Motivation, Stress & Emotion MK Flashcards
Hypothalamus
couples body states to systemic and neural-behavioural responses
The hypothalamus is a group of nuclei which INTEGRATE VITAL INFO:
- sensory input
- physiological input
- direct smapling of blood and CSF
- Time (internal clock, internal cues)
- threat/stress information (amygdala and others)
What is the job of the hypothalamus?
- Core of the CNS -
- Head ganglion of the ANS
- Group of nuclei concerned with body maintenance eg. feeding, drinking, sexual activity, sleep/wake cycle, hormones.
- Homeostatic relfexes
- Drives, which interact with memory, judgement and experience, to shape behaviour
which responses does it organise?
PITUITARY: for hormone output
AUTONOMIC CONTROL
influences behaviour via drives (thirst, hunger etc).
How does the pituitary control hormonal regulation
The pituitary, endocrine controller, is half CNS tissue (posterior) and half epithelial (anterior)
Hormone secretion from both are under direct hypothalamic control (also hormonal feedback)
Explain : DRIVES
‘drives occur when you force the cortex to help’
Drive = a motivation of behaviour to suit physiological (and more complex) needs.
Can be ignored at onset, biasing behaviour
- Become more dominant as the need increases
- Eventually push aside other behavioural considerations, judgement, taboos
- Satiety relieves pressure on behavoiur
Explain the THIRST drive
Low water in the body is detected byt he kidneys, vessel sensors, the hypothalamus (osmoreceptors in the lamina terminalis)
Acts on the lateral hypothalamus, influencing:
- –> the posterior pituitary: systemic ADH response (kidneys, vasculature)
–> Autonomics sustain BP via vasomotor centre
–> Limbic system (cingulate and amygdala) to cortex etc: behaviour (whatever gets the job done)
HORMONES & AUTONOMICS ARE A SHORT TERM FIX -> drive reflex = The hypothalamus creates a behavioural drive, thirst through
Explain the THERMOREGULATION drive
HYPOTHALAMUS monitors core temperature;
- low in medial preoptic area
- high in anterior hypothalamus
OUTPUTS:
- anterior pituitary -> thyroid stimulating hormone : metabolic regulation (as appropriate),
- autonomics (piloerection, blood flow, shivering, sweating)
- limbic system (cingulate, amygdala) to CORTEX etc -> behavioural change: put on clothing, seek shade etc.
There is no drive for BLOOD PRESSURe, why?
Maintaining BP is important. - multiple levels of redundant control: pacemakers, renal arteries, brainstem
Changes in BP stimulate SNS and PSNS, alters pacemaking and cardiac output appropriately, BUT it doesnt create a behavioural drive, WHY?
Behaviour cant effect BP much, beyond the things the brainstem is already doing, so this information is not passed on to consciousness.
How do people get MOTIVATED?
Reward and reinforcement system:
- Berridge made a useful distinction- between wanting and liking behaviour.
- Wanting isa state or urgency, a way to sustain behaviour over long periods.
- Liking is the positive reinforcement- the satisfaction when behaviour achieves a goal
- You also have to figure out what you need
- In neurobiological terms, this means reward systems influence the cortex and vice versa.
How is PLEASURE involved?
Pleasure is an added emotional dimension to an ordinary stimulus
- a neural code- activity in the septal nuclei : tagging something we want to seek or do
- Signalled independently, since we may change our minds about what’s pleasant.
- For example, you can be driven to seek something without particularly enjoyin git
What is the anaotmy of seeking and reward?
Ventral Tegmental Area (VTA) - midbrain Ventral pallidum (VP) - base of striatum Nucleus accumbens (Acb) - basal forebrain
Explain a classical reward system
Forebrain dopamine systems are called the REWARD pathways of the CNS
VTA projects dopaminergic fibres to ventral forebrain as a motivator (drives action)
Nucleus Accumbens uses DOPAMINE to signal satiety ot the cortex- goal has been met, stop seeking now
- the goals of behaviour are negotiated
The brain works on a VALUE system -> explain.
VTA pushes motivation to the nucleus accumbens which is put into an unresolved state of ‘goal not met’ stage, ‘wanting’
The prefrontal cortex negotiates with nucleus accumbens with Acb about what needs to be done and when its been achieved.
Feedback on what we like/dislike
“Hedonistic” transmitters – opioids, GABA, endocannabinoids – are used to signal “good things”
Sugar and sweet
When we taste something sweet, neuronal firing INCREASES In nucleus accumbens etc. versus when we taste something salty, firing decreases.
BUT when we are salt depleted, sugar still tastes nice, but salt is more tasty, and neuronal firing is increased–> THE IDEA OF PLEASANT HAS CHANGED, because the needs of the mouse have changed
