia (MYELOID LEUKEMIA, CHRONIC), but although symptomatic relief is provided, no permanent remission is brought about. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), busulfan is listed as a known carcinogen.Transplantation, Homologous: Transplantation between individuals of the same species. Usually refers to genetically disparate individuals in contradistinction to isogeneic transplantation for genetically identical individuals.Memory: Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory.Hematopoietic Stem Cell Transplantation: Transfer of HEMATOPOIETIC STEM CELLS from BONE MARROW or BLOOD between individuals within the same species (TRANSPLANTATION, HOMOLOGOUS) or transfer within the same individual (TRANSPLANTATION, AUTOLOGOUS). Hematopoietic stem cell transplantation has been used as an alternative to BONE MARROW TRANSPLANTATION in the treatment of a variety of neoplasms.Behavior, Animal: The observable response an animal makes to any situation.Acoustic Stimulation: Use of sound to elicit a response in the nervous system.Galvanic Skin Response: A change in electrical resistance of the skin, occurring in emotion and in certain other conditions.Vidarabine: A nucleoside antibiotic isolated from Streptomyces antibioticus. It has some antineoplastic properties and has broad spectrum activity against DNA viruses in cell cultures and significant antiviral activity against infections caused by a variety of viruses such as the herpes viruses, the VACCINIA VIRUS and varicella zoster virus.Myeloablative Agonists: Agents that destroy bone marrow activity. They are used to prepare patients for BONE MARROW TRANSPLANTATION or STEM CELL TRANSPLANTATION.Whole-Body Irradiation: Irradiation of the whole body with ionizing or non-ionizing radiation. It is applicable to humans or animals but not to microorganisms.Graft vs Host Disease: The clinical entity characterized by anorexia, diarrhea, loss of hair, leukopenia, thrombocytopenia, growth retardation, and eventual death brought about by the GRAFT VS HOST REACTION.Learning: Relatively permanent change in behavior that is the result of past experience or practice. The concept includes the acquisition of knowledge.Appetitive Behavior: Animal searching behavior. The variable introductory phase of an instinctive behavior pattern or sequence, e.g., looking for food, or sequential courtship patterns prior to mating.Rats, Long-Evans: An outbred strain of rats developed in 1915 by crossing several Wistar Institute white females with a wild gray male. Inbred strains have been derived from this original outbred strain, including Long-Evans cinnamon rats (RATS, INBRED LEC) and Otsuka-Long-Evans-Tokushima Fatty rats (RATS, INBRED OLETF), which are models for Wilson's disease and non-insulin dependent diabetes mellitus, respectively.Cues: Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.Transplantation Chimera: An organism that, as a result of transplantation of donor tissue or cells, consists of two or more cell lines descended from at least two zygotes. This state may result in the induction of donor-specific TRANSPLANTATION TOLERANCE.Bone Marrow Transplantation: The transference of BONE MARROW from one human or animal to another for a variety of purposes including HEMATOPOIETIC STEM CELL TRANSPLANTATION or MESENCHYMAL STEM CELL TRANSPLANTATION.Startle Reaction: A complex involuntary response to an unexpected strong stimulus usually auditory in nature.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Odors: The volatile portions of substances perceptible by the sense of smell. (Grant & Hackh's Chemical Dictionary, 5th ed)Hematologic Neoplasms: Neoplasms located in the blood and blood-forming tissue (the bone marrow and lymphatic tissue). The commonest forms are the various types of LEUKEMIA, of LYMPHOMA, and of the progressive, life-threatening forms of the MYELODYSPLASTIC SYNDROMES.Hippocampus: A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Neuronal Plasticity: The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.Nictitating Membrane: A fold of the mucous membrane of the CONJUNCTIVA in many animals. At rest, it is hidden in the medial canthus. It can extend to cover part or all of the cornea to help clean the CORNEA.Smell: The ability to detect scents or odors, such as the function of OLFACTORY RECEPTOR NEURONS.Reinforcement (Psychology): The strengthening of a conditioned response.Retention (Psychology): The persistence to perform a learned behavior (facts or experiences) after an interval has elapsed in which there has been no performance or practice of the behavior.Antilymphocyte Serum: Serum containing GAMMA-GLOBULINS which are antibodies for lymphocyte ANTIGENS. It is used both as a test for HISTOCOMPATIBILITY and therapeutically in TRANSPLANTATION.Cerebellar Nuclei: Four clusters of neurons located deep within the WHITE MATTER of the CEREBELLUM, which are the nucleus dentatus, nucleus emboliformis, nucleus globosus, and nucleus fastigii.Cerebellum: The part of brain that lies behind the BRAIN STEM in the posterior base of skull (CRANIAL FOSSA, POSTERIOR). It is also known as the "little brain" with convolutions similar to those of CEREBRAL CORTEX, inner white matter, and deep cerebellar nuclei. Its function is to coordinate voluntary movements, maintain balance, and learn motor skills.