BN Summary Study Guide PDF

**Evolution:** change in species properties over generations. The value of studying species by outstanding features, convenience, comparison, preservation, economic importance, and treatment of disease. Evolution is NOT linearly oriented. Homology: similar traits indicating relationships among spec...

**Evolution:** change in species properties over generations. The value of studying species by outstanding features, convenience, comparison, preservation, economic importance, and treatment of disease. Evolution is NOT linearly oriented. Homology: similar traits indicating relationships among species. Paleontology: study fossils to understand evolution. Charles Darwin: naturalist known for evolution theory and natural selection. Theory Observations 1. Reproduction unless factors limit it 2. Individuals in a species are not identical 3. Some variation among individuals is inherited 4. Not all offspring survive to reproduce "natural selection" is the differential survival and reproduction of organisms with heritable characteristics. Cofounder developer of natural selection theory is Alfred Russel Wallace Sexual selection: Darwin's addition to natural selection regarding mate choice. Convergence: independent evolution of similar traits. Example: bats and birds or dolphins and fish. Homoplasy: features that evolved separately. Example: elephant trunk and human hand. Analogy: similar function, different species. Example: wings of a bird vs a butterfly. Mendel: founder of laws of inheritance. Hugo De Vries: proposed mutations as a source of variation. Taxonomy: classification system for organisms. Phylogeny: evolutionary history of species. Today we classify by phylogenetic closeness. DNA changes serve as a "clock" for gene mutations (good and bad). Invertebrates: most animals, fewer neurons but complex nervous system. Vertebrate nervous system: hollow dorsal neural tube, bilateral symmetry, segmentation, hierarchical control, sperate systems, and functional specialization. "altered" motor brain visual reflex center. HVC- higher vocal center in songbirds Cortex Representation: brain area dedicated to specific functions. 50% brain devoted to neocortex. Neural Tube: origin of vertebrate nervous systems (hollow). Bilateral Symmetry: body plan with symmetrical left and right. Encephalization Factor: brain size relative to body size. Considers each class deviation from center line. Regions of brain that develop later = larger. Small gene changes big changes in brains. Protracted Brain Development: extended growth period affecting brain size. Hominin Evolution: study of human ancestor's brain size increase. - Hypothesis one: social brain hypothesis- larger brains needed for complex social interactions - Others suggest: behavioral interventions, tool use, and social learning by observing. Survival of the Fittest: process by which individuals that are better suited for their environment survive and reproduce most successfully. Contrast with Homology: features based on ancestry. Segmentation: division of the body of an organism into a sense of similar parts. Ecological Niche: unique assortment of environmental opportunities and challenges to wgich each organism is adapted. Behaviorism: a view that adopts the idea that a learner is essentially passive, responding to environmental stimuli. The learner starts off as a clean slate and behavior is shaped through positive reinforcement or negative reinforcement (conditioning). - Gain information about human behavior by observing, measuring, and interpreting animal behavior - Argued to be objective Cognitive Ethology: a view concerned with the influence of conscious awareness and intention on the behavior of an animal. Argues that studying animals in a lab favors the study of artificial issues that are not relevant to an understanding of the natural behavior of animals. - Emphasizes observing animals under natural conditions - Argued to be subjective - Cognitive Ethologists: All behaviors sustained outside of natural conditions are "perversions" without real biological significance and "The only stupid creatures at work in such projects are the experimental psychologists..." Behaviorists: Reinforcers mindlessly strengthened the behaviors and behaviors that so happen to result in positive feedback may increase that behavior even if it does not result in a reward every time. Synesthesia: The ability to feel colors, or taste shapes, or see sounds 2 forms: projective synesthesia: seeing colors, forms, or shapes when stimulated and associative synesthesia: feeling a very strong an involuntary connection between the stimulus and experience. The types are grapheme color, chromesthesia, spatial sequence, lexical gustatory, and misophonia. Apoptosis: natural programmed cell death. "Neuronal cell death." Apoptotic Process 1. Ca2+ ions form outside cell and release of Ca2+ ions from internal stores, raising intercellular Ca2+ levels. 