Loss of or impaired ability to smell. This may be caused by OLFACTORY NERVE DISEASES; PARANASAL SINUS DISEASES; viral RESPIRATORY TRACT INFECTIONS; CRANIOCEREBRAL TRAUMA; SMOKING; and other conditions.

The ability to detect scents or odors, such as the function of OLFACTORY RECEPTOR NEURONS.

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.

The volatile portions of substances perceptible by the sense of smell. (Grant & Hackh's Chemical Dictionary, 5th ed)

Proteins, usually projecting from the cilia of olfactory receptor neurons, that specifically bind odorant molecules and trigger responses in the neurons. The large number of different odorant receptors appears to arise from several gene families or subfamilies rather than from DNA rearrangement.

Neurons in the OLFACTORY EPITHELIUM with proteins (RECEPTORS, ODORANT) that bind, and thus detect, odorants. These neurons send their DENDRITES to the surface of the epithelium with the odorant receptors residing in the apical non-motile cilia. Their unmyelinated AXONS synapse in the OLFACTORY BULB of the BRAIN.

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.

The process by which the nature and meaning of olfactory stimuli, such as odors, are recognized and interpreted by the brain.

Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.

That portion of the nasal mucosa containing the sensory nerve endings for SMELL, located at the dome of each NASAL CAVITY. The yellow-brownish olfactory epithelium consists of OLFACTORY RECEPTOR NEURONS; brush cells; STEM CELLS; and the associated olfactory glands.

Neurons which activate MUSCLE CELLS.

Paired sense organs connected to the anterior segments of ARTHROPODS that help them navigate through the environment.

Ovoid body resting on the CRIBRIFORM PLATE of the ethmoid bone where the OLFACTORY NERVE terminates. The olfactory bulb contains several types of nerve cells including the mitral cells, on whose DENDRITES the olfactory nerve synapses, forming the olfactory glomeruli. The accessory olfactory bulb, which receives the projection from the VOMERONASAL ORGAN via the vomeronasal nerve, is also included here.

Collective name for a group of external MECHANORECEPTORS and chemoreceptors manifesting as sensory structures in ARTHROPODS. They include cuticular projections (setae, hairs, bristles), pores, and slits.

Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.

Specialized afferent neurons capable of transducing sensory stimuli into NERVE IMPULSES to be transmitted to the CENTRAL NERVOUS SYSTEM. Sometimes sensory receptors for external stimuli are called exteroceptors; for internal stimuli are called interoceptors and proprioceptors.

The proximal portion of the respiratory passages on either side of the NASAL SEPTUM. Nasal cavities, extending from the nares to the NASOPHARYNX, are lined with ciliated NASAL MUCOSA.

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.

Neurons whose primary neurotransmitter is DOPAMINE.

Specialized organs adapted for the reception of stimuli by the NERVOUS SYSTEM.

The observable response an animal makes to any situation.

Isomeric forms and derivatives of pentanol (C5H11OH).

The minimum amount of stimulus energy necessary to elicit a sensory response.

The ability to detect chemicals through gustatory receptors in the mouth, including those on the TONGUE; the PALATE; the PHARYNX; and the EPIGLOTTIS.

Neurons whose primary neurotransmitter is GAMMA-AMINOBUTYRIC ACID.

Chemical substances, excreted by an organism into the environment, that elicit behavioral or physiological responses from other organisms of the same species. Perception of these chemical signals may be olfactory or by contact.

An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.

The 1st cranial nerve. The olfactory nerve conveys the sense of smell. It is formed by the axons of OLFACTORY RECEPTOR NEURONS which project from the olfactory epithelium (in the nasal epithelium) to the OLFACTORY BULB.

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.

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.

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.

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.

Sensory ganglia located on the dorsal spinal roots within the vertebral column. The spinal ganglion cells are pseudounipolar. The single primary branch bifurcates sending a peripheral process to carry sensory information from the periphery and a central branch which relays that information to the spinal cord or brain.

Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.

The 5th and largest cranial nerve. The trigeminal nerve is a mixed motor and sensory nerve. The larger sensory part forms the ophthalmic, mandibular, and maxillary nerves which carry afferents sensitive to external or internal stimuli from the skin, muscles, and joints of the face and mouth and from the teeth. Most of these fibers originate from cells of the TRIGEMINAL GANGLION and project to the TRIGEMINAL NUCLEUS of the brain stem. The smaller motor part arises from the brain stem trigeminal motor nucleus and innervates the muscles of mastication.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

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.

Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.

Refers to animals in the period of time just after birth.

Use of electric potential or currents to elicit biological responses.

'Nerve tissue proteins' are specialized proteins found within the nervous system's biological tissue, including neurofilaments, neuronal cytoskeletal proteins, and neural cell adhesion molecules, which facilitate structural support, intracellular communication, and synaptic connectivity essential for proper neurological function.

Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.

Neurons whose primary neurotransmitter is ACETYLCHOLINE.

A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.

The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.

The most common inhibitory neurotransmitter in the central nervous system.

Histochemical localization of immunoreactive substances using labeled antibodies as reagents.

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).

Pheromones that elicit sexual attraction or mating behavior usually in members of the opposite sex in the same species.

The function of opposing or restraining the excitation of neurons or their target excitable cells.

Neurons which send impulses peripherally to activate muscles or secretory cells.

Diseases characterized by a selective degeneration of the motor neurons of the spinal cord, brainstem, or motor cortex. Clinical subtypes are distinguished by the major site of degeneration. In AMYOTROPHIC LATERAL SCLEROSIS there is involvement of upper, lower, and brainstem motor neurons. In progressive muscular atrophy and related syndromes (see MUSCULAR ATROPHY, SPINAL) the motor neurons in the spinal cord are primarily affected. With progressive bulbar palsy (BULBAR PALSY, PROGRESSIVE), the initial degeneration occurs in the brainstem. In primary lateral sclerosis, the cortical neurons are affected in isolation. (Adams et al., Principles of Neurology, 6th ed, p1089)

A ubiquitous, cytoplasmic protein found in mature OLFACTORY RECEPTOR NEURONS of all VERTEBRATES. It is a modulator of the olfactory SIGNAL TRANSDUCTION PATHWAY.

Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.

A plant genus of the family ACORACEAE, order Arales, subclass Arecidae most notable for Acorus calamus L. root which contains asarone and has been used in TRADITIONAL MEDICINE.

Elements of limited time intervals, contributing to particular results or situations.

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.

Projection neurons in the CEREBRAL CORTEX and the HIPPOCAMPUS. Pyramidal cells have a pyramid-shaped soma with the apex and an apical dendrite pointed toward the pial surface and other dendrites and an axon emerging from the base. The axons may have local collaterals but also project outside their cortical region.

Proteins found in any species of insect.

The lower portion of the BRAIN STEM. It is inferior to the PONS and anterior to the CEREBELLUM. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities.

Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.

One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action.

A part of the upper respiratory tract. It contains the organ of SMELL. The term includes the external nose, the nasal cavity, and the PARANASAL SINUSES.

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.

Most generally any NEURONS which are not motor or sensory. Interneurons may also refer to neurons whose AXONS remain within a particular brain region in contrast to projection neurons, which have axons projecting to other brain regions.

The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the PONS and the DIENCEPHALON. Midbrain contains two major parts, the dorsal TECTUM MESENCEPHALI and the ventral TEGMENTUM MESENCEPHALI, housing components of auditory, visual, and other sensorimoter systems.

A species of fruit fly much used in genetics because of the large size of its chromosomes.

An accessory chemoreceptor organ that is separated from the main OLFACTORY MUCOSA. It is situated at the base of nasal septum close to the VOMER and NASAL BONES. It forwards chemical signals (such as PHEROMONES) to the CENTRAL NERVOUS SYSTEM, thus influencing reproductive and social behavior. In humans, most of its structures except the vomeronasal duct undergo regression after birth.

Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.

Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.

The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.

Neurons whose primary neurotransmitter is SEROTONIN.

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)

A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.

Family of large marine CRUSTACEA, in the order DECAPODA. These are called clawed lobsters because they bear pincers on the first three pairs of legs. The American lobster and Cape lobster in the genus Homarus are commonly used for food.

The increase in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.

The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.

A progressive, degenerative neurologic disease characterized by a TREMOR that is maximal at rest, retropulsion (i.e. a tendency to fall backwards), rigidity, stooped posture, slowness of voluntary movements, and a masklike facial expression. Pathologic features include loss of melanin containing neurons in the substantia nigra and other pigmented nuclei of the brainstem. LEWY BODIES are present in the substantia nigra and locus coeruleus but may also be found in a related condition (LEWY BODY DISEASE, DIFFUSE) characterized by dementia in combination with varying degrees of parkinsonism. (Adams et al., Principles of Neurology, 6th ed, p1059, pp1067-75)

Compounds with a core of 10 carbons generally formed via the mevalonate pathway from the combination of 3,3-dimethylallyl pyrophosphate and isopentenyl pyrophosphate. They are cyclized and oxidized in a variety of ways. Due to the low molecular weight many of them exist in the form of essential oils (OILS, VOLATILE).