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.H-Reflex: A monosynaptic reflex elicited by stimulating a nerve, particularly the tibial nerve, with an electric shock.Graft Survival: The survival of a graft in a host, the factors responsible for the survival and the changes occurring within the graft during growth in the host.Lymnaea: A genus of dextrally coiled freshwater snails that includes some species of importance as intermediate hosts of parasitic flukes.Muscimol: A neurotoxic isoxazole isolated from species of AMANITA. It is obtained by decarboxylation of IBOTENIC ACID. Muscimol is a potent agonist of GABA-A RECEPTORS and is used mainly as an experimental tool in animal and tissue studies.Memory, Long-Term: Remembrance of information from 3 or more years previously.Reward: An object or a situation that can serve to reinforce a response, to satisfy a motive, or to afford pleasure.Melphalan: An alkylating nitrogen mustard that is used as an antineoplastic in the form of the levo isomer - MELPHALAN, the racemic mixture - MERPHALAN, and the dextro isomer - MEDPHALAN; toxic to bone marrow, but little vesicant action; potential carcinogen.Reaction Time: The time from the onset of a stimulus until a response is observed.Hermissenda: A genus of marine sea slugs in the family Glaucidae, superorder GASTROPODA, found on the Pacific coast of North America. They are used in behavioral and neurological laboratory studies.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Transplantation, Autologous: Transplantation of an individual's own tissue from one site to another site.Habituation, Psychophysiologic: The disappearance of responsiveness to a repeated stimulation. It does not include drug habituation.Neural Pathways: Neural tracts connecting one part of the nervous system with another.Mice, Inbred C57BLNeurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Cyclophosphamide: Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the LIVER to form the active aldophosphamide. It has been used in the treatment of LYMPHOMA and LEUKEMIA. Its side effect, ALOPECIA, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer.Aplysia: An opisthobranch mollusk of the order Anaspidea. It is used frequently in studies of nervous system development because of its large identifiable neurons. Aplysiatoxin and its derivatives are not biosynthesized by Aplysia, but acquired by ingestion of Lyngbya (seaweed) species.Bees: Insect members of the superfamily Apoidea, found almost everywhere, particularly on flowers. About 3500 species occur in North America. They differ from most WASPS in that their young are fed honey and pollen rather than animal food.Long-Term Potentiation: A persistent increase in synaptic efficacy, usually induced by appropriate activation of the same synapses. The phenomenological properties of long-term potentiation suggest that it may be a cellular mechanism of learning and memory.Mollusca: A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.Chimerism: The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from different individuals. This contrasts with MOSAICISM in which the different cell populations are derived from a single individual.Discrimination Learning: Learning that is manifested in the ability to respond differentially to various stimuli.Histocompatibility Testing: Identification of the major histocompatibility antigens of transplant DONORS and potential recipients, usually by serological tests. Donor and recipient pairs should be of identical ABO blood group, and in addition should be matched as closely as possible for HISTOCOMPATIBILITY ANTIGENS in order to minimize the likelihood of allograft rejection. (King, Dictionary of Genetics, 4th ed)Peripheral Blood Stem Cell Transplantation: Transplantation of stem cells collected from the peripheral blood. It is a less invasive alternative to direct marrow harvesting of hematopoietic stem cells. Enrichment of stem cells in peripheral blood can be achieved