- Born relatively helpless, often with little or no fur or feathers generally incapable of locomotion or ingestion of solid food
- E.g. Humans, song birds, mice, kittens, puppies
- Born more advanced, capable of locomotion and other behavior patterns, consume some solid food.
- E.g. horses, cattle, giraffe, fish, etc
- Sign stimulus
- Innate releasing mechanism (IRM)
- Fixed action pattern (FAP)
A specific stimulus that results in a specific behavior pattern. One example is the red bellied stipled back. If it has a red belly (regardless of what shape it is) the fish will attack
Innate releasing mechanism (IRM)
A neural process triggered by the sign stimulus that preprograms an animal for receiving the sign stimulus and mediates a specific behvarioural response.
Fixed action pattern (FAP)
An innate behavior pattern that is stereotyped, spontaneous and independent of immediate control, genetically encoded and independent of individual learning.
- A stimulus that produces more vigorous response than the normal stimulus.
- E.g. the cow bird that is laid in another bird's nest but gets the most food because it is larger, looks older and talks the loudest...
- Time in the life of an animal when a small amount of experience (or lack of experience) will have a large effect on later behavior (experience ranges from internal to external factors)
- e.g. In mammals a brief hormone signal from the genitals induces sex-related changes int he brain that ultimately mediate sex-typical behavior, and manipulating embryo hormones outside this period has no effect on adult behavior
Sensitive period and intrauterine position
- Many affects of intrauterine hormone exposure
- Rodents, swine, 0M females more 'attractive"
- Rodents, 2M females more aggressive
- Also occurs in animals which normally have 1 offspring, females with male twins show "masculination" effects. Females can be sterile.
- Possible to observe effect of a particular hormone by studying behavior: in the absence of the hormone (if absence is not lethal); after the injection of known amounts of the hormone
- Used to investigate influence of testosterone on male sexual behavior in the rat
Ways Prenatal Stress Can Affect Offsprin
- Production: birth weight, mortality, reproductive status
- Behavior: fear & anxiety, memory & learning, maternal behavior, aggression
- Physiology: Immune status, glucose metabolism, HPA axis
- Conditions during pregnancy influence health in later life
- Heart disease, diabetes higher in people with low birth weights
- Poor nutrition, drug and alcohol use, poverty
- Intergenerational effects
- Maternal nutrient restriction affects properties of skeletal muscle in offspring
- Maternal nutrient restriction alters gene expression in the ovine fetal heart
- Influence of matternal undernutrtion and overfeeding on cardiac ciliary neurotrophic factor receptor and ventricular size in fetal sheep
External factors after birth
- Handled rat pups
- open eyes sooner, heavier at later age
- Less fearful in novel situation (open field test)
- Mallard duck's strong response to mother's call depends on hearing the calls of other ducklings while they are still in the egg
- Kittens vision needs to be primed with certain types of visual experiences (vertical and horizontal environments from 2wks-5 months)
- Quail young emit clicking noises in the egg
- 2 days prior to hatch chicks start to emit clicks (80-150/min)
- If eggs are in contact chick hatch within a few minutes of each other
- If eggs separated so they cannot communicate, hatching is spread over 2 days
- Hens and chicks communicate through vocalizations prior to hatch
- Communication may play a role in synchronizing the hatch
- Commercial environments void of hen sounds
- Influence choice by chicks, attracted to sounds heard during incubation
Maternal effects and phenotypic plasticity
- Mothers often play a role in determining the behavior of their offspring as adults
- Phenotypic plasticity - genotype is flexibly expressed as different phenotypes, depending on the environment: Allows faster-than evolution adaptation to the environment.
Adaptability of behavioral development
- Harlow's "experiments" with Rhesus monkeys showed that rhesus monkeys entirely derived of contact with mothers and "reared" by artificial surrogates: gained weight, grew normally, behaviorally developed abnormally and were terrified of other monkeys if exposed
- However, monkeys given even 15 min contact a day with other young monkeys developed essentially normally.
- As adults: monkeys interacted normally unlike those individuals which had no social contacts as infants, which were withdrawn or very aggressive
Maternal licking behavior
- During first 2 postnatal weeks, rats do anogenital licking, males more than females.
- This is important for brain development and behavior, including stress reactivity, emothionality, learning and memory, and sexual behavior.
- It induces epigenetic changes after birth
- DNA methylation patterns in the hippocampus cells of licked and non-licked varied
- Mother's licking activity had the effect of removing dimmer switches on a gene that shapes stress receptors in the pup's growing brain
- The well-licked rats had better developed hippocampi and released less of the stress hormone cortisol, making them calmer when startled
Food preferences and mothers
- Food choices by mother can influence offspring's food preference
- Examples are mother's milk containing olfactory cue, breath, and observation
- Special form of learning
- Precocial young form an attachment to and follow a large moving object in their environment
- Various behavioural changes whereby a young animal becomes attached to its mother (naturally) or another object
- Occurs soon after birth or hatching
- Birds and mammals
- Method by which animals learn to recognize speices for reproduction
- Occurs later
- ducks try to mate with Lorenz
- Time when animals can develop an attachment
- eg. Puppies 3-13 weeks for forming normal social contacts
- Rats: first week of life
- Pigs: birth to 3 weeks
- Young ruminants, first days
- Part of sensitive period when the attachment response performance and reinforcement is greatest
- E.g. Goats, the 1st hour after parturition, mother must smell and lick offsping