Memory

Question 1

H.M. - The Pivotal Case

Answer 1

His medial temporal lobectomy showed that specific brain structures are critical for memory, revealed different memory types (explicit vs. implicit), and identified memory consolidation as a key process.

Question 2

H.M.’s Surgery & Core Deficit

Answer 2

A medial temporal lobectomy (removing hippocampus, amygdala). His core deficit was severe anterograde amnesia – the inability to form new explicit long-term memories.

Question 3

Retrograde vs. Anterograde Amnesia

Answer 3

Retrograde: Cannot remember events before the brain damage.

Anterograde: Cannot form new memories after the brain damage.

Question 4

Explicit vs. Implicit Memory

Answer 4

Explicit: Memory you can declare (facts, events). H.M. lost this.

Implicit: Memory you show (skills, habits). H.M. retained this.

Question 5

Episodic vs. Semantic Memory

Answer 5

Episodic: Autobiographical, personal experiences (your last birthday).

Semantic: General knowledge and facts (knowing Paris is the capital of France).

Question 6

Cerebral Global Ischemia

Answer 6

A reduction in blood supply to the brain (e.g., from a heart attack). The CA1 region of the hippocampus is highly vulnerable, leading to memory problems.

Question 7

Korsakoff’s Syndrome Cause & Symptoms

Answer 7

Cause: Thiamine (B1) deficiency, often from chronic alcoholism.

Symptoms: Anterograde amnesia early on, progressing to retrograde amnesia in late stages.

Question 8

Korsakoff’s Syndrome Brain Damage

Answer 8

Medial diencephalon (medial thalamus & hypothalamus). Diffuse damage can also occur in the neocortex, hippocampus, and cerebellum.

Question 9

Alzheimer’s Disease - Key Features

Answer 9

Features: Progressive memory loss, especially for new info (anterograde amnesia), without initial dementia.

Regions: Basal forebrain (reduced acetylcholine), medial temporal lobe, and prefrontal cortex.

Question 10

Post-Traumatic Amnesia (PTA)

Answer 10

Amnesia from closed-head injury (e.g., concussion). Characterized by:

Intact short-term memory but impaired long-term memory formation.

Islets of memory: Brief, clear flashbacks during the amnesic period.

Duration: Coma < Retrograde Amnesia < Anterograde Amnesia.

Question 11

Place Cells vs. Grid Cells

Answer 11

Place Cells: Fire when an animal is in a specific location (the “place field”).

Grid Cells: Fire in a hexagonal grid pattern across the environment, providing a spatial map for place cells.

Question 12

Concept Cells

Answer 12

Neurons that fire in response to a specific concept (a person, place, object), regardless of how it’s perceived. They create associative networks.

Question 13

Engram Cells

Answer 13

Engram cells : any change in your nervous system that forms as a result from memory formation is an engram.
These cells are involved in maintaining that change and memory.

Question 14

Inferotemporal Cortex Role

Answer 14

Part of the “what” pathway; crucial for recalling visual information and learning relationships between visual stimuli.

Question 15

Amygdala Role

Answer 15

Strengthening the emotional component of memories, especially fear-related memories.

Question 16

Prefrontal Cortex Role

Answer 16

Working memory (e.g., remembering where you parked) and memory for the temporal order of events.

Question 17

Cerebellum Role

Answer 17

Motor learning where precise timing is critical (e.g., adapting to a split-belt treadmill).

Question 18

Striatum Role

Answer 18

Critical for habit formation and procedural learning for both motor and cognitive activities.

Question 19

Memory Consolidation & Reconsolidation

Answer 19

Consolidation: The initial process of stabilizing a memory from short-term to long-term storage.

Reconsolidation: The process of re-stabilizing a memory after it is recalled, allowing it to be updated or strengthened.

Question 20

Long-Term Potentiation (LTP)

Answer 20

A long-lasting strengthening of synaptic connections following high-frequency stimulation. It is the primary cellular model for learning and memory.

Question 21

Key Requirement to Induce LTP

Answer 21

Co-occurrence (Associativity): The presynaptic neuron and postsynaptic neuron must be activated at the same time.

Glutamate binding to AMPA and NMDA receptors is essential for LTP because it depolarizes the postsynaptic neuron, removes the Mg²⁺ block from NMDA receptors, allows Ca²⁺ influx, and triggers the molecular changes that strengthen the synapse.

Question 22

NMDA Receptors & LTP

Answer 22

They are the “coincidence detectors.” When both glutamate binds (from presynaptic activity) and the postsynaptic neuron is depolarized, the Mg2+ block is removed, allowing Ca2+ to flood in, triggering LTP.

Question 23

Long-Term Depression (LTD)

Answer 23

The opposite of LTP; a long-lasting weakening of synaptic connections. It is crucial for clearing old memories and fine-tuning neural circuits.

Question 24

Metaplasticity

Answer 24

“Plasticity of plasticity.” It refers to how the history of a synapse’s activity influences its future capacity to undergo LTP or LTD.

Question 26

What are the differences between anterograde and retrograde amnesia.?

Answer 26

1. Retrograde amnesia: cannot remember events prior to brain damage. 2. Anterograde amnesia: complete loss of forming new explicit long term memory.

Question 27

Describe the divisions and subdivisions of long-term memory.

Answer 27

Long term memory is divided into 2: Declarative or explicit memory: Things you can tell others Procedural or implicit memory: Thing that you must show others Declarative memory is divided into: episodic(info about yourself, biographical ) and semantic (knowing general info)

Question 28

What are the neural correlates of amnesia in Korsakoff's Syndrome and Alzheimer's disease?

Answer 28

Korsakoff's correlate = Medial Diencephalon / Mediodorsal Thalamus Alzheimer's correlate = Basal Forebrain, Medial Temporal Lobes, Prefrontal Cortex

Question 29

What happens after a closed-head traumatic brain injury?

Answer 29

The amnesia following a closed-head TBI is called **posttraumatic amnesia.** Initial Coma: The injury causes an immediate state of unconsciousness (coma), which can last from seconds to weeks. Period of Confusion: After regaining consciousness, the person experiences a confused state. Permanent Memory Loss: Once the confusion clears, permanent memory problems are revealed, including: Anterograde and retrograde amnesia

Question 30

What is the role of the inferotemporal and prefrontal cortices in memories?

Answer 30

Inferotemporal Cortex: Stores long-term visual memories (e.g., objects, faces) Works with perirhinal cortex in visual memory formation and retrieval Shows reversed activation patterns during memory recall versus learning Prefrontal Cortex: Critical for temporal memory (remembering sequence/order of events) Essential for working memory (maintaining and manipulating information during tasks) Damage causes disorganized memory despite preserved event recall