9.0 Motivation, Arousal and Homeostasis Flashcards
Define consummatory behaviours:
<b>Interaction with goal object (e.g. ingestive responses)</b><br></br>- Inflexible<br></br>- Species specific behaviour
Define appetitive behaviours:
<b>Voluntary behaviour to seek out goal</b> (e.g. food searching)<br></br>- Flexible
What are the different inputs to the hypothalamus?
<b>1) From brainstem</b><br></br>- a) Somatic afferents (somatosensory reflexes)<br></br>- b) Visceral afferents (taste/olfaction)<br></br><b>2) From Amygdala/orbitofrontal cortex</b><br></br>- Motivation/emotional meaning of stimuli<br></br><b>3) Input to neurons that directly respond to hormones</b><br></br>- Steroids e.g. oestrogen (sexual behaviour)<br></br><b>4) Temperature</b><br></br>- Pre-optic area<br></br><b>5) Osmolarity sensitive neurons</b><br></br>- OVLT
Where are the temp. sensitive neurons in the hypothalamus?
Pre-optic area
Where are the osmolarity sensitive neurons in the hypothalamus?
OVLT
What are the outputs of the hypothalamus?
<b>1) Endocrine</b><br></br>- Direct (posterior pituitary)<br></br>- Indirect (anterior pituitary)<br></br><br></br><b>2) Behavioural responses</b><br></br>- Biting/shivering/drinking/mounting<br></br><br></br><b>3) Autonomic responses</b><br></br>- Fight or flight response<br></br>- There are reciprocal connections between NST and hypothalamus for ANS control
What do lesions in the pre-optic area of hypothalamus cause?
Impaired temperature regulation<br></br><br></br>(mice will not shiver but will press button for warm air)
Role of lateral hypothalamus?
Feeding centre
Role of ventromedial hypothalamus?
Satiety centre
Hormones involved in eating/hunger?
<b>NPY</b> increases <b>orexin</b> + <b>melanin concentrating hormone</b> (both found in LH) which both cause hunger<br></br><b>Ghrelin</b> increases NPY<br></br><b>Leptin</b> decreases NPY
Role of arcuate nuclei:
Contain cell bodies of NPY neurons (stimulated by ghrelin and inhibited by leptin)
Role of paraventricular nuclei:
Receive input from NPY. Output to braintsem nuclei to control ANS (reduce metabolic rate and insulin secretion)
What is found in the medial preoptic area (mPOA) of the hypothalamus?
Steroid (androgen) receptors are especially concentrated here<br></br><br></br>Essential for male sexual response
What happens with lesions in the medial preoptic area (mPOA)?
Abolishes consummatory sexual behaviour in male
What is found in the ventromedial nucleus of the hypothalamus (VMH)?
Female sex hormone receptors
What occurs with a lesion of ventromedial nucleus (VMN) of the hypothalamus?
Loss of female sexual behaviour
What region in the hypothalamus is associated with feeding (feeding centre)?
Lateral hypothalamus (actually a tract of fibres that runs through it- median forebrain bundle)
What region in the hypothalamus is associated with satiety?
Ventromedial hypothalamus
What two neuropeptides are important for feeding?
1) Orexin<br></br>2) Melanin concentrating hormone (MCH)<br></br><br></br>Both are activated by Neuropeptide Y
What are the three divisions of the amygdala?
1) Corticomedial<br></br>2) Central<br></br>3) Basolateral
What happens in corticomedial division?
Receives <b>olfactory</b> info<br></br><b>Pheromones</b> elicit social/sexual behaviour
What happens in central division?
Receives info from solitary tract<br></br>Output to hypothalamus/brain stem<br></br><br></br>Controls:<br></br>1) ANS<br></br>2) Endocrine system<br></br>3) Simple motor reflexes
What happens in basolateral division?
Input from higher-order sensory/motivational/emotional assessment<br></br><br></br>Projects to regions of planning and action
What are the effects of amygdala lesions on :<br></br><br></br>1) Sex<br></br>2) Feeding<br></br>3) Fear
<b>1) Sex</b><br></br>- Loss of appetitive motivation. Rats do not press a lever to access the partner (but would still mount the female)<br></br><br></br><b>2) Feeding</b><br></br>- Loss of appetitive motivation. Rats do not press a lever to access the partner (but would eat if food is presented to them)<br></br><br></br><b>3) Fear</b><br></br>- Reduced fear and lack of avoidance of adverse stimuli <br></br>- Prevention and impairment of fear conditioning in humans with Urbach-Weithe disease <br></br>- Overactive in anxiety disorders
Through which neural pathway does the amygdala control voluntary action?
Output to ventral striatum (nucleus accumbens and ventral caudate + putamen)
What is the role of dopamine on the<br></br>1) Ventral striatum<br></br>2) Dorsal striatum
<b>1) Ventral striatum</b> - Activates appetitive behaviours<br></br><b>2) Dorsal striatum</b> - Activates consumatory behaviours