Biopsychology of Motivation and Internal Regulation Flashcards
What did Richtor (1922) hypothesise?
Richtor hypothesised Endogenous circadian rhythms = internally controlled cycles that last about a day
How much of our lives do we spend sleeping
We spend one third of our lives in a suspended state doing almost nothing
How do we know that this rhythm is internally generated?
If you stay up all night, you feel sleepier as it gets later, but then perk up a bit in the morning. Humans kept in an environment with a 28hr cycle cannot synchronise, they slip back into a 24hr cycle.
What generates rythm
Richter (1967) theorised that we all have a biological clock
Define biological clock
a mechanism in our brain that generates our sleep and wake cycle
Where is the biological clock
Suprachiasmatic nucleus or SCN
How do we know it generates a rhythm automatically?
Remove the SCN and keep it as a tissue culture it continues to produce a 24hr rhythm of action potentials…(Earnest et al, 1979)
What happens when the SCN is damaged?
Damage to SCN causes damage to circadian rhythms
Zeitbeger
Define Zeitbeger
Stimulus which changes the biological clock
Define Jet Lag
Is the disrupting of sleeping rythms through changing time zones
Why is light so important?
It helps ‘reset our rythms’
What study backs the idea that light can help reset our sleeping cycle
Miles (1977) Blind man needed sedatives to settle circadian rythm to 24 hr cycle
Name the 4 stages of sleep that exhibit different levels of brain activity than relaxed wakefulness
Stage 1 and 2
Stage 3 and 4
What is involved in stages 1 and 2
Irregular activity
Neuronal activity high
Sensory input reduced
What is involved in stages 3 and 4
Slow wave sleep (SWS) = neuronal activity is highly Synchronised
Chronic masturbation
Sensory input reduced
What is REM?
Rapid Eye Movement sleep
- Also called paradoxical sleep
- Neither light nor deep sleep
- Light because lots of brain activity
- Deep because muscles are relaxed
Name 4 Sleeping Disorders
- Insomnia
- Sleep Apnea
- Narcolepsy
- Periodic Limb Movement Disorder
Define Insomnia
– Stress, anxiety, depression
– Shifting circadian rhythms
– Dependence on sleeping pills
Define Sleep Apnea
– Inability to breathe while sleeping
– Obesity? Old-age?
Narcolepsy
– Attacks of sleepiness during the day
– REM during the day?
Define Periodic Limb Movement Disorder
– Involuntary movement of the legs/arms
– Maybe something to do with the pons?
Is sleep a form of Hibernation?
– Conserving energy when you can’t get much done
– when food is scarce, light is too high, too low etc.
– Hibernating hamsters live longer than other hamsters (Lyman et al. 1981)
How do animals vary in how much sleep they need?
– Safety from predators
– How much time they need to find food
– Whether they need to surface for air! (dolphin sleeps on one side of the brain at a time..)
What suggests that there must be mor to sleep than just conservation of energy?
– Sleep deprivation causes dizziness, hallucinations etc.
– Eventually the immune system fails in animals severely deprived
– Sleep enhances memory
Why do we need sleep?
- To strengthen memories, and weed out the pointless connections
- Moistening the eyeballs…
Name 2 hypotheses that may explain why we dream?
The Activiation-Synthesis Hypothesis
The Clinico-Anatomical Hypothesis
Describe the Activation-Synthesis Hypothesis
- Effort to make sense of distorted info
- PGO waves from pons activate parts of the cortex, which synthesises a story
- But not always in REM…
Describe the Clinico-Anatomical Hypothesis
- Dreaming is thinking…
- Senses are suppressed, so brain left to its own devices
- Motor cortex suppressed, so no action
- Pre-frontal cortex suppressed, so no working memory to link a believable story together!
How do we react to temperature change?
Responds to changes in its own temp, and also temp receptors in the skin
What do we do when we are thirsty?
If water is scarce, the pituitary gland secretes vasopressin
Blood vessels constrict
Raises blood pressure and compensates for the low fluid volum
What is Vasopressin
Vasopressin in also an antidiuretic hormone (ADH) – makes urine more concentrated by causing the kidneys to reabsorb fluid from urine
How do we know what to eat
combination of learned and unlearned strategies
- learned from peers, culture
- but, innate tastes are essential
- likeness of sweet food, disgust for bitter/sour
How do we know when to eat?
- centres around the hypothalamus (forebrain area associated with regulating behaviours)
- hypothalamus has neurons sensitive to hunger and feeling full
- these feeding mechanisms seem to have changed very little during mammalian evolution (more relevant to study animals?
How can our understanding of when and what we should eat help us with understanding eating disorders?
- Obesity
- Big problem in industrialised countries, excessive eating due to huge availability of food - Anorexia Nervosa and Bulimia Nervosa
- Poorly understood, biological issues associated with it, but cultural and individual issues are more likely to be the cause
Describe Obesity
- Huge cultural influence
- Social aspect of eating
- Still rooted in our biology, propensity to like fatty foods!
What is Anorexia Nervosa
- unwillingness to eat
- 0.3% young women
- perception of fatness, even when thin
- body can deteriorate, muscle wasting, can even cause death
Define Bulimia Nervosa
- extreme dieting mixed with binge eating
- vomit after mealtimes (not all)
- imbalance of hormones associated with feeding
How does our sex (and gender) affect our behaviour?
Evolutionary theory
- we are the product of successful strategies, so we should have inherited successful strategies
- men and women were subject to different selection pressures in evolutionary history, therefore exhibit different traits
Name 2 ways in which men and women may differ in reproductive behaviours
- Sexual strategies – reproductive behaviour - Mate choice, attitudes to sexual behaviour
- Cognition - Cognitive skills rooted in different reproductive and survival strategies
How do Men and Women differ in terms of Sexual Strategies
Men – Numerous, mobile sperm; potential to father many offspring
Women – Few, immobile eggs; maximum 20 (?) in lifetime - the ‘choosy’ sex
Name the role of hormones in sexual strategies for men
- androgens (testosterone) produced in the testes and the adrenal gland (in the brain)
- sensitises regions of the brain underlying sexual motivation
- removal of the testes (i.e. cancer) results in decreased sex drive, BUT still some production in the brain
Name the role of hormones in sexual strategies for women
- oestrogens produced by the ovaries
- AND androgens produced by the adrenal gland
- as in men, androgens associated with sex drive
- postmenopausal women can still have high sex drive due to androgen production (even when oestrogens have dropped)
