PSC 137 Midterm 1 Flashcards

Allocortex

3-layer cortex; the hippocampus is allocortex (vs. neocortex's 6 layers)

Anterograde Amnesia

Inability to form NEW memories after brain damage

CA1, CA2, CA3

Subfields of hippocampus proper (cornu ammonis / Ammon's horn)

Cognitive Map

Tolman's theory: internal spatial representation of the environment

Conditioned Response (CR)

Learned response (e.g., freezing) to the CS

Dentate Gyrus (DG)

First relay in trisynaptic loop; receives input from EC via perforant path

Engram

Permanent change in the nervous system representing an experience (Semon, 1921)

Episodic Memory

Personal, autobiographical memories with 'what, where, when'

Field EPSP

Extracellular measure of synaptic strength in LTP experiments

Freezing

Measure of conditioned fear; complete immobility expressed as % time

Grid Cells

Neurons in entorhinal cortex firing in hexagonal grid patterns (Moser & Moser, 2005)

Hippocampal Replay

During SWRs, place cells replay previously traveled sequences (often in reverse)

Amygdala

Encodes emotional/fear memories; required for fear conditioning CR

BNST (Bed Nucleus of Stria Terminalis)

generates sustained fear responses

Claparede Anecdote

Amnesic patient avoided Claparède's hand after shock — emotional memory without declarative memory

Conditioned Stimulus (CS)

Stimulus that predicts the US after Pavlovian conditioning

Declarative Memory

Conscious, explicit memory (episodic + semantic); requires hippocampus

Double Dissociation

Two lesions that produce opposite deficits, proving two independent systems

Entorhinal Cortex (EC)

Gateway to hippocampus; LEC (what) and MEC (where)

Equipotentiality

Lashley's conclusion that memory is distributed equally throughout cortex (later disproven)

Fimbria/Fornix (ff)

Output pathway from CA1/CA3 back to entorhinal cortex

Galvanic Skin Response (GSR)

Skin conductance measure correlated with emotional responding

Hippocampal Formation

Hippocampus proper + Dentate Gyrus + Subiculum + Entorhinal Cortex

LEC (Lateral Entorhinal Cortex)

carries WHAT (object identity) information to hippocampus

LTP (Long-Term Potentiation)

Increase in synaptic response strength following strong stimulation (Bliss & Lømo, 1973)

Morris Water Maze

Spatial memory task; circular pool with hidden platform and distal room cues

Multiple Memory Systems

Framework: different memory types stored in different brain regions based on content

Perforant Path (pp)

Axons from entorhinal cortex → dentate gyrus (Synapse 1 of trisynaptic loop)

Place Cells

Hippocampal neurons firing at specific locations; discovered by O'Keefe (1971)

Procedural Memory

Implicit motor skill memory (e.g., riding a bike)

Retrograde Amnesia

Loss of memories formed BEFORE brain damage

Semantic Memory

General factual knowledge (e.g., ‘The White House is in D.C.')

Subiculum (SU)

Output structure of hippocampus; projects back to EC

TGA (Transient Global Amnesia)

focal CA1 lesion causing spatial memory impairment

Unconditional Stimulus (US)

Stimulus that innately produces a response (e.g., foot shock)

MEC (Medial Entorhinal Cortex)

carries WHERE (spatial/contextual) information to hippocampus

Mossy Fibers (mf)

Axons of dentate gyrus granule cells → CA3 (Synapse 2 of trisynaptic loop)

Non-declarative Memory

Unconscious/implicit memory (procedural, perceptual, emotional)

Perirhinal Cortex (PER)

Critical for object recognition memory in DNMS task

Place Field

The specific location where a place cell fires

Remapping

Place cells adopt new, random place fields in a different environment

Schaffer Collaterals (sc)

Axons from CA3 → CA1 (Synapse 3 of trisynaptic loop)

Sharp-wave Ripples (SWR)

150–250 Hz oscillations during rest/sleep; associated with hippocampal replay

Theta Rhythm

4–10 Hz hippocampal oscillation during active movement

Trisynaptic Pathway

EC → DG (pp) → CA3 (mf) → CA1 (sc) — the core hippocampal circuit

Unconditional Response (UR)

Innate response to the US (before conditioning)

KO mice

Knockout mice — DNA/gene editing to remove specific genes

Transgenic Mice

Fluorescently labeled neurons/circuits visible in brain tissue

Optogenetics

Fiber optic probe implanted in mouse brain to control neurons with light

Patient H.M.

Bilateral hippocampal removal (also amygdala, entorhinal, perirhinal cortex removed), Impaired Declaritive (Explicit) Memory

Mirror Learning Task

H.M. learned quickly and remembered across 3 days (errors per trial decreased), but had NO declarative memory of ever doing the task.

Patient E.P.

Both anterograde AND retrograde amnesia, Normal priming scores (intact non-declarative) but near-zero recognition (absent declarative)

Depolarization

Membrane potential becomes less negative (moves toward 0 mV)

Hyperpolarization

Membrane potential becomes more negative (below –70 mV)

PFC/ACC (Prefrontal Cortex + Anterior Cingulate Cortex in humans)

Exerts top-down control over subcortical structures to regulate appropriate behavioral responses.

Thalamus

Processes sensory information about aversive and fear-associated stimuli