Lecture 9 Flashcards
Emotion, motivation and behaviour
Guyton Medical Physiology: “A thought probably results from the momentary pattern of stimulation of many different parts of the nervous system at the same time, probably involving most importantly the cerebral cortex, the thalamus, the limbic system and the upper reticular formation of the brain stem”.
Enormous degree of complexity in neuronal activity
For emotions, motivation and behaviour, what is needed?
An interacting network is needed: limbic system
For emotions, motivation and behaviour
What parts of the brain?
Portion of:
lobes of the cerebral cortex, basal nuclei, thalamus, hypothalamus
Feeling (anger, fear, happiness) + physical responses/behavioural pattern associated (laughing, crying, blushing)
Stimulation of limbic system during brain surgery can
elicit various emotions
Amygdala
processing inputs that lead to the sensation of fear
Anger:
hypothalamus controls heart rate, respiratory rate, blood pressure etc
Smiling:
stereotypical sequence of movement for expression of smiling can be elicited by the limbic system
Cortex:
refines instinctive response
Link between emotions and physiological functions
Limbic System is not a
separate structure but a ring of forebrain structures that surround the brain stem
Limbic system includes
portions of the hypothalamus and other forebrain structures that encircle brain stem
Limbic system responsible for
Emotion
Basic, inborn behavioral patterns related to survival and perpetuation of the species
Plays important role in motivation and learning
Motivation is the
Ability to direct behaviour goal specifically
- Homeostatic drives (eg thirst)
Influenced by experience, learning and habit
Reward and punishment centers in defined regions of limbic system (self-stimulation device experiments)
Facilitated by neurotransmitters: norepinephrine, dopamine, serotonine and acetylcholine
- Reuptake inhibitor effects: cocain-dopamine
- Serotonine or norepinephrine deficiencydepression
Electroencephalogram (EEG)
Extracellular current flow arising from electrical activity within cerebral cortex detected by EEG
Record of postsynaptic activity in cortical neurons
“Brain waves”
- Represent momentary collective postsynapic potential activity (EPSPs and IPSPs)
Electroencephalogram (EEG)
3 Major uses
Clinical tool in diagnosis of cerebral dysfunction
Used in legal determination of brain death
Used to distinguish various stages of sleep
Function of sleep
-is unclear
(restoration, recovery, learning, memory, consolidation, energy conservation)
- 1/3 of life time
Sleep-wake cycle
Normal cyclic variation in awareness of surroundings
Sleeping people are not consciously aware of external world
Active process consisting of two types of sleep characterized by different EEG patterns and different behaviors
Slow-wave sleep
Paradoxical, or REM sleep
Note that the EEG pattern during paradoxical sleep is similar to that of an alert, awake person, whereas the pattern during slow-wave sleep displays distinctly different waves
