Zol 402 Notes

01.13.08 Fact1: we have feelings and experiences that are ours alone: subjective feelings, consciousness. Fact2: At the same time I experience pain, or red or sexual orgasm; related events, specific to that experience, occur in my brain. (When I experience pain there is a release of P-molecules that are released in my brain) Conclusion: Fact 1 depends upon Fact 2. (When I have a feeling of hate or pain, my brain will have a certain path it takes) Nervous systems translate physical energy in the environment into information the organism can use. Receptor is integrated which is translated to output. Your genome is different from birth to death due to the environmental signals. The neuron has many appendages (dendrites) and Axon. Information goes in the dendrite and out the axon. The appendages increase surface area to receive more signals. Over 100 billion nerve cells! These neurons are interconnected by over 500 trillion synaptic connections. There are one million new neuronal connections are formed every second! Very dynamic. The brain is continuously active! Mode1: awake Mode2: sleep. We do not go from active to inactive, the brain is always awake. Bayesian Probability Theory: brain can be viewed as a probability machine that constantly making predictions about the world and updating those predictions based on what it senses. (The brain only takes cues, it doesn?t look at the full picture, it doesn?t need it. That?s why we make mistakes) Cellular connectionism: functions, vision, audition, olfaction, depend upon extensive nerve circuits. So we can localize functions and construct circuits that control such things. Nerve cells are arranged in functional groups that connect to one another in a precise fashion. Any particular function, such as speech or hearing, might use multiple groups of interconnected cells. Lateralization: On a global scale we see that many functions are localized on a specific side of the brain. For example, with motor movement we see that the right side of the body seems to be controlled by the left side of the brain and vice versa. Other functions have much more specific localization. All messages from the brain cross. (Speech comes from our left hemisphere) Afferent: any information entering the brain. Efferent: any information leaving the brain. Ganglion: collection of cells outside an aggregation of nerve cells in the PNS. Usually encased by connective tissue. Neuron: is the basic unit of the nervous system, Classification of neurons Unipolar: one process, not found in adult Pseudounipolar: found in sensory ganglia, processes function as axons Bipolar: found in ganglia associated with special senses: olfaction, vision Multipolar: most popular tons of dendrites Glia: the second major type of cell in the CNS -Astrocytes: star shaped by its many branches. Found in white matter. -Protoplasmic astrocytes: found in gray matter. Many terminate on blood vessels. -oligodendrocytes: Myelin: speeds up action potential(sheath on axon) Appraisal: decision making Stimulus - appraisal ? feelins/response What is involved in appraisal?? Two key factors -logic (reasoning) -Feelings (emotional responses) Humans are governed by logic and reason. When the brain is confronted with problems it places an emotional label on that problem. That emotional response comes from amygdalate. Amygdalate is known as the watch dog of the brain. It gets our conscious attention by assigning emotional significance to events. It never forgets. Neurons communicate by relaying an action potential from one to the other. The change in each axon may only be momentary. (this just passes the message) Genomic communication: stimulating one cell will release second messengers which cascade. Rebecca is 3 and it?s her birthday. At the petting zoo Rebecca get to close to a goose with babies and it attacks. She is cut up all over. Three to four weeks she is back to normal. At 15 pigeons land on the side walk and she freak, she has no idea why. Mom and dad noticed at 16 for a birthday party shes nervous. These feelings are all emotional reactions which override reason. She would have no record of what happened on her 3rd birthday party. Genomic communication induced memory bank with the amygdale (birds are bad) This watch dog protects her from birthday parties and birds. Post traumatic stress system : is a recall of something. The genome is physicaly different at 16 then it was before 3 Ecstasy can rewire your amygdala. (genes turn on and turned off) 01.15.09 Genes in the brain are suppressed by events in our life. It gets mentholated and turns off. That gene has nothing to do with the next generation. Membrane potential (Ch 3): Cells depolarization. If we measure the nerve cell?s electrical potential would be (inner -, outer +) -65mV. Cell system has 3 components Inside -cytoplasm, organelles, water, proteins (- charged), inorganic ions (cations +, aninons -), K+, Na+, Cl-, and Ca++ Outside -aqueous medium, blood water, K, Na, Cl and Ca but different quantity Cell membrane K= high in inside 100:5 Na= high out 150:15 Cl= high out 150:13 Membrane ion channels Passive: molecules moves down concentration gradient Specific: allows specific ions Controllable: open under some conditions closed under other Percent open determines permeability 3 forces that governed ion movement Concentration gradient Electrical gradients Ion pumps Anode + Cathode ? Na+ sodium ion channels stay closed therefore high {} on the outside. K channels are gradients therefore higher {} inside due to ? charged cell. Each ion has it?s own equilibrium potential. When a cell is shocked Na channels open and Na comes into the cell. The cell then depolarizes(becoming more positive ? to 0) K channels open with a delay (.7 msec)