Term | Definition |
| Action Potential | Spike; Transient, all-or-none reversal of membrane potential that sweeps along the membrane of a nerve or muscle cell. When stimulated the cell membrane changes conductances for various ions. Sodium ions rush in and the electrical charge across the membrane becomes positive. Local membrane depolarization stimulates the neighboring region to depolarize and then returns to its resting state; Synonyms: Spike; Related Terms: Resting Membrane Potential |
| Active Transport | Movement of ions or molecules against an electrochemical gradient by ulilization of metabolic energy; Related Terms: Extinction |
| Acquisition | Association between stimulus and behavior strengthens after pairing of CS and US |
| Adaptation | Decline in the amplitude of a sensory response in the prescence of a constant stimulus |
| Allopatric Speciation | Development of a genetic discontinuity between groups of individuals as they become geographically separated from each other; Related Terms: Speciation, Sympatric Speciation |
| Altruism | A "helper" individual reduces its own reproductive potential while increasing that of the "helped" individual |
| Anadromous | Migration in which adults spend lives at sea and return to freshwater to spawn |
| Analogy | Resemblance in characteristics (e.g., body form, behavior) as a consequence of independent adaptation to the same or similar environmental conditions and not due to common ancestry; Related Terms: Homology |
| Anaxonal Neuron | Neuron that has no neurites or extremely short ones. These neurons are typically found in sensory systems, such as the vertebrate visual and auditory systems |
| Anisogamy | Condition in which the female gamete is larger than the male gamete; contrast with Isogamy |
| Animal Behavior | Wild and wonderful ways in which animals interact with each other, with members of other species, and with the environment; Related Terms: Behavior |
| Associative Learning | Form of behavioral plasticity in which an animal forms an association between a stimulus that initially evoked little or no response (the conditioned stimulus) and one that normally evokes a reflex response (the unconditioned stimulus). The association is formed as a consequence of the paired presentation/ocurrence of the two stimuli; Related Terms: Conditioning |
| Axon | Elongated process for long-distance signalling.The part of the neuron that conveys information away from the cell body |
| Back Propagation | Technique for training a model network of neural elements |
| Behavior | All coordinated actions and responses of an individual; Related Terms: Animal Behavior |
| Behaviorism | Movement in psychology that advocates the use of strict experimental procedures to study observable behavior (or responses) in relation to the environment (or stimuli). Behaviorism deals with learning or memory under strictly controlled conditions; Related Terms: Ethology |
| Bipolar Neuron | Neuron with two dendrites, one extending from each end of the cell body. This structure is typical of many invertebrate sensory neurons |
| Cable Properties | Passive conducting properties of axons and dendrites i.e. when the cell membrane is passive an axon or dendrite behaves electrically like an insulated cable |
| Capacitance | Property of the cell membrane that allows an electrical charge to be stored. It measures the amount of charge that needs to be transferred between conductors for setting up a given potential difference. Capacitance introduces distortion in the time course of passively conducted signals as this storage takes time to get charged. Capacitance thus slows down a voltage response by a characteristic time factor, the Time Constant; Unit: farad [F] |
| Carrying Capacity | Environment's maximum persistently supportable load (Catton 1986) |
| Cell Body | Region of the neuron that includes the nucleus and associated intracellular organelles |
| Center-surround | Connectivity of a receptive field in which stimuli elicit the largest response in a central region with an opposite polarity in the surrounding region |
| Central Nervous System | Main organ of the nervous system. In vertebrates, it is made up of the brain and the spinal cord |
| Central Pattern Generator | Group of neurons in the central nervous system that, due to the properties of the neurons and the connections between them, can produce a specific pattern (usually rhythmic) of output in the absence of sensory feedback |
| Channel | Opening or "pore" in a membrane through which ions or molecules can move |
| Chemical Synapse | Type of synapse in which communication is achieved by release of chemicals from the pre-synaptic membrane, diffusion across the synaptic cleft, and binding to receptors on the post-synaptic membrane |
| Chemoreceptor | Sensory receptor that responds to binding of a specific class of molecule |
| Circadian Clock | Inherent timekeeping mechanism with a capacity to drive or coordinate a circadian rhythm |
| Circadian Rhythm | Biological rhythms with periodicity of approximately 24 hours |
