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New Unit Begins today … BOA will not have a comprehensive final exam … But … remembering and understanding certain concepts will be expected all semester. EXAMPLE BOA will mostly focus on certain familiar groups: 1) “insects” = Phylum Arthropoda Class Insecta 2) “vertebrates” = Phylum Chordata Subphylum Vertebrata Class Osteichthys (bony fish) Class Amphibia (amphibians) Class Reptilia (reptiles) Class Aves (birds) Class Mammalia (mammals) EXAMPLE Evolution by Natural Selection … Know This!! EXAMPLE Endothermic Homeotherms – birds & mammals Ectothermic Poikilotherms – all other animals Animal Nervous Systems Nervous systems separate animals from other life. Life without nervous systems: plants single celled organisms fungi What advantages are conferred by NS?? Possibilities due to a nervous system: 1) Awareness of the “world” via sensory systems • • • • • • • • Vision Audition Senses that humans Olfaction can relate to Gustation Tactile Thermoreception Magnetoreception Can’t easily relate to Electroreception Neurobiology of Sensation Antenna Mosquito Compound eye More Possibilities due to a nervous system: 2) Memory (short- & long-term) 3) Anticipation 4) Learning 5) Strategy (e.g., stalking strategy of lions) 6) Motor output (body control via muscles) A Nervous system is an input-output device: Inputs to brain or cord are “sensory” Brain processes input (information) Outputs are “motor” (to muscles) Input-Output Example: Simple Reflex “INPUT” “OUTPUT” QUESTION: How many types of basic tissues are there in animal bodies? What are they? 4 TYPES -Connective tissue -Epithelial tissue (e.g. outer skin) -Muscle tissue -Nervous tissue Nervous systems consist of nerve cells called NEURONS Neurons are highly specialized for transmitting INFORMATION Anatomy of a typical neuron Direction of Information (wrong) Neural Information involves both (1) ELECTRICAL excitation (2) CHEMICAL excitation Electrical excitation is called an Action Potential Action Potentials are due to Na+ entering the neuron + Na Electrically Positive http://www.blackwellpublishing.com/matthews/channel.html Na+ is entering the axon Action potential “flowing” down an axon Chemical Information involves the SYNAPSE. What is a synapse?? A synapse involves 2 neurons and consists of - an axon end - the synaptic cleft - a dendrite beginning Neurotransmitter Molecules SYNAPSE AXON DENDRITE Arriving action potential Action potential continues INFORMATION DIRECTION More Realistic Number of Synapses 3 Unsurprising Observations About Nervous Systems * Simple/primitive animals have simple ones * Complex/advanced animals have complex ones * Homo sapiens are the most complex What makes a nervous system complex? 1) Brain size? … NO!! MALES are larger by … * 7.5% in body size * 15% in BRAIN size E Brain Size: How Important?? Brain Weight (g) Body Size (kg) Relative Brain sizes . Tarsier Order Primates Relative Brain sizes ADVICE . Never confuse brain mass with … sophistication or …… survival probability H. sapiens H. neanderthalensis What makes a nervous system complex? 1) Brain size … NO!! * ants vs frogs? * mice vs whales? 2) Neural Circuit complexity … YES!! * convergence & divergence * numbers of synapses * excitatory & inhibitory synapses * speed of action potentials (e-reserve) Neural Circuits – pathways of communication among neurons simple to horrendously complex EXAMPLE: Some Circuitry in the Primate Visual Cortex Relationships Among Neurons Convergence & Divergence 10 neurons converging onto 1 neuron 1 neuron diverging onto 10 neurons N N N N N N N N N N N N N N N N N N N N N N (3:1) (1:4) Excitatory Synapse AXON DENDRITE Arriving action potential Action potential continues Inhibitory Synapse AXON Arriving action potential DENDRITE Excitation suppressed!! CIRCUIT COMPLEXITY CIRCUIT COMPLEXITY Moore's law describes a long-term trend in the history of computing hardware. The number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years.[note 1] This trend has continued for more than half a century and is expected to continue until at least 2015 or 2020.