by inducing mobilization of stem cells from the BONE MARROW.Neural Inhibition: The function of opposing or restraining the excitation of neurons or their target excitable cells.Evoked Potentials: Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.Taste: The ability to detect chemicals through gustatory receptors in the mouth, including those on the TONGUE; the PALATE; the PHARYNX; and the EPIGLOTTIS.Maze Learning: Learning the correct route through a maze to obtain reinforcement. It is used for human or animal populations. (Thesaurus of Psychological Index Terms, 6th ed)Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Immunosuppressive Agents: Agents that suppress immune function by one of several mechanisms of action. Classical cytotoxic immunosuppressants act by inhibiting DNA synthesis. Others may act through activation of T-CELLS or by inhibiting the activation of HELPER CELLS. While immunosuppression has been brought about in the past primarily to prevent rejection of transplanted organs, new applications involving mediation of the effects of INTERLEUKINS and other CYTOKINES are emerging.Tissue Donors: Individuals supplying living tissue, organs, cells, blood or blood components for transfer or transplantation to histocompatible recipients.TurtlesHistocompatibility: The degree of antigenic similarity between the tissues of different individuals, which determines the acceptance or rejection of allografts.Physical Conditioning, Animal: Diet modification and physical exercise to improve the ability of animals to perform physical activities.Psychology, Experimental: The branch of psychology which seeks to learn more about the fundamental causes of behavior by studying various psychologic phenomena in controlled experimental situations.Cord Blood Stem Cell Transplantation: Transplantation of STEM CELLS collected from the fetal blood remaining in the UMBILICAL CORD and the PLACENTA after delivery. Included are the HEMATOPOIETIC STEM CELLS.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Motor Neurons: Neurons which activate MUSCLE CELLS.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.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.Synapses: Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.Reflex: An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Amnesia, Retrograde: Loss of the ability to recall information that had been previously encoded in memory prior to a specified or approximate point in time. This process may be organic or psychogenic in origin. Organic forms may be associated with CRANIOCEREBRAL TRAUMA; CEREBROVASCULAR ACCIDENTS; SEIZURES; DEMENTIA; and a wide variety of other conditions that impair cerebral function. (From Adams et al., Principles of Neurology, 6th ed, pp426-9)GABA Agonists: Endogenous compounds and drugs that bind to and activate GAMMA-AMINOBUTYRIC ACID receptors (RECEPTORS, GABA).Graft vs Tumor Effect: Immunological rejection of tumor tissue/cells following bone marrow transplantation.Inhibition (Psychology): The interference with or prevention of a behavioral or verbal response even though the stimulus for that response is present; in psychoanalysis the unconscious restraining of an instinctual process.Recurrence: The return of a sign, symptom, or disease after a remission.Stem Cell Transplantation: The transfer of STEM CELLS from one individual to another within the same species (TRANSPLANTATION, HOMOLOGOUS) or between species (XENOTRANSPLANTATION), or transfer within the same individual (TRANSPLANTATION, AUTOLOGOUS). The source and location of the stem cells determines their potency or pluripotency to differentiate into various cell types.Mental Recall: The process whereby a representation of past experience is elicited.Pons: The front part of the hindbrain (RHOMBENCEPHALON) that lies between the MEDULLA and the midbrain (MESENCEPHALON) ventral to the cerebellum. It is composed of two parts, the dorsal and the ventral. The pons serves as a relay station for neural pathways between the CEREBELLUM to the CEREBRUM.Anemia, Aplastic: A form of anemia in which the bone marrow fails to produce adequate numbers of peripheral blood elements.Prefrontal Cortex: The rostral part of the frontal lobe, bounded by the inferior precentral fissure in humans, which receives projection fibers from the MEDIODORSAL NUCLEUS OF THE THALAMUS. The prefrontal cortex receives afferent fibers from numerous structures of the DIENCEPHALON; MESENCEPHALON; and LIMBIC SYSTEM as well as cortical afferents of visual, auditory, and somatic origin.Cerebellar Cortex: The superficial GRAY MATTER of the CEREBELLUM. It consists of two main layers, the stratum