| Classical Conditioning | Behavior changes when an organism comes to associate one stimulus with another, a reflexive or automatic response transfers from one stimulus to another. For instance, a person who has had painful experiences at the dentist's office may become fearful at just the sight of the dentist's office building, In classical conditioning the conditioned and unconditioned stimuli are presented regardless of what the learner does. see also Operant Conditioning |
| Coding | Means by which information about sensory quality or strength is conveyed to the central nervous system, see also Frequency Code |
| Command neurons | Cells, when activated, are capable of producing complex behavior patterns in the absence of any meaningful external stimuli. These are both necessary and sufficient to control the onset, duration, and vigor of a complex behavior pattern without sensory input. |
| Communication | Intentional information transfer between sender and receiver. It is usually of advantage to both. |
| Compass | Mechanisms that allow you to find a particular spatial direction, see Map |
| Conditioning | Reflexive or automatic response transfers to an unrelated stimulus/behavior. see also Operant Conditioning, Classical Conditioning, Garcia Conditioning |
| Connective | Relatively large nerve trunk in invertebrates consisting of axons that connect one ganglion of the central nervous system to another |
| Contrast | Difference in the relative brightness of two objects |
| Core Area | Area of heaviest use, may center on a resource, i.e. nest, water source, food source |
| Critical Period | xxxx |
| Current | Moving charge in an electrical circuit; Unit: ampere [A] |
| Dark Adaptation | Adaptation to decreasing levels of ambient illumination by an increase in receptor sensitivity |
| Dedicated Circuit | Neural configuration of particular sensory, inter- and motor neurons responsible for generating a specific behavior |
| Dendrite | One of the branching small neural processes carrying signals to the cell body of a neuron |
| Depolarization | Change in the cell's membrane potential where the interior becomes less negative (i.e., a shift towards zero) |
| Descending Contralateral Movement Detector | Neuron which in locusts and grasshoppers responds vigorously to images of approaching objects; the axon crosses the brain descending from hindbrain to thorax to excite motor neurons concerned with jumping and flying, and responds to movements detected by the opposite eye |
| Diffraction | Waves are scattered when they pass through an aperture or are bent by passing from one medium to another |
| Direct Fitness | probability of reproductive success through one's own offspring; Related Terms: Inclusive Fitness, Fitness, Indirect Fitness |
| Directional Selectivity | Most vigorous neuronal response to stimulation from a particular direction |
| Dispersal | Travel of Individuals, which (1) as an ecological process affects distribution of individuals; (2) as a genetic process affecting geographic differentiation and variation; Related Terms: Successful Dispersal |
| Displacement Activity | Behavior patterns seemingly unrelated to the behavioral context in which it occurs |
| Echolocation | Emission of loud pulses of sound and analysis of returning echoes in order to find what lies ahead; used by many bats for hunting and navigating |
| Electrical synapse | Type of synapse in which communication is by electrical synaptic transmission. Potentials are transmitted by direct flow of ions through gap junctions |
| Electromyograms | Recording of the electrical activity of a muscle by placing extracellular electrodes on or near the muscle |
| Elementary Motion Detector | Units which detect movement of images in a particular direction over a small part of the insect eye |
| Emergent Property | High-order feature that arises from synaptic interactions of neurons or group of neurons, that is not intuitively obvious from an analysis of its individual elements |
| Endocrine System | Combination of all neural and glandular mechanisms which control physiological functions/behavior via the secretion of hormones |
| Entrainment | Organism's response to environmental cues such as light that enables resetting of the clock; Related Terms: Free running |
| Epigenetic Effects | Explanations that go beyond a pure genetic determination of traits |
| Ethogram | Comprehensive compilation of the different behaviors exhibited by a species; A catalog of actions as complete and precise as possible. |
| Ethology | Biological study of animal behavior; comprises study of proximate causes of behavior, including external stimulation and internal physiological mechanisms and states; development, including the ontogenesis and genetics of behavior; biological function, including immediate effects and ultimate consequences; and evolutionary origins and modifications |
| Evolution | Processes by which living things on earth have diversified and changed. It involves changes in gene frequency within populations over time, which ultimately results in behavioral and phenotypic changes; Related Terms: Phylogeny |
