Limbic System (Exam4Quiz1)

What is the limbic system and why is it called that?

Limbic = "border" (Latin). It forms a border around the brainstem and is involved in homeostasis, olfaction, memory, and emotion.

Name the main structures of the limbic system.

Cingulate gyrus, fornix, hippocampus, amygdala, anterior thalamus, hypothalamus, olfactory cortices.

What are the main functions of the limbic system?

• Homeostasis: Drives (hunger, thirst, sex), autonomic/endocrine regulation, temperature, circadian rhythms, stress responses.
• Olfaction: Smell & taste linked to memory, emotion, eating behavior, and safety.
• Memory: Encoding, storage, working memory, declarative/episodic/semantic, non-declarative (motor/emotional/conditioned reflexes).
• Emotion: Emotional regulation, reward circuits, learned responses.

What are the key thalamic nuclei in the limbic system and their functions?

• Mediodorsal (Dorsomedial) Nucleus: Connections = prefrontal cortex, hippocampus, amygdala, limbic system; Functions = mood, emotion, cognition, personality, memory, language.
• Anterior Nucleus: Connections = hippocampus, cingulate gyrus, frontal lobe; Functions = memory, emotion, executive function.

Where is the hippocampus and what is its role?

Located in the medial temporal lobe. Critical for encoding new memories (STM
→ LTM) and memory storage; works with frontal lobes, basal ganglia, cerebellum, anterior thalamus.

What are the types of memory associated with the limbic system?

• Working memory: Temporary storage + processing.
• Declarative (explicit): Facts (episodic = events, semantic = info).
• Non-declarative (implicit): Skills, motor learning, emotional learning, conditioned reflexes.

What is working memory, and who is in charge of it?

Temporary storage and processing of information. Helps you hold and use info while thinking or completing a task. Controlled by the neocortex (especially the frontal lobe).

What is declarative memory, and what are its two types?

Memory for facts and events that can be consciously recalled. Includes:

• Episodic: events or experiences (ex: first day of school)

• Semantic: facts and general knowledge (ex: knowing that Paris is in France)
  Structures: Medial temporal lobe (hippocampus) and medial thalamus, hypothalamus

What is non-declarative memory, and what are its types?

Unconscious memory — skills or behaviors learned through experience. Includes:

• Skills and habits: controlled by basal ganglia, cerebellum, neocortex

• Emotional associations: controlled by the amygdala

• Conditioned reflexes: controlled by the cerebellum

What are the main functions of the hypothalamus?

• Regulates endocrine system (via pituitary)
• Controls autonomic nervous system
• Drives & emotions (eating, drinking, sex)
• Circadian rhythms, temperature, blood volume
• Connected to limbic system for emotional regulation

How does the pituitary gland interact with the hypothalamus?

Connected via the infundibulum; controls hormone synthesis and release.

What does the amygdala do?

• Emotional regulation, decisions, memory
• Learned responses (anxiety, stress)
• Reward circuits
• Outputs to hypothalamus and reticular formation to initiate behavior

What are the connections of the amygdala?

Prefrontal cortex, anterior/medial temporal lobe, insula, thalamus.

What happens if the hippocampus is damaged?

Severe memory impairment, difficulty forming new memories (anterograde amnesia).

What happens if the amygdala is damaged?

Emotional dysregulation, impaired fear responses, inappropriate social behavior.

What happens if the hypothalamus is damaged?

Homeostasis problems: endocrine issues, sleep disturbances, appetite dysregulation.

What happens if the anterior thalamus is damaged?

Memory deficits, executive function problems.

What are the main left hemisphere language areas?

Broca‘s area, Wernicke’s area, angular gyrus, supramarginal gyrus. Extensively connected for integration of comprehension (posterior) and production (anterior).

What is the function of Broca’s area and effects of damage?

• Function: Speech production, grammar, motor planning for speech.
• Damage: Broca’s aphasia → non-fluent speech, difficulty forming sentences; Apraxia of speech.

What is the function of Wernicke’s area and effects of damage?

• Function: Language comprehension, semantic processing.
• Damage: Wernicke’s aphasia → fluent but meaningless speech, poor comprehension.