Which brain structure is most critically associated with the formation of new episodic memories?

A: Amygdala

B: Hippocampus

C: Cerebellum

D: Basal ganglia

Correct: Hippocampus

The hippocampus is essential for consolidating new episodic and declarative memories. This was dramatically demonstrated by patient H.M. (Henry Molaison), whose bilateral hippocampal removal left him unable to form new long-term memories while retaining older ones and procedural learning.

Working memory has an unlimited capacity for holding information.

Answer: False

Working memory is severely capacity-limited. George Miller's classic 1956 paper proposed the "magical number seven, plus or minus two" — roughly 5–9 items. More recent models by Cowan suggest the core capacity limit is closer to 4 chunks. Duration is also limited to roughly 15–30 seconds without rehearsal.

Long-term potentiation (LTP) is primarily associated with which mechanism?

A: Decreased GABA release at inhibitory synapses

B: Strengthening of synaptic connections through repeated activation

C: Pruning of dendritic spines during sleep

D: Reduction in NMDA receptor density

Correct: Strengthening of synaptic connections through repeated activation

LTP is the sustained strengthening of synaptic transmission following high-frequency stimulation. It depends critically on NMDA receptors acting as coincidence detectors and the subsequent insertion of AMPA receptors into the post-synaptic membrane. LTP is widely considered the cellular basis of learning and memory.

Match each memory system to its defining characteristic.

What is the primary role of sleep in memory consolidation?

A: Encoding new information from the environment during REM

B: Replaying and stabilising newly acquired memories

C: Increasing hippocampal volume through neurogenesis

D: Transferring implicit memories to explicit storage

Correct: Replaying and stabilising newly acquired memories

During slow-wave (NREM) sleep, hippocampal sharp-wave ripples replay recently encoded experiences, coordinating with cortical slow oscillations and thalamic sleep spindles to transfer memories to neocortical long-term storage. REM sleep appears particularly important for emotional memory and procedural consolidation.

The amygdala plays a role in enhancing the consolidation of emotionally significant memories.

Answer: True

The amygdala modulates memory consolidation in the hippocampus and elsewhere during emotionally arousing experiences via noradrenergic and glucocorticoid signalling. This explains why emotional events (positive or negative) tend to be remembered more vividly — a phenomenon termed the "flashbulb memory" effect in extreme cases.

Place these landmark memory research milestones in the correct chronological order.

Which model proposes that working memory consists of a central executive, phonological loop, visuospatial sketchpad, and episodic buffer?

A: Atkinson–Shiffrin multi-store model

B: Levels-of-processing framework (Craik & Lockhart)

C: Baddeley's multi-component working memory model

D: Cowan's embedded-processes model

Correct: Baddeley's multi-component working memory model

Baddeley & Hitch (1974) proposed the multi-component working memory model with a central executive controlling two slave systems: the phonological loop (verbal/acoustic) and the visuospatial sketchpad (visual/spatial). The episodic buffer — a limited-capacity store linking working memory to long-term memory — was added by Baddeley in 2000.