| Evolutionay Stable Strategy | Strategy that when common cannot be invaded by an alternative (mutant) strategy under the influence of natural selection. i.e. a strategy that performs better than any other strategy against itself. |
| Extinction |
|
| Excitatory Transmission | Synaptic transmission that has a depolarizing effect on the postsynaptic neuron and which increases the probability that the postsynaptic neuron will fire an action potential or the amount of neurotransmittor release |
| Excitatory Postsynaptic Potential | Potential that is generated in a postsynaptic neuron by activation of an excitatory synapse, usually depolarizing |
| Facilitation | Increase in the amplitude of postsynaptic responses as a result of repetitive activation of the synapse |
| Feature Detector | Interneuron or group of neurons that specifically responds to a particular configuration of stimuli representing an object's features |
| Filter | High-order neurons in a sensory system which transmit only certain aspects of the signals they receive |
| Fitness | Probability that an animal of a particular genotype and phenotype will reproduce; in game theory models used to judge the success of a strategy (commonly denoted as (w) or EI(J) = expected pay-off to I when playing against J); see also Inclusive Fitness, Direct Fitness, Indirect Fitness |
| Fixed Action Pattern | Term used by early ethologists to describe stereotyped patterns of movement common to all members of a species, often performed in response to specific sign stimuli. Once initiated FAPs continue until completion. Examples described by early ethologists include the egg-rolling behaviour of geese (and also gulls). This is a consistent pattern of movement performed in response to specific features of an egg that is outside the nest; see also Motor Pattern. |
| Flow Field | Pattern of coherent motion associated with a particular kind of movement |
| Fovea | In the vertebrate retina, the region specialized for high visual acuity |
| Free Running | xxxx |
| Frequency | Reciprocal of the wavelength (the interval from a given point on one sound wave to the equivalent point on the next sound wave), unit: Hertz = cycles/s |
| Frequency Code | Information transfer based on the rate of action potentials reaching more than 100/s for intense stimuli |
| Fundamental Niche | Set of resources and physical factors required for survival and reproduction of individuals of a species; see also Realized Niche |
| Ganglion | Discrete mass of cell bodies and neurites surrounded by a connective tissue sheath. In invertebrates, the central nervous system frequently consists of a chain of ganglia joined by connectives. In vertebrates, ganglia are always located outside the central nervous system. Also an obsolete term for a brain nucleus, now used only for basal ganglia |
| Gap Junction | Channel formed by proteins that allows ions and other molecules to pass between adjacent cells |
| Garcia Conditioning | Mammals readily associate taste, but not visual or auditory cues with nausea, even if the taste is separated from the nausea by hours. This works even when an animal is unconscious; see also Conditioning, Operant Conditioning, Classical Conditioning |
| Gene | Segment of DNA that specifies the structure of proteins (e.g., serum albumin); see also Locus |
| Genotype | Organism's genetic composition, see also Phenotype |
| Giant Motor Neuron | Motor Giant; Exceptionally large motor neuron of the crayfish which sends an axon branch to every fast flexor muscle fiber on both sides of each abdominal segment; Synonyms: Motor Giant |
| Giant Neuron | Neuron in an invertebrate in which the axon diameter is especially large, often more than 10 times larger than other axons in the nervous system |
| Glial Cell | Non-neural cells in the nervous system, see also Neuron |
| Glomerulus | Discrete, globular tangle of densely packed dendrites and axons found in the vertebrate olfactory bulb and in invertebrate olfactory processing centers |
| Graded Potential | Response that varies in proportion to the strength of the stimulus evoking it. For example, the graded potential produced in a receptor is typically a direct function of the intensity of its adequate stimulus, in contrast to the action potential produced by a nerve cell,which is an all-or-nothing response |
| Habitat | Any part of the biosphere where a species can successfully live and reproduce |
| Habituation | Gradual decline in response to recurrent stimuli without specific significance. The tendency to become familiar with a stimulus of no consequence after repeated exposure to it. Learned suppression of response to a repeated stimulus. |
| Heritability | Statistical estimate of variation in a trait that is attributable to genetic differences among individuals within a group. It is commonly expressed as a proportion. |
| Homerange | Area which an individual, pair, or group occupies or regularly returns to, see also Territory, Core Area |
| Homing | Ability to return to a home site after being displaced, see Homing, Kinesis, Navigation, Orientation, Piloting, Taxis |