2. High levels of Ca2+ invade mitochondria and diablo proteins are released inside cell. 3. Diabo binds to IAPS (inhibitors of apoptosis proteins) so they can no longer block caspases. 4. A cascade of caspases destroys various proteins and DNA of the cell, making it incapable of survival. Apoptosis is reached. 5. Family of BCl-2 proteins can inhibit apoptosis by blocking release of diablo from mitochondria. **What keeps the Cell alive?** - Cell interactions - Availability of synaptic targets which provide neurotrophic factors cells with enough will survive. Neurotrophic factors: support survival and growth of neurons. Nerve growth factors: prevent death of sympathetic neurons. Brain Derived Neurotrophic Factor (BDNF): support survival of neurons and synaptic plasticity. Cells have "birth dates" when they stop dividing. - Intrinsic factor: genetic determination of a cell's fate. - Extrinsic factor: cell interactions determine fate (harder to predict). Vertebrate Neuron Development: less hard wired and extrinsic factors. Invertebrates: intrinsic factors. **Development of nervous system** Neurogenesis: division of cells in the ventricular zone. Ventricular zone: source of all neurons and glial cells. Cell migration: movement of cells to their final locations. - CAMs (cell adhesion molecules): guide migrating cells and axons - Radial Glial Cell influences migration of newly formed nerve cells Cell differentiation: process where cells become specialized types. Synaptogenesis: formation of synapses between neurons. New synapses formed by chemoattractants and repellents. Synapse rearrangement: modification of synaptic connections over time. Internal Factors: chromosomal abnormalities (down syndrome and fragile x syndrome) and mutations in single genes (phenylketonuria) External Factors: Cell-cell interactions (neurotrophic factors), Neural activity, Epigenetics, Teratogens (fetal alcohol syndrome), Basic biological factors (hypoxia, malnutrition) Ectoderm: outer layer of embryo developing into nervous system. Only this structure. Stem cells: undifferentiated cells capable of specialization. Chemoattractant: chemical signals guiding axon growth. Chemorepellent: chemical signals repelling axon growth. Neural tube: structure from which the nervous system develops Basal forebrain nuclei: region where acetylcholine neurons are located. Hippocampal volume: brain region size linked to memory function. Dendritic spines: projections on neurons important for synaptic connections. **Genes** Phenotype: physical characteristics from genotype and environment. Genotype: genetic makeup - Operant conditioning: Appetitive event -- something presented that the subject does like (e.g., treat, sugar water, drug) - Aversive event -- something is presented that the subject doesn't like (e.g., foot shock) - Contingencies -- unpredicted schedule of reward/punishment Knockout mice: Mice with selectively inactivated genes for research Transgenic mice: mice with introduced genes for studying function. Conditional systems: techniques allowing controlled gene activation in research. Epigenetics: study of gene expression regulation influenced by environment. Methylation: addition of methyl group reducing gene expression. Amblyopia: impaired vision due to misaligned eyes if untreated. Sensitive period: critical developmental window for optimal outcomes **Impacts and Disease** Behavioral teratology: study of maternal environments impact on fetal development. Hypoxia: oxygen deficiency at birth causing disabilities. Teratogens: exogenous agent that may harm fetal development. Thalidomide: drug with known teratogenic effects on fetal limbs. Accutane: drug causing severe birth defects if taken during pregnancy. Mutations: random changes in genes affecting development. Trisomy 21: genetic condition causing down syndrome with cognitive variability Alzheimer's disease: common dementia characterized by loss of memory and personality change. - Neurofibrillary tangles: protein TAU accumulations inside neurons in Alzheimer's. - Amyloid plaques: extracellular beta-amyloid accumulations in Alzheimer's. Know this related to Alzheimer's and dementia 1. An extracellular portion of the amyloid precursor protein (APP) is removed by B-secretase: an intercellular portion is cleaved by presenilin, releasing B-amyloid extracellularly. 