3: Limbic System and Emotions Flashcards

1
Q

What is the limbic system? What is its general function? (4)

A

Several functionally and anatomically interconnected nuclei in the telencephalon and diencephalon

Functions: control of functions necessary for self and species preservation

  • -Regulate endocrine and autonomic function
  • -Involved in arousal, motivation, memory, and emotion
  • -Closely connected to olfaction
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2
Q

(OBJ) Identify the cortical components of the limbic system. (7)

A

CORTICAL: (limbic lobe)

  • -Piriform olfactory cortex
  • -Hippocampus
  • -Insular cortex
  • -Orbital frontal cortex
  • -Subcallosal gyrus
  • -Cingulate gyrus
  • -Parahippocampal gyrus
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3
Q

(OBJ) Identify the subcortical components of the limbic system. (6)

A

SUBCORTICAL:

  • -Olfactory bulb
  • -Hypothalamus
  • -Amygdala
  • -Septal nuclei
  • -Some thalamic nuclei (anterior and dorsomedial nuclei)
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4
Q

Give a brief overview of the overall organization of the limbic system. (4 steps)

A

Association neocortex (thinking)

  • > Limbic cortex
  • > Limbic subcortical regions (emotional response)
  • > Effector sites (hypothalamus = endocrine, autonomic, and behavioral effects)
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5
Q

True/false: The limbic cortex is critical in subjective experience: not what something is, but what it means to you, and how you should react.

A

TRUE.

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6
Q

(OBJ) Describe the consequences of frontal lobe damage as a reflection of its functions. (2)

A

Difficulty in:
1. Executive functions (DLPFC): solving puzzles, abstract reasoning/judgment, dividing attention between tasks

  1. Emotional responses (orbital/medial PFC): moods (apathy for RH, euphoric for LH), behavior (rude, tactless, inconsiderate)
    - ->Personality
    - -Most affected by alcohol
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7
Q

Which area of the brain undergoes the greatest amount of postnatal development?

A

The prefrontal cortex - makes it most susceptible to injury in utero and in early childhood

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8
Q

(OBJ) Describe the afferent connections of the prefrontal cortex with other components of the limbic system.

A

AFFERENTS:

  • -Limbic cortex (especially cingulate gyrus and medial temporal)
  • -Amygdala
  • -Septal nuclei
  • -Hippocampus
  • -Reciprocal connection with DM of thalamus
  • -Hypothalamus
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9
Q

(mOBJ) The PFC connects with other cortical lobes via long association bundles. Name the four most relevant ones and where they connect.

A

Uncinate fasciculus –> anterior temporal lobe, AMYGDALA

Arcuate fasciculus –> more posterior parts of cortex

Cingulum –> cingulate gyrus

Medial forebrain bundle –> hypothalamus

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10
Q

What changes in brain activity are seen in patients with depression? (4) In what other circumstances are these changes seen?

A

Overactivity in medial PFC, especially subcallosal region and anterior cingulate cortex

Posterior cingulate gyrus is underactive
Dorsolateral PFC is UNDERactive as well -> problems with executive functions

Also, -> changes in hippocampus, amygdala, thalamus, basal ganglia

–Changes also seen in patients with chronic pain!

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11
Q

What are the functions of the insular cortex? (3 main)

A

INTEROCEPTION: response to internal signals
–Regulation of visceral (autonomic) responses
–Processing visceral pain
EMOTIONS: through amygdala
–Subjective emotional experience
–Participates in emotional reactions
ADDICTION

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12
Q

State the pathway of olfactory neurons from the olfactory epithelium to central olfactory structures.

