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Chapter 6

PSYC18H3 Chapter Notes - Chapter 6: Reuptake, Otto Loewi, Nasal Administration

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PSYC18 Chapter 6 Emotions and the Brain
- Brain regions and neurotransmitters are intimately involved in emotions
- E.g. Sleeping sickness (encephalitis lethargica) made people act like zombies until they got a dose of L-DOPA
- They began to act spontaneously with emotion, passion, appetite and sexual desires
How do brain mechanisms of emotion work?
- Neuroimaging: machine monitors biochemical events in a series of conceptual slices through a person’s brain,
while computer takes info and constructs images of the brain to show where it is most active
- E.g. Positron Emission Tomography (PET) and functional Magnetic Resonance Imaging (fMRI)
- Neuroscientists study emotional effects of accidental damage to the brain while others have made lesions
deliberately in brains of animals
- Neurophysiologists have stimulated parts of the brain electrically and pharmacologically stimulated parts of
the brain with chemical mechanisms of neurons. One can also record the electrical activity of single neurons.
- Anatomy, lesions, stimulation, pharmacology, electrical recording
- Left to right: Spinal cord, cerebellum, pineal gland, cerebrum, corpus callosum, thalamus, hypothalamus,
pituitary gland, midbrain, pons, medulla
- Hindbrain controls basic physiological processes
o Medulla regulates cardiovascular activity
o Pons control sleep
o Cerebellum controls motor movement
- Forebrain
o Thalamus: integrating sensory information
o Hippocampus: memory processes
o Hypothalamus: regulates important biological functions (eating, sexual behaviour, aggression, etc.)
o Limbic system: with structures involved in emotions like amygdala
o Cortex: ability to lead complex social lives, plannign and intentional action, emotion regulation
- Early Research on brain lesions and stimulation
o First theory of brain mechanisms of emotion was proposed by Cannon
o Cannon’s graduate student Bard: cats deprived of cortex were liable to make sudden attacks coined
with term “sham rage” Cortex usually inhibits this expression
o Children abound with uncontrolled emotion until cortex develops sufficiently to inhibit their lower
- The Limbic System
o MacLean from Papez: sensory impulses from the body and outside world reach the thalamus and
split into three main pathways
Striatal region (stream of movement)
Neocortex (stream of thought)
Limbic system (stream of feeling)
o MacLean proposes that the human forebrain includes three distinct systems
Striatal region (reptilian level): earliest and most basic part of the forebrain, scheduling and
generating basic behaviours,
Limbic system (Paleomammalian level): Hypothalamus connections, autonomic nervous
system and control of body’s hormonal system via pituitary gland as well(Mammals are social
creatures, maternal caregiving, vocal signaling, and play)
Klüver: Wild monkeys became docile after large parts of limbic system were removed
Weiskrantz: Monkeys also approached everything without fear
PSYC18 Chapter 6 Emotions and the Brain
Olds: rats and their levers
o Stimulation of septal region of limbic system induces a tendency to approach
o Glickman: if mood produced by some kind of electrical stimulation is based on approach: mood of
encouragement. If based on withdrawal, avoidance, escape and rejection of anything that
tastes/smells bad
o Those with temporal lobe epilepsy (discharge of nerve sells contained within limbic region): preceded
by auras, subjective states that often include strong emotions
o MacLean-Panksepp conjecture: Experience of emotions is generated in the limbic system, and that
each distinct emotion type is based on a particular system of limbic brain circuitry
Circuitry creates a readiness for a set of species-characteristic brain processes and
behaviours, somewhat appropriate to the event that triggered them experience of a
particular emotion arises and the experience (happiness, anger, etc.) is something we share
with other animals
Each is associated with an urge to engage in a particular kind of action, and each is adapted
to circumstances that recurred during mmalian evolution
“I think therefore I am” “I feel therefore I am”
New developments of culture did not replace these fundamental circuits, they have
augmented them
- The Amygdala as an Emotional Computer
o Joseph LeDoux proposes that the amygdala is the central emotional computer for the brain: the
appraisal mechanism for emotions
o Amygdala receives inputs from reginos of the cortex concerneed with visual recognition of objects
and sounds. Also has close connectinos with the hypothalamus. Theory: Also the thalamus.