A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.

A non-essential amino acid naturally occurring in the L-form. Glutamic acid is the most common excitatory neurotransmitter in the CENTRAL NERVOUS SYSTEM.

A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.

The motion of air currents.

Sexual activities of animals.

An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.

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.

Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.

Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.

The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA.

A compound given in the treatment of conditions associated with zinc deficiency such as acrodermatitis enteropathica. Externally, zinc sulfate is used as an astringent in lotions and eye drops. (Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Englewood, CO, 1995)

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.

An enzyme that catalyzes the conversion of L-tyrosine, tetrahydrobiopterin, and oxygen to 3,4-dihydroxy-L-phenylalanine, dihydrobiopterin, and water. EC 1.14.16.2.

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.

Benzaldehydes are aromatic organic compounds consisting of a benzene ring connected to a formyl group (-CHO), which is the simplest and most representative compound being benzaldehyde (C6H5CHO).

The act of BREATHING in.

Differential response to different stimuli.

The selection of one food over another.

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.

Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.

The process in which specialized SENSORY RECEPTOR CELLS transduce peripheral stimuli (physical or chemical) into NERVE IMPULSES which are then transmitted to the various sensory centers in the CENTRAL NERVOUS SYSTEM.

General name for two extinct orders of reptiles from the Mesozoic era: Saurischia and Ornithischia.

Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.

The disappearance of responsiveness to a repeated stimulation. It does not include drug habituation.

A species of nematode that is widely used in biological, biochemical, and genetic studies.

In tissue culture, hairlike projections of neurons stimulated by growth factors and other molecules. These projections may go on to form a branched tree of dendrites or a single axon or they may be reabsorbed at a later stage of development. "Neurite" may refer to any filamentous or pointed outgrowth of an embryonal or tissue-culture neural cell.

The process by which the nature and meaning of gustatory stimuli are recognized and interpreted by the brain. The four basic classes of taste perception are salty, sweet, bitter, and sour.

A phase transition from liquid state to gas state, which is affected by Raoult's law. It can be accomplished by fractional distillation.

Nerve cells where transmission is mediated by NITRIC OXIDE.

Neurons whose primary neurotransmitter is EPINEPHRINE.

The number of CELLS of a specific kind, usually measured per unit volume or area of sample.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.

A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.

Formation of NEURONS which involves the differentiation and division of STEM CELLS in which one or both of the daughter cells become neurons.

The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.

The black substance in the ventral midbrain or the nucleus of cells containing the black substance. These cells produce DOPAMINE, an important neurotransmitter in regulation of the sensorimotor system and mood. The dark colored MELANIN is a by-product of dopamine synthesis.

Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.

The non-neuronal cells of the nervous system. They not only provide physical support, but also respond to injury, regulate the ionic and chemical composition of the extracellular milieu, participate in the BLOOD-BRAIN BARRIER and BLOOD-RETINAL BARRIER, form the myelin insulation of nervous pathways, guide neuronal migration during development, and exchange metabolites with neurons. Neuroglia have high-affinity transmitter uptake systems, voltage-dependent and transmitter-gated ion channels, and can release transmitters, but their role in signaling (as in many other functions) is unclear.

Ganglia of the sympathetic nervous system including the paravertebral and the prevertebral ganglia. Among these are the sympathetic chain ganglia, the superior, middle, and inferior cervical ganglia, and the aorticorenal, celiac, and stellate ganglia.

The scroll-like bony plates with curved margins on the lateral wall of the NASAL CAVITY. Turbinates, also called nasal concha, increase the surface area of nasal cavity thus providing a mechanism for rapid warming and humidification of air as it passes to the lung.

Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.

Paired bodies containing mostly GRAY MATTER and forming part of the lateral wall of the THIRD VENTRICLE of the brain.

A genus of sphinx or hawk moths of the family Sphingidae. These insects are used in molecular biology studies during all stages of their life cycle.

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.

Act of eliciting a response from a person or organism through physical contact.

The mucous lining of the NASAL CAVITY, including lining of the nostril (vestibule) and the OLFACTORY MUCOSA. Nasal mucosa consists of ciliated cells, GOBLET CELLS, brush cells, small granule cells, basal cells (STEM CELLS) and glands containing both mucous and serous cells.

