Synaptic Plasticity and Memory

These flashcards cover key concepts related to synaptic plasticity, learning, and memory, as discussed in the lecture notes.

Synaptic Plasticity

The ability of synapses to strengthen or weaken over time in response to increases or decreases in activity.

Long-Term Potentiation (LTP)

A long-lasting strengthening of synapses based on recent patterns of activity, important for learning and memory.

Long-Term Depression (LTD)

A long-lasting decrease in synaptic strength, resulting from activity-dependent processes.

Hippocampus

A brain region in the medial temporal lobe crucial for learning and memory, known for its role in synaptic plasticity.

NMDA Receptor

A type of glutamate receptor that is critical for synaptic plasticity and memory function, requiring coincidence of presynaptic activity and postsynaptic depolarization.

Why are NMDA Receptors called “coincidence detectors”?

They require both glutamate binding and postsynaptic depolarization (to eject Mg²+ block).

AMPA Receptor

A subtype of glutamate receptor that mediates fast synaptic transmission in the central nervous system (no protein synthesis).

Input Specificity

A characteristic of LTP and LTD indicating that only the synapses receiving strong inputs are strengthened or weakened, respectively.

Calcium Influx

The entry of Ca2+ ions into the postsynaptic neuron, which is pivotal for the induction of LTP and LTD (high calcium = kinases → LTP, low calcium = phosphatases → LTD).

Habituation

A form of non-associative learning characterized by a decreased response to a repeated, benign stimulus (siphon touch).

Sensitization

An increase in behavioral response following exposure to a strong or noxious stimulus, which can reverse habituation (head shock).

Declarative Memory

The conscious recall of facts, events, and information that can be verbally expressed (dates, places, names, etc.)

Regions of Brain Involved in Declarative Memory

Hippocampus → critical for consolidation, Medial Temporal Lobe

Non-declarative Memory

Unconscious memory of skills, habits, and conditioned responses that don’t require conscious thought (riding a bike, tying shoes, classical conditioning, etc.).

Regions of Brain Involved in Non-Declarative Memory

Cerebellum → motor skills, Basal Ganglia → procedural memory, Amygdala → emotional conditioning

Case of H.M.

Medial temporal lobe (hippocampus) is critical for forming new declarative memories but not for working memory.

Retrograde Amnesia

The loss of memories for events that occurred before the onset of amnesia.

Anterograde Amnesia

The inability to form new memories following a traumatic event.

Dendritic Spine Morphogenesis

The structural changes in dendritic spines that increase synaptic connectivity and efficiency following LTP.

Cognitive Neuroscience

The field that studies the relationships between brain function and cognitive processes, such as learning and memory.

Glutamate

The main excitatory neurotransmitter in the brain involved in synaptic plasticity and cognitive functions like learning and memory.

Consolidation

The process by which short-term memories are transformed into long-term memories.

Hippocampus Pathways

Performant: Entorhinal Cortex (EC) → Dentate Gyrus (DG) input highway to hippocampus (exhibits LTP)

Mossy Fiber: Dentat Gyrus (DG) → CA3 pattern completion (non-NMDA LTP)

Schaffer Collateral: CA3 → CA1 output pathway in the hippocampus (NDMA receptor-dependent LTP).