The Role of Hormones and Environment in Behavioral Development: Interactive Theory, Study notes of Zoology

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The Development of

Behavior: The Role of the

Environment

Chapter 3b Or Experiences and Hormones!

Main Points

Hormonal influences on behavior Interaction between learning and behavioral development – biased learning focus Interactive theory of behavioral development

Effects of Hormonal Environment

Organizational Structure produced during development due to hormonal condition Ex. Neurological structures in male birds Activational Behavior triggered by hormone that turns on an organizational effect. Ex. Actual singing in male birds as adults

Testosterone is Both Organizational

and Activiation in Mammals

Uterine Environment in Mammalian

Litters

Location during development of embryos along uterine wall influences behavior. ♂ flanked by ♀’s will be less “male” ♀ flanked by ♂’s will be more masculine than normal. This is due to leaking testosterone and estrodial.

Rodent Porn

Another Example

Organizational and Activational effects in bird song. Ex. Remember male WCSP and testosterone treated female WCSPs.

Cascade of Activational Events

Ringed Doves Breeding behavior/cycle Assume – all organization effects are properly in place. aka. normal adults. Note – there are no seasons to dove breeding, they will breed all year long if they can.

Nest Building Stage

Begins shortly after courtship Presence of nest and nest-building in general triggers progesterone release Progesterone is important for incubation behavior. ♂ must participate in nest building, otherwise he will have no progesterone and no egg incubation behavior later

Egg Laying

Steps 1 and 2 are important for the production of lutinizing hormone (LH) by the ♀ pituitary gland This stimulates egg laying in the ♀.

Feeding Offspring

Requires parental care for survival Prolactin activates proper parental feeding behavior in ♀ and ♂. Parental behavior declines as prolactin declines late in the season. As prolactin , then FHS and LH (in females) As prolactin , T (in males) Back to step one again

Dove Breeding Behavior

Examples of Neurogenesis in Adults

Neurogenesis in “singing centers” in brains of birds Happens each spring and goes away each fall. Saves 15-20% energy use over the year. Neurogenesis in rat sexual behavior Testosterone “activation” causes slight change in neural anatomy Creates machinery to do behavior.

More Examples

Neurogenesis in hippocampus Involved with function of memory Grows with increased use and demand Neurogenesis in sex changes among some fish species. Big ♀ will become ♂ in adulthood if it would be more fit.