PSYC 2900 Part 3 Flashcards

What are the three fundamental stages of every memory?

Acquisition (encoding) – initial formation of the trace; Retention (storage) – maintaining the trace over time; Retrieval – re-activating the stored trace when it is needed.

Define anterograde versus retrograde amnesia and the memory processes they illuminate.

Anterograde amnesia is the inability to form new memories after brain damage or an event, emphasizing acquisition mechanisms; Retrograde amnesia is the loss of memories formed before the event, highlighting retention and/or retrieval mechanisms.

What did Karl Lashley’s cortical-lesion studies lead him to propose about memory storage?

Memory is stored diffusely across the cortex because maze retention was largely unaffected by the location of cortical lesions.

How did Penfield’s electrical-stimulation experiments challenge Lashley’s view?

Focal cortical stimulation could evoke specific sensations and autobiographical scenes, indicating localized engrams despite overall distributed coding.

What are “feature-detector” cells and which researchers identified them?

Neurons in visual cortex that respond selectively to simple visual features such as edges and orientations; discovered by Hubel and Wiesel in 1977.

Explain the “grandmother-cell” problem and the modern alternative.

A single neuron dedicated to one concept is implausible because its loss would erase the memory and infinite neurons would be needed; modern view holds that memories are stored in distributed networks of interconnected neurons that enable pattern completion.

Give two everyday demonstrations that memory relies on pattern completion.

Filling-in of the blind spot in visual illusions and the use of schemas to rapidly understand familiar situations like weddings.

What cellular mechanism did Hebb propose for associative learning?

Repeated co-activation of presynaptic and postsynaptic neurons strengthens the synapse—“cells that fire together, wire together.”

Describe Bliss and Lomo’s discovery of long-term potentiation (LTP).

Brief high-frequency stimulation of hippocampal presynaptic fibers produced a long-lasting increase in the postsynaptic response to later low-frequency stimulation.

List three characteristics of LTP that link it to natural learning and memory.

It is induced by biologically realistic firing rates, is prevalent in hippocampus and cortex, and persists for days to weeks.

Name two manipulations that block both LTP and learning.

NMDA-receptor antagonists and prior saturation of LTP before behavioral training.

Why can’t all synapses remain potentiated indefinitely, and what prevents this?

Runaway potentiation would saturate coding capacity; passive decay and long-term depression counteract excessive synaptic strengthening.

Define Activity-Dependent Facilitation as described by Kandel and Hawkins.

Co-activation of a modulatory neuron with a presynaptic neuron strengthens the synapse even without postsynaptic activity, demonstrating presynaptic plasticity.

Outline the two broad phases of memory consolidation and their timescales.

Cellular consolidation occurs over minutes to hours and involves protein synthesis and synaptic remodeling, whereas systems consolidation spans days to years and redistributes memories from hippocampus to neocortex.

What classic experiment demonstrated a time-dependent window for cellular consolidation using electroconvulsive shock?

Duncan (1949) showed that electroconvulsive shock shortly after training caused severe amnesia in rats, but the effect diminished as the delay increased, producing a graded retrograde amnesia curve.

Explain the “dialogue” model between hippocampus and cortex during systems consolidation.

Newly encoded memories are stored in hippocampus and replayed during slow-wave sleep to strengthen cortical representations; over time retrieval relies more on neocortex and less on hippocampus.

What evidence supports replay of hippocampal activity during sleep?

Single-unit recordings reveal that hippocampal neurons re-express waking firing sequences during non-REM sleep.

Why might some learning have to occur slowly, according to McClelland, McNaughton and O’Reilly?

Rapid cortical learning can interfere with existing knowledge, so a complementary system allows fast hippocampal encoding while cortex integrates the information gradually to avoid catastrophic interference.

What are the three principal brain structures highlighted in contextual fear-conditioning studies and their roles?

Amygdala generates fear responses, hippocampus binds context with shock, and medial prefrontal cortex contributes to timing, rule extraction, and extinction.

Summarize frontal-cortex contributions to learning and memory.

It mediates attention, working memory, planning, rule generalization, cost-benefit analysis, and extinction learning.

What is pattern completion, and which hippocampal cells exemplify it?

Retrieval of a complete memory from partial cues; hippocampal place cells demonstrate this by firing for a location even when some cues are missing.

Give two cognitive phenomena illustrating reconstructed memory.

Tip-of-the-tongue states and eyewitness memory distortions due to suggestive questioning.

How does reconsolidation differ from initial consolidation, and why is it therapeutically important?

Reactivated memories become temporarily labile and must reconsolidate, providing a window to modify or weaken maladaptive memories such as in PTSD.

List six mechanistic levels of plasticity or learning outlined by Markus lecture 23.

Short-term channel changes; cellular consolidation; systems consolidation; adult neurogenesis and new connections; developmental overproduction and pruning; synaptic-weight modifications via LTP and LTD.

What receptor and ionic signal act as critical molecular coincidence detectors for LTP?

NMDA receptors allow calcium influx when glutamate binding coincides with postsynaptic depolarization.

How do passive decay and LTD together solve the synaptic saturation problem?

Passive decay weakens potentiated synapses over time, while LTD actively depresses weakly correlated synapses, maintaining overall balance.

What behavioral evidence links motor learning to synaptic potentiation?

Acquisition of new motor skills induces potentiation in motor cortex similar to LTP.

Identify two experimental manipulations besides electroconvulsive shock that induce graded retrograde amnesia.

Administration of protein-synthesis inhibitors and deep anesthesia or brain cooling.

How might distributed storage explain recovery after partial brain damage?

Because memories are represented across overlapping neural ensembles, remaining portions of the network can still support recall after a lesion.

What key practical implication arises from reconsolidation research for eyewitness testimony?

Because recalled memories can be altered during reconsolidation, interview techniques must minimize suggestion to avoid planting false details.

Why does LTP decay faster in aged or cognitively impaired animals, and what does this indicate?

Age-related molecular changes reduce maintenance of potentiation, correlating with memory decline and showing that LTP stability underlies memory competence.

What is Long-Term Depression (LTD) and which stimulation conditions evoke it?

LTD is a lasting decrease in synaptic strength produced by prolonged low-frequency stimulation or in synapses adjacent to potentiated ones.

How do new neurons contribute to learning according to plasticity mechanisms?

Adult-born neurons integrate as highly plastic units that may aid pattern separation and acquisition of new memories.

What behavioral and imaging evidence demonstrates the hippocampus functions as a spatial map?

Rodent hippocampal lesions impair spatial navigation, London taxi drivers have enlarged hippocampi, and neuroimaging shows hippocampal activation during human navigation tasks.

Describe the role of medial prefrontal cortex in learning paradigms.

It supports temporal organization, rule extraction, planning, and extinction learning.