Lecture 11- Neuroscience of emotion I Flashcards
What is the paradox of emotions?
“The paradox of emotions is that, on the one hand, they seem self-evident and obvious when examined introspectively;
on the other hand, they have been extremely difficult to define in objective scientific terms.”
Has a consensus on a definition of emotion been reached?
“Attempts to achieve a consensus definition across the fields from neuroscience to psychology to philosophy have repeatedly failed”
-emotions can drive how the body operates
What is an emotion?
- An emotion constitutes an internal, central (as in central nervous system) state, which is triggered by specific stimuli (extrinsic or intrinsic to the organism)
- what defines the state is that it is triggered by specific stimuli
- emotional stimuli trigger emotional responses
- we usually connect emotion with the outward appearance of it
What is the traditional behaviourist view on emotion?
- have emotional stimuli and get behaviour and other responses that are outwards
- and in humans have additional feature that is subjective feeling
What is the new view on emotion?
- have emotional stimulus and get outward behaviour and other responses this is underlined with central emotion state and in humans have subjective feelings
- the central emotion state is the circuits in the brain producing the feeling and responses
- Humans show unique species typical behaviours and subjective feelings
- However, underlying states with certain fundamental properties are shared across emotions and across species (from humans to flies)
What did Darwin do on emotion?
- wrote a book on expression of emotions in animals and humans
- Identified examples of human emotional expression that are easily recognised in other primates, and domestic animals
- link between subjective feeling and the outward expression
PIC1What was the idea on emotion put forward by William James?
- it is the physical response from the body that makes you afraid
- so the physical state is then triggering the emotional state
- “I feel ‘afraid’ because I run from the bear; I do not run because I feel afraid”
PIC2What type of responses do we associate with emotion?
3 basic classes:
- visual
- tactile/touch, pain system
- auditory
- these go to the hypothalamus and brain stem where the effector system is in the brain, where output is coordinated, the response to the inputs
PIC2What 3 system drive the response to emotional stimuli?
- can break it up into systems that are all activated by the brain stem and particularly the hypothalamus: Somatic, autonomic and endocrine
- skeletal muscle:-such as freezing, part of the fear response
- see coordinated responses from the autonomic nervous sytstems, compliment the skeletal behaviour
- and endocrine systems, activation of the pituitary
- different type of emotions are associated with different patterns in responses of the skeletal, autonomic and endocrine systems
What is the Cannon-Bard theory?
- shown the involvement of the hypothalamus in emotion, identified hypothalamus as key in outward signs of emotions
- ability to show outside signs of emotion are based on the hypothalamus, and the brain stem in general
- 1928: looked at rage responses in cats, transecting brain above hypothalamus reveals sham rage
- Lost following transection below hypothalamus
- Hess: more experiments, electrical stimulation of hypothalamic sites produces rage responses in cats
PIC3What does the hypothalamus do in emotion?
-early idea
- Hypothalamus evaluates emotional significance of external stimuli, with the resulting appraisal determining emotional reactions
- hypothalamus produces responses without cortical input
- information goes to the cortex from the hypothalamus to cause emotional states
What is the limbic system?
-the emotional circuitry
-Papez (1937) inserted
anterior thalamus and cingulate cortex circuit between hypothalamus and sensory cortex forming a loop
-involves old parts of the brain (evolutionarily)
-include cortical structures but not neocortex, only old cortex (hippocampus and amygdala)
-
PIC4What happens when you remove temporal lobes in monkeys?
Klüver & Bucy (1930s)
Behavioural deficits in monkeys after removing temporal lobes
e.g. loss of fear of snakes (basis of Klüver-Bucy
syndrome= cannot detect emotion in people an dcannot express it)
-normally have innate fear of snakes
PIC5What is in this picture:
- in blue have the limbic lobes
- major pathways connecting the parts of the limbic circuitry
- pathways: 1.ventral amygdalofugal pathway= away from amygdala
2. median forebrain bundle= descending into the brani stem
3. Dorsal longitudinal fasciculus= descending into the brain stem
4. stria terminalis= from amygdala as well
PIC6What is this?
Papez circuit
- how emotions work
- a loop = “limbic loop”
What are the six basic emotions and what is important about them?
- happy, sad, fearful, angry, surprised, disgusted
- the motor representation of the emotions are pretty objective, same in most people
What is the facial action coding system and what does it show?
- acronym FACS
- had the basic human emotions and coded the muscle groups activated in each type of emotion
- looking at groupings of muscles
- different types of muscular outputs depending on the emotion
- from the basic emotions generated subemotions like happily surprised or happily disgusted
- in terms of bodily response the motor output of emotion is very objective
- AUs are individual or sets of muscles activated during specific emotions
What did neuroimaging of human emotions show?
- mapping patterns of brain activation generally does not correspond with human categories of emotion
- evidence of highly distributed processing
- the one structure that is always activated when emotion is in play seems to be the forebrain structure amygdala
What is a crucial role of the amygdala?
