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PSYC18H3 Lecture Notes - Lateralization Of Brain Function, Cholecystokinin, Reuptake

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G Cupchik

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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
- 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
oMedulla regulates cardiovascular activity
oPons control sleep
oCerebellum controls motor movement
- Forebrain
oThalamus: integrating sensory information
oHippocampus: memory processes
oHypothalamus: regulates important biological functions (eating, sexual behaviour,
aggression, etc.)
oLimbic system: with structures involved in emotions like amygdala
oCortex: ability to lead complex social lives, plannign and intentional action, emotion
- Early Research on brain lesions and stimulation
oFirst theory of brain mechanisms of emotion was proposed by Cannon
oCannon’s graduate student Bard: cats deprived of cortex were liable to make
sudden attacks coined with term “sham rage” Cortex usually inhibits this
oChildren abound with uncontrolled emotion until cortex develops sufficiently to
inhibit their lower functions
- The Limbic System
oMacLean 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)
oMacLean proposes that the human forebrain includes three distinct systems

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PSYC18 Chapter 6 – Emotions and the Brain
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
Olds: rats and their levers
oStimulation of septal region of limbic system induces a tendency to approach
oGlickman: 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
oThose with temporal lobe epilepsy (discharge of nerve sells contained within limbic
region): preceded by auras, subjective states that often include strong emotions
oMacLean-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
oJoseph LeDoux proposes that the amygdala is the central emotional computer for
the brain: the appraisal mechanism for emotions
oAmygdala 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.
oLeDoux: uses Pavlovian conditioning readiness for something pleasant or
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
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