A

Olfactory filaments -(converge)-> mitral cells in olfactory bulb glomeruli -(olfactory tract)-> olfactory cortex (3 parts)

  1. Olfactory tubercle
  2. Piriform cortex (rostral surface of uncus)
  3. Medial amygdala
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13
Q

Where are olfactory signals relayed after their initial termination in the olfactory cortex? (2)

A

Medial dorsal nucleus of the thalamus –> orbitofrontal cortex

From amygdala -(stria terminalis)-> VMN nucleus of hypothalamus
–Affect emotional and endocrine reactions

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14
Q

Where are the septal nuclei located? To which regions do they make reciprocal connections? (3) Efferent connections? (2)

A

Located between the frontal horns of the lateral ventricles

  • -Dorsal to the anterior commissure
  • -Ventral to corpus callosum

RECIPROCAL:

  • -Hippocampal formation
  • -Amygdala
  • -Hypothalamus - POA

EFFERENT: mammillary body, median eminence of hypothalamus

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15
Q

What are the functions of the septal region? What results from a lesion of the septal region?

A

Functions:

  • -Neuroendocrine regulation of reproductive behaviors via GnRH projection to median eminence
  • -Association with memory via cholinergic pathway to hippocampus

Lesion –> “septal syndrome”
–Behavior overreaction; “septal rage” following minimal stimulation

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16
Q

Where is the amygdala?

A

Large, almond-shaped nucleus

Located in rostral, medial part of temporal lobe beneath uncus

17
Q

(OBJ) List the connections of the amygdala with other components of the limbic system. (7)

A

Almost all connections are reciprocal

  • -Olfactory tract (not reciprocal)
  • -Autonomic nuclei of brainstem (solitary and parabrachial nucleus - GVA & SVA)
  • -Limbic neocortex (esp. frontal and medial temporal)
  • -MD nucleus of thalamus
  • -Septal nuclei
  • -Hypothalamus
  • -Sensory and association cortices
18
Q

(mOBJ) Which are the most important outputs of the amygdala? (2) Why are they necessary? What connects the amygdala to these targets?

A

HYPOTHALAMUS - via stria terminalis and ventral amygdalofugal pathway

LIMBIC NEOCORTEX - directly or via the MD of the thalamus

Necessary to generate the normal behavioral, autonomic, and endocrine responses to frightening, stressful, and anxiety producing situations

19
Q

(mOBJ) What are the functions of the amygdala? What results from lesions of the amygdala? Stimulation?

A

Functions: helps you decide when certain responses are appropriate by matching inputs

  • -Coordinating behavioral, autonomic and endocrine responses to environmental stimuli
  • -Feeding, drinking, fighting, mating, maternal care, responses to stressors
  • -Assigns emotional value to sensory cues in environment

Lesions:

  • -Reduce responses to stress (ANS and behavioral)
  • -Bilateral lesions -> Kluver-Bucy syndrome (inability to identify/draw fear, blunted fear reactions)

Stimulation -> behavioral arousal, directed rage reactions

20
Q

(OBJ) Explain the ability of the amygdala to participate in emotional memory and conditioned stress, fear and anxiety reactions. (2 statements)

A

Cells of the amygdala “learn” to pair stimuli with emotional state, particularly stress and anxiety responses

Associative learning between sensory inputs and stressors that impact neurons of amygdala can result in innocuous stimuli triggering a behavioral response indicating an anxiety reaction
–This can happen through direct connections between the sensory thalamus and the amygdala, resulting in amygdalar activation through stimuli that the patient isn’t even aware of (“the low road”)

21
Q

What is the neurological background for cognitive behavioral therapy of patients with conditions such as PTSD?

A

Inputs to the amygdala from the frontal lobe can reverse some of the long-term potentiation that occurs within amygdala neurons -> reduce conditioned emotional responses

22
Q

(OBJ) Describe the role of corticotropin releasing factor in stress pathways of the central nervous system.
(OBJ) Describe the basic functions and connections of the hippocampus with areas of the limbic system including the hypothalamus and septal nuclei and the capacity of the hippocampus to influence regions of limbic cortex.

A

FINISH?

23
Q

What nucleus is associated with generalized anxiety disorder? Is it over- or underactive?

A

The bed nucleus of the stria terminalis - overactivity

–Gives GnRH input to the hypothalamus