2. B-amyloid clumps together, forming extracellular plaques, some of which accumulate on axons and dendrites, impairing synaptic function. 3. B-amyloid also accumulates inside neurons, which respond by forming neurofibrillary tangles filled with Tau proteins. 4. Basal forebrain neurons, in response to amyloid plaques and neurofibrillary tangles, cease producing acetylcholine, leading to dementia. 5. Apolipoprotein E (ApoE) may normally break down B-amyloid, preventing formation of plaques. People with one or two copies of the ApoE4 version are at greater risk for the disease. Fragile X syndrome: genetic disorder from excessive trinucleotide repeats on X chromosome. Phenylketonuria (PKU): disorder causing intellectual disability from phenylalanine buildup. Amblyopia: impaired vision due to misaligned eyes if untreated. **Sensory systems/ Somatosensory system** Sensory processing: detection and interpretation of sensory stimuli. Sensory receptor organs: organs specialized to detect specific stimuli. Adequate Stimulus: stimulus type to which an organ is adapted. Mechanical sensory system: detects touch and tissue damage. Touch, pain, hearing, vestibular joint, muscle. Visual sensory system: processes visible radiant energy. Seeing. Chemical sensory system: detects substances in air or water. Smell, taste, vomeronasal. Electrical sensory system: detects differences in electrical currents. Magnetic sensory system: detects earths magnetic field orientation. Action potentials: electrical signals used by all senses Labeled lines: distinct nerve tracts for different senses. Sensory transduction: conversion of stimulus energy into electrical signals. Generator potentials: local changes in membrane potential. Pacinian corpuscle: skin receptor detecting vibration Coding: patterns of action potentials reflecting stimuli. Range fractionation: different cells fire at varied stimulus intensities. Receptive field: area affecting a neurons firing rate. Adaptation: progressive loss of response to constant stimuli. Tonic receptors: show slow or no decline in firing frequency in adaptation. Phasic receptors: adapt quickly, decreasing firing frequency in adaptation. Somatosensory system: detects body sensations like touch and pain. Cerebral cortex: final processing area for sensory patterns. Thalamus: relay station for sensory information. Primary sensory cortex: dedicated area for each sensory modality. Secondary sensory cortex: receives input from primary sensory areas. Primary somatosensory cortex: receives touch information from opposite body side. Secondary somatosensory cortex: maps touch information from both body sides. Polymodal cells: allow intersensory interactions in the brain. Synesthesia: stimulus in one modality creates sensation in another. Pacinian corpuscles: fast-adapting receptors for vibration. Sense vibration. Meissner's corpuscles: fast-adapting receptors for light touch. Touch: less defined borders. Merkel's discs: slow-adapting receptors for sustained touch. Touch: two-point discrimination. Ruffini's endings: slow adapting receptors for stretch. Sense stretch. Dorsal column system: carries somatosensory information to the brain Dermatome: skin strip innervated by a spinal root. Cortical map: represents body region innervation density. Receptive fields: the space in which a stimulus will alter a neurons firing rate Pain: unpleasant experience associated with tissue damage Congenital insensitivity to pain: inherited syndrome, can still sense touch. Tells us that pain and touch are separate systems. Nociceptors: receptors responding to painful stimuli. Capsaicin: chemical in chili peppers activating pain receptors. TRPV1 receptor: detects painful heat, binds to capsaicin TRPV2 receptor: detects higher temperatures, does not bind to capsaicin. C fibers: thin axons conducting slow, lasting pain. CMR1 receptor: responds to menthol and cool temperatures. Anterolateral system: transmits pain and temperature sensations Cingulate cortex: integrates pain information, involved in empathy. Analgesia: loss of pain sensation Opioids: drugs that control pain by acting on receptors Opioid-peptides: natural pain-relieving neurotransmitters in the brain Periaqueductal gray: midbrain area involved in pain modulation Transcutaneous electrical nerve stimulation (TENS): relieves pain by delivering electrical pulses to skin. Depends on endogenous opioid release. Naloxone: opioid antagonist blocking analgesic effects. Placebo effect: relief from pain despite