🔑 Key Definitions
Engram: Physical memory trace in brain; Lashley searched for it but never found localized engram
Equipotentiality: Lashley's principle that all cortical areas contribute equally to complex functions like learning
Mass Action: Lashley's principle that amount of tissue damage matters more than location for learning deficits
Consolidation: Hebb's theory that memories strengthen over time through repeated neural activity
Equipotentiality: Lashley's principle that all cortical areas contribute equally to complex functions like learning
Mass Action: Lashley's principle that amount of tissue damage matters more than location for learning deficits
Consolidation: Hebb's theory that memories strengthen over time through repeated neural activity
👤 Important Figures
- Karl Lashley - Searched for engram through systematic lesion studies; discovered equipotentiality and mass action principles
- Donald Hebb - Proposed consolidation theory; famous phrase "neurons that fire together wire together"
🧠 Memory & Learning
- Memory Definition: Retention of learned information over time
- Learning vs Memory: Learning = acquisition, Memory = storage and retrieval
- STM (Short-Term Memory): Temporary storage; limited capacity (~7 items); brief duration (~30 seconds)
- LTM (Long-Term Memory): Permanent storage; unlimited capacity; can last lifetime
🧠 Lashley's Search for the Engram
- Engram Quest: Systematically lesioned different cortical areas to find memory location
- Equipotentiality: Found that any cortical area could support learning; no single "memory center"
- Mass Action: Learning impairment correlated with AMOUNT of damage, not specific location
- Conclusion: Memories are distributed, not localized to single area
🧠 Hebb's Consolidation Theory
- Consolidation: Memories strengthen through repeated activation; STM gradually becomes LTM
- "Fire Together, Wire Together": Simultaneous activation of neurons strengthens their connections
- Hebbian Synapse: Synapse that strengthens when pre- and postsynaptic neurons fire together
- LTP (Long-Term Potentiation): Cellular mechanism supporting Hebb's theory
💡 Exam Tips
- Lashley never found the engram - proved memories are distributed, not localized
- Equipotentiality = all areas equal, Mass action = amount of damage matters
- STM = temporary (~30 sec, ~7 items), LTM = permanent (unlimited)
- Hebb's rule: "Neurons that fire together wire together"
- Consolidation = process of strengthening memory over time
- Modern view: Lashley was partly right (distributed) but some specialization exists