Lecture 22: Time, place and space Flashcards
Why were Lashley’s cortical lesions so ineffective at diminishing learned performance in tasks like conditioned reflexes and maze running?
the hippocampus is essential for the consolidation of explicit episodic memory and not the cerebrum
What does the “canonical” hippocampal circuit receive input from, and project back to?
the Entorhinal cortex
What is a preparation that is commonly used to study synaptic plasticity?
rodent hippocampal connections, esp. CA3 to CA1
When can the NMDA receptor channel open?
only during depolarisation
What are many if not most hippocampal neurons sensitive to?
place
What are examples of space-encoding neurons?
place cells, grid cells, border cells, head direction cells and speed cells
What does it mean since place cells do not have topography?
neighboring cells are not necessarily nearby place fields but combination of place cells provided a pattern unique for each location
When were place fields discovered?
when unit recordings were made of freely behaving rats
When do grid cells fire?
unlike place cells (that fire when the rat is in a particular location) grid cells fire when a rat is in a multiple of a particular distance
What structure do grid cells form?
a grid (triangular or hexagonal) they are non-topographic but denser space dorsally and wider ventrally the mesh size varies from about 30cm to over 3 meters
What does the sequential firing of cells representing larger and larger grids give the rat?
a reference system for its location in its environment
What does navigation require?
a combination of a) “dead reckoning” or self-referenced movement from a known location, and b) the generation of landmark-based maps
What does the formation of a detailed map rely on?
repeated experiences with self- referencing explorations, the same way as semantic memories may become context-independent with repetition of episodic memories concerning a semantic relationship
