Navigation and the Hippocampus Lecture Review

This set of flashcards covers the fundamental concepts of navigation, scene recognition, and the specific neural mechanisms including place cells, grid cells, and head direction cells as discussed in the lecture notes.

Scene recognition

The process of identifying a specific familiar location or determining the geometry and type of an unfamiliar place.

Mental map

A necessary representation required for navigation when the destination is not visible or audible.

Landmarks

Environmental features that provide information about location and direction even in places an individual has never visited before.

Parahippocampal place area (PPA)

A brain region involved in scene recognition that shows significantly more signal change for scenes than for objects.

Cognitive map

A mental field map of the environment indicating routes, paths, and environmental relationships that determine an animal's responses.

Visual snapshots

Mental representations that capture the appearance of a place from a particular point-of-view, similar to a photograph.

Tolman, Ritchie & Kalish (1946)

Researchers who studied spatial learning in rats, showing they could find shortcuts when paths were blocked.

Tinbergen's study

Research suggesting that wasps navigate back to their nests using landmarks or visual snapshots.

Tri-synaptic circuit

The information flow pathway in the medial temporal lobe memory system within the hippocampus.

Dentate Gyrus

A specific structure within the hippocampal formation that processes information from the entorhinal cortex.

Entorhinal cortex

The brain region that encodes head direction and contains grid cells which provide input to place cells.

Place cells

Pyramidal cells in the hippocampal CA1 and CA3 regions that have discrete firing fields representing an animal's position.

Hippocampal firing fields

Specific locations in an environment that cause a particular place cell to fire.

Cell ensemble

A functional unit of neurons with temporally and spatially correlated activity that encodes the current position of the animal.

Remapping

The reorganization of hippocampal cell ensembles representing an animal's position when environmental changes occur.

Global remapping

A type of remapping where all or most of the place cell firing fields in an environment are reorganized.

Partial remapping

A phenomenon where only a portion of the hippocampal cell ensembles representing position are changed.

Rate remapping

A change in the firing rate of hippocampal cells without a change in the location of their spatial firing fields.

Complex bursts

The multi-spike action potential patterns fired by place cells when an animal moves through an environment.

Salient environmental cues

Prominent features of the environment that control and guide place cell activity.

Social place cells

Neurons in the dCA1 region that exhibit place fields representing the position of other demonstrator animals.

Grid cells

Cells in the medial entorhinal cortex that fire in hexagonal patterns covering the local area.

Head direction cells

Neurons in the entorhinal cortex that signal the current heading of an animal, such as its azimuth or pitch.

Border cells

Specific types of navigation cells that fire predominantly when an animal is near the boundaries of an area.

Speed cells

Neurons identified as being part of the navigation system that fire based on the animal's velocity.

Medial Entorhinal Cortex (MEC)

The specific region of the entorhinal cortex housing grid cells and head direction cells.

Azimuth

The horizontal component of head direction measured in degrees, from $0^{\circ}$ to $360^{\circ}$.

Pitch

The vertical component of head direction, particularly relevant for navigation in 3D space during flight.

Hexagonal patterns

The characteristic geometric arrangement of firing locations produced by grid cells in the entorhinal cortex.

Perforant Path

The neural pathway that carries information from the entorhinal cortex to the hippocampus.

Subiculum

A structure within the hippocampal formation that is part of the information flow in the medial temporal lobe.

CA1 and CA3

The layers of the hippocampus containing the pyramidal cells that serve as place cells.

Hertz (Hz)

The unit of measurement used to describe the frequency of action potential firing, ranging from approximately $0.2\,Hz$ to over $15\,Hz$ in place cells.

Electrocorticography (ECoG)

A method of recording brain activity used during surgery to identify responsive cells in the human brain.

Medial temporal lobe memory system

A collection of interconnected brain structures including the hippocampus and surrounding cortices dedicated to memory and navigation.

T. Danjo et. al (2018)

Researchers who published findings on the spatial representations of self and others in the hippocampus.

Kanwisher and Epstein

The scientists associated with identifying the function of the Parahippocampal place area.

Stratum Pyramidale

A specific layer of the hippocampus involved in the tri-synaptic circuit.

Perirhinal cortex

A component of the medial temporal lobe system that provides input to the entorhinal cortex.

Field stability

The property of place cell fields remaining consistent for many hours or days once they are established.

Directional heading independence

A feature of place cells where their firing is determined by location rather than the direction the animal is facing.

Geometry of location

The spatial layout and physical constraints of a place that the brain uses for scene recognition.

Maze # 3, Lab 205

The specific task environment referenced in the rhyme comic for hippocampal navigation.

Pyramidal cells

The specific type of hippocampal neurons in fields CA1 and CA3 that demonstrate place-selective activity.

Signal change (%)

The metric used in fMRI studies to show how the PPA responds more strongly to place changes than view changes.

Spatial cognitive map

A high-level navigation strategy used by mammals to create a flexible mental representation of space.

Relative stability

The characteristic of place cells to maintain their firing fields over time as long as the environment is consistent.

Functional unit

A term describing cell ensembles that work together to encode the animal's current environmental position.

Medial temporal lobe system

The group of regions comprising the hippocampus, subicular cortex, entorhinal cortex, and perirhinal/postrhinal cortices.

Social place representation

The finding that some neurons in the dCA1 represent the spatial coordinates of other individuals.