College 3: emotions and neuroscience Flashcards
Maclean’s stages of evolution (layers) in the brain
- The reptilian system (animals): basic bodily functions
- The limbic system: emotions and memory
- Neocortex: high-order thinking
Het universal limbic system
Is a universal core-old system that is also present in other animals, like rodents, snakes, cats etc. The limbic system is important for emotional processing (but not unique in this). This is why we can also study emotions in animals.
The limbic system consists of (THACO)
- Hippocampus: memory consolidation.
- Amygdala: emotions regulation, processing of biological relevant stimuli.
- Hypothalamus: arousal, hormones.
- Orbitofrontal cortex: high order cognition and higher order emotions.
- Thalamus: relay station, connection networks in the brain, direct route to the amygdala.
- Corpus callosum: n.v.t.
Panksepp’s idea
All layers of the brain are important for emotion:
1. Reptilian
2. limbic system
3. Neocortex
Berridge’s view on the processing of emotions in the brain
Emotion processing is shifted upwards in humans and is processed by the upper 2 layers:
1. Neocortex
2. Limbic system
In animals this is processed by the:
1. Limbic system
2. Reptilian system
Somatic marker hypotheses / theory (Damasio)
- Somatic markers are changes in the body and brain, based on previous outcomes of decisions.
- Somatic markers are therefore necessary for making the appropriate decisions.
- Somatic markers are processed by the OFC and the amygdala.
- The amygdala puts a marker/stamp on a certain emotional situation to remember them better in the future. This is communication with the OFC.
Orbitofrontal cortex (OFC or VM)
Is important for adaptive learning based on reward and punishment.
Phineas cage: had no OFC and was unable to learn form pervious experiences.
Damage to the OFC causes problems with:
- Problem solving
- Decision making
- Disinhibited, impulsive behaviour
- Inapropriate humor
- Emotional lability
- Poor judgement and insight
- Distractibility
There is impaired decision making because the OFC can not communicate with the amygdala anymore and can’t put a somatic marker on the experience. This was, people can not learn form their previous experiences –> emotions are necessary for appropriate decision making.
The Iowa Gambling Task
Normal people learn over time that it’s beneficial to pick from the ‘good deck’. People with lesion to the amygdala or OFC don’t learn from these previous emotional experiences. These patients can understand that this behaviour is bad, but they don’t learn form it.
–> They can still learn explicitly.
–> They can not learn implicitly.
LeDoux’s dual route theory
There are 2 pathways for processing emotional stimuli:
1. The high (cortical) indirect route: identifying stimulus –> emotional evaluation –> action.
2. The low (subcortical) direct route: direct evolutionary shortcut via thalamus and amygdala to action.
The low, subcortical, direct route (LeDoux)
When a fearful stimuli is experienced (like a snake), the information goes directly to the amygdala and the thalamus, which causes direct action.
In Ledoux’s theory is true then:
- Humans should be able to respond more quickly to emotional stimuli (threats) than to neutral stimuli –> true, because snakes are faster noticed than flowers.
- The amygdala should be involved in recognising threat and signal the body for fast response –> true, because attentional blink paradigm.
- We don’t need a visual cortex and still react adequately to stimuli or threat –> true, people with affective blindsight can still process emotional stimuli.
Attentional blink test / paradigm.
If you show a neutral stimulus within a very short time after the first stimulus, this seconds stimulus is not processed. When the seconds stimulus is emotional, the stimulus is still processed (via the quick route to the amygdala).
Kluver-Bucy syndrome (amygdala lesion)
The amygdala was removed in monkeys. This caused:
- No fear response
- Not taking care of their offspring
- No recognition of fear in others
Humans with a lesion to the amygdala show similar symptoms. Participants didn’t show fear anymore and look less at the eyes of emotional faces. They still recognise other emotions, but not fear anymore.
affective blindsight with TMS / Lesion to the visual cortex
People who do not experience visual stimuli on one side (being cortically blind) still unconsciously process emotional stimuli. This is because the direct route of processing is taking over (via the thalamus and the amygdala) and the stimuli is still processed.