inert substance Acupuncture: pain relief method inducing endorphin release. Receptor cells: convert the stimulus into electrical signal. **Auditory System** Auditory transduction steps: KNOW! The basic mechanism by which airwaves are transduced into neural signals. - The ear converts sound waves in the air into electrical impulses, which can be interpreted by the brain. - Sound enters ear and passes through the external auditory canal, where it meets the tympanic membrane, which vibrates in response to the sound. - Movements of the tympanic membrane vibrates the ossicles and passes information to frequency and amplitude. - Stapes presses onto the oval window of the cochlea, fluid on other side of window goes up and is vibrating - For fluid to move- round window bulges out at same time stapes push in - Sound waves = liquid waves now Sound: oscillation of air pressure increases and decreases. Frequency: measured in Hertz (HZ) cycles per second. Pitch: perception of frequency: higher frequency equals higher pitch Amplitude: loudness of sound: intensity measured in decibels (dB). Pure Tone: sound with a single frequency, not common in nature. Harmonics: multiples of the fundamental frequency produced by instruments. Fourier Analysis: Decomposes sound into separate sine waves. Mechanoreceptors: sensory receptors detecting mechanical forces like sound Pinnae: external ear structures adapted to species ecological niches Middle ear: contains stapedius and tensor tympani muscles controlling ear bones: can reduce sound effectiveness. Inner hair cells (IHCs): transduce physical sound into neural signals. Tectorial membrane: membrane where hair cells are lodged, responding to fluid waves. Basilar membrane: different sensitivities to frequencies: base for high, apex for low. Outer hair cells (OHCs): amplify cochlear responses: fine tune organ of Corti. Tuning Curve: neurons sensitivity to specific frequencies and nearby frequencies. Binaural interactions: two-ear processing occurs in the brain stem Tonotopic organization: frequency organization maintained from cochlea to cortex. Place theory: pitch encoded by area of basilar membrane excited. Volley theory: frequency encoded by firing rate of neurons. Sound localization: determining sound source using intensity and latency differences. Intensity differences: volume variation between ears help locate sound. Latency differences: time difference of sound arrival at each ear. Auditory map of space: neural representation of sound location in birds. Lateral superior olive: processes intensity difference for sound localization. Medial superior olive: processes latency differences: compares activity between ears. Auditory cortex: processes complex sounds, not basic discrimination. Dorsal stream: focuses on sound localization Ventral stream: analyzes components of sound. Plasticity: ability of auditory cortex to adapt based on experience Conduction deafness: transmission issue in outer/middle ear, not nervous system Sensorineural deafness: auditory nerve damage affects signal conduction, cant conduct signals. Caused by genetic mutation, toxic drug, or loud sounds. Cochlear implants: Devices for treating functional sensorineural deafness. Auditory brainstem: bypass auditory nerve, stimulate brainstem directly. **Vestibular system:** informs about body forces, crucial for balance and body-head position awareness. Informs you about forces acting on your head (gravity and acceleration). - Utricle: detects horizontal linear forces in vestibular system. - Saccule: detects vertical linear forces in vestibular system - Semicircular canals: detects rotational forces in vestibular system Vestibulo-ocular reflex: controls eye muscles during head movement. **Taste system:** processes taste through papillae and taste buds. Taste buds: contain 50-150 taste receptor cells each Five tastes: sweet, sour, salty, bitter, umami detected Umami: savory flavor detected by specific amino acid receptors Taste to brain path- receptors on tongue and back of throat. 