Loss of functional activity and trophic degeneration of nerve axons and their terminal arborizations following the destruction of their cells of origin or interruption of their continuity with these cells. The pathology is characteristic of neurodegenerative diseases. Often the process of nerve degeneration is studied in research on neuroanatomical localization and correlation of the neurophysiology of neural pathways.

Factors which enhance the growth potentialities of sensory and sympathetic nerve cells.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.

Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.

Learning that is manifested in the ability to respond differentially to various stimuli.

The anterior of the three primitive cerebral vesicles of the embryonic brain arising from the NEURAL TUBE. It subdivides to form DIENCEPHALON and TELENCEPHALON. (Stedmans Medical Dictionary, 27th ed)

Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.

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.

The class Insecta, in the phylum ARTHROPODA, whose members are characterized by division into three parts: head, thorax, and abdomen. They are the dominant group of animals on earth; several hundred thousand different kinds having been described. Three orders, HEMIPTERA; DIPTERA; and SIPHONAPTERA; are of medical interest in that they cause disease in humans and animals. (From Borror et al., An Introduction to the Study of Insects, 4th ed, p1)

A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.

The functional hereditary units of INSECTS.

An enzyme that catalyzes the formation of acetylcholine from acetyl-CoA and choline. EC 2.3.1.6.

Insects of the suborder Heterocera of the order LEPIDOPTERA.

The largest portion of the CEREBRAL CORTEX in which the NEURONS are arranged in six layers in the mammalian brain: molecular, external granular, external pyramidal, internal granular, internal pyramidal and multiform layers.

The largest and uppermost of the paravertebral sympathetic ganglia.

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.

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.

Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.

Proteins from the nematode species CAENORHABDITIS ELEGANS. The proteins from this species are the subject of scientific interest in the area of multicellular organism MORPHOGENESIS.

Drugs that bind to but do not activate GABA RECEPTORS, thereby blocking the actions of endogenous GAMMA-AMINOBUTYRIC ACID and GABA RECEPTOR AGONISTS.

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.

A species of the genus MACACA inhabiting India, China, and other parts of Asia. The species is used extensively in biomedical research and adapts very well to living with humans.

Striped GRAY MATTER and WHITE MATTER consisting of the NEOSTRIATUM and paleostriatum (GLOBUS PALLIDUS). It is located in front of and lateral to the THALAMUS in each cerebral hemisphere. The gray substance is made up of the CAUDATE NUCLEUS and the lentiform nucleus (the latter consisting of the GLOBUS PALLIDUS and PUTAMEN). The WHITE MATTER is the INTERNAL CAPSULE.

Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists.

The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.

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.

Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.

The largest family of cell surface receptors involved in SIGNAL TRANSDUCTION. They share a common structure and signal through HETEROTRIMERIC G-PROTEINS.

The inferior (caudal) ganglion of the vagus (10th cranial) nerve. The unipolar nodose ganglion cells are sensory cells with central projections to the medulla and peripheral processes traveling in various branches of the vagus nerve.

An amino acid that, as the D-isomer, is the defining agonist for the NMDA receptor subtype of glutamate receptors (RECEPTORS, NMDA).

INSECTS of the order Coleoptera, containing over 350,000 species in 150 families. They possess hard bodies and their mouthparts are adapted for chewing.

The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.

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.

The time from the onset of a stimulus until a response is observed.

The four cellular masses in the floor of the fourth ventricle giving rise to a widely dispersed special sensory system. Included is the superior, medial, inferior, and LATERAL VESTIBULAR NUCLEUS. (From Dorland, 27th ed)

STILBENES with AMIDINES attached.

The process by which the nature and meaning of sensory stimuli are recognized and interpreted.

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.

Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)

The distal terminations of axons which are specialized for the release of neurotransmitters. Also included are varicosities along the course of axons which have similar specializations and also release transmitters. Presynaptic terminals in both the central and peripheral nervous systems are included.

Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.

The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.

Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.

Collections of small neurons centrally scattered among many fibers from the level of the TROCHLEAR NUCLEUS in the midbrain to the hypoglossal area in the MEDULLA OBLONGATA.

Neurons in the SPINAL CORD DORSAL HORN whose cell bodies and processes are confined entirely to the CENTRAL NERVOUS SYSTEM. They receive collateral or direct terminations of dorsal root fibers. They send their axons either directly to ANTERIOR HORN CELLS or to the WHITE MATTER ascending and descending longitudinal fibers.

