Week B1: Motivation, Stress and Emotion Flashcards
In simple terms, how does the hypothalamus couple behaviour to physiology?
Hypothalamus recieves information, from various systems, about body states. It then couples these body states to systemic and neural-behavioural responses.
It enables physiological needs to drive the nervous system.
Integrates this function with needs/wants/likes -> via input from limbic system (emotion), prefrontal cortex (higher-thinking, desires, etc), autonomic physiological states (e.g. heat, dehydration), etc.
What is the hypothalamus?
What types of vital information is integrated by the hypothalamus?
Group of smal nuclei all concerned with ‘body maintenance’
Integrates:
- Sensory input (exeroception)
- Interoception (physiological monitors)
- Direct sampling of blood and CSF (open to BBB via lamina terminalis)
- Time (internal clock, time cues)
- Threat/Stress information (from amygdala and other structures)
What kinds of responses does the hypothalamus prompt, by interacting with other structures?
(i.e. how does the nervous system feed back to change our physiology)
Via which key structures/systems does the hypothalamus do this?
Via Homeostatic Reflexes
Formation of ‘drives’ - these interact with memory, judgement, experience, to shape behaviour
Pituitary -> hormone output
Autonomic control -> brainstem
Influences behaviour -> via ‘drives’ -> via cortex
What is the pituitary? How is it controlled?
Pituitary = endocrine controller
Posterior half = CNS
Anterior half = Epithelial
Under direct hypothalamic control
Also controlled/modulated by hormonal feedback
How does the hypothalamus force the cortex to help?
How do ‘drives’ impact upon our judgement, depending on the severity of the situation?
Formation of ‘drive’ - i.e. morivation of behaviour that suits the physiological need
Drives can be ignored at first
However, as the physiological need increases, the drive becomes more dominant
This involves decreasing other behavioural considerations - e.g. taboo, judgement, etc. - in order for the drive to be carried out
What is the term used to describve when a ‘drive’ has been fulfilled?
Satiety -> relieves the pressure on behaviour
Describe how the hypothalamus would deal with dehydration…
Low water in body -> detected by osmoreceptors in lamina terminalis (as well as kidneys, vessel sensors, etc) ->
Acts upon Lateral Hypothalamus, influencing
1. Release of ADH from posterior Pituitary
2. Stimulation of ANS -> sustain BP via vasomotor centre
3. Activation of Limbic System (cingulate gyrus, amygdala) and cortex to elicit the ‘behaviour’
The latter is achieved by creating a behavioural DRIVE
*I.e. adjustments to hormones and autonomics are a short-term fix -> we require a certain behaviour to ultiamately fix the physiological need
Drive = thirst
Describe hoe hypothalamus deals with thermoregulation…
Hypothalamus monitors core temperature.
Low temperatures -> in medial preoptic area
High temperatures -> in anterior hypothalamus
Outputs:
Pituitary -> Thyroid stimulating hormone to adjust metabol regulation as necessary
ANS -> stimulation of sweating/shivering, blood flow, piloerection etc
Limbic System (cingulate, amygdala) to Cortex -> create the drive to elicit behaviour -> seek shade/put on clothing, etc.
Why doesn’t the hypothalamus create a behaviour dive via the limbic system (cingulate and amygdala) and cortex to deal with changes in BP?
Because behavioural changes have little effect on blood pressure.
most effective mechanism to deal with it are exacted via the brainstem -> thus the information isn’t passed on to consciousness
Define: ‘wanting’ and ‘liking’
Wanting = A state of urgency for something -> a way to sustain a behaviour over long periods of time (i.e. establish a want)
Liking = is the positive reinforcement achieved when the behaviousachieves the goal
What is meant by “reward systems influence the cortex and vice versa”
Reward systems - e.g. ‘likeing’ (positive reinforcement when behaviour achieves ‘wanted’ goal) influence the cortex -> we learn to tailor our behaviour to achieve the desired result.
This involves figuring out what you need to do (cortex)
What is ‘pleasure’ - in neurobiologiacl terms
Activity in which area of the brain is responsible?
Like a ‘gloss’ - an added dimension to an ordinary stimulus
This neural code (via activity in the septal nuclei) tags something that we want to seek or do
Deriving ‘Pleasure’ from something is something that is signalled independently - this is because we can change our minds about what is considered ‘pleasant’
Which structures of the brain are integral to the seeking of ‘reward’?
Ventral Tegmental Area (VTA) - in midbrain Ventral Pallidum (VP) - Base of Striatum Nucleus Accumbens (Acb) - Basal Forebrain
Describe the ‘classical reward systems’ of the brain
Forebrain DA systems are called the ‘reward’ pathways of the CNS
The VTA projects DA fibres to the Ventral Forebrain.
This drives action (acts as a motivator).
The Acb then uses DA to signal satiety to the cortex ->
This indicates that the goal has been met, and seeking can cease
How area the ‘goals of behaviour’ negitated between different areas of the brain?
Several interrepated structures form a ‘consensus opinion’ about the value of behavioural choices
The VTA pushes motivation to the Nucleus Accumbens (Acb)
This creates the ‘wanting’ state
The Prefrontal Cortex then negotiates with Acb about what needs to be done, and when it’s been achieved
When achieved, Acb uses DA to signal satiety to the cortex