3 cranial nerves communicate info. Afferent nerve on taste cells and so they come up to brain stem in the nucleus of the solitary tract. From there those neurons send axons up to the thalamus and the thalamus to the primary gustatory cortex. **Olfactory System**: processes smell, bypasses thalamus to cortex Olfactory receptor cells: sample chemicals in olfactory mucosa for detection. Transduction (olfactory): conversion of odor stimuli to neural signals. Vomeronasal System: detects pheromones, influences reproductive behavior Major histocompatibility complexes (MHCs): detects relatedness among animals via receptors. Glomeruli: receive input from similar olfactory receptor neurons. Cilia: hair like structures on olfactory receptor cells. Hair cells: sensory cells in vestibular and auditory systems Otoliths: enhance sensitivity of receptors in utricle and saccule Ampulla: enlarged region in semicircular canals for rotation Cochlear activation: stimulates auditory nerve for sound perception Central deafness: deafness resulting from disease and tumors in the auditory pathways or auditory cortex of the brain. **The Visual System** Vision: detection of light in the environment Correct order in which visual information is transmitted: optic nerve lateral geniculate nucleus visual cortex How the Visual Information is transmitted to the Brain 1\. Light hyperpolarizes receptor cells (rods and cones) on the retina 2\. Graded potentials (release of neurotransmitters) activated bipolar cells 3\. Graded potentials activate ganglion cells 4\. Ganglion cells **[fire action potentials]** which activates the optic nerve \- Graded potentials depend on the strength of a stimulus and can vary in magnitude \- Action potentials cannot be summed, and are all-or-none Light: certain frequencies of electromagnetic waves Photoreceptors: cells in the retina responding to light Retina: layer containing photoreceptors at the back of the eye. Only cells in retina that produce action potentials are ganglion cells. Temporal retina: half of the retina closer to the temples Nasal retina: half of the retina closer to the nose Rods: photoreceptors for dim light: scotopic vision Cones: photoreceptors for bright light: color vision Photopic: vision system using cones: day vison Scotopic system: vision system using rods: night vision Rhodopsin: photopigment in rods: sensitive to light Visual acuity: clarity of vision: high in fovea. Lateral inhibition: process enhancing contrast in visual perception. Adaptation: adjustment of photoreceptors to different light intensities Range fractionation: different photoreceptors handle varying light intensities Calcium Ions: Regulate intracellular levels affecting neuron sensitivity. Bipolar Cells: Retinal cells connecting photoreceptors to ganglion cells. Ganglion Cells: Retinal cells sending information to the brain. Receptive Fields: Area of visual field affecting neuron response. Pupil Response: Pupils constrict or dilate to control light entry. Fovea: Central region of retina; high cone density. in the fovea, light reaches the cones without having to pass through blood vessels and other layers of cells Aperture: Opening allowing light to enter the eye. Visual Pathways: Pathways from retina to visual cortex. On-center/off-surround fields: Bipolar cells activated by light in center. Off-center/on-surround fields: Bipolar cells activated by light in surround. Concentric receptive fields: Fields with center subfield and antagonistic surround. [Ganglion cells:] Neurons that transmit visual information to LGN. Ganglion cells and LGN cells are spectrally opponent cells. Certain wavelengths excite while others inhibit activity. [+L-M cells- ganglion cells activated by L cones and inhibited by M cones. More M cone activation is inhibition and more L cone is excitation. ] [+M-L have reverse where M cone activates cell and L cone inhibits it. Flipped. ] [+(L+M)/-S now have L and M together- they excite and S inhibits. And then reverse +S/-(L+M) where S excites and L and M inhibit. ] Lateral geniculate nucleus (LGN): Thalamic relay station for visual information. Parvocellular cells: Small receptive fields, responsive to wavelengths. Magnocellular cells: Large receptive fields, not wavelength responsive. Simple cortical cells: Respond to edges with specific width and orientation. Complex cortical cells: Elongated fields, less tied to specific location. Hierarchical construction: Visual processing builds complex perceptions gradually. Spatial-frequency filter model: Analyzes light-dark cycles in visual space. High frequencies: Require small receptive fields for detail processing. Low frequencies: Involve larger receptive fields for gradual transitions. V1 cortex: Primary visual cortex, initial visual processing area. Layer IV: Receives monocular input from LGN in V1. Ocular dominance columns: Columns in V1 responding to same eye input. Trichromatic hypothesis: Color perception based on three photoreceptor types. Opponent-process hypothesis: Color perception through opposing color pairs. Spectrally opponent cells: Cells that excite or inhibit based on wavelength. V4 region: Processes color and responds to