| Homology | Resemblance in characteristics (e.g., body form, behavior) as a consequence of common ancestry, also see Analogy |
| Hyperpolarization | Change of the cell's membrane potential towards increasingly negative values, Increased membrane polarization |
| Ideal Free Distribution | Theoretical expectation in which individuals should distribute themselves among habitats so that every individual maximizes its net rate of return |
| Imprinting | Capacity to learn specific types of information at certain critical periods in development |
| Inbreeding | Preferential mating between relatives, extreme inbreeding: mating between sibs, half-sibs, parent-offspring, see Outbreeding |
| Inclusive Fitness | Sum of Direct Fitness, and Indirect Fitness |
| Indirect Fitness | Probability of reproductive success through non-descendant relatives. see also Fitness, Inclusive Fitness, Direct Fitness |
| Individual Distance | Defended space surrounding the individual's own body |
| Inhibition | Inhibitory synaptic transmission |
| Inhibitory Postsynaptic Potentials | (ipsp) Potential generated in a postsynaptic neuron by activation of an inhibitory synapse; usually hyperpolarizing |
| Innate Releasing Mechanism | Replaced with Releasing Mechanism, see also Innate |
| Innate | Refers to built-in, inborn, hereditary. It is no longer used and has been replaced by a continuum from "open" to "closed" developmental systems |
| Input Resistance | Tendency of a cell to impede the flow of current into the cell. Equal to half the square root of the membrane resistance times the internal resistance |
| Intention Movement | Behavior patterns that precede, signal or prepare for another behavior |
| Internal Resistance | (ri) Resistance along the length of the inside of a neuron or axon |
| Instinct | Capacity of an animal to complete a complex behavior in response to a first-time encounter with a given situation; purposeful action without foresight of the ends and without previous education in the performance, an inborn behavioral mechanism that manifest itself in an ordered movement sequence (FAP); see also Innate |
| Integration | Process by which signals in the nervous system interact; the decision-making capability of neurons |
| Interneuron | Neuron that is neither purely sensory nor motor but connects and interfaces between other neurons, see also Sensory neuron, Motor neuron |
| Intrinsic Neuromodulation | xxxx |
| Ion Channel | Protein or group of proteins that form a pore through a cellular membrane allowing a particular class of ions to cross the membrane. Passive channels are always open, while active (or gated) channels are opened or closed by a signal. Examples of the latter include voltage-gated (open state controlled by changes in membrane potential) or ligand-gated (controlled by the binding of a chemical molecule) ion channels. |
| Ionotropic Receptor | Ion channel that binds a neurotransmitter or other ligand causing a rapid change in its permeability to ions and thus a rapid change in membrane potential |
| Isogamy | Condition in which the gametes from both partners in sexual reproduction are of equal size, see also Anisogamy |
| Key Stimulus | see Sign Stimulus |
| Kin Selection | Selection for traits that lower an individual's personal fitness, but raise a relative's fitness |
| Kinesis | Non-directional orienting reactions in the presence of a particular sensory stimulus. Animals which suddenly find themselves in an unfavorable environment (e.g. with regard to humidity, temperature, or salt concentration) may change direction by trial and error. By such a method paramecia or woodlice become hedged in an area with favorable environmental conditions, see Homing, Navigation, Orientation, Piloting, Taxis |
| Lateral Inhibition | Arrangement of neurons common in sensory or escape systems in which adjacent neurons in the array make reciprocal inhibitory connections with each other, resulting in constrast enhancement |
| Law of Effect | Behaviors that are followed by a positive outcome are repeated, while those followed by a negative outcome or none at all are extinguished (Edward L. Thorndike) |
| Learning | Adaptive modification of behavior in response to specific experiences during the individual's life. Acquiring knowledge or developing the ability to perform new behaviors. Changes that are not due to fatigue or differences in motivation. |
| Lek | Communal mating area in which individuals hold small territories solely for courtship and copulation |
| Length Constant | See Space Constant |
| Light Adaptation | Process in which the sensitivity of the photoreceptor response decreases when exposed to light, so that each additional photon generates a smaller response |
| Local Circuit | xxxx |
| Local Interneuron | xxxx |
| Locus | Functional unit of heredity on a chromosome that specifies the structure of proteins; see also gene |
| Map | Mechanisms that allow an individual to find a precise location, see also Compass |
| Maternal Effect | Attributes influenced by effects of the mother and which are not due to direct genetic inheritance |
