Hormones and behavior Unit 4

De Marian isolation experiment in heliotropic plants

Types of biological rhythms coupled with environmental cues

-rotation of earth, tides, phase of the mon, season of the year

diurnal, nocturnal, or crepuscular

-but many are independent of environmental cues

diurnal

during the day

Rhythmic variation of serum LH levels in hamsters

changes hourly, hourly (increase at night time till midnight), and yearly changes (increase in april to September)

evidence for endogenous clocks

0in constant conditions away from subtle geophysical cues (ex spacecraft)

-individual differences in the absence of environmental cues

-the pattern can be transformed by tissue transplants

Frequency of wheel

when lights were off the number of revolution increase

Zeitgeber

a potent environment cue regulating on onset of rhythmic activities

Free running

biological rhythm that is not synchronized with environmental cues

Entrainment

the process of synchronization of endogenous biological rhythms with a zeitgeber

a hamster free running is is independent from

behavioral expression

phase response curve

graphic representations of differential effects than environmental zeitgeber has on the timing of the biological rhythm

phase shifts in humans

weekend parties – jet lag (phase delay vs phase advance) – light at night causing internal desynchronization: disruption of sleep, digestive and psychological process

During the day for humans

• growth hormones decreases

• melatonin is low

• plasma cortisol decreases

• temo increases

  • K+ excretion increases

functional significance of biological clock

-Synchronizing the internal physiological and biochemical processes to promote efficient functioning

• Synchronizing the activities of animals with their environments and enabling them to prepare for predictable events

circadian clocks

at every levels of organization within an organism

• inheritance • limited entrainment

• independence from behavioral feedback

localization of circadian clocks

the nervous system cannot be the fundamental level

• at the cellular level

– discover the basic chemical agents

– identify the genes

• at the physiological and anatomical level

– lesion

– isolation

circadian oscillators

• eyes of amphibians

• pineal glands of fish, reptiles and birds

• the suprachiasmatic nucleus of mammals

what proves the SCN as containing circadian pacemaker

lesions

• slice in culture dish - rhythmic electrical activities

• transplant - phase similarities

• SCN - “master clock” but other circadian pacemakers may also exist

individual SCN neurons show

precise circadian rhythm

Neurochemicals in SCN

Vasopressin (AVP)

• Vasoactive intestinal polypeptide (VIP)

• Estrogen

• others

Three main components of a mammalian biological clock system

1. retinohypothalamic tract

2. (receive from the tract) suprachiasmatic nucleus (send neural signal & humoral signal)

   1. clock control genes

central and peripheral oscillators: different phase relationship

The network of connectivity among SCN cells allows for the synchronization of independent cellular oscillators for coherent tissue-level clock functioning. • The SCN is the only clock with access to environmental light information • And through neural and hormonal communication

Missing notes

Glucocorticoids on immune function

-inhibit cytokines release

-inhibit the sensitivity of target cells to cytokines

-block maturation of developing leukocytes

(both T and B cells)

-destroy some leukocytes

the sympathetic nervous sytem on stress

projects into immune tissue, where it has also inhibited effect on immune functions

acute stress versus sustained stress

activates immune response while sustained damages and inhibits the immunes system

monkey show

stressed captive vertet monkey show deficit in the hippocampal neurons

data suggest that social structure has an effect in brain structure, decrease cells

exercise in men

cause an increase in testosterone and LH

learning

an adaptive change in behavior that results from experience

-acquisition, consolidation, retrieval, and extinction

arousal and learning

stressful event can be arousing and cause an increase in hormonal events which cause an increase in performance but is a bell shape curve so too must arousal cause low preformance

non associative learning

-after repeated presentation of single stimuli

-sensitization: to evoke stronger response (learned)

-habituation: learn not to respond (squirrels learns not be scared to humans)

-different from fatigue: loss of motor response and sensory adaptation: info from CNS- these are not learned

Associated learning

-classical condition: ivan pavlov

-operant learning: skinner

-aversive (conditioning) : active and passive avoidance. you can have a mice learn to pair tone with electrical shock so that they will move at the sound of the tone- active avoidance

and passive avoidance is having the nocturnal chamber aviod the dark by shocking them in the dark (goes against natural behavior)

appetitive learning: radical arm maze

rat learns which arm to go to as they are reward with food and eventually animals will be able to use reference point and working memory to go to the arm with food.

fear conditioning

chamber with tone = no response

chamber with shock= animal will freeze

chamber with only tone after many rounds= animal freeze (same behavioral response to when there is a shock)

memory

-can be short term or long term

-working v reference memory

three steps:

-enter info into storage

-retain stored info

-retrieve

missing some notes

Effects of epinephrine are

time dependent, 1 minute after training was the highest performance

How does epinephrine effect the body when it can not cross blood brain barrier

1. gluco hypothesis: dose and time dependent, but glucose was shown to improve performance at certain times and dose (bell curve) similar to NE

2. The peripheral receptor hypothesis: that Epinephrine activates peripheral receptors that communicate with the CNS.

evidence for glco hypothesis

-stress increases both epinephrine and glucose

-epinephrine induces glucose levels similar to that in response to potainal training conditions

-glucose injection enhance memory

-block epinephrine receptors impairs epinephrine but not glucose and still effects memory

glucose affects memory evidence

-fuels the brain

-glucose to neurons cause release Ach

-Ach at synapses is associated with enhanced cognitive functions

-Alzheimer or AIDS patient have marked reduction in Ach producing neurons

impaired learning and memory

-aging in both rats and humans

-epinephrine enhances memory in old rats

-glucose enhances memory in the elderly people (health ot with alzheimer)

-glucose enhances memory

evidence for peripheral receptor hypothesis

1. Alpha and beta receptors (the receptors for epinephrine) when blocked 30 min before injection of epinephrine does not show normal increase in performance

2. the amygdala plays large role in memory (electrical stim increase memory recitation) local injection and beta blockage cause no increase in memory

3. epinephrine acts on beta receptors which activates ascending neurons in the vagus nerve to the basolateral amygdala

insulin involvement in learning

-diabetes exhibit learning difficulties and cognitive impairment

-brain insulin receptors associated learning

-desory of b cell by drug induced deficits in passive avoidance learning (insulin treatment prevents)

glucocorticoids

amygdala is important for

memory consolidation

hippocampus is important for

spatial memory