sinusoidal frequencies. Dorsal stream: Visual processing pathway for movement and location. Ventral stream: Visual processing pathway for object recognition. Patient D.F.: Case study illustrating ventral stream damage. Inferior temporal (IT): Region responsible for recognizing complex forms. V5 (MT area): Area involved in perception of motion. Color context: Determining color requires comparison with surroundings. Myopia: nearsightedness; eyeball is too long Photon: a particle of light Ciliary muscle: muscle that helps focus light on the retina by controlling the curvature of the lens of the eye Accommodation: the process by which the eye\'s lens changes shape to focus near or far objects on the retina Ocular dominance: degree to which visual cortical cells respond to light in one eye vs the other. some more than others or equal. One eye dominates to drive responses. Can look at how ocular deprivation alters ocular dominance in a developing cat: *Normal development: showing cell responses to eyes. Tend to respond equally, some respond more to others though.* *Sew eyelid shut for period, see when looking in cortex- all cells respond exclusively to eye open. If two eyes aren't aligned, cut eye muscles, then one is deviated. Both working, but looking at different things, not working together- this makes cortical cells less likely to respond to both eyes. When you get to cortex, it having cells from left or right eye, firing together and connecting. If not coming together, they keep firing and results in synapses withering away.* Know for exam label diagram! Cornea (outside of eye, bends light to help focus on back of eye), then passes thru pupil (aperture of eye, empty space created by the iris around it), then it passes thru lens which is adjustable and does final amount of focus. It adjusts from ciliary muscles that pull on the lens or shrink it to make it more smashed or flat, helps focus on far away to close. Now the image reaches the back of the eye and what it hits back there is the retina (where rods and cones are found). Behind the retina is the choroid layer, this is important for: helps photoreceptors to stay alive and absorbs access light. Important because don't want eye bouncing around all over other retina parts. Behind that is the sclera: sits in front of retina, blood vessels all around here which light passes thru before rod and cons. Then in back is phobia: center of vision. Phobia has greatest and sharpest visual acuity. Not as good in peripheral vision. The blood vessels come thru optic disc that has vessels and nerve. The optic disk has no receptors- hole in back of retina- leads to a blind spot (no rod or cones- photoreceptors). **Motor Control** Spinal reflexes: automatic responses to sensory stimuli, bypassing the brain. Dorsal root: sensory nerve fibers entering the spinal cord Ventral root: motor nerve fibers exiting the spinal cord Knee-Jerk Reflex: A simple reflex action involving leg extension. Extrapyramidal Systems: Motor pathways outside the pyramidal tract. Cerebellum: Brain region coordinating voluntary movements and balance. Basal Ganglia: Subcortical nuclei regulating movement and motor control. Reticulospinal Tracts: Pathways from brainstem influencing spinal cord motor output. Rubrospinal Tract: Pathway from red nucleus regulating motor output. Corticospinal Tracts: Direct pathways controlling voluntary movements. Motor Output: Signals sent from the brain to muscles. Amplitude of movement: magnitude or extent of physical movement. Direction of Movement: Pathway or orientation of physical movement. [Brain control of motor output: 2 major pathways] 1. Pyramidal system - Neurons originate in the cortex and synapse onto neurons in the medulla of the brainstem and then on to the spinal cord - Direct control over movements 2. Extrapyramidal system - Involves neurons that are OUTSIDE of the medulla - Modulates movement - Prevents erratic movement and maintains muscle tone (basal ganglia) **Motor disease/injuries** Muscular Dystrophy: Group of disorders causing muscle degeneration. Biochemical abnormalities in muscles, muscles waste away, genetic disease. Multiple Sclerosis: caused by myelin sheath being destroyed Duchenne\'s Muscular Dystrophy: Common, fatal X-linked muscle disorder. Myasthenia Gravis: Autoimmune disorder causing muscle weakness. Attacks acetylcholine receptors, causes weakness of skeletal muscle. Poliovirus: Virus destroying motoneurons, leading to muscle atrophy. ALS: Progressive neurodegenerative disease affecting motoneurons. Spinal Cord Injury: Damage to spinal cord affecting mobility