- in response to a fear stimulus pathways from the thalamus bring visual information to the amygdala
- key defense mechanism= rapid responses to threats
- amygdala can coordinate rapid response to threat
- gets information from the cortex as well when the stimuli significance is processed
- this circuitry has the ability to alert you to potential danger and keep you vigilant for some time after
What does the amygdala comprise?
- allocortex and basal forebrain
- the basolateral amygdala sends projections to central amygdala and bed nucleus of the stria terminalis
What is the amygdala made up of?
- basolateral amygdala complex (bottom)
- central amygdala (also to the side of this is the extended amygdala)
- bed nucleus of the stria terminalis BDNT
- all of this is the striatopallidal system and above it is the cortex
- called cerebral nuclei, basal forebrain as well= critical in coordinating higher functions
What is the striatopallidal system connection?
- cortical brainstem interface
- have striatum, pallidum and cortex and brain stem, all these form an elementary circuit
- have cortical circuits that can project to the motor system in the brainstem, and also massive input into the striatum
- striatal projections go to the pallidum and the motor system in the brain stem (all inhibitory)
- pallidal projections go to the motor system and the thalamus
- also the thalamic input can be fed back to the cortex=massive feedback system
What neurotransmitters are involved in the stratopallidal system?
- cortical projections are via glutamate
- striatal and pallidal are via GABA so inhibitory
What is the striatopallidal system for?
- hierarchical system, excitatory projections from the cortex, inhibitory from striatum and pallidum and inhibitory projectons of pallidum that can themselves be inhibited by striatal inhibitory projections
- the system is good at promoting, repressing and maintaining motor behaviour
What are some diseases connected to the striatopallidal system?
- in Parkinson’s the dorsal striatumm dies and really hard to initiate movement then
- tardykensia= hyperactive behaviour also related to the dysfunction in the striatopallidal system
What is the functional organisation of the nervous system showing state systems?
- have sensory, state and cognitive system feeding into the motor system (there is feedback to all those too)
- the motor system affects behaviour and vital functions that then can affect the outside environment
How is the motor system hierarchical?
- locomotor pattern controller (subthalamic locomotor region) 2. affects the locomotor pattern initiator (mesencephalic locomotor region)
- affects the locomotor pattern generator (spinal cord)
- affects the somatomotor neuron pools that then affect locomotor behaviour
Is the striatopallidal system mapped in the cortex?
- yes, there is a topographical map of the striatopallidal system in the cortex
- have these region that give info to the particular regions
How is the hypothalamic behaviour regulated?
- visceral parts of the cortex, cingular cortex and prefrontal cortex
- the flow of information enters the cortical parts of the amygdala and goes to the brain stem
- have gaba projections from the cortical amygdala and from central medial nuclei and bed terminalis nucleus
- all of this controls and regulates hypothalamic behaviour
How does the amygdala affect bodily responses as an emotional response to fear?
- the basolateral and lateral part of the amygdala is cortical and the central nucleus is subcortical
- cortex and thalamus send information to both and the central nucleus of the amygdala projects to the brain stem target to illicit a bodily response= the fear response
- the amygdala can is not just a relay station, it can also informs higher order functions like the fear learning involvement
- it can process stimulus that is conditioned and unconditioned (the one we do not learn we respond to it without learning0
- the basis of fear learning experiments
What are the brainstem targets of the central amygdala and what response do they cause (fear or panic symptoms)?
- lateral hypothalamus=increased heart rate and blood pressure, perspiration
- dorsal vagal nucleus= bradycardia, ulcers
- parabrachial nucleus= panting, respiratory distress
- basal forebrain= increased arousal, vigilance attention
- nucleus reticularis pontis caudalis= increased startle response
- central gray area= freezing, diminished social interaction
- paraventricular nucleus= corticosteroid release
What is fear and aversive learning?
- have a mouse in a cage, give it an unconditioned stimulus (one that will fear without learning like pain)
- then pair this stimulus with a sound or so that is the conditioned stimulus, after time the mouse will associate the two together and fear the sound alone
- this is associative learning= basis of fear learning
What is the circuitry of fear conditioning?
- have the sound and pain
- sound goes via auditory thalamus and auditory cortex
- pain goes via somatosensory thalamus and cortex
- they converge in the lateral nucleus of the amygdala
- then goes to the central amygdala and from there to the brain stem targets to illicit a fear response
- CG(central gray area)= freezing
- lateral hypothalamus= autonomic nervous system and paraventricular nucleus= hormones
- the connection between cortex and amygdala is not clear how the info gets there
What does the lateral amygdala respond to?
- fear learning
- experiment showing that the response of the lateral amygdala to the conditioned stimulus increases after conditioning
- the delay in response was also shortened after conditioning
What is amygdala critical for?
-for producing the motor patterns of emotions and high order processing of these emotions and attaching emotional meaning to stimuli that would normally be neutral
Are human bodily responses to fear similar to human anxiety?
-yes