Nerve cells of the RETINA in the pathway of transmitting light signals to the CENTRAL NERVOUS SYSTEM. They include the outer layer of PHOTORECEPTOR CELLS, the intermediate layer of RETINAL BIPOLAR CELLS and AMACRINE CELLS, and the internal layer of RETINAL GANGLION CELLS.

Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.

A class of large neuroglial (macroglial) cells in the central nervous system - the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from "star" cells) are irregularly shaped with many long processes, including those with "end feet" which form the glial (limiting) membrane and directly and indirectly contribute to the BLOOD-BRAIN BARRIER. They regulate the extracellular ionic and chemical environment, and "reactive astrocytes" (along with MICROGLIA) respond to injury.

Bluish-colored region in the superior angle of the FOURTH VENTRICLE floor, corresponding to melanin-like pigmented nerve cells which lie lateral to the PERIAQUEDUCTAL GRAY.

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.

Warm-blooded VERTEBRATES possessing FEATHERS and belonging to the class Aves.

An isoquinoline alkaloid obtained from Dicentra cucullaria and other plants. It is a competitive antagonist for GABA-A receptors.

The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges.

A SMN complex protein that is essential for the function of the SMN protein complex. In humans the protein is encoded by a single gene found near the inversion telomere of a large inverted region of CHROMOSOME 5. Mutations in the gene coding for survival of motor neuron 1 protein may result in SPINAL MUSCULAR ATROPHIES OF CHILDHOOD.

One of two ganglionated neural networks which together form the ENTERIC NERVOUS SYSTEM. The myenteric (Auerbach's) plexus is located between the longitudinal and circular muscle layers of the gut. Its neurons project to the circular muscle, to other myenteric ganglia, to submucosal ganglia, or directly to the epithelium, and play an important role in regulating and patterning gut motility. (From FASEB J 1989;3:127-38)

The semilunar-shaped ganglion containing the cells of origin of most of the sensory fibers of the trigeminal nerve. It is situated within the dural cleft on the cerebral surface of the petrous portion of the temporal bone and gives off the ophthalmic, maxillary, and part of the mandibular nerves.

The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.

Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.

A pyridoxal-phosphate protein that catalyzes the alpha-decarboxylation of L-glutamic acid to form gamma-aminobutyric acid and carbon dioxide. The enzyme is found in bacteria and in invertebrate and vertebrate nervous systems. It is the rate-limiting enzyme in determining GAMMA-AMINOBUTYRIC ACID levels in normal nervous tissues. The brain enzyme also acts on L-cysteate, L-cysteine sulfinate, and L-aspartate. EC 4.1.1.15.

The relationships of groups of organisms as reflected by their genetic makeup.

Ganglia of the parasympathetic nervous system, including the ciliary, pterygopalatine, submandibular, and otic ganglia in the cranial region and intrinsic (terminal) ganglia associated with target organs in the thorax and abdomen.

Hyperpolarization of membrane potentials at the SYNAPTIC MEMBRANES of target neurons during NEUROTRANSMISSION. They are local changes which diminish responsiveness to excitatory signals.

The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.

The GTPase-containing subunits of heterotrimeric GTP-binding proteins. When dissociated from the heterotrimeric complex these subunits interact with a variety of second messenger systems. Hydrolysis of GTP by the inherent GTPase activity of the subunit causes it to revert to its inactive (heterotrimeric) form. The GTP-Binding protein alpha subunits are grouped into families according to the type of action they have on second messenger systems.

Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism.

A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes.

The directed transport of ORGANELLES and molecules along nerve cell AXONS. Transport can be anterograde (from the cell body) or retrograde (toward the cell body). (Alberts et al., Molecular Biology of the Cell, 3d ed, pG3)

The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian).

A region extending from the PONS & MEDULLA OBLONGATA through the MESENCEPHALON, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network.

The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.

A member of the nerve growth factor family of trophic factors. In the brain BDNF has a trophic action on retinal, cholinergic, and dopaminergic neurons, and in the peripheral nervous system it acts on both motor and sensory neurons. (From Kendrew, The Encyclopedia of Molecular Biology, 1994)

Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.

The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.

ANIMALS whose GENOME has been altered by GENETIC ENGINEERING, or their offspring.

A species of mosquito in the genus Anopheles and the principle vector of MALARIA in Africa.