lecture 4 - hormones and neurobiology Flashcards
when do proximate factors operate
within an animal lifetime
what type of questions are proximate factors
how
what do proximate factors relate to
causation and development
what do ultimate factors relate to
function and evolution
what type of questions are ultimate factors
why question
how do ultimate and proximate perspectives relate
knowing information about one another can help us design our questions about the other
they can provide focus on where to approach the opposite type of analysis
how can proximate analysis help understand natural selection
helps us understand the raw material that natural selection may operate on in the future
what does proximate analysis shed light on
neurobiology, endocrinology, molecular genetics and developmental factors
what are four components of proximate causation
- hormonal
- neurobiological
- molecular genetic
- developmental
what is the endocrine system
a communication network that influences many aspects of AB
what is the endocrine system composed of
ductless glands that secrete hormones into blood stream (for vertebrates) or surrounding tissue (for invertebrates)
what do endocrine cells do within glands
synthesize and secrete hormones (trigger by internal or external stimuli) that work as chemical messengers to directly or indirectly affect AB
what are the type of hormones and explain them
- protein hormones: soluble in blood
- steroid hormones: non-soluble so require carrier through blood stream.
give example of protein hormone
prolactin
give example of steroid hormone
testosterone
which type of hormone has longer lag time between stimulus and affect on behavior
steroid hormones
explain how the changing of seasoning affects birds endocrine system
as the number of light hours (photoperiod) increases, it triggers an increase in gonadotropin which increases sperm production and testosterone. this increased testosterone increases male aggression and other mating activities (like nest building, mate guarding). the testosterone will bind to receptor cells in the brain to to evoke mating and paternal care.
what can hormones affect
- input systems (sensory systems)
- central nervous system functioning
- output systems (effectors like muscles controlling movement)
how can hormones affect behavior
can modify ongoing behavior (changes to frequency and duration), trigger onset or end of behavior
what is a positive feedback loop
a typical behavior with hormones where an increase in the hormone will cause an increase in something else which in turn will increase hormone production
what type of relationship does testosterone and winning a fight have
positive feedback loop. higher testosterone = increased probability of winning fight
what is the effect of human disturbance on penguins/many animals
when animals are stressed they have high plasma corticosterone and stress hormones levels to trigger anti-predator responses. when super stressed the stress hormones have negative effect (poorer memory and navigation abilities)
for young penguins, even just being exposed to humans through ecotourism groups causes these increases, which causes detrimental effects when they mature
what does vasopressin do
play central role in parental care
what is the difference between male prairie and meadow voles? how does this affect their brains?
prairie voles display parental care while meadow do not
prairie voles have more vasopressin receptors in their ventral pallidum. when these receptors are experimentally increased in meadow voles they display more parental care
when do honey bees become foragers and what is that related to
at ~21 days and it’s related to the Juvenile Hormone (JH III) that stimulates foraging behavior. when you remove the corpus allatum gland (which produced JH III) that they forage significantly later
explain noradrenaline and octopamine hormones
they are both stress hormones that prepare animals for “fight or flight”, stimulate sugar production and regulate arousal in the nervous system. they are very similar
noradrenaline in vertebrates and octopamine in invertebrates
how quickly does the nervous system allow for animals to respond to stimuli
very fast! <1 sec
what is the relationship between axon thickness and action potential speed
thicker = faster
what is a reflex
simplest form of behavior that is just a reaction to a stimulus. complex behaviors require reflexes to work
how does walking require reflexes
need reflexes to stay upright
what is a response latency? what causes it and where is it seen?
delay between stimuli and response
due to delay at synapse
seen for both reflexes and complex behavior
when are there shorter latencies
in response to strong/frightening stimuli
what is summation
excitation from different sources or rapidly occurs to trigger nerve impulse
what is an example of summation and reflexes
the scratch response dogs have
when does summation occur and give example
more often during complex behavior
ex. sight/smell of prey summate to make predator more hungry
what is inhibition? why is it important? how is it used in muscles?
inhibition is blocking use of something
important for coordinating muscle activity
muscles are arranged in antagonistic pairs and excitation of one muscle means inhibition of the other in the pair. inhibition of muscle groups on different limbs is important for locomotion
what is a closed loop system and give example
system used when output needs to be constant. used to regulate behavior. eg: keeping yourself upright
what is open-loop systems and give example
cannot use feedback control. one it starts it cannot be stopped. eg salamander (hydromantes) striking with their fast tongue
what is neuroethology
study of neurobiological underpinnings of behavior
why is sleep a problem
high predation risk while sleeping
how do some animals deal with sleeping risk
sleeping with one eye open and one shut (chicken and mallards). mallards can use unihemispheric sheep where one eye and one hemisphere of the brain is awake. they can put the hemisphere active into slow-wave sleep which allows for quick predator response