| Mauthner Neuron | Pair of large, identifiable neurons in fish that originate in the brainstem, cross over and project the length of the body coordinating and controlling muscles involved in escape swimming |
| Mechanoreceptor | Sensory receptor for mechanical (movement) energy |
| Membrane Potential | Difference in the distribution of electrical charges across the membrane of a cell, see Resting Membrane Potential, Action potential |
| Membrane Resistance | Property of the cell membrane that impedes the flow of current. unit: ohm |
| Metabotropic Receptor | Membrane receptor that binds a neurotransmitter and thereby begins a sequence of biochemical reactions in second messenger systems that ultimately cause a slow change in the electrical properties or physiological state of the cell, see also Ionotropic Receptor |
| Migration | Active travel between distant locations; see also Dispersal |
| Monopolar Neuron | Neuron with the axon and dendrites at only one side, or pole, of the cell which extend from a single neurite |
| Motor Pattern | Stereotyped pattern of movement common to all members of a species; see also Fixed Action Pattern. |
| Motor Neuron | Neuron that sends neural signals to muscles or glands, see also Sensory neuron, Interneuron |
| Multipolar Neuron | Neuron with a single long axon and many dendrites extending form the cell body |
| Mushroom Body | Brain region of insects containing Kenyon cells; may be implicated in more complex types of behavior such as learning, social behavior and spatial memory |
| Natural Selection | Process by which environmental effects lead to varying degrees of reproductive success among individuals of a population of organisms with different hereditary characters, or traits. The characters that inhibit reproductive success decrease in frequency from generation to generation, see also Sexual Selection |
| Navigation | Animal moves about using external cues to determine its position relative to a goal, see Homing, Kinesis, Orientation, Piloting, Taxis |
| Nernst Potential | Equilibrium potential (voltage) for a given ion if present at different concentrations on the two sides of the cell membrane |
| Neurite | Fine projection from the cell body that may carry input or output information |
| Neuroethology | Subfield of neurobiology devoted to the explicit study of the neural basis of behavior; some neuroethologists concentrate especially on biologically important behaviors such as communication, escape, or prey capture |
| Neurohormone | Compound that is released at a synapse and diffuses across the synaptic cleft to act on a receptor located on the membrane of a postsynaptic cell, which may be another neurone, a muscle cell or a specialized gland cell. It is released from nerve endings by nerve impulse activity at morphologically distinguishable synaptic junctions producing suitable changes in the excitability of the postsynaptic membrane, also see Neuromodulator, Neurotransmitter |
| Neuromodulator | Compound that is released within a localized region of CNS, the receptor for which is not necessarily sited on an anatomically apposed postsynaptic cell. Thus a neuromodulator may affect several postsynaptic cells with specificity conferred mainly by the distribution of receptors. Main action is on second messenger systems, eg. cAMP or inositole triphosphate, presumably affecting protein phosphorylation, also see Neurohormone, Neurotransmitter |
| Neuron | nerve cell; Cell type that conveys information in the nervous system, see also Glial Cell; Synonyms: nerve cell |
| Neuropil | Central region of an invertebrate ganglion, containing dendrites and synapses |
| Neurotransmitter | Compound that is released at a synapse and diffuses across the synaptic cleft to act on a receptor located on the membrane of a postsynaptic cell, which may be another neurone, a muscle cell or a specialized gland cell. It is released from nerve endings by nerve impulse activity at morphologically distinguishable synaptic junctions producing suitable changes in the excitability of the postsynaptic membrane, also see Neuromodulator, Neurohormone |
| Niche | Function of a particular species in an ecological community; all aspects of an organisms existence that enable it to survive and reproduce - see also Fundamental Niche vs. Realized Niche |
| Non-spiking Neuron | Neurons function without producing action potentials. The cell is incapable of generating action potentials due to a lack of voltage sensitive ion channels |
| Nucleus |
|
| Null Direction | Movement in this direction inhibits neurons; opposite to the most effective direction for exciting a neuron, see Preferred Direction |
| Ommatidium | Discrete optical unit of the insect compound eye, with a lense focusing light from a small angle of the visual field onto a small group of photoreceptors |
| Open Loop | Any type of circuit, electrical or neural, in which there is no feedback to help regulate the performance of the circuit |
