Psychobiology part 2 unit 6 Flashcards
Where is the limbic system located in the brain?
The limbic system lies in the middle of the brain, hidden beneath the cerebral cortex, which evolved later in brain development.
How does the hypothalamus regulate physiological responses?
The hypothalamus controls the autonomic nervous system (ANS) to regulate internal states (e.g., temperature, hunger, stress).
Example: It triggers shivering when cold or sweating when hot.
What elements of emotional responses does the limbic system integrate?
The limbic system integrates:
Physiological responses (e.g., increased heart rate via ANS).
Hormonal responses (e.g., adrenaline release).
Behavioral responses (e.g., fight or flight).
What is the Papez Circuit, and what was its significance?
Proposed in 1937 by James Papez as a neural circuit responsible for emotion generation.
The circuit links the thalamus, sensory cortex, hypothalamus, cingulate cortex, and hippocampus.
What is the pathway of the Papez Circuit?
Thalamus receives emotional stimuli.
Sends signals to:
Sensory cortex: For conscious perception.
Hypothalamus: For physiological responses.
Hypothalamus connects to the anterior nuclei of the thalamus.
Cingulate cortex produces the conscious experience of emotion.
Hippocampus communicates with the hypothalamus via the entorhinal cortex and fornix.
How has the understanding of the Papez Circuit changed over time?
The Papez Circuit was an early model, but it is now considered an oversimplification.
Modern research includes additional structures, such as the amygdala and orbitofrontal cortex.
What is the Papez Circuit and how does it process emotions?
The Papez Circuit is a brain “highway” for processing emotions, connecting areas involved in feelings, reactions, and memory.
Starts in the Thalamus: Collects sensory information (e.g., a scary sound).
Info Pathways:
Sensory Cortex: Understands “what’s happening.”
Hypothalamus: Prepares the body’s response (e.g., heart racing).
The Emotional Loop:
Thalamus → Hypothalamus → Anterior Thalamus → Cingulate Cortex (feeling emotion).
Cingulate Cortex → Entorhinal Cortex → Hippocampus (emotion connected to memory).
Hippocampus → Hypothalamus (feedback loop via the fornix).
What are the core structures of the limbic system?
Amygdala: Processes emotions (e.g., fear, aggression).
Hippocampus: Involved in memory and learning.
Hypothalamus: Regulates physiological responses.
Mammillary bodies: Memory processing.
Septum (septal area): Emotional regulation.
What are the associated regions of the limbic system?
Thalamus: Relays sensory and emotional signals.
Olfactory bulb: Links smell to memories and emotions.
Orbitofrontal cortex: Involved in decision-making and emotion.
What role does the amygdala play in the limbic system?
The amygdala processes emotions, especially fear and aggression.
It is involved in integrating autonomic, hormonal, behavioral, and conscious emotional responses.
Why is the limbic system described as a phylogenetically ancient system?
The limbic system evolved early in brain development and predates the cerebral cortex, which handles higher-order functions like reasoning and planning.
What is the amygdala, and where is it located?
The amygdala is an almond-shaped structure involved in processing emotions.
Located in the temporal lobe, next to the lateral ventricle and just anterior to the hippocampus.
What role does the amygdala play in emotional processing?
The amygdala is crucial for emotions, particularly fear and aggression.
It integrates autonomic, hormonal, and behavioral responses to emotional stimuli.
What are the key nuclei of the amygdala?
The amygdala contains ~12 nuclei, but the most well-researched are:
Lateral nucleus: Receives input from the thalamus and cortex.
Basal nucleus: Processes and relays emotional signals.
Central nucleus: Produces emotional responses.
What is the role of the central nucleus in the amygdala?
The central nucleus sends signals to the hypothalamus and brainstem.
It triggers behavioral and physiological responses to emotional stimuli (e.g., fight or flight).
What does the lateral nucleus of the amygdala do?
The lateral nucleus is responsible for learning that a stimulus is threatening.
Example: A mouse learns to fear a bell after repeated pairing with a shock
What are the effects of bilateral amygdala damage in animals and humans?
Animals: Leads to Klüver-Bucy Syndrome with symptoms like:
Loss of fear, hyperorality, hypersexuality, and excessive docility.
Humans: Causes amnesia, aphasia, and visual agnosia.
Front:
What are the functions and key components of the hippocampus?
Function: Memory and learning.
Components of Limbic System for Memory:
Hippocampus: Memory processing.
Limbic Cortex: Includes:
Cingulate Cortex: Around corpus callosum.
Medial Temporal Lobe Areas:
Parahippocampal Gyrus
Entorhinal Cortex
Piriform Cortex
Perirhinal Cortex
How does the hippocampus receive sensory information? (afferent)
The entorhinal cortex provides processed sensory information to the hippocampus.
Inputs come from:
Amygdala.
Limbic cortex.
Association areas of the cerebral cortex.
The entorhinal cortex receives sensory information from the amygdala ,different parts of the limbic cortex and from all association areas of the cortex.
How does the hippocampus send information to other brain areas?
Major efferent pathway is the fornix, connecting the hippocampus to:
Mammillary bodies of the hypothalamus.
Anterior nucleus of the thalamus.
Sends information back to the entorhinal, perirhinal, and parahippocampal cortices.
What is the hippocampus’s role in declarative memory?
The hippocampus forms declarative (explicit) memories, such as:
Episodic memory: Remembering experiences/events.
Semantic memory: Remembering facts.
It is critical for memory consolidation, converting short-term memories (STM) to long-term memories (LTM).
What is memory consolidation, and how does the hippocampus support it?
Memory consolidation is the process of committing short-term memories (STM) to long-term memory (LTM).
Learning causes changes in the nervous system, and consolidation strengthens these changes.
Evidence suggests consolidation occurs during certain stages of sleep, improving retention of learned material.
How does the hippocampus send information to other brain areas?
The fornix connects the hippocampus to:
Mammillary bodies: Structures in the hypothalamus involved in memory processing.
Anterior nucleus of the thalamus: A region that supports emotional learning and memory.
What are flashbulb memories, and how are they formed?
Flashbulb memories are vivid, emotionally significant memories.
Highly emotional events trigger the locus coeruleus, increasing noradrenaline and dopamine release in the hippocampus, which strengthens memory formation.
What was learned about the hippocampus from Patient HM?
Patient HM, after bilateral hippocampal removal:
Developed anterograde amnesia, losing the ability to form new declarative memories.
Retained pre-existing memories, suggesting the hippocampus is not the site of long-term memory storage.
Could still learn non-declarative (implicit) memories.
What causes Korsakoff’s Syndrome, and what are its effects on memory?
Caused by chronic alcohol abuse leading to vitamin B1 (thiamine) deficiency.
Symptoms include anterograde amnesia and irreversible damage to mammillary bodies.