moleculare and the stratum granulosum.Olfactory Pathways: Set of nerve fibers conducting impulses from olfactory receptors to the cerebral cortex. It includes the OLFACTORY NERVE; OLFACTORY BULB; OLFACTORY TRACT; OLFACTORY TUBERCLE; ANTERIOR PERFORATED SUBSTANCE; and OLFACTORY CORTEX.Unrelated Donors: Providers of tissues for transplant to non-related individuals.Feeding Behavior: Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.Synaptic Transmission: The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.Learning Disorders: Conditions characterized by a significant discrepancy between an individual's perceived level of intellect and their ability to acquire new language and other cognitive skills. These disorders may result from organic or psychological conditions. Relatively common subtypes include DYSLEXIA, DYSCALCULIA, and DYSGRAPHIA.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Mushroom Bodies: Prominent lobed neuropils found in ANNELIDA and all ARTHROPODS except crustaceans. They are thought to be involved in olfactory learning and memory.Tissue Conditioning (Dental): The use of a treatment material (tissue conditioner) to re-establish tone and health to irritated oral soft tissue, usually applied to the edentulous alveolar ridge.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Receptors, N-Methyl-D-Aspartate: A class of ionotropic glutamate receptors characterized by affinity for N-methyl-D-aspartate. NMDA receptors have an allosteric binding site for glycine which must be occupied for the channel to open efficiently and a site within the channel itself to which magnesium ions bind in a voltage-dependent manner. The positive voltage dependence of channel conductance and the high permeability of the conducting channel to calcium ions (as well as to monovalent cations) are important in excitotoxicity and neuronal plasticity.Disease-Free Survival: Period after successful treatment in which there is no appearance of the symptoms or effects of the disease.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Cocaine: An alkaloid ester extracted from the leaves of plants including coca. It is a local anesthetic and vasoconstrictor and is clinically used for that purpose, particularly in the eye, ear, nose, and throat. It also has powerful central nervous system effects similar to the amphetamines and is a drug of abuse. Cocaine, like amphetamines, acts by multiple mechanisms on brain catecholaminergic neurons; the mechanism of its reinforcing effects is thought to involve inhibition of dopamine uptake.Discrimination (Psychology): Differential response to different stimuli.Association: A functional relationship between psychological phenomena of such nature that the presence of one tends to evoke the other; also, the process by which such a relationship is established.Severe Combined Immunodeficiency: Group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. It is inherited as an X-linked or autosomal recessive defect. Mutations occurring in many different genes cause human Severe Combined Immunodeficiency (SCID).Exploratory Behavior: The tendency to explore or investigate a novel environment. It is considered a motivation not clearly distinguishable from curiosity.Leukemia: A progressive, malignant disease of the blood-forming organs, characterized by distorted proliferation and development of leukocytes and their precursors in the blood and bone marrow. Leukemias were originally termed acute or chronic based on life expectancy but now are classified according to cellular maturity. Acute leukemias consist of predominately immature cells; chronic leukemias are composed of more mature cells. (From The Merck Manual, 2006)Auditory Pathways: NEURAL PATHWAYS and connections within the CENTRAL NERVOUS SYSTEM, beginning at the hair cells of the ORGAN OF CORTI, continuing along the eighth cranial nerve, and terminating at the AUDITORY CORTEX.Myelodysplastic Syndromes: Clonal hematopoietic stem cell disorders characterized by dysplasia in one or more hematopoietic cell lineages. They predominantly affect patients over 60, are considered preleukemic conditions, and have high probability of transformation into ACUTE MYELOID LEUKEMIA.Combined Modality Therapy: The treatment of a disease or condition by several different means simultaneously or sequentially. Chemoimmunotherapy, RADIOIMMUNOTHERAPY, chemoradiotherapy, cryochemotherapy, and SALVAGE THERAPY are seen most frequently, but their combinations with each other and surgery are also used.Food Preferences: The selection of one food over another.Survival Analysis: A class of statistical procedures for estimating the survival