| Operant Conditioning | Behavior changes after the results of an action proved of consequence (e.g. rewarding, noxious), (same as trial-and-error learning, instrumental conditioning), compare with Classical Conditioning |
| Outbreeding | Preferential mating between non-relatives, see Inbreeding |
| Orientation | Individual positions itself with regard to external cues, see Homing, Kinesis, Navigation, Piloting, Taxis |
| Pacemaker | Internal timekeeping mechanism capable of generating or coordinating circadian rhythms |
| Pacemaker Neuron | Neuron that in the absence of any input spontaneously generates individual spikes or bursts of spikes |
| Perception | Interpretation of sensory signals within the CNS where it produces an internal representation of electrical activity from sensory organs. This is largely dependent on which part of the brain receives the signals. |
| Period | Elapsed time before a rhythm repeats itself |
| Peripheral Nervous System | Complete set of nerves and ganglia carrying information towards or away from the central nervous system |
| Phase-Resetting | Experiments which reveal whether or not a particular neuron is involved in the clock mechanism that determines the timing of cycles in a rhythmically repeating activity. Injection of a brief pulse of current into a neuron should reset the rhythm by advancing or delaying the time of subsequent bursts of spikes in the interneurons and motor neurons depending on the phase of the cycle in which the stimulus current is delivered |
| Phasic Receptor | Type of receptor cell in which adaption is so rapid that the response of the cell to the stimulus declines to zero very quickly, see also Tonic Receptor |
| Phenotype | Observable characteristics (traits) of an organism, see also Genotype |
| Philopatry | Limited dispersal where average propagule moves less than 10 homeranges away from natal site |
| Photon | Discrete packet of light energy; the amount of which depends on the color or wavelength of light |
| Photoreceptor | Receptor cell specialized to respond to light energy |
| Phylogeny | Origin and ancestral succession constituting the evolutionary descent of a species, or class of species. It traces origins and transformations by identifying Homologies |
| Phyletic Gradualism | Both micro- and macroevolutionary change is gradual; see also Punctuated Equilibrium |
| Piloting | Active travel between locations using familiar landmarks to reach a goal, also see Homing, Kinesis, Navigation, Orientation, Taxis |
| Pleiotropy | Situation under which a gene may influences multiple phenotypes (i.e., there is no 1:1 correspondence between gene and behavior) |
| Polygenic Trait | Phenotypic trait that is under the control of multiple genes |
| Postsynaptic Neuron | At a synapse, the neuron that receives a signal from another neuron. In the retina, the direction of movement of a visual stimulus that elicits a maximal response in a directionally selective visual neuron, see also null direction |
| Preferred Direction | Movement in this direction optimally excites the neuron, see Null Direction |
| Presynaptic Inhibition | Form of inhibition in which the inhibitory effect is brought about by a reduction in the amount of neurotransmitter released by the target neuron, hence reducing the probability that excitation of the target neuron will produce an action potential in a postsynaptic neuron |
| Proprioceptor | Sensory receptor that provides an animal with information about the relative position or movement of its body parts |
| Psychophysics | Use of behavioral assays to establish sensory capabilities of an individual |
| Punctuated Equilibrium | Macroevolutionary changes occur as "sudden" bursts, separated by long periods of stasis, see also Phyletic Gradualism |
| Realized Niche | Set of resources and physical habitats actually used by individuals of a species in an area (a subset of the Fundamental Niche) |
| Rebound Spike | Spike in the neuron triggered by the release from a hyperpolarizing event |
| Receptive Field | In sensory systems, the specific region of a sensory surface that when stimulated causes a change in activity of a neuron |
| Receptor Cell | Peripherally located neuron, often anaxonal, that can detect and respond to a sensory stimulus. May also be used generically to mean any neuron that can respond to a sensory stimulus |
| Receptor Potential | Electrical potential that appears in sensory neurons when a stimulus is applied |
| Refractory Period | Brief period following an action potential during which it is more difficult than normal or impossible to excite a neuron to generate another action potential |
| Reinforcement | Process in operant conditioning where a response is strengthened by reward (positive reinforcement) or avoidance of punishment (negative reinforcement). Negative reinforcement is not the same as punishment. see also Acquisition |
| Releasing Mechanism | Functionally organized, neural circuit that filters just the required features from the sensory input and detects a specific sign stimulus and then initiates the appropriate behavioral response. Previously the RM was referred to as the Innate releasing mechanism, see for discussion of Innate. |
