15.3 Neural bases of Emotion

2 types of facial muscles

Superficial facial muscles

Deep facial muscles

Superficial facial muscles

muscles that conjoined to facial skin

• movement of skin helps change shape of mouth, eyes, nose, needed for visible emotional expression

Deep facial muscles

muscles conjoined to the skeletal bones of the head

allows one to do bigger facial and jaw movements (chew)

what are facial muscles innervated/connected to

cranial verves:

facial nerve (VII) and

trigeminal nerve (V) motor branch

Facial feedback hypothesis

facial muscle movements can affect our emotional experience becuase of sensory feedback (pencil between teeth - feel happy)

amplifying or dampening it

has mixed empirical support (context dependent, small effects, and not enough to generate emotion alone)

how does parkinson’s and schizophrenia impair facial expression

these conditions both reduce facial expresivness, or make atypical expressions

How does Bell’s palsy impair facial expression

this condition paralyzes facial muscles one side (cranial nerve VII) → droopy

is there one part of the brain related to each emotion or is it more of a network.

some areas have a bias to some emotion (amygdala) but overall emotional processing uses overlapping brain systems

same neural mechanisms are used for many emotions

Antonio Damasio

said that emotions and feelings are distinct and get confused everyday and in science

Emotions (Damasio)

preprogrammed action from the brain

can be done unconsciously

after stimuli body rapidly responds

Feelings (Damasio)

conscious mental experience of physiological state

can arise from experiencing emotion

can arise from perceiving bodily reaction

can emotions be researched? two ways as to how

if emotions are just property of the brain they can be studied as any other brain function:

using animals you can manipulate brain and thus emotion

and using behavioural, physical measures, and brain activity

can feelings be researched. why or way not

cant research feelings since they rely on conscious experience and can’t experiment

how is brain stimulation used to study emotion

uses awake, feely moving animals, so can directly observe their behaviour

outcomes of brain stimulation (studying emotion)

what sites were found, what behaviour associated?

findings show

rewarding sites, when stimulated seeks more stimulation - approach and motivation

aversive sites, when stimulated wants to avoid: avoidance and defensive behaviour

some sites are for organizing emotional behaviour (structured emotional response patterns)

Brain self stimulation (w/ animals)

how was experiment conducted, what were findings, what did findings suggest

animals would get stimulation in certain brain areas after performing a certain task

findings showed that subcortical stimulation was rewarding and cortical stimulation was not

suggesting that subcortical areas contained emotion, motivation systems

Medial forebrain bundle (rat)
what, where, why important

a key fiber tract that goes through hypothalamus and midbrain
crossed several brain self stimulation sites: targets the nucleus accumbens: rewarding area

what happens to the emotions of an animal that does not have a cortex?

you still have emotions because emotions don’t come from the cortex (it comes from subcortical area)

cortex provides inhibition of emotion, so without → more unhinged emotions

Decorticate rage (cat experiment)

cannon bard removed the cortex of cats and found they became extremely aggressive very easily, anger undirected (no clear cause)

some evidence that the cortex modulates and inhibits emotions, and without no filter behaviour

core emotions come from subcortical levels since not gone when cortex removed

cannon bard theory for what causes emotion (brain)

believed the thalamus was responsible for simultaneously making emotion and autonomic response

Papez circuit

worked off cannon bard theory (thalamus), proposing a circuit that links emotion systems: cortex,(thalamus), hypothalamus

not just subcortical that controls emotion, Papez studied animals with brain leisions, rabies (damages hippocampus)

Key areas in Papez Circuit (HACHi Four)

interconnected system:
(no i)
Hypothalamus
anterior thalamus

Cingulate cortex

Hippocampus

Fornix

how Papez circuit areas interact (HACHFN)

hypothalamus emotional, behavioral expression signals to anterior thalamus

cingulate cortex connects to cortex and hippocampus

hippocampus sends info back to hypo using fornix

neocortex: emotionally colors experience, provides context analyze info

The Limbic System (maclean)

Maclean added onto Papez circuit: adding amygdala etc

main idea: big network rather than circuit, innervating many brain nuclei (emotion, motivation, memory)

limitations of limbic system

emotional processing is much distributed that originally thought: parts of papez and limbic system removed like hippocampus

evidence does not support single emotion system

different emotions involve other brain systems too, overlapping