function (function of time, starting with a population 100% well at a given time and providing the percentage of the population still well at later times). The survival analysis is then used for making inferences about the effects of treatments, prognostic factors, exposures, and other covariates on the function.Nicotine: Nicotine is highly toxic alkaloid. It is the prototypical agonist at nicotinic cholinergic receptors where it dramatically stimulates neurons and ultimately blocks synaptic transmission. Nicotine is also important medically because of its presence in tobacco smoke.Hepatic Veno-Occlusive Disease: Liver disease that is caused by injuries to the ENDOTHELIAL CELLS of the vessels and subendothelial EDEMA, but not by THROMBOSIS. Extracellular matrix, rich in FIBRONECTINS, is usually deposited around the HEPATIC VEINS leading to venous outflow occlusion and sinusoidal obstruction.Remission Induction: Therapeutic act or process that initiates a response to a complete or partial remission level.Locomotion: Movement or the ability to move from one place or another. It can refer to humans, vertebrate or invertebrate animals, and microorganisms.Nicotinic Agonists: Drugs that bind to and activate nicotinic cholinergic receptors (RECEPTORS, NICOTINIC). Nicotinic agonists act at postganglionic nicotinic receptors, at neuroeffector junctions in the peripheral nervous system, and at nicotinic receptors in the central nervous system. Agents that function as neuromuscular depolarizing blocking agents are included here because they activate nicotinic receptors, although they are used clinically to block nicotinic transmission.Excitatory Amino Acid Antagonists: Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists.Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Courtship: Activities designed to attract the attention or favors of another.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Lymphatic Irradiation: External or interstitial irradiation to treat lymphomas (e.g., Hodgkin's and non-Hodgkin's lymphomas) and lymph node metastases and also some autoimmune diseases, such as rheumatoid arthritis.Lymphocyte Depletion: Immunosuppression by reduction of circulating lymphocytes or by T-cell depletion of bone marrow. The former may be accomplished in vivo by thoracic duct drainage or administration of antilymphocyte serum. The latter is performed ex vivo on bone marrow before its transplantation.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.Ibotenic Acid: A neurotoxic isoxazole (similar to KAINIC ACID and MUSCIMOL) found in AMANITA mushrooms. It causes motor depression, ataxia, and changes in mood, perceptions and feelings, and is a potent excitatory amino acid agonist.Thalamus: Paired bodies containing mostly GRAY MATTER and forming part of the lateral wall of the THIRD VENTRICLE of the brain.Anisomycin: An antibiotic isolated from various Streptomyces species. It interferes with protein and DNA synthesis by inhibiting peptidyl transferase or the 80S ribosome system.Motor Cortex: Area of the FRONTAL LOBE concerned with primary motor control located in the dorsal PRECENTRAL GYRUS immediately anterior to the central sulcus. It is comprised of three areas: the primary motor cortex located on the anterior paracentral lobule on the medial surface of the brain; the premotor cortex located anterior to the primary motor cortex; and the supplementary motor area located on the midline surface of the hemisphere anterior to the primary motor cortex.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Escape Reaction: Innate response elicited by sensory stimuli associated with a threatening situation, or actual confrontation with an enemy.Lithium Chloride: A salt of lithium that has been used experimentally as an immunomodulator.Eyelids: Each of the upper and lower folds of SKIN which cover the EYE when closed.Reflex, Monosynaptic: A reflex in which the AFFERENT NEURONS synapse directly on the EFFERENT NEURONS, without any INTERCALATED NEURONS. (Lockard, Desk Reference for Neuroscience, 2nd ed.)Siblings: Persons or animals having at least one parent in common. (American College Dictionary, 3d ed)Brain Mapping: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.Cycloserine: Antibiotic substance produced by Streptomyces garyphalus.Electrodes, Implanted: Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.Ischemic Postconditioning: The application of repeated, brief periods of vascular occlusion at the onset of REPERFUSION to reduce REPERFUSION INJURY that follows a prolonged ischemic event. The techniques are similar to ISCHEMIC PRECONDITIONING but the time of application is after