| Resting Membrane Potential | Neuronal membrane with differential conductance for different ions produces unequal concentations of ions inside and outside the cell. This results in an electrical potential across the membrane with the inside around -70 mV relative to outside, see also Action Potential |
| Retinula | In insects, the light-sensing structure of the eye, formed by parts of the retina cells |
| Rhabdom | In insects, the light-sensing structure of the eye, formed by eight rhabdomeres |
| Rhabdomere | In insects, the specialized photoreceptive area of each retinal cell. Eight rhabdomeres together form a rhabdome |
| Ritualization | Process by which a functional behavior pattern or structure is transformed into a communication signal |
| Search Image | Restriction of an animal's interest to a single class of object as a consequence of focused attention on particular stimuli |
| Sensation | Neuronal activity resulting from the transduction of stimulus energy into electrical activity |
| Sensitization | Enhancement of response to most stimuli following exposure to a significant signal.; Related Terms: Pseudoconditioning; Example: We blink everytime a puff of air is blown onto our cornea. A subsequent sound will also produce an eye blink even though UCS (air puff) and CS (tone) had never been paired with each other. |
| Sensory Adaptation | Decreased signalling of a peripheral sense organ with continued exposure to a stimulus |
| Sensory Filtering | Receptors responding only to very specific types of disturbance |
| Sensory Neuron | Neuron that carries sensory information into the central nervous system, see also Interneuron, Motor neuron |
| Sensory Receptor | Cell endowed with the ability to respond to a specific stimulus (i.e., absorb a specific kind of stimulus energy) |
| Sensory Selectivity | Subset of stimuli, which an animal detects and responds to, see also Umwelt |
| Sensory Transduction | Chain of physiological reactions in a sensory receptor, which convert sensory stimuli into electrical impulses; see also Frequency code |
| Sexual Selection | Process by which changes in gene frequencies result from individuals that are better than others at either competing for or at attracting mates - i.e. the evolution of traits based on differences in mating success, see also Natural Selection |
| Sign Stimulus | Particular subset of features or qualities of a natural stimulus or complex environmental cues sufficient to elicit a behavioural response. (e.g., FAP) via a releasing mechanism The stimulus to which a specific reaction pattern is tuned. Examples include the red spot on the beak of a herring gull, which evokes a pecking response from nestlings (which in turn prompts the parent to regurgitate food for the young); the size, colour, and degree of speckling of eggs vary the effectiveness as sign stimuli for the egg-rolling behaviour; Toads have particular sensitivity to small objects (potential prey items) moving in their visual field, and also to large objects (potential predators) moving in their visual field. see also Stimulus |
| Signal | Physical coding of information (e.g., a message) capable of transmission through environment |
| Skinner Box | Animal placed inside the box is rewarded with a small bit of food each time it makes the desired response, such as pressing a lever or pecking a key. A device outside the box records the animal's responses; also see Operant conditioning |
| Sodium-Potassium ATPase | Type of membrane protein that uses the energy of ATP to move sodium ions out of the cell and potassium ions in the opposite direction across the membrane, thereby establishing their concentration gradients and creating the membrane potential |
| Soma | Cell body of a neuron |
| Somatotopic | Topographical organization of the somatosensory system, in which there is a point-to-point mapping of the surface of the body onto the somatosensory cortex |
| Sound Pressure Level | Pressure generated by a sound wave measured on a logarithmic scale and expressed relative to the human threshold at 1kHz |
| Space constant | Distance along a membrane at which a constant voltage will decay to 37% of its original size. This effectively measures the distance over which a postsynaptic potential can spread. = square root [membrane resistance (rm) / internal resistance (ri)] |
| Spatial Summation | In a neuron, summation of two or more inputs of the same type from different locations that occur at about the same time |
| Speciation | Phylogenetic split in a group of related individuals to the point where they become different enough to be considered separate species (e.g., unable to produce viable offspring); also see Allopatric Speciation, Sympatric Speciation |
| Spike | Action potential, so called because it usually has a sharp, pointed appearance on an oscilloscope |
| Spike initiation zone | Region of an axon at which an action potential is normally initiated when the neuron is excited |
