Brain and Behavior Test #1 Study Guide:Lecture 1: Genetics- DNA is transcribed to RNA RNA is translated to protein- Proteins (workhouses of the cell): determines body development by forming part of body structure, and by servingas enzymes(catalysts that regulates chemical reactions in the body)- Mendel’s law of inheritance: govern what traits we have (one gene copy from each parent)- Genes: autosomal, sex linked (usually linked to X chromosome), or sex limited (present in both sexes but expression is contingent upon exposure to factors such as hormones)- Epigenetics: changes in gene expression based on environment(without modification of DNA sequence)– can be active at certain time of day, or point in one’s life – central to learning and memory and is a likely explanation for differences between MZ twins- Ex of epigenetics: in HLG rats becoming high grooming mothers- Transgenic/mutant gene(to study a particular gene)– see how gene change/gene knocked out affect trait/behavior- Twins:- MZ twins (1 egg split): share identical genetics & prenatal environment- DZ twins (2 eggs made at same time): share 50% of DNA & same prenatal environment *Similar traits between twins are often confused to be genetic similarities but are actually a result of a shared prenatal environment- Genes do NOT produce behavior but produce proteins that increase the probability that a behavior will develop under certain circumstances- Multiplier effect: behaviors may be overestimated and increased due to positive feedback (ex: temper tantrums)Lecture 2: Nerve Cells- People used to believe cells grew into each other, rather than the fact that the nervous system was comprised of individual cells- Neurons (like other cells) contain: membrane, nucleus, mitochondria, ribosomes, and ER- Cell: - Nucleus: contains chromosomes (strands of genes)- Mitochondria: performs metabolic activities and provides ATP (fuel) for cell - Mitochondrial Disease- muscle, hearing, vision, learning, neurological, heart, etc. problems - Mitochondrial Eve- mitochondria has own mtDNA, is unilateral, and passed on unchanged- Ribosomes: synthesizes new protein molecules- ER: thin tubes that transport newly synthesized proteins to location- Membrane: phospholipid bilayer with protein molecules as gates/channels that uses active transport for things against concentration gradient and facilitated diffusion for things with concentration gradient (glucose or oxygen)- Proteins make you who you are: one missing or off AA can cause Cystic Fibrosis, tumor suppressor, neurological disorders (Alzheimer, Parkinson, Huntington), or membrane problem- Neurons:- Soma: cell body that contains nucleus, mitochondria, and ribosomes - Presynaptic terminals (axon terminals): The “Squirter”-releases chemical to next neuron- Axon: thin fiber responsible for transmitting nerve impulses toward other neurons, organs, or muscles (some are covered by myelin sheath)- Dendrites (postsynaptic terminals): branching fibers lined with synaptic receptors that receive messages from previous neuron- Interneuron (bipolar/relay neuron): contained within single structure – soma in middle - Sensory neuron (unipolar): highly sensitive at one end to a particular stimulus – soma in middle- Motor neuron (multipolar): makes muscles move – soma in spinal cord (at top)- Pyrimidal cell: widely branching dendrites – soma around middle - Afferent axon: bringing information into- Efferent axon: carrying information out- Neuron to neuron signal:1) Dendrites receive signal2) If enough signal, current goes through soma3) The current can trigger a signal at base of axon4) Signal travels down to axon terminal5) This releases neurotransmitters into synaptic cleft6) Signal received by dendrites of next neuron- Glia: other major component of nervous systema) Astrocytes: synchronize activity by wrapping around presynaptic axon terminal and waiting for enough signal from axon for one pulse (temporal or spatial)b) Microglia (garbage men): remove waste or harmful material c)Oligodendrocytes (in CNS) and Schwann cells (in peripheral NS): build myelin sheath -Myelin sheath: fat and protein membrane around axon that insulates and speeds reaction (pain is not myelinated)d)Radial Glia: guide migration and growth of neurons during embryotic development- Blood Brain Barrier: gooey membrane that blocks harmful material from entering brain – uses proteins for active transport of energy, oxygen, chemicals, hormones, amino acids, and nutrients (glucose) in and out of brain- Brain neurons generally do not regenerate so VERY dangerous for things to sneak across BBB (genital herpes / rabies / psychotrophic drugs) – penicillin / chemotherapy work peripherally Lecture 3: Action Potential- Nerve impulse is like domino effect NOT like electric wire: electricity carries signal down axon to synapse, chemical transmission at synapse to next neuron- Neuroanatomy of cockroach leg:- Cockroach has sensory neuron under each hair- Music stimulates motor neuron / touch stimulates sensory neuron- Nerve impulse closer to the brain affects you more quickly than from farther - Membrane maintains electrical gradient (by charge concentration) and concentration gradient (by ion concentration) by being selectively permeable with ion channels (protein complex) - For every 2 K ions in cell, 3 NA ions are transported out- Resting potential: inside of cell has more potassium (K-), outside has more sodium (NA+)- At resting potential, NA channels closed and K channels a bit open- Polarization: difference in electrical charge inside and outside of cell- Sodium (NA) wants to enter cell by electrical AND concentration gradient- Potassium (K) is thus pushed out by concentration gradient (pushed in by electrical gradient)- Threshold of excitement: level above which any stimulation produces a massive depolarizationAfferent to… Efferent from…- Depolarization: uses electricity to fire neuron – decrease polarization in cell (making inside more + and outside more -)- At the end of depolarization, there is more Sodium and less Potassium in cell- Refractory period (after neuron fires) – like a toilet:- Absolute refractory period: sodium channels close and cell cant fire for 1 ms- Relative refractory period: requires more than normal stimulation to fire for 2-4 ms- All or none law: action potential is independent of stimulus (neuron either fires or it doesn’t)- Anesthetics (novicaine/xylocane)
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