the ischemic event instead of before.Evoked Potentials, Motor: The electrical response evoked in a muscle or motor nerve by electrical or magnetic stimulation. Common methods of stimulation are by transcranial electrical and TRANSCRANIAL MAGNETIC STIMULATION. It is often used for monitoring during neurosurgery.Photic Stimulation: Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.Substance Withdrawal Syndrome: Physiological and psychological symptoms associated with withdrawal from the use of a drug after prolonged administration or habituation. The concept includes withdrawal from smoking or drinking, as well as withdrawal from an administered drug.Saccharin: Flavoring agent and non-nutritive sweetener.Red Nucleus: A pinkish-yellow portion of the midbrain situated in the rostral mesencephalic tegmentum. It receives a large projection from the contralateral half of the CEREBELLUM via the superior cerebellar peduncle and a projection from the ipsilateral MOTOR CORTEX.Transfer (Psychology): Change in learning in one situation due to prior learning in another situation. The transfer can be positive (with second learning improved by first) or negative (where the reverse holds).Animals, Newborn: Refers to animals in the period of time just after birth.Silanes: Compounds similar to hydrocarbons in which a tetravalent silicon atom replaces the carbon atom. They are very reactive, ignite in air, and form useful derivatives.Methylergonovine: A homolog of ERGONOVINE containing one more CH2 group. (Merck Index, 11th ed)Multiple Myeloma: A malignancy of mature PLASMA CELLS engaging in monoclonal immunoglobulin production. It is characterized by hyperglobulinemia, excess Bence-Jones proteins (free monoclonal IMMUNOGLOBULIN LIGHT CHAINS) in the urine, skeletal destruction, bone pain, and fractures. Other features include ANEMIA; HYPERCALCEMIA; and RENAL INSUFFICIENCY.Survival Rate: The proportion of survivors in a group, e.g., of patients, studied and followed over a period, or the proportion of persons in a specified group alive at the beginning of a time interval who survive to the end of the interval. It is often studied using life table methods.Auditory Cortex: The region of the cerebral cortex that receives the auditory radiation from the MEDIAL GENICULATE BODY.Generalization (Psychology): The phenomenon of an organism's responding to all situations similar to one in which it has been conditioned.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Reinforcement Schedule: A schedule prescribing when the subject is to be reinforced or rewarded in terms of temporal interval in psychological experiments. The schedule may be continuous or intermittent.Nerve Net: A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction.Models, Neurological: Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Host vs Graft Reaction: The immune responses of a host to a graft. A specific response is GRAFT REJECTION.Lymphocyte Transfusion: The transfer of lymphocytes from a donor to a recipient or reinfusion to the donor.Ganglia, Invertebrate: Clusters of neuronal cell bodies in invertebrates. Invertebrate ganglia may also contain neuronal processes and non-neuronal supporting cells. Many invertebrate ganglia are favorable subjects for research because they have small numbers of functional neuronal types which can be identified from one animal to another.Dihydro-beta-Erythroidine: Dihydro analog of beta-erythroidine, which is isolated from the seeds and other plant parts of Erythrina sp. Leguminosae. It is an alkaloid with curarimimetic properties.Leukemia, Myeloid, Acute: Clonal expansion of myeloid blasts in bone marrow, blood, and other tissue. Myeloid leukemias develop from changes in cells that normally produce NEUTROPHILS; BASOPHILS; EOSINOPHILS; and MONOCYTES.Nucleus Accumbens: Collection of pleomorphic cells in the caudal part of the anterior horn of the LATERAL VENTRICLE, in the region of the OLFACTORY TUBERCLE, lying between the head of the CAUDATE NUCLEUS and the ANTERIOR PERFORATED SUBSTANCE. It is part of the so-called VENTRAL STRIATUM, a composite structure considered part of the BASAL GANGLIA.Phosphoric Acids: Inorganic derivatives of phosphoric acid (H3PO4). Note that organic derivatives of phosphoric acids are listed under ORGANOPHOSPHATES.Abducens Nerve: The 6th cranial nerve which originates in the ABDUCENS NUCLEUS of the PONS and sends motor fibers to the lateral rectus muscles of the EYE. Damage to the nerve or its nucleus disrupts horizontal eye movement control.Spatial Behavior: Reactions of an individual or groups of individuals with relation to the immediate surrounding area including