4 Chapter Membrane potential- the difference in electrical charge between the inside and the outside of a cell. Microelectrodes- extremely fine recording electrodes, which are used for intracellular recording. Resting potential- the steady membrane potential of a neuron at rest, usually about -70 mV. Ion channels- pores in neural membranes through which specific ions pass Sodium-potassium pumps- active transport mechanisms that pump Na+ ions out of neurons and K+ ions in. Depolarize- to decrease the resting membrane potential. Hyperpolarize- to increase the resting membrane potential. Excitatory postsynaptic potentials (EPSPs)- graded postsynaptic depolarizations, which increase the likelihood that an action potential will be generated. Inhibitory postsynaptic potentials (IPSPs)- graded postsunaptic hyperpolarizations, which decrease the likelihood that an action potential will be generated. Graded responses- responses whose magnitude is indicative of the magnitude of the stimuli that induce them. Axon hillock- the conical structure at the junction between the axon and cell body. Threshold of excitation- the level of depolarization necessary to generate an action potential, usually about 65 mV. Action potential (AP)- a massive momentary reversal of a neuron's membrane potential from about -70mV to about +50 mV. All-or-none responses- responses that are not graded, that either occur to their full extent or not at all. Integration- adding or combining a number of individual signals into one overall signal. Spatial summation- the integration of signals that occur at different sites on the neuron's membrane
Temporal summation- the integration of neural signals that occur at different times at the same synapse. Voltage-activated ion channels- ion channels that open and close in response to changes in the level of the membrane potential. Absolute refractory period- a brief period (typically 1 to 2 milliseconds) after the initiation of an action potential during which it is impossible to elicit another action potential in the same neuron. Relative refractory period- a period after the absolute refractory period during which a higher-than-normal amount of stimulation is necessary to make a neuron fire. Antidromic conduction- axonal conduction opposite to the normal direction; conduction from axon terminals back toward the cell body. Orthodromic conduction- axonal conduction in the normal direction--from the cell body toward the terminal buttons Nodes of Ranvier- the gaps between adjacent myelin segments on an axon. Salutatory conduction- conduction of an action potential from one node of Ranvier to the next along a myelinated axon. Dendtiric spines- tiny nodules of various shapes that are located on the surfaces of many dendrites and are the sites of most excitatory synapses in the mature mammalian brain Presynaptic inhibition- a form of inhibition that reduces a neuron's responsiveness to specific synaptic input and is mediated by excitatory axoaxonal synapses. Postsynaptic inhibition- a form of inhibition that reduces a neuron's responsiveness to all excitatory synaptic inputs. Directed synapses- synapses at which the site of neurotransmitter release and the site of neurotransmitter release and the site of neurotransmitter reception are in close proximity. Nondirected synapses- synapses at which the site of neurotransmitter release and the site of neurotransmitter reception are not close together. Peptides- short chains of amino acids, some of which function as neurotransmitters. Synaptic vesicles- small spherical membranes that store neurotransmitter molecules and release them into the synaptic cleft. Golgi complex- structures in the cell bodies and terminal buttons of neurons that package neurotransmitters and other molecules in vesicles.
Coexistence- the presence of more than one neurotransmitter in the same neuron. Exocytosis- the process of releasing a neurotransmitter Receptors- cells that are specialized to receive chemical, mechanical or radiant signals from the environment; also proteins that contain binding sites for particular neurotransmitters. Ligand- a molecule that binds to another molecule; neurotransmitters are ligands of their receptors. Receptor subtypes-the different types of receptors to which a particular neurotransmitter can bind. Ionotropic receptors- receptors that are associated with ligand-activated ion channels Metabotropic receptors- receptors that are associated with signal proteins and G proteins. Second messenger- a chemical synthesized in a neuron in response to the binding of a neurotransmitter to a metabotropic receptor in its cell membrane Autoreceptors- a type of metabotropic receptor located on the presynaptic membrane and sensitive to a neuron's own neurotransmitter Reuptake- the drawing back into the terminal button of neurotransmitter molecules after their release into the synapse; the more common of the two mechanisms for deactivating a released neurotransmitter. Enzymatic degradation- the breakdown of chemicals by enzymes- one of the two mechanisms for deactivating release neurotransmitters. Enzymes- proteins that stimulate or inhibit biochemical reactions without being affected by them. Acetylcholinesterase- the enzyme that breaks down the neurotransmitter acetylcholine Gap junctions- narrow spaces between adjacent neurons that are bridged by fine tubular channels containing cytoplasm, through which electrical signals and small molecules can pass readily. Amino acids- the building blocks and breakdown products of proteins. Glutamate- the brain's most prevalent excitatory neurotransmitter, whose excessive release causes much of the brain damage resulting from cerebral ischemia.
