Encoding Part 2 - Lecture 4

Flashcards about the Hippocampus, Storage, Modification, and Indexing

What is the main function of the hippocampus?

Storage, modification, and indexing of memories

Where is Wernicke's Area located?

Temporal Cortex

What brain areas are part of the information flow for learning and memory according to the lecture?

Cortical association areas, parahippocampal and rhinal cortices, hippocampus, fornix, sensory information, thalamus, and mamillary bodies

What is the role of the parahippocampal and perirhinal cortices?

Connections between association cortices and the hippocampus

Removal of the medial temporal lobe results in what condition?

Severe anterograde amnesia

What type of memories does the Hippocampus form?

Declarative/explicit memories

Besides explicit memories, what else does the Hippocampus allow us to do?

Tells you where you are in space, Spatial memory/learning

What disease is the Hippocampus often lost early in?

Alzheimer's

What are the encoding patters of the Hippocampus?

Pattern Completion and Pattern Separation

What is pattern completion?

Recognizing something from a partial representation

What is pattern separation?

Learning to distinguish between similar patterns

What is the function of pattern completion?

Recognising something from a partial representation

What is the function of pattern separation?

Learning to distinguish between similar memories

What type of signals exist as 'Information' in our nervous system?

Electrical and chemical signals

What is the major electrical cell type of the nervous system?

The neuron

What is an action potential?

Electric signal that travels along neurons.

What does a chemical signal consist of?

Travels between neurons as neurotransmitters

What is the role of excitatory neurotransmitters?

Increase probability of target neuron firing action potential.

What is the role of inhibitory neurotransmitters?

Reduce probability of target neuron firing action potential.

What are some possible components of the 'code'?

Which neurons fire, what causes them to fire, how often they fire, how long they fire for, where they project to, how many other neurons they are connected to, numbers/types of neurotransmitter receptors, etc

What does Hippocampal Indexing do?

The basis for 'retrieval' of memories using Pattern Completion and Pattern Separation

In hippocampal anatomy, what are the connections between Association cortices and the hippocampus?

Parahippocampal and perirhinal cortices

What subpopulation of neurons does activity from the cortex activate in CA3?

Specific subpopulation

How are neurons in CA3 connected?

Densely, reciprocally

What happens to CA3 neurons with partial input?

The whole group is activated.

What is synaptic plasticity?

Cellular basis for Learning and Memory

What saying describes synaptic plasticity?

Neurons that fire together… wire together

What ions are more concentrated outside the cell?

Na+, Cl-, Ca2+

What ions are more concentrated inside the cell?

K+

What two forces are at work in neuron physiology?

Electrical force (opposites attract) and Chemical force (concentration gradient)

What is the resting membrane potential?

Poised and ready to fire, Measured as an electrical potential

What needs to happen for action potentials to be released?

1. Presynaptic neuron releases neurotransmitter. 2. Enough ligand-gated channels open. 3. Membrane reaches threshold. 4. Action potential will fire

What do Excitatory neurotransmitters bind to conduct?

Ligand-gated channels which conduct sodium

What is Long-term potentiation

Frequent firing strengthens synapses

During Long Term Potentiation, what is the Excitatory Neurotransmitter

Glutamate

What receptor does the Glutamate bind to during long term potentiation?

AMPA receptors

Brief, intense firing by presynaptic neuron causes what during long term potentiation?

Abundant glutamate release, Opens NMDA-type glutamate receptors,Increases expression and insertion of AMPA-type glutamate receptors

In what hippocampal region are long term potentiation best understood?

Synapse between CA3 (Schaffer collaterals) and CA1 (Pyramidal cells)

What are two distinct groups formed as part of

Pattern Separation

What two receptors is Long Term Potentiation linked to?

NMDA and AMPA

Why should you NOT eat glutamate to boost memory?

Systemic stimulation can cause seizures because NMDA and AMPA receptors are everywhere

Where does Allocentric Spatial Representation live?

Hippocampus

Where does egocentric spatial representation live?

Posterior Parietal Cortex + Prefrontal Cortex

Which environmental cues activate Place Cells?

Allocentric environmental cues - Visual, olfactory, other senses

What are Head Position Cells

Fire when oriented towards a specific direction

What do Border Cells do?

Place Cells that are specifically activated by barriers

What do Reward-place neurons do?

Learn about a reward in a particular place. Connection between where is it and what is it.

Where are Grid cells found?

Entorhinal cortex

What type of map are Grid Cells?

Hexagonal Map

What is the function of Grid Cells?

Measure distance?'Dead Reckoning' or 'Path Integration'

Why is the Hippocampus very important for spatial memory?

Stores memory as a neuronal ‘code’ which can be activated to allow finer distinctions through pattern separation