Hypothalamus Flashcards
What is the role of the anterior pituitary?
Master gland - regulates function of other endocrine glands
What is the role of the posterior pituitary?
Secretes oxytocin and vasopressin
Mediates sexual, maternal, fluid balance functions
What are the 3 functional divisions of the hypothalamus and what are their roles?
Periventricular zone - neuroendocrine motor zone
Medial zone - controls diverse set of behaviours
Lateral zone - contains neurons expressing substances (orexins and corticotrophin releasing hormone)
What do orexins regulate?
Ingestive behaviour
Circadian rhythm
What does corticotrophin releasing hormone regulate?
Fluid balance
What are the areas of the medial hypothalamus and which behaviours do they control?
Medial preoptic nucleus - reproductive, social
Anterior hypothalamic nucleus - defensive
Paraventricular nucleus - ingestive
Ventromedial nucleus - reproductive, social, defensive
Mammillary body - exploratory
Which hypothalamic region is sexually-dimorphic in humans?
Interstitial nuclei of anterior hypothalamus (INAH)
What are the proceptive sexual behaviours in male and female rats?
Female - hopping, head-wiggling, 50kHz calls
Males - cruising (searching for females), 50kHz calls
What are the consummatory sexual behaviours in male and female rats?
Female - lordosis
Male - mounting
What are the post-consummatory sexual behaviours in male and female rats?
Female - intense grooming
Male - intense grooming, 22kHz ‘leave-me-alone’ calls - avoidance
Which hypothalamic region is sexually-dimorphic in rats?
Sexually dimorphic neurons in preoptic area (SDN-POA)
Which hypothalamic region is active during mating in male rats?
SDN-POA
Which receptors are found on SDN-POA neurons?
Testosterone receptors
Where does the POA receive input from?
Vomeronasal organ - via medial amygdala and BNST
Where does the POA project to and what is the role of this projection?
PAG
Activate spinal MNs for pelvic organs involved in copulation
Which hypothalamic area coordinates sexual behaviour in female rats?
Ventromedial nucleus of hypothalamus (VMH)
Which receptors are found on VMH neurons?
Oestrogen receptors
Progesterone receptors
Which neuropeptides are key to support sexual behaviour?
Oxytocin (OT) Arginine vasopressin (AVP)
Where are oxytocin and arginine vasopressin made?
Posterior hypothalamus
What are the peripheral effects of oxytocin?
Uterine contractions
Milk ejection reflex
What are the central effects of oxytocin?
Sexual behaviour
Maternal care
Adult social bonding
Adult pair-bonding
How do AVP and OT levels change during male rat sexual behaviour?
AVP increase during anticipatory behaviour
OT increase at ejaculation
What are Panksepp’s 3 types of aggression and which circuits do they involve?
Affective/defensive attack - RAGE system
Quiet-biting - SEEKING system
Inter-male aggression - circuits interacting with RAGE and SEEKING systems
Which brain areas are involved in affective/defensive attack?
Ventrolateral and medial hypothalamus
Dorsal PAG
BNST
Which brain areas are involved in quiet-biting?
Dorsolateral hypothalamus
Ventral PAG
Which brain areas are involved in inter-male aggression?
Medial amygdala
Preoptic and anterior hypothalamus
PAG
What are the 2 model species of maternal behaviours?
Rat
Sheep
What are the characteristics of rat maternal behaviour?
Altricial species
Long bonding window
Accept alien pups
What are the characteristics of sheep maternal behaviour?
Precocial species
Short bonding window
Selective maternal care - reject alien lambs
What hormonal changes occur at the end of pregnancy in rats?
Increased oestradiol and prolactin
Decreased progesterone
Which neuropeptide is needed for maternal behaviour induction in rats?
OT
Through which brain areas do pup stimuli trigger maternal responses after parturition in rats?
Pup stimuli - medial preoptic nucleus (MPOA) - VTA - NAc - ventral pallidum (VP) - active maternal responses
Pup stimuli also activate limbic system - disinhibits NAc and VP - modulates circuit
What hormonal change occurs at the end of pregnancy in sheep?
Increased oestrogen
Which neuropeptide is needed for maternal behaviour induction in sheep, what triggers its release, and from where?
OT
Vagino-cervical stimulation (VCS) of birth
From paraventricular nucleus (PVN)
Through which brain areas does VCS trigger maternal responses after parturition in sheep?
VCS - PVN - MPOA - VTA - NAc - VP - active maternal responses
How does the OT released by VCS lead to maternal selectivity in sheep?
OT induces plastic changes in mitral cell responsiveness - in main olfactory bulb - more cells respond preferentially to lamb odour
What causes pair-bonding (monogamy) in prairie voles compared to non-monogamous voles?
Higher OT receptor density in key areas (PFC, NAc)
What is the circuit for prairie vole pair bonding?
In males and females - mating causes DA release - from VTA to NAc and PFC
In males - AVP release - in lateral septum
In females - OT release - in NAc and PFC
Concurrent release of DA and OT/vasopressin - consolidates conditioned partner preference
What is the role of the NAc-ventral pallidum projection in prairie vole pair bonding?
Relays info to motor system - pair bonding translates to behaviour
Which phenomena do OT affect in humans?
Maternal behaviour
Sexual behaviour/pair bonding
Theory-of-mind-related abilities - memory for faces, inferring others’ emotions
Trust
What is the medial forebrain bundle (MFB) and which areas does it involve?
Dense fibre system
VTA - lateral hypothalamus - NAc
Which NT projections run through the medial forebrain bundle?
5HTergic (from raphe nuclei)
ACh (from forebrain nuclei)
DA (mesolimbic, mesocortical)
