Limbic system

Question 1

What does the limbic system control?

Answer 1

generates feelings/emotions from sensory inputs, promotes survival so activity varies depending on physiologic needs
- bridges autonomic/voluntary responses to environmental changes

Question 2

What parts of brain are in the limbic system?

Answer 2

cingulate and parahippocampal gyrus (limbic lobe), amygdala, hippocampus, etc

Question 3

What is the amygdala’s role? hippocampus?

Answer 3

emotional responses

learning and memory

Question 4

What is the direct continuation of the fimbria?

Answer 4

fornix

Question 5

Short term memory

Answer 5

hold info briefly in mind while need it (telephone number)

Question 6

Long term memory

Answer 6

stored info, can be retrieved

• explicit: recall of facts/events (declarative memory or episodic)
• semantic: pertains to spoken/written words, extended to knowledge of facts/concepts
• implicit: performing a learned motor function (riding a bike)

Question 7

Working memory

Answer 7

needed for task at hand (driving along a known route)

Question 8

consolidation

Answer 8

process of storing new info in long-term memory

Question 9

How are novel facts recalled?

Answer 9

relayed from sensory association areas to hippocampus for encoding, processed, encoded info sent back to association area it came from and does not depend on hippocampus for retrieval

Question 10

What happens in bilateral removal of hippocampus?

Answer 10

can not form new episodic (past personal experiences) or semantic memories (ideas and concepts not related to personal experience)
- working memory intact and could learn new skills

Question 11

Where do all amygdala afferent sensory association areas have direct input?

Answer 11

lateral nucleus, also linked to prefrontal cortex via association fibers so sensations can be cognitively evaluated

Question 12

Kluver-Bucy syndrome

Answer 12

• bilateral temporal lobe injury, involves amygdala and parahippocampal gyrus
• fearless, placid, no emotional reactions, don’t respond to threats, don’t flee
• males hypersexual, indiscriminate, will seek stimulation from inanimate or inappropriate objects
• inordinate attention to all sensory stimuli, sniff and examine everything orally, if possible will eat it
• visual agnosia (recognize nothing)

Question 13

What forms CA3?

Answer 13

axons from subiculum and hippocampus

Question 14

Hippocampal connections

Answer 14

• fornix crouches under corpus callosum
• crus arches up beneath corpus callosum
• joins crus on other side forming trunk (near hippocampal commissure)
• trunk divides into 2 pillars, split near ant commissure

Question 15

What does the trunk divide into?

Answer 15

precommissureal fibers = septal area

postcommissural fibers = hypothalamus, mammillary body