Nitric oxide- a soluble-gas neurotransmitter that is thought to serve as a signal from postsynaptic neurons to presynaptic neurons in the maintenance of LTP. Endorphins- endogenous (internally produced) opiate analgesics. Agonists- drugs that facilitate the effects of a particular neurotransmitter. Antagonists- drugs that inhibit the effects of a particular neurotransmitter. Receptor blockers- antagonistic drugs that bind to postsynaptic receptors without activating them and block the access of the usual neurotransmitter. Cocaine- a potent catecholamine agonist and stimulant that is highly addictive. Benzodiazepines- a class of GABA agonists with anxiolytic, sedative, and anticonvulsant properties; drugs such as chlordiazepoxide (Librium) and diazepam (Valium) Atropine- a receptor blocker that exerts an antagonistic effect at muscarinic receptors. Neuromuscular junctions- the synapses of a motor neuron on a muscle.
Chapter 5 Alpha waves- regular, 8- to 12-per-second, high-amplitude EEG waves that typically occur during relaxed wakefulness and just before falling asleep. Aspiration- a lesion technique in which tissue is drawn off by suction through the fine tip of a glass pipette. Autodiography- the technique of photographically developing brain slices that have been exposed to a radioactively labeled substance such as 2-DG so that regions of high up-take are visible. Behavioral paradigm- a single set of procedures developed for the investigation of a particular behavioral phenomenon. Bregma- the point on the surface of the skull where two of the major sutures intersect, commonly used as a reference point in stereotaxic surgery on rodents. Cannula- a fine, hollow tube that is implanted in the body for the purpose of introducing or extracting substances. Cerebral angiography- a contrast X-ray technique for visualizing the cerebral circulatory system by infusing a radiotranslucent dye into a cerebral artery.
Cerebral dialysis- a method for recording changes in brain chemistry in behaving animals in which a fine tube with a short semipermeable section is implanted in the brain, and extracellular neurochemicals are continuously drawn off for analysis. Cognitive neuroscience- a division of biopsychology that focuses on the use of functional brain imaging to study the neural bases of human cognition. Colony-intruder paradigm- a paradigm for the study of aggressive and defensive behaviors in male rats; a small male intruder rat is placed in an established colony in order to study the aggressive responses of the colony's alpha male and the defensive responses of the intruder. Computed tomography- a computer-assisted X-ray procedure that can be used to visualize the brain and other internal structures of the living body. Conditioned defensive burying- the burial of a source of aversive stimulation by rodents Conditioned taste aversion- an avoidance response developed by animals to the taste of food whose consumption has been followed by illness Constituent cognitive processes- simple cognitive processes that combine to produce complex cognitive processes and that are assumed to be mediated by neural activity in particular parts of the brain. Contrast X-ray techniques- x-ray techniques that involve the injection into one compartment of the body a substance that absorbs X-rays either less than or more than the surrounding tissue. Cryogenic blockade- the temporary elimination of neural activity in an area of the brain by cooling the area with a cryoprobe. 2-deoxyglucose- a substance similar to glucose that is taken up by active neurons in the brain and accumulates in them because, unlike glucose, it cannot be metabolized. dichotic listening test- a test of language lateralization in which two different sequences of three spoken digits are presented simultaneously, one to each ear, and the subject is asked to report all of the digits heard. digit span- the longest sequence of random digits that can be repeated correctly 50% of the time--most people have a digit span of 7. Ejaculates- to eject sperm from the penis. Electrocardiogram- a recording of the electrical signals associated with heartbeats.
Electroencephalography- a technique for recording the gross electrical activity of the brain through disk-shaped electrodes, which in humans are usually taped to the surface of the scalp. Electromyography- a procedure for measuring muscle tension by recording the gross electrical discharges of muscles. Electrooculography- a technique for recording eye movements through electrodes placed around the eye. elevated plus maze- an apparatus for recording defensiveness or anxiety in rats by assessing their tendency to avoid the two open arms of a plus-sign-shaped maze mounted some distance above the floor of a lab. event-related potentials- the EEG waves that regularly accompany certain psychological events. far-field potentials- EEG signals recorded in attenuated form at the scalp because they originate far away- for example, the brain stem. functional MRI- a magnetic resonance imaging technique for inferring brain activity by measuring increased oxygen flow into particular areas. Gene knockout techniques- procedures for creating organisms that lack a particular gene. Gene replacement techniques- procedures for creating organisms in which a particular gene has been replaced with another. Hypertension- chronically high blood pressure. Immunocytochemistry- a procedure for locating particular proteins in the brain by labeling their antibodies with a dye or radioactive element and then exposing slices of brain tissue to the labeled antibodies. In situ hybridization- a technique for locating particular proteins in the brain; molecules that bind to the mRNA that directs the synthesis of the target protein are synthesized and labeled, and brain slices are exposed to them. Intromission- insertion of the penis into the vagina. Lordosis- the arched-back, rump-up, tail-to-the-side of posture female rodent sexual receptivity, which serves to facilitate intromission. Lordosis quotient- the proportion of mounts that elicit lordosis.