o LeDoux: uses Pavlovian conditioning readiness for something pleasant or unpleasant
Emotional conditioning is expressed in species-typical actions: e.g. dog wagging its tail when
hungry, freezing when scared, monkeys learn to be frightened of snakes because another
monkey acted afraid
Rats who learn association with shock to the feet are unable to do so as long as the amygdala
and the thalamus are present (cortex can be removed)
Amygdala seems to be the site of primary appraisal: automatic evaluation of events in
relation to goals and cocerns. Seems to be responsible for assigning emotional significance to
events that signal dangers and threats
o The amygdala has been found to increase activation in response to emotionally evocative stimuli (e.g.
sad or erotic film clips, disturbing slides, experiencing unpleasant tastes and odours)
o Using fMRI, young black and white male viewed photographs and deemed them male or female: as
they did it for longer, activation of amygdala decreased in Black people to black faces and white
people to white faces (unfamiliar faces are more threatening)
o Amygdala activation appears to predict whether people will recall emotionally evocative stimuli
(people recall negative slides like guns and gore more than postive emotion like icecream..?)
o Amygdala not involved in the experience of emotions. Damage of amygdala also did not impair
patients’ expression of emotions
- Prefrontal cortex, emotion, and emotion regulation
o MacLean: third largestep in evolution of the human brain is the neocortex (distinctive to higher
mammals), neocortex aka cortex (meaning outer layer) reaches largest development in humans.
o Frontal lobes: close connections with limbic system and plays important role in regulation of emotion
PSYC18 Chapter 6 Emotions and the Brain
o Cortex inhibits more “primitive” behaviours served by lower regions
o Frontal lobes have been seen as centers of regulation or executive control
o Prefrontal cortex includes three areas of interest: orbitofrontal region, dorsolateral prefrontal region,
and the anterior cingulate and medial frontal regions
o Regions in prefrontal cortex have dense reciprocal connections to amygadala and nucleus
accumbens: centrally involved in valence, wanting and liking
o Prefrontal cortex (particularly orbitofrontal region): centrally involved in representation of goals,
rewards and approach- and withdrawal-related tendencies
o Two kinds of evidence suggest that prefrontal cortex is important to regulation of emotion
1) Patients with damage to orbitofrontal cortex with normal language/memory/sensory
process, have problems regulating emotional behaviour (e.g. inappropriate jokes and actions
with strangers) attributed to difficulties with emphasizing and judging others’ emotions
2) imaging studies have begun to show that regions of the prefrontal cortex are activated
when people try to inhibit emotional responses to evocative stimuli
- Lateralization effects and emotions
o Humans: Information from outside world crosses over to opposite side of brain
o Right side of brain more closely associated with processing of emotional events (patients with
damage to right side of cortex often have difficulty recognizing facial expressions of emotion) Three
kinds of evidence:
1) Normal people shown faces with half upturn half downturn smiles on different sides of the
brain tend to go in terms of part relayed to right side of brain
2) Strauss (1981) found that when pictures of faces are flashed quickly onto a screen,
recognition, recognition of emotional expressions better for faces in left visual field (of right
o Etcoff (1992) tested the ability to detect lying and its relation to hemispheric lateralization. People
with damage to left cortex did better than those with damage to right cortex. Etcoff stated that those
who attend to language were more likely to be misled by words
o Right-brain superiority in recognizing facial expresisons of emotion is separate from recognizing the
person to whom the face belongs, tone of voice and other nonverbal aspects of speech
o Tucker and Frederic (1989): argued that right side of cortex has closer connections to amygdala,
develops earlier during infnacy and is generally attuned for emotional processing. Left cortex is
specialized for processing which is verbal, symbolic and analytical.
o Lois Bloom: found that babies who made more emotional expressions started to talk later than those
who made fewer (shows that it is difficult for integration of both hemispheres)
o Cortical effects: for experience, there is no overall right-sided superiority for emotional events as
compared with non-emotional ones
o For positive episodes, more activation on left. Negative on the right
Davidson (1990):subjects individually watch four short film clips (animals playing, nurse
training videos). While each subject watched, electroencephalogram (EEG) recordings were
made from four psoitions on each side of scalp and facial expressiosn were videotaped
Greater activation in left hemisphere to sweet tastes
Explanation: frontal region of brain is specialized for intention, self-regulation, and planning
(approach to something involves using right hand, controlled by left side, positive emotions
like hapiness involve approach tendencies. Negative emotions such as disgust and fear are
associated with withdrawal and activation is controlled in right frontal and temporal regions)