Chapter 18: Emotion

studying emotion and neuroscience

Affective neuroscience

Brain mechanisms of emotion derived from these 3 things

• Animal models

• Human studies

• Brain lesions

emo system is dif than sensory system because

• Diversity of emotions and brain activity

• Many structures involved in emotion

• No one-to-one relationship between structure and function

def 2 Early Theories of Emotion

The James–Lange theory: emotion experienced in response to physiological changes in body

The Cannon–Bard theory: emotions occur independent of emotional expression—no correlation with physiological state

Can stimulus have emotional impact without conscious

awareness.

yes

• Aversive conditioning to masked stimulus results in increased skin conductance (ex. sweating)

• Increased activity in the amygdala

Many possible ways for the brain to process emotional information

def Broca’s limbic lobe structures

Areas of brain forming a ring around corpus callosum:

• cingulate gyrus

• medial surface temporal lobe

• hippocampus

def Broca’s limbic lobe funct

high cog functioning

The Papez Circuit

Limbic structures, including cortex, involved in emotion

• hippocampus

• hypothalamus

• thalamus

• cingulate cortex

• neocortex

• fornix

def Papez Circuit funct

Emotional system on the medial wall of the brain linking cortex with hypothalamus

what strengthens memory

cortosol

what governs behavioral expression of emotion

hippocampus

• evidence: Rabies infection implicates hippocampus in emotion -> hyperemotional responses

Lesions to what lead to spontaneous laughing or crying

thalamus

Evolution of limbic system allows animals to…

experience and express emotions beyond stereotyped brain stem behaviors

Early theories of emotion and limbic system built on…

introspection and inference from brain injury and disease

Studies of disease and consequences of lesions not ideal for revealing…

normal funct

*This is a drawback

def 2 more recent theories of emotion

• Basic emotion theories

• Dimension emotion theories

Certain emotions thought… experiences.

unique, indivisible, universal experiences

hypothesis for basic emo theories

basic emotions have distinct representations or circuits in brain

Analogous to distinct representations for sensory experiences

def 6 basic emotions

Anger, disgust, fear, happiness, sadness, surprise

fMRI shows _____ activation with the basic emotions.

different

not single areas but…may represent emotions.

Patterns of activity

Emotions can be…. into…. fundamental elements. Combined in… ways and… amounts

broken down, smaller, different, differing

Emotions correspond to brain activation along dimensions such as…

valence and arousal

• Psychological constructionist theories of emotion

• Variation on dimensional theories

• Includes nonemotional psychological components

• Emotion an emergent consequence of combined components

• Unknown whether each emotion is represented by:

Activity in a specialized area of the brain – A network of areas – A more diffuse network of neurons

def 3 Study approaches for defining emo

Behavioral observations – Physiological recordings – Studies of effects of lesions and disease

ex of studying emo

studying fear and anger

def 2 things that produced the Klüver–Bucy Syndrome

• temporal lobectomy in rhesus monkeys

• Temporal lobe lesions in humans—particularly lesions in amygdala

what are the symptoms of Klüver–Bucy Syndrome

Decreased fear and aggression – Decreased vocalizations and facial expressions of fear– Flattened emotions

what does Bilateral amygdalectomy lead to

reduced fear and aggression in all animals tested

Anger, sadness, and disgust may also be affected

what is the S.M. case study

inability to recognize fear in facial expressions

how does anxiety and fear in humans arise

Electrical stimulation of amygdala → increased vigilance or attention

what does fMRI imaging show about fearful faces

Fearful faces evoke greater amygdala activity than happy or neutral faces.

what is involved in forming memories of emotional and painful events

amygdala - learned fear

what are Intertwined in Animals

anger and agression

predatory aggression vs affective aggression

attack

• Against different species for food – Few vocalizations, attack head or neck – No activity in sympathetic division of ANS.

for show

• Used for show, not kill for food – High levels of sympathetic activity – Makes vocalizations, threatening posture

what operation leads to less aggression in animals

Amygdala lesions in animals

what operation leads to less aggression in humans/treats medical aggression

Amygdalectomy →

• Reduced aggressive behavior

• Relief from anxiety

• Profound, unpleasant side effects

Psychosurgery—now treatment of last resort

Removal of cerebral hemispheres but not hypothalamus →

rage beh

• Behavior reversed with additional lesions in hypothalamus

Hypothalamus may normally be inhibited by…

telencephalon

• Flynn’s research on affective and predatory aggression

• Elicited affective aggression by stimulating medial hypothalamus

• Predatory aggression elicited by stimulating lateral hypothalamus

Midbrain and Aggression

Two hypothalamic pathways to brain stem involving autonomic function

• Medial forebrain bundle → ventral tegmental area; predatory aggression

• Dorsal longitudinal fasciculus → periaqueductal gray matter; affective aggression

A Neural Circuit for Anger and Aggression

what NT Regulates Anger and Aggression

Serotonin

what is the Serotonin deficiency hypothesis

Aggression is inversely related to serotonergic activity.

Serotonergic raphe neurons project to the hypothalamus and limbic structures via the medial forebrain bundle

dec in Serotonin turnover →

inc of aggression in rodents

Drug PCPA blocks serotonin synthesis →

inc in aggression

humans: _______ correlation between

serotonin activity and aggression