and function. Stroke: Brain injury causing paralysis or weakness. Apraxia: Inability to perform movements without muscle weakness. Plegia: Complete paralysis of a muscle group. Paresis: Partial weakness of a muscle group. Spasticity: Increased muscle tone leading to stiffness. Loss of inhibition Ideomotor apraxia: Inability to carry out simple motor activity. Ideational apraxia: Impairment in carrying out sequence of actions. [Parkinson\'s disease]: Symptoms include tremors, loss of facial muscle tone, difficulty initiating movements, and general difficulty in all motor activities. Motor symptoms in Parkinson\'s disease: Caused by loss of dopamine input from the basil ganglia to caudate-putamen (striatum) which causes movement difficulties. Deep brain stimulation (DBS): recently used in severe cases of Parkinsons disease. L-dopa: precursor to dopamine that gets converted to dopamine in the brain: cured their symptoms, just as it helps Parkinson's patients. Frozen addict case: In the early 1980s, several patients in California displayed typical symptoms of advanced Parkinson\'s disease from contaminated meth. It wasn't produced properly. MPTP: Chemical that is converted to MPP+, which is highly toxic and was found in contaminated meth. Huntington\'s disease: Initial symptoms include clumsiness and small twitches, eventually leading to constant involuntary movements and cognitive problems due to nerve cells in the brain breaking down over time= physical and mental disabilities. Caused by inherited single dominant gene defect (gene HTT). Strongly affects the basal ganglia nuclei. Onset to death in Huntington\'s disease: Approximately 20 years. HTT gene: Gene responsible for Huntington\'s disease; produces protein huntingtin and is abnormally lengthened due to trinucleotide repeats. **Skeletal System: compromises skeletal muscles, not smooth or cardiac muscle. Striated and voluntary.** EMG: electromyography: a method to measure muscle activity by recording action potentials produced by muscles. Feedforward control: interdependence of the effectors is preplanned and is visible before sensory feedback arising from the movement can be utilized. Ex: gastrocnemius contraction. Muscle contraction: Muscles can create force only through contraction; relaxation reverses contraction. When your muscle is contracted- Golgi tendon organ is excited and muscle spindle activity is low. Antagonists (motor): Muscles that oppose each other. Neuromuscular junction: Like a synapse, it is the connection between an axon terminal and a muscle cell. Motor unit: Consists of a motoneuron and all fibers it innervates. Fast-twitch fibers: React quickly and strongly but tire quickly; typically used for activities requiring frequent muscle contraction changes. Slow-twitch fibers: Have a slower response but do not tire as quickly; usually involved in posture. Size principle: Weak contraction activates small, low-threshold neurons, which correspond to slow-twitch fibers. Proprioception: A sensory system crucial for knowing where your body is in space, involving Golgi tendon organs and muscle spindles. Muscle spindle: Contains intrafusal muscle fibers important for sensing muscle stretch. Golgi tendon organ: Located in tendon; monitors muscle tension and can detect overloads to prevent damage. Spinal reflexes: Movement controlled at different levels of the nervous system; some reflexes are entirely spinal. Central pattern generator: Neural circuit responsible for generating basic rhythmic patterns of motor behavior. Pyramidal motor system: Also called the corticospinal system; axons pass through the pyramid of the medulla. Primary motor cortex (M1): Located in the precentral gyrus; shows highest firing rates for movement in a particular direction. Motor cortex plasticity: Motor representations can shift; for example, training can induce changes in the motor cortex. Supplementary motor area (SMA): Crucial for voluntary movement, especially initiating movement sequences. Mirror neurons: Located in the ventral premotor cortex; fire before an action and when observing the same action. **Hormones and their impact on the brain and behavior** Hormones: Chemicals secreted into bloodstream affecting target cells. Hormone actions: 8 principles 1. Hormones act in a gradual fashion 2. Hormones act by changing the probability or intensity of a behavior- they don't switch behaviors on and off 3. The relationship between behavior and hormones is reciprocal- they influence each other 4. A hormone may have multiple effects and one behavior can be affected by several hormones. 