Magnetic resonance imaging- a procedure in which high-resolution images of the structures of the living brain are constructed from the measurement of waves that hydrogen atoms emit when they are activated by radio-frequency waves in a magnetic field. Magnetoencephalography- a technique for recording changes produced in magnetic fields on the surface of the scalp by changes in underlying patterns of neural activity. Morris water maze- a pool of milky water that has a goal platform invisible just beneath its surface and is used to study the ability of rats to learn spatial locations. Neurotoxins- neural poisons. Open-field test- a method for recording and scoring the general activity of an animal in a large, barren chamber. Operant conditioning paradigm- a paradigm in which the rate of a particular voluntary response is increased by reinforcement or decreased by punishment. P300 wave- the positive EEG wave that usually occurs about 300 milliseconds after a momentary stimulus that has meaning for the subject. Paired-image subtraction technique- the use of PET or fMRI to locate constituent cognitive processes in the brain by producing an image of the difference in brain activity associated with two cognitive tasks that differ in terms of a single constituent cognitive process. Pavlovian conditioning paradigm- a paradigm in which the experimenter pairs an initially neutral stimulus (conditional stimulus) with a stimulus (unconditional stimulus) that elicits a reflexive response (unconditional response); after several pairings, the neutral stimulus elicits a response (conditional response). Plethysmography- any technique for measuring changes in the volume of blood in a part of the body. Positron emission tomography- (PET) a technique for visualizing brain activity, usually by measuring the accumulation of radioactive 2-DG or radioactive water in the various areas of the brain. Radial arm maze-a maze in which several arms radiate out from a central starting chamber, commonly used to study spatial learning in rats. Repetition priming tests- tests of implicit memory; in one example, a list of words is presented, then fragments of the original words are presented and the subject is asked to complete them.
Self-stimulation paradigm- a paradigm in which animals press a lever to administer reinforcing electrical stimulation to their own brains. Sensory evoked potential- a change in the electrical activity of the brain (e.g. in the cortical EEG) that is elicited by the momentary presentation of a sensory stimulus. Signal averaging- a method of increasing the signal-to-noise ratio by reducing background noise. Skin conductance level- (SCL) the steady level of skin conductance associated with a particular situation. Skin conductance response (SCR) the transient change in skin conductance associated with a brief experience. Sodium amytal test- a test involving the anesthetization of first one cerebral hemisphere and tehn the other to determine which hemisphere plays the dominant role in language. Spatial resolution- ability of a recording technique to detect differences in spatial location (e.g., to pinpoint a location in the brain). Species-common behaviors- behaviors that are displayed in the same manner by virtually all like members of a species. Stereotaxic atlas- a series of maps representing the three-dimensional structure of the brain that is used to determine coordinates for stereotaxic surgery. Stereotaxic instrument- a device for performing stereotaxic surgery, composed of two parts: a head holder and an electrode holder. Temporal resolution- ability of a recording technique to detect differences in time (i.e., to pinpoint when an event occurred). Thigmotaxic- tending to stay near the walls of an open space such as a test chamber. Token test- a preliminary test for language-related deficits that involves following verbal instructions to touch or move tokens of different shapes, sizes and colors. Transcranial magnetic stimulation- (TMS) a technique for disrupting the activity in an area of the cortex by creating a magnetic field under a coil positioned next to the skull; the effect of the disruption on cognition is assessed to clarify the function of the affected area of cortex. Transgenic mice- mice into which the genetic material of another species has been introduced.
Wechsler Adult Intelligence Scale- (WAIS) a widely used test of general intelligence that includes 11 subtests. Wisconsin Card Sorting Test- a neuropsychological test that evaluates a patient's ability to remember that previously learned rules of behavior are no longer effective and to learn to respond to new rules.
Chapter 6 Absorption spectrum- a graph of the ability of a substance to absorb light of different wavelengths. Accommodation- the process of adjusting the configuration of the lenses to bring images into focus on the retina. Achromatic colors- black, white and gray. Acuity- the ability to see the details of objects. Amacrine cells- a type of retinal neurons whose specialized function is lateral communication. Binocular- involving both eyes. Binocular disparity- the difference in the position of the retinal image of the same object on the two retinas. Bipolar cells- bipolar neurons that form the middle layer of the retina. Blind spot- the area on the retina where the bundle of axons of the retinal ganglion cells penetrate the receptor layer and leave the eye as the optic nerve. Blobs- peg-like, cytochrome oxidase-rich, dual-opponent color columns. Chromatic colors- the hues- colors such as blue, green, and yellow. Ciliary muscles- the eye muscles that control the shape of the lenses. Color constancy- the tendency of an object to appear the same color even when the wavelengths of light that it reflects change. Complementary colors- pairs of colors that produce white or gray when combined in equal measure; every color has a complementary color.
