Physiology & Behavior 4

2 effects of the environment on behavior.Cassandra P.

Felicia H.

Kim N.

The brain’s ability to rearrange the connections between its neurons.

Changes represent an adaptation to the environment. Ex.) The brain of an expert musician should have a

thicker area in the cortex related to mastery of music when compared to the brain of a non-musician

Dendric Branching: when we learn something new, neurons connect to create a new trace in the brain.

Brain Plasticity

Rosenzweig and Bennet (1972)◦ Rats were placed into one of two environments to

measure the effects of either enrichment or deprivation on the development of neurons in the cerebral cortex.

◦ Enriched environment contained toys whereas the deprived environment had nothing.

◦ The rats spent 30-60 days in one of the environments and then killed.

◦ The brains showed that the rats in the enriched environment had increased thickness in the cortex and a heavier frontal lobe.

Brain Plasticity cont.

Stress and Reproduction Stress as it relates to reproduction

◦ Imbalance of homeostasis in the struggle of survival of the fittest.

◦ It affects the HPA, HPG, Immune, and oxidative pathways. HPA- hypothalamic-pituitary-adrenal axis its a

complex set of direct influences and feedback of interactions among the Hypothalamus, the Pituitary Gland (a pea-shaped structure located below the hypothalamus), and the Adrenal glands (small, organs above the kidneys).

Stress and reproduction cont. It effects both sexes. Qualifiers of stress response

◦ Previous experience (adaption to stimuli)◦ Genetics (bos indicus vs. bos tarsus (study of different types of beef

cattle and how they are able to produce milk in different environments.))

◦ Species◦ Age (last chance effort)

Lower levels of glucocorticiods released in a response to handling stress with age (Heildlinger 2006)

Stress and Reproduction cont. Stress qualifiers continued Physiological status (negative & positive

energy) Gender

◦ Women have higher glucocorticiods after HPA stimulation (Aloisi 2006)

Stress and reproduction Types of stress

◦ Physiological Nutritional deficiency

◦ Psychological Over crowding

◦ Environmental temperature

Stress and Reproduction cont. Pre-fertilization

◦ Depression, anxiety, and chronic stress can interfere with your sexual response (sex drive). Zoo animals have reduced reproductively associated with

captivity.

Effects on men◦ Stress can lower testosterone◦ Lower sperm fertility

Effects on women◦ Lower estrogen levels◦ While menstruating the urge to have sex will be

practically nonexistence.

Stress & reproduction: Pregnancy During Pregnancy

◦ Miscarriage◦ Low birth weight◦ Reduced fetal oxygen levels◦ http://youtu.be/xr2uJtQLPXc

Post pregnancy◦ Stress during pregnancy can determine behavior

defects of the child.

Stress ≠ infertility Stress doesn’t mean you cant have children, but

it can make it harder.◦ PTSD can create more complication( seng 2005)

Certain oxidative stress is necessary for pregnancy

Acute stress has been found to increase testosterone in boars