Module Four Flashcards
(191 cards)
Define behaviorist stimulus–response approach.
Early 20th-century approach focused solely on external stimuli directly evoking observable responses.
What did Tolman propose in 1948?
Internal spatial representations (‘cognitive maps’) based on rat navigation experiments.
Who revived Tolman’s cognitive map idea with electrophysiology?
O’Keefe & Nadel in 1978.
Define place cells.
Hippocampal neurons that fire when an animal occupies specific locations, forming a neural map.
Define head direction cells.
Neurons firing according to the animal’s facing direction, acting like an internal compass.
Define grid cells.
Neurons in medial entorhinal cortex firing in a hexagonal pattern, providing metric for distance and direction.
What additional spatial neurons exist beyond place, head-direction, and grid cells?
Cortical and subcortical spatially tuned neurons aiding spatial encoding.
Who was Henry Molaison (H.M.) and his significance?
Patient with bilateral hippocampal removal causing severe anterograde amnesia and spatial impairments.
What did the radial-arm maze demonstrate about hippocampus?
Its involvement in spatial working memory tasks.
What does the Morris water maze test?
Spatial mapping ability independent of explicit working-memory demands.
What happens to Morris water maze performance after hippocampal lesions?
Performance abolished, confirming deficits due to impaired spatial mapping.
Discovery of place cells occurred through what method?
Single-unit hippocampal neuron recordings in freely moving rats by O’Keefe & Dostrovsky (1971).
Do primates and humans have place cells?
Yes, but fewer, often encoding conjunctive spatial features.
What ensures long-term stability of place fields?
Place fields persist days to weeks, although some cells show turnover for temporal coding.
Do place cells rely solely on visual cues?
No, they integrate olfactory, tactile, and self-motion inputs, remaining stable in darkness.
What is place-cell remapping?
Reorganization of place fields forming a distinct spatial code when environment changes.
How do primates differ from rodents in navigation strategies?
Primates emphasize visual landmarks; rodents require direct exploration.
Describe head-direction cell firing.
Cells fire maximally when head points in specific directions, independent of location.
What circuitry generates head-direction signals?
Angular-velocity neurons in DTN and LMN relayed through thalamic and cortical structures.
Grid cell identification location?
Medial entorhinal cortex, pre- and parasubiculum.
What happens to grid cells during external cue rotation?
Grid fields rotate coherently with distal landmarks.
Grid cells’ role in path integration?
Persist in darkness using self-motion computation; lesions impair path integration.
Identify supporting cell types for grid cells.
Speed cells encoding locomotor velocity and band cells potentially scaffolding grid formation.
Define interneurons.
Diverse, GABAergic inhibitory neurons modulating circuitry throughout hippocampal and cortical regions.