Completion- the visual system's automatic use of information obtained from receptors around the blind spot, or scotoma, to create a perception of the missing portion of the retinal image. Complex cells- neurons in the visual cortex that respond optimally to straight-edge stimuli in a certain orientation in any part of their receptive field. Component theory- the theory that the relative amount of activity produced in three different classes of cones by light determines its perceived color (also called trichromatic theory). Cones- the visual receptors in the retina that mediate high-acuity color vision in good lighting. Contrast enhancement- the intensification of the perception of edges. Cytochrome oxidase- an enzyme present in particularly high concentrations in the mitochondria of dual-opponent color cells of the visual cortex. Dual-opponent color cells- neurons that respond to the differences in the wavelengths of light stimulating adjacent areas of their receptive field. Duplexity theory- the theory that cones and rods mediate photopic and scotopic vision, respectively. Fourier analysis- a mathematical procedure for breaking down a somplex wave form (e.g., an EEG signal) into component sine waves of varying frequency. Fovea- the central indentation of the retina, which is specialized for high-acuity vision. Horizontal cells- type of retinal neurons whose specialized function is lateral communication. Lateral geniculate nuclei- the six-layered thalamic structures that receive input from the retinas and transmit their output to the primary visual cortex. Lateral inhibition- inhibition of adjacent neurons or receptors in a topographic array. Magnocellular layers- the layers of the lateral geniculate nuclei that are composed of neurons with large cell bodies; the bottom two layers (also called M layers). Microspectrophotometry- a technique for measuring the absorption spectrum of the photopigment contained in a single cone. Monocular- involving only one eye.
Nasal hemiretina- the half of each retina next to the nose. Off-center cells- visual neurons that respond to lights shone in the center of their receptive fields with "off" firing and to lights shone in the periphery of their fields with "on" firing. Ommatidia- the visual receptors of the horseshoe crab. On-center cells- visual neurons that respond to lights shone in the center of their receptive fields with "on" firing and to lights shone in the periphery of their fields with "off" firing. Opponent-process theory- the theory that a visual receptor or a neuron signals one color when it responds in one way (e.g., by increasing its firing rate) and signals its complementary color when it responds in the opposite way (e.g., by decreasing its firing rate.) Parvocellular layers- the layers of the lateral geniculate nuclei that are composed of neurons with small cell bodies; the top four layers (also called P layers). Photopic spectral sensitivity curve- the graph of the sensitivity of cone-mediated vision to different wavelengths of light. Photopic vision- cone-mediated vision, which predominates when lighting is good. Primary visual cortex- the area of the cortex that receives direct input from the lateral geniculate nuclei (also called striate cortex). Purkinje effect- in intense light, red and yellow wavelengths look brighter than blue or green wavelengths of equal intensity; in dim light, blue and green wavelengths look brighter than red and yellow wavelengths of equal intensity. Receptive field- the area of the visual field within which it is possible for the appropriate stimulus to influence the firing of a visual neuron. Receptors- cells that are specialized to receive chemical, mechanical, or radiant signals from the environment; also proteins that contain binding sites for particular neurotransmitters. Retina-geniculate-striate pathway- the major visual pathway from each retina to the striate cortex (primary visual cortex) via the lateral geniculate nuclei of the thalamus. Retinal ganglion cells- retinal neurons whose axons leave the eyeball and form the optic nerve.
Retinex theory- Land's theory that the color of an object is determined by its reflectance, which the visual system calculates by comparing the ability of adjacent surfaces to reflect short, medium, and long wavelengths. Retinotopic- organized, like the primary visual cortex, according to a map of the retina. Rhodopsin- the photo-pigment of rods. Rods- the visual receptors in the retina that mediate achromatic, low-acuity vision under dim light. Saccades- the rapid movements of the eye between fixations. Scotopic spectral sensitivity curve- the graph of the sensitivity of rod-mediated vision to different wavelengths of light. Scotopic vision- rod-mediated vision, which predominates in dim light. Sensitivity- in vision, the ability to detect the presence of dimly lit objects. Simple cells- neurons in the visual cortex that respond maximally to straight-edge stimuli in a certain position and orientation. Sine-wave grating- an array of equally spaced, parallel, alternating dark and light stripes that is created by varying the light across the grating in a sine-wave pattern. Spatial-frequency theory- the theory that the visual cortex encodes visual patterns in terms of their component sine waves. Stabilized retinal image- a retinal image that does not shift across the retina when the eye moves. Temporal hemiretina- the half of each retina next to the temple. Transduction- the conversion of one form of energy to another.