| Society | Group of individuals of the same species that is organized in a cooperative manner extending beyond sexual and parental care |
| Stimulus | Any form of stimulus energy that can be detected by the body, requires Sensory Transduction |
| Successful dispersal | Dispersal is successfull if propagule obtains opportunity to breed and raise young (i.e. genes migrate) |
| Sympatric Speciation | Development of a genetic discontinuity within a population even in the absence of geographic separation; also see Speciation, Allopatric Speciation |
| Synapse | Specialized site at which communication between one neuron and another takes place |
| Synaptic plasticity | Changes in excitability and transmiter release at synaptic junctions between neurons |
| Syrinx | Sound-producing organ in birds located where the trachea joins the bronchi of the two lungs |
| Taxis | Act of orienting towards some external stimulus or combination of stimuli. Spatial orientation, aided by different sensory modalities, is described by the corresponding term e.g. relative to light (phototaxis), smell (chemotaxis), sound (phonotaxis), or gravity (geotaxis). If orientation is towards the source, it is called a positive taxis, and away from the source a negative taxis. In such instances individuals move in a directed fashion along a particular stimulus gradient until they reach a perceived optimal range. also see Homing, Kinesis, Navigation, Orientation, Piloting |
| Temporal Summation | In neurons, summation of two or more inputs of the same type that occur at different times |
| Territory | Any defended area; area of more or less fixed boundaries from which rival conspecifics are excluded, see Homerange |
| Threshold | Minimum depolarization of the membrane potential necessary to evoke an action potential in a neuron |
| Time Constant | Time it takes a change in membrane potential to reach 63% of its final value or the time it takes for it to decay to 37% of its peak value. It determines how long a synaptic signal lasts = exp. func [membrane resistance (rm) * membrane capacitance (cm)] |
| Tonic Receptor | Type of receptor cell in which adaption is slow that the response of the cell to the stimulus does not declines quickly, see also Phasic Receptor |
| Topographic Map | The point-to-point representation of a sensory surface in the central nervous system |
| Tonotopic | In the auditory system, the hearing organ is mapped point-to-point onto the auditory portion of the CNS |
| Transduction | In the context of sensory systems, the transformation of the energy of a stimulus to a change in membrane potential of a sensory cell |
| Trial and Error Learning | Behavioral plasticity, see Operant conditioning |
| Umwelt | Sensory World. Subjective set of stimuli to which an animal is responsive in a given motivational state. Each species has evolved responses only to those stimuli that prove relevant. It is this simpler world that actually falls within the animal's perception at any particular moment. |
| Vagrancy | Wide dispersal where average propagule moves more than 30 homeranges away from natal site |
| Ventricle | One chamber among the several fluid-filled compartments of the vertebrate brain |
| Voltage | Electrical potential able to move charge in a current; Unit: volt [V] |
| Voltage-gated Channel | Ion channel that opens or closes according to the level of the voltage difference across the neuronal membrane |
| Post Stimulus Time Histogram | A method to analyse stimulus-linked cell responses. A stimulus is presented repeatedly and the cell's responses are grouped into a number of bins following the stimulus onset. Each action potential increases the count for the acticity during that time bin. |
| Learning | An adaptive change in behavior resulting from experience; Related Terms: Conditioning |
| Song | An extended melodious pattern of acoustic vocalizations |
| Syrinx | A pair of membranes at the stem of the bronchi which are able to vibrate and produce sound when air is passed over them |
| Drive | An internal factor that determines how likely an animal is to perform a behavior; Related Terms: Actionspecific energy, Motivation |
| Actionspecific Energy | An internal factor that determines how likely an animal is to perform a behavior; Related Terms: Drive, Motivation |
| Motivation | An internal factor that determines how likely an animal is to perform a behavior; Related Terms: Drive, Actionspecific Energy |
| Incidental Learning | Children readily imitated behavior exhibited by an adult model |
| Language Learning | Humans have an inborn capacity to extract word meanings, sentence structure, and grammatical rules from the complex stream of sounds they hear |
| Memory | The capacity to retain an impression of past experiences; Related Terms: Declarative Memory, Procedural Memory |
| Procedural Memory | The capacity to retain information about past experiences related to procedures and skill; Related Terms: Declarative Memory, Memory |
| Declarative Memory | The capacity to retain information about past experiences related to facts, figures, and events; Related Terms: Memory, Procedural Memory |