the animate or inanimate objects within that area.Synaptophysin: A MARVEL domain-containing protein found in the presynaptic vesicles of NEURONS and NEUROENDOCRINE CELLS. It is commonly used as an immunocytochemical marker for neuroendocrine differentiation.Olfactory Perception: The process by which the nature and meaning of olfactory stimuli, such as odors, are recognized and interpreted by the brain.Acute Disease: Disease having a short and relatively severe course.Graft Rejection: An immune response with both cellular and humoral components, directed against an allogeneic transplant, whose tissue antigens are not compatible with those of the recipient.Nervous System Physiological Phenomena: Characteristic properties and processes of the NERVOUS SYSTEM as a whole or with reference to the peripheral or the CENTRAL NERVOUS SYSTEM.Receptors, AMPA: A class of ionotropic glutamate receptors characterized by their affinity for the agonist AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid).Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Amnesia, Anterograde: Loss of the ability to form new memories beyond a certain point in time. This condition may be organic or psychogenic in origin. Organically induced anterograde amnesia may follow CRANIOCEREBRAL TRAUMA; SEIZURES; ANOXIA; and other conditions which adversely affect neural structures associated with memory formation (e.g., the HIPPOCAMPUS; FORNIX (BRAIN); MAMMILLARY BODIES; and ANTERIOR THALAMIC NUCLEI). (From Memory 1997 Jan-Mar;5(1-2):49-71)Cyclosporine: A cyclic undecapeptide from an extract of soil fungi. It is a powerful immunosupressant with a specific action on T-lymphocytes. It is used for the prophylaxis of graft rejection in organ and tissue transplantation. (From Martindale, The Extra Pharmacopoeia, 30th ed).Dopamine Uptake Inhibitors: Drugs that block the transport of DOPAMINE into axon terminals or into storage vesicles within terminals. Most of the ADRENERGIC UPTAKE INHIBITORS also inhibit dopamine uptake.Sucrose: A nonreducing disaccharide composed of GLUCOSE and FRUCTOSE linked via their anomeric carbons. It is obtained commercially from SUGARCANE, sugar beet (BETA VULGARIS), and other plants and used extensively as a food and a sweetener.Snails: Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man.Excitatory Postsynaptic Potentials: Depolarization of membrane potentials at the SYNAPTIC MEMBRANES of target neurons during neurotransmission. Excitatory postsynaptic potentials can singly or in summation reach the trigger threshold for ACTION POTENTIALS.Aconitine: A C19 norditerpenoid alkaloid (DITERPENES) from the root of ACONITUM plants. It activates VOLTAGE-GATED SODIUM CHANNELS. It has been used to induce ARRHYTHMIAS in experimental animals and it has antiinflammatory and antineuralgic properties.Antineoplastic Combined Chemotherapy Protocols: The use of two or more chemicals simultaneously or sequentially in the drug therapy of neoplasms. The drugs need not be in the same dosage form.Graft vs Leukemia Effect: Immunological rejection of leukemia cells following bone marrow transplantation.Memory Disorders: Disturbances in registering an impression, in the retention of an acquired impression, or in the recall of an impression. Memory impairments are associated with DEMENTIA; CRANIOCEREBRAL TRAUMA; ENCEPHALITIS; ALCOHOLISM (see also ALCOHOL AMNESTIC DISORDER); SCHIZOPHRENIA; and other conditions.Septal Nuclei: Neural nuclei situated in the septal region. They have afferent and cholinergic efferent connections with a variety of FOREBRAIN and BRAIN STEM areas including the HIPPOCAMPAL FORMATION, the LATERAL HYPOTHALAMUS, the tegmentum, and the AMYGDALA. Included are the dorsal, lateral, medial, and triangular septal nuclei, septofimbrial nucleus, nucleus of diagonal band, nucleus of anterior commissure, and the nucleus of stria terminalis.Subliminal Stimulation: Stimulation at an intensity below that where a differentiated response can be elicited.Central Nervous System Depressants: A very loosely defined group of drugs that tend to reduce the activity of the central nervous system. The major groups included here are ethyl alcohol, anesthetics, hypnotics and sedatives, narcotics, and tranquilizing agents (antipsychotics and antianxiety agents).Adaptation, Physiological: The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.HLA Antigens: Antigens determined by leukocyte loci found on chromosome 6, the major histocompatibility loci in humans. They are polypeptides or glycoproteins found on most nucleated cells and platelets, determine tissue types for transplantation, and are associated with certain diseases.