[ http://en.wikipedia.org/wiki/Moore's_law Examples of Animal Nervous Systems Ultra-simple ………….to …………..Ultra-complex ULTRA-SIMPLE Nerve Nets are typical of jellyfish, corals, and sea anemones (Note body symmetry) FAIRLY SIMPLE Flatworms have the basic components of advanced systems (note bilateral symmetry) Mudworms BRAIN REGENERATION!!! How possible?? -Neurons divide to create more neurons -Synapses form between new neurons -Circuits appear where none existed HORRENDOUSLY COMPLEX Homo sapiens -Billions of neurons -Trillions of synapses -1300 g = 3 lbs - Jello consistency - Male brain superiority? - 15 % larger (7.5% body wt. difference) - gender difference seen at age 2-3 yrs Animal brains are specialized for specific “life styles” Different brains might be good at …. •Night vision •Balance & equilibrium in trees •Learning •Coordinating flight muscles •Interpreting communication signals (Rare: no apparent function) Human Sensory Worlds - all animals are different in sensory capabilities - impossible to truly know about other animals - senses are matched to specific habitats and life styles Example of sensory specialization: star-nosed mole • lives in tunnels in the soil • “appendage” is specialized for tactile sensation • each “finger” is loaded with neurons sensitive to touch • brain is disproportionately devoted to touch interpretation http://animal.discovery.com/videos/fooled-by-nature-star-nosed-mole.html Note speed of probing … try to imagine “seeing” with touch Nares (nostrils) Cortex Area Devoted to each Appendage Tactile Cortex Region (region where “touch” is processed) Now think about the HUMAN brain Human tactile sensation is mapped onto the cortex of the brain… If the male brain shows cortical magnification, what will it look like? Tactile Cortex Region (region where “touch” is processed) Human Cortical Magnification Q: Which vertebrate can “see” in 2 different ways? A: Pit Vipers - about 150 species worldwide - North America rattlesnakes water moccasins copperheads Warms when IR radiation Is absorbed Sensory neuron responds to a ΔT = 0.003 C !! Both visible light vision and infrared “vision” project to the Optic Tectum !! ANIMAL CONSCIOUSNESS CLASS: What is consciousness?? Dictionary: 1) awareness; especially of something with in oneself 2) being "aware" of external object. What is "aware"?? Dictionary: Aware = to realize Realize = to understand Understand = to grasp the meaning Are nonhuman animals conscious? CLASS: Are nonhumans conscious?? At the heart of this question is the concept of SOLIPSISM. Philosophers have argued that any individual can only be sure of his/her own consciousness. Is this concept believable? Useful? What about "species solipsism"? How can humans know if animals are conscious? How would you scientifically deal with it? CLASS: Think of examples of animal consciousness (2 min) Some animal communication suggests a consciousness. Animals exchange information when communicating Is it accurate/honest?? What if animals intentionally convey inaccurate information?? Is it conscious deception? Maybe. EXAMPLE: Piping plovers are shore birds that nest on sandy beaches – nests are hidden. Plovers have ways of distracting and diverting intruders: -"peep" and walk just ahead (not deceptive) -false brooding (appear to be sitting on eggs) - broken wing displays for 40% of approaches Risk assessment precedes response. Consciousness or simply mental flexibility? EXAMPLE: East African vervet monkeys use alarm calls to warn others of danger. The warnings are CONTEXT-SPECIFIC: - eagle alarm call - leopard alarm call - snake alarm call Are all monkeys equally likely to give the alarm calls? Fact: high-ranking individuals alarm call more than subordinates. Subordinates look for and see danger, but less likely to report it. Are subordinates "aware" of their rank .... Do they "assess" their situation and acting accordingly? Fact: Females give more alarm calls in the presence of their offspring -- less with unrelated juveniles. Fact: Males call more when with females -- less if with other males. Monkey's intent to communicate seems to take into account immediate social environment. Are these conscious intentions? Or simply the workings of a “hard-wired” neural program? Strong argument for animal consciousness is an evolutionary one. Did human consciousness arise with no ancestral precursors?? If yes, explain how that could happen. reptiles birds primitive mammals early humans Other complex traits build on ancestral versions: learning memory vocal communication problem solving etc. etc. humans Can anything be said about brain size & consciousness??? Dogma: consciousness implies big brains. Tarsiers (and humans) are primates … rat size Blue whale: largest animal ever! Are blue whales more likely to be conscious?? In proposing animal consciousness, avoid imposing a human type of consciousness. Perhaps no other animal can step outside of itself and reflect on its own thoughts. Perhaps only humans know that they know something. Perhaps only humans know that they know that they know something.