(E1, L1) Intro to Behavioral Endocrinology Flashcards
What is behavioral endocrinology?
The study of how hormones affect behavior and how stimuli, contests, and behaviors affect hormone release
It is bidirectional!!
What does it mean for behavioral endocrinology to be bidirectional?
hormones can affect behavior
behavior can influence hormones
Why might we remove testes from the males of animal species?
decrease aggression
keep meat tender
singing voice
guarding females
Describe the first formal study of endocrinology!
Arnold Berthold in 1849
castrated chicks and had three groups in experiment
first group was castrated and left–> capon
second group was castrated and reimplanted in abdominal cavity–> full rooster
third group was castrated and then the testes were switched between chicks before reimplanted in abdominal cavity –> full rooster
What were the overarching themes from Arnold Berthold’s experiment?
Testes can be transplanted (before development, in critical window)
Transplanted testes can function and create sperm
There are no specific nerves directing testicular function, but secretory product of the testes was necessary to fully develop
What do gonads create?
Reproductive hormones and gametes
What are hormones?
Chemical messengers that travel through the blood to influence the nervous system, regulating physiology and behavior
What can hormones change?
- gene expression or rate of cellular function
- change the probability that a given behavior will occur
How do hormones work?
Not all cells are influenced by each hormone; hormones must bind to specific receptors to produce any effects
A minimal amount of hormone is required to activate sufficient receptors to affect behavior–> there is a threshold level needed for behavior to change
These changes are transient
How does hormonal communication work?
Hormones are released from vesicles into the blood stream, where the distance they need to travel, level of hormones, and number of receptors affect the speed in which they reach the target cells. Those hormones then bind to receptors in those cells, similar to NTs. They need to build up in the cell to create the action potential
Draw out and label the major parts of the neuron and their functions
Dendrites: receptors of NTs
Cell Body: basic cell functions
Axon Hillock: if enough NTs, fires action potential
Myelin Sheath: encapsulates axon
Axon: carries fired action potential
Nodes of Ronviea: drives action potential
Axon terminals: releases NTs
What is behavior?
- considered “output”, but not always motoric (sometimes you can’t see it happening–lack of movement can be behavior)
- can also be excretion of scents and chemicals, changes in skin color, flashing lights of fireflies, production of electrical signals in some species
What are the four levels of analysis when looking at endocrinology?
Adaptive function: what adaptive role does the behavior play?
Evolution: how does natural selection over generations change behavior?
Immediate causation: underlying physiological or proximate mechanisms
Development: how an animal’s development and experiences change the individual
What causes a zebra finch to sing using the four levels of analysis?
Adaptive function: attract, ward, communicate
Evolution: all finches sing–>evolved from this branch
Immediate causation: levels of T are high, increasing neural activation
Development: exposed to T in early development–>brain organization!
How can hormones affect behavior?
(Table of boxes and arrows) Essentially, hormones play a regulatory or permissive role in emission of behavior, but they don’t cause it
