🤖 Autism Biological Explanation- Amygdala Flashcards
(16 cards)
Structure of the Amygdala
Q: What is the amygdala, and where is it located?
- A cluster of 13 nuclei (grey matter) in the medial temporal lobe, part of the limbic system.
- There are two amygdalae, one in each brain hemisphere.
- Highly interconnected with the hypothalamus, prefrontal cortex, hippocampus, and other brain regions.
Functions of the Amygdala
Q: What key behaviors does the amygdala influence?
Motivation, emotion, threat detection, and social interaction due to its widespread neural connections.
Amygdala Development in ASD
Q: How does amygdala development differ in children with ASD?
- 2+ years old: 6–9% larger volume in ASD (Nordahl et al., 2012).
- Typical children: Amygdala grows later (adolescence).
- Adulthood: No size difference, but early overgrowth in ASD may disrupt neural organization/function.
Amygdala as the “Social Brain”
Q: Why is the amygdala called the “social brain”?
- Leslie Brothers coined the term due to its role in social behavior.
- Baron-Cohen (2000): Abnormal amygdala development → social deficits in ASD (e.g., emotion recognition, social perception).
Baron-Cohen’s Eye Task Study (1999)
Q: What did Baron-Cohen’s study reveal about amygdala function in ASD?
- Compared ASD adults vs. matched controls.
- Viewed photos of eyes showing emotions; fMRI measured brain activity.
- ASD group performed worse at emotion recognition.
- Left amygdala activated in controls but not in ASD participants.
- Suggests amygdala dysfunction impairs reading emotions from eyes.
Flashcard 6: Neural Connections in ASD
Q: How might abnormal amygdala development lead to ASD symptoms?
- Early overgrowth disrupts connections to frontal cortex, impairing:
- Social perception (e.g., understanding facial expressions).
- Processing social information.
- Emotional inference (e.g., “mind-reading”).
Critical Period Hypothesis
Q: Why is the timing of amygdala growth important in ASD?
Early overgrowth (before age 2) may “wire” the brain atypically, causing lasting social deficits even after size normalizes in adulthood.
Key Study Support
Q: What evidence supports the link between amygdala dysfunction and ASD?
- Nordahl (2012): Early amygdala overgrowth in ASD children.
- Baron-Cohen (1999): Left amygdala inactivity during emotion-recognition tasks in ASD.
Evaluation: Support from Clinical Studies
Q: How does research on amygdala damage (e.g., patient SM) support the amygdala dysfunction theory of ASD?
- Kennedy et al. (2009): SM (with amygdala damage) showed reduced personal space preference, mirroring ASD social deficits.
- Implication: Amygdala dysfunction may underlie impaired social behavior in ASD.
- Limitation: Correlational—doesn’t prove causation; other brain areas may contribute.
Evaluation: Inconsistent Findings on Amygdala Volume
Q: Why are inconsistent findings about amygdala volume problematic for the theory?
- Howard et al. (2000): Increased amygdala volume in ASD adults.
- Pierce et al. (2001): Decreased volume.
- Nordahl vs. Herbert (children): Conflicting results (increase vs. decrease).
- Conclusion: No clear pattern → weakens theory. Methodological differences may explain discrepancies.
Evaluation: Indirect Effects via Anxiety
Q: How might amygdala dysfunction indirectly cause ASD symptoms?
- Amygdala regulates anxiety/fear responses.
- Ollendick et al. (2009): High anxiety in ASD may disrupt social interactions.
- Limitation: Doesn’t explain ASD cases without anxiety, suggesting other factors (e.g., genetics, prefrontal cortex).
Evaluation: Danger of Oversimplification
Q: Why is focusing solely on the amygdala an oversimplification?
- Paul et al. (2010): Isolated amygdala damage (e.g., SM) caused milder deficits than full ASD.
- Implication: ASD likely involves multiple brain regions (e.g., hippocampus, prefrontal cortex).
- Conclusion: A network-based approach (connectivity) is needed.
Key Criticism – Lack of Causality
Q: What’s the main limitation of clinical studies like SM’s case?
- Shows correlation, not causation.
- ASD is heterogeneous; amygdala dysfunction may not apply to all cases.
Alternative Explanations
Q: What other brain areas might contribute to ASD symptoms?
- Prefrontal cortex: Decision-making/social cognition.
- Mirror neuron system: Imitation/empathy deficits.
- Hippocampus: Memory/context processing.
Evaluation: Future Research Directions
Q: How could future studies address current limitations?
- Longitudinal studies: Track amygdala development in ASD vs. controls.
- Advanced imaging: Examine connectivity between amygdala and other regions.
- Genetic studies: Explore links between amygdala function and ASD risk genes.
Summary of Evaluation
Q: What’s the overall strength of the amygdala dysfunction theory?
âś… Supported by:
Clinical cases (SM) and some volume studies.
Role in anxiety/social processing.
❌ Limited by:
Inconsistent findings.
Oversimplification (ignores other brain areas).
Indirect effects complicate causality.
