limbic and physiology of emotion

Question 1

Describe the anatomy of Broca’s “Great Limbic Lobe.

Answer 1

look at a diagram

Question 2

Recognize that “Papez’s circuit” and hypotheses about a “Limbic System” involve some structures that are, and some that are not involved in the physiology of emotion.

Answer 2

Papez’s Circuit: emotion is not a function of any specific brain center but of a circuit that involves 4 basic interconnected structures, the hypothalamus w/ mamillary bodies, anterior thalamic nucleus, the cingulated gyrus, and the hippocampus.

Question 3

emotion, 3 fundamental components

Answer 3

Emotion: complex psycho-physiological experience of a state of mind as interacting with biochemical and environmental influences.
• Three fundamental components:
o 1). Physiological arousal
o 2). Expressive behaviors, actions, and tendencies
o 3). Conscious experience
• Associated: mood, temperament, personality, and motivation.
• Emotion and motivation are linked ==> emotional physiology linked to motivation and the motor system
• Subjective experience occurs in conjunction w/ disposition towards certain stereotypical behaviors/movements.
• Can produce “automatic” reactions.

Question 4

mood

Answer 4

Affective states. While emotions have a clear focus, a mood tends to be unfocused and diffuse.
• Involves a tone, intensity, and a set of predictions about future experience of reward or punishment.
• Change with expectations of future pleasure or pain, moods, being diffused and unfocused, and thus harder to cope with, can last for days, weeks, months, or years.
• Hypothetical constructs depicting an individual’s emotional state.

Question 5

cognition

Answer 5

a sense for the processing of information, applying knowledge, and changing preferences. It includes such processes as memory, attention, language, problem solving, and planning.

Question 6

motivation

Answer 6

states that bias towards specific action patterns or patterns of behavior.

Question 7

Relate the roles of amygdalae to current theories of emotion and theories of decision-making.

Answer 7

primary roles in the formation and storage of memories associated w/ emotional events. Creates associations between sensory stimuli and specific behavioral and autonomic responses.
• What do lesions to the amygdala do?
o Impairs the acquisition and expression of Pavlovian fear conditioning.
• Structures of importance:
o Central nucleus: involved in the production of fear responses, including freezing, tachycardia, increased respiration, and stress-hormone release. Mediates EXPRESSION of emotional responses.
• Connected to the lateral nuclei to elicit fear behavior.
o Lateral nuclei: memories of emotional experiences imprinted in strength of synaptic connections here.
o Bed nucleus of the stria terminalis: derivative of the central nucleus of the amygdala that mediates the release of pituitary-adrenal stress hormone CRH (Corticotropin-Releasing Hormone).
• CRH: causes the adrenal gland to release epinephrine and cortisol.
• Sensory stimuli reach the basolateral complexes of the amygdalae, esp lateral nuclei, where they form associations w/ memories of the stimuli.
o LTP: long term potentiation, the association between stimuli and aversive events they predict.
• Appetitive conditioning: positive conditioning that the amygdalae is involved in, but there isn’t a clear anatomical location in the amygdala.

Question 8

Cingulated cortex role in emotion

Answer 8

determines experience of emotion

Question 9

Hypothalamus role in emotion

Answer 9

emotional expression

Question 10

where does the cingulate gyrus project?

Answer 10

to the hippocampus

Question 11

where does the hippocampus project?

Answer 11

to the hypothalamus by way of the fornix

Question 12

where do hypothalamic impulses go

Answer 12

relay synapse on anterior thalamic nuclei on their way to the cortex

Question 13

How does emotional experience in the cingulated becomes expression?

Answer 13

indirect transmission to the hypothalamus

Question 14

how does hypothalamic expression get back to cingulate gyrus?

Answer 14

Hypothalamic expression goes back to cingulated through thalamus anterior nucleus

Question 15

Is hippocampus involved with emotion?

Answer 15

no

Question 16

Relate the roles of ventral striatum to current theories of emotion and theories of decision-making.

Answer 16

contains the nucleus accumbens and gets reinforcing VTA neuronal projections. Projects the output back to the VMPFC.
• Critical for generating predictions about the risks and rewards associated w/ given behaviors.
• Can have synaptic plasticity and associative learning.

Question 17

Relate the roles of ventral tegmental area to current theories of emotion and theories of decision-making.

Answer 17

in the midbrain adjacent to the substantia nigra. VTA neuronal pathways project to the nucleus accumbens of in the ventral striatum.
• VTA releases dopamine in response to errors in predictions about reward.
o Predictions likely calculated in PFC and amygdala (which project to VTA).
o Dopaminergic projections: Nigrostriatal, Mesolimbic, Mesocortical (VMPFC) , and Tuberoinfindibular.
o VTA neuronal pathways project to nucleus accumbens in ventral striatum, which when stimulated, is highly reinforcing.
• Presence or absence of dopamine can reinforce or reduce activity in networks that generate predictions about the risks or rewards of a given behavior.
• Excess dopamine: excessively reinforce networks that were active during behavior that produced the dopamine surge (how cocaine becomes addictive).

Question 18

Relate the roles of ventromedial prefrontal cortex to current theories of emotion and theories of decision-making.

Answer 18

necessary for the prediction of consequences, but not for registering the actual consequences. Pts demonstrate inadequate inhibition of aggression, sexual behavior, anxiety, and appetitive functions and to correctly employ these behaviors in the appropriate settings.
• Lesions to the VMPFC - Characteristic performance on the Iowa Gambling Task
o Pts continue to to draw from bad decks, even though they are losing.
o Do not display the typical anticipatory emotional response (stress responses) to an impending punishment (losing money from drawing form a bad deck).
o They DO have intact stress responses to the receipt of actual rewards and punishments, which suggests they can still register the actual consequences.