5. Hormones often have a pulsatile secretion pattern- in bursts 6. Some hormones are controlled by circadian clocks (24 hr clock) 7. Hormones can interact with other hormones and change their effects 8. Hormones can only affect cells with a receptor protein for that hormone. Endocrine glands: Glands releasing hormones internally into the body. Exocrine glands: Glands secreting fluids outside the body via ducts. Synaptic communication: Chemical release across a synapse between neurons. Endocrine communication: Hormone release into bloodstream for distant effects. Autocrine communication: Chemical acts on the releasing cell itself. Paracrine communication: Chemical diffuses to nearby target cells. Pheromone communication: Hormones released to communicate between same species. Allomone communication: Chemicals affecting behavior of different species. Arnold: testes and roosters Castration: Removal of gonads (testes) causing behavioral and physiological changes. Note: the testosterone amount produces by testes can pass through the blood brain barrier and is transformed into producing estradiol in the brain. Neurosecretory cells: Neurons releasing hormones into the bloodstream. Target cell feedback- hormone acts on a target cell that has a biological response that provides that negative feedback. The biological effect is detected by the endocrine gland and inhibits further release. Example- Insulin Neural communication: Rapid, precise messages traveling short distances. Hormonal communication: Slower messages spreading throughout the body. Protein hormones: Hormones made of amino acid chains. Amine hormones: Hormones derived from modified amino acids. Steroid hormones: Hormones based on cholesterol structure. Second messenger: Molecule activated by hormone-receptor binding. Genomic effects: Steroid hormones altering gene expression. Receptor isoforms: Different receptors for the same steroid hormone. Steroid receptor cofactors: Proteins required for steroid hormone response. Different cells express different cofactors leads to different effects of the same steroid receptor complex depending on the cofactor present. Steroids such as estradiol can have a nongenomic effect- a rapid and brief involving neuronal membrane receptor (GPCRs). Negative feedback: Output inhibits further hormone secretion. Target cell feedback: Hormone effects inhibit further hormone release. Hypothalamus: Brain region directing hormone release regulation. Anterior pituitary gland: Gland releasing tropic hormones affecting other glands. Tropic hormones: Pituitary hormones influencing other endocrine glands. Posterior Pituitary: Back part of the pituitary, secretes oxytocin and vasopressin. Releasing Hormones: Hormones from hypothalamus controlling pituitary hormone release. Tropic Hormones: Pituitary hormones that regulate other endocrine glands. Thyrotropin Releasing Hormone (TRH): Stimulates the release of thyroid-stimulating hormone (TSH). Thyroid Stimulating Hormone (TSH): Increases thyroid hormone release from the thyroid gland. Oxytocin: Hormone involved in reproduction and milk letdown reflex. Arginine Vasopressin (AVP): Also known as ADH, regulates water retention and blood pressure. Adrenocorticotropic Hormone (ACTH): Controls adrenal cortex and steroid hormone release. Follicle-Stimulating Hormone (FSH): Stimulates egg and sperm production in gonads. Luteinizing Hormone (LH): Stimulates testosterone release and corpus luteum formation. Prolactin: Stimulates lactation and parental behavior in females. Growth Hormone (GH): Influences growth, particularly during sleep. Psychosocial Dwarfism: Growth failure due to early life stress. Adrenal Cortex: Outer part of adrenal gland, secretes steroid hormones. Adrenal Medulla: Inner part of adrenal gland, releases amine hormones. Cortisol: Glucocorticoid stress hormone, increases blood glucose. HPA Axis: Hypothalamus-pituitary-adrenal system regulating stress response. Aldosterone: Mineralocorticoid that retains sodium in kidneys. Thyroid Hormones: Regulate growth and nervous system function. Goiter: Swelling of the thyroid due to iodine deficiency. Gonadotropin-Releasing Hormone (GnRH): Stimulates release of FSH and LH from anterior pituitary. Testosterone: Male sex hormone produced by testes. Progesterone: Progestin hormone produced by ovaries. Melatonin: Hormone secreted by pineal gland, regulates sleep cycles. Vasopressin in Prairie Voles: Facilitates pair-bonding in male prairie voles. Endocrine Pathology: Hormonal disorders resembling psychiatric conditions. Kisspeptin: Hypothalamic peptide involved in puberty onset.