WEEK 11 LECTURE + TUTORIAL Flashcards
hypothalamus, sleep, neural connections (25 cards)
What is Neural Control
-Functional interactions between networks of neurons that regulate or control a behaviour or function
Neural Control of Breathing
-Increase and decrease of volume
-Decrease and increase of pressure
-controlled by the brainstem, pons and medulla
Neural Control of Breathing
Part 2
- Basal breathing
-Dorsal respiratory region of the medulla
-Inspiratory neurons spontaneously fire (no signals needed)
-Signals through C3,4,5 to innervate the diaphragm via phrenic nerve
Neural control of breathing
Part 3
-More air is needed when CO2 goes up, or when O goes down
Hypothalamus Structure
-small, but important
-Below the thalamus at the base of the brain
-Ventral part of the diencephalon
-Consists of a group of nuclei and fibre tracts
-ANS, Endocrine system
Hypothalamus Function
-Hormone production
-The primary function is homeostasis
-Organises survival behaviours
-Contains ‘biological clock’ which regulates certain bodily functions
-Involved in emotional expression
-Controls autonomic NS, and endocrine system
Fighting, Fleeing, Feeding, Fortification (4 Fs of Function)
Pituitary gland
-Important structure near the hypothalamus
-Attached to base of hypothalamus via pituitary stalk
-Two main lobes, anterior and posterior
-Anterior pituitary gland is considered ‘master gland’
Hypothalamus control of the pituitary gland
-Communicates with both anterior and posterior pituitary gland to alter hormone secretion
-Anterior pituitary gland (indirect)= hormones
-Posterior pituitary gland = Synaptic transmission
Anterior Pituitary Gland
Indirect control - Hormones
-Specialised neurons in hypothalamus secrete hormones
-Hormones travel to anterior pituitary via blood vessels
-Hormones secreted from hypothalamus stimulate hormone release from anterior pituitary gland
Hypothalamic Pituitary Axis (HPA)
-Paraventricular nucleus of hypothalamus secretes corticotropin-releasing hormone (CRH)
-Stimulates anterior pituitary gland to release adrenocorticotropic hormone (ACTH)
-Enters blood and stimulates adrenal cortex to release cortisol
-The stress response
Effects of cortisol exposure
- Increasing risks of health issues
-Heart disease
-Obesity
-Anxiety/ Depression
Cortisol and Epigenetics
-Stress responses seem to be altered by environment and epigenetics
-Alteration in the expression of genes due to nurture
Rat studies:
-Offspring of nurturing mothers more resilient to stress
-Offspring of negligent mothers more affected by stress
-Effect seen in future generations
Posterior pituitary gland
Direct control- synaptic transmission
-Considered an extension of hypothalamus
-Hypothalamus actually produces the posterior pituitary hormones and directly controls their secretion
-neurons in hypothalamus have axons which extend down pituitary stalk and end in posterior pituitary gland
Sexual Behaviour
- Spinal areas involved in sexual behaviour - lumbar region
-Medial preoptic area, males - Ventromedial nucleus of hypothalamus, VMH females
-Medial Amygdala received chemosensory info from the vomeronasal system and somatosensory info from genitals
-mediates signals to the brain and medulla
Studies on Humans, sexual behaviour
-Work on sexually impulsive men show weaker areas of connectivity between the PFC and amygdala
-Cingulate cortex interacting with hypothalamus during sexual arousal
-Biological, Physiological, Social contexts interact and moderate regional brain activity
Neural Regulation of sexual behaviour
Circuit includes:
-Limbic (hypothalamus, amygdala)
-Paralimbic areas (ACC, Frontal lobe, insula)
-Associative cortices (inferior temporal lobe, occipital cortices)
-Thalamus, secondary somatosensory cortex
Eating Behaviour
Hypothalamus, role in hunger, role in safety
Hunger is primarilya biologically instigated drive for food that is essential for life
-Safety isthe psycho-biological process that suppresses hunger after an eating and prevents further eating; it is said to control snacking between meals
Complicated gut-brain interactions: - gut brain axis
Intestines gives off signals to brain (CCK, PYY)
Liver and pancreas (insulin) give feed-back to brain
Adipose tissue (leptin): metabolic rate/satiety
Stim lateral hypothalamus: eating (neuropeptide Y)
Arcuate nucleus hypothalamus has leptin receptors (inhibit NPY) decreases eating, increases metabolic rate
-Two regions of the hypothalamus are critical to regulating ingestive behavior. The lateral hypothalamus regulates hunger while the ventromedial hypothalamus regulates satiety. Stimulating the lateral hypothalamus produces eating behavior while lesioning it abolishes this behavior.
Environmental cues for hunger
Environmental cues
Clocks/schedules: learned response
Smells/sights/taste: feed-back to brain
Size meal/fat content (except when with others)
What is sleep?
‘The natural, easily reversible periodic state of living beings, marked by the absence of wakefulness and by the loss of consciousness of one’s surroundings, accompanied by a typical posture, the occurrence of dreaming, and changes in brain activity and physiological functioning..’
Brain Activity during REM sleep
-Prefrontal cortex: Low activity in this region during REM, reflects the lack of organisation in dreams
-Extrastriate Cortex: High activity in this region during REM, reflects visual hallucinations
-Striate Cortex: Low activity in this region during REM, due to lack of visual input
slow wave sleep
-decreased activity in cortex except visual and auditory cortex’s
-decreased activity in cerebellum
hypothalamic control of sleep/wake cycle
-orexin neurons involved in maintenance of arousal state
-input and output pathways to orexin neurons
-manipulation and recording of orexin neurons in vivo
-Melanin Concentrating Hormone in sleep/ wake cycle
-Central circadian clock, SCN and sleep wake regulation
Preoptic area of hypothalamus
-controls arousal neurons
-anterior hypothalamus
-supress/inhibit arousal neurons
-release GABA
Circadian Rhythms
-24 hour rhythmical change in behaviour
-Zietgeber- stimulus that resets the bio clock responsible for circadian rhythm
-melanopsin in ganglion cells
-stimulus of SCN
-Inhibits production of melatonin in the pineal gland
