Hippocampus and Memory

Practice flashcards based on the lecture notes about the hippocampus and its role in memory.

The hippocampus is important for __________ memory.

episodic

The hippocampal complex consists of the hippocampus, subiculum, __________ cortex, perirhinal and post-rhinal cortex.

entorhinal

The CA1 region receives cortical input via __________ pathways.

two

Hippocampal synapses undergo long-term __________ and depression.

potentiation

Different parts of the hippocampus perform __________ separation and pattern completion.

pattern

Memory is ultimately consolidated in the __________.

cortex

In humans, declarative memory can be consciously recalled and expressed in __________.

language

Episodic memory is for __________ experiences.

specific

The hippocampus and surrounding structures were discovered to be critical for episodic memory due to the patient known as __________.

HM

HM had __________ epilepsy and had surgery to remove parts of the brain, including the hippocampus.

intractable

Older memories were __________, but memory of the years just before the surgery was impaired.

retained

HM could remember the most recent few minutes normally and could learn new skills normally, although he could not remember having done so. This condition is known as __________ amnesia.

anterograde

Mice probably possess __________ memory.

episodic

Episodic memory combines what, where, and __________ elements.

when

Hippocampal lesions impair discrimination of all three factors: what, where, and when, as shown in studies by __________ and __________.

Dere et al., DeVito & Eichenbaum

The hippocampus is much older than the __________.

neocortex

The hippocampus deals only with __________ information in some species.

spatial

Episodic memory seems to be common to __________ and birds.

mammals

The hippocampus is needed to find the __________ location in the Morris water maze.

platform

The __________ is an experiment where animals swim in opaque liquid with an invisible submerged platform.

Morris water maze

The hippocampal complex includes the hippocampus, __________, entorhinal cortex, and others.

subiculum

The CA1 region receives cortical input via __________ pathways.

two

The Cornu Ammonis (CA) regions are named after the ancient Egyptian diety __________, who had ram's horns.

Ammon

The __________ region is a major source of output from hippocampus to other structures.

CA1

Entorhinal cortex provides a major input; this reaches CA1 through both direct path and __________ path.

trisynaptic

Lesions of the dentate gyrus or CA3 impair __________ memory formation.

short-term

Each hippocampal structure has multiple subregions with distinctions in __________ and gene expression.

connectivity

The broad distinction between dorsal and ventral circuits in the hippocampus is involved in __________ cognition and affect, respectively.

spatial

Hippocampal synapses undergo long-term potentiation and __________.

depression

LTP, or long-term potentiation, is persistent strengthening of a __________ following artificial high-frequency stimulation.

synapse

LTP in the Schaffer collateral pathway depends on __________ receptors.

NMDA

LTP can occur at a weakly active synapse if there is sufficient __________ due to other simultaneously weakly inactive synapses.

depolarization

In contrast, LTP in the mossy fiber pathway does not depend on __________.

NMDA

Synaptic strength can’t only grow indefinitely; many synapses can be weakened experimentally via long-term __________.

depression

Mechanisms of synaptic depression can result in __________ of AMPA receptors.

endocytosis

Some synapses in the hippocampus change in accordance with the relative timing of pre- and postsynaptic __________.

spikes

Hebb’s hypothesis states that when axon of cell A repeatedly excites cell B, some growth process or metabolic change takes place to increase A's efficiency. This is known as "__________ changes".

metabolic

Content-addressable memory or associative memory is when a network recovers the full memory from __________ of it.

part

In Hopfield networks, neurons have binary outputs and fixed __________.

thresholds

The memory is a vector. To store a list of memories, the weights are set to __________ .

T_{ij} = (2V_i - 1)(2V_j - 1)

About __________ states can be memorized by the Hopfield network before recall degrades severely.

0.15N

Follow-up work has extended Hopfield’s idea notably by developing models with stronger __________ in memory capacity.

nonlinearities

HM lost the ability to store new memories but retained distant memories normally, indicating that the hippocampus is not necessary for __________ storage.

long-term

Remote memory recall is associated with activity in __________, temporal, and retrosplenial cortex.

prefrontal

During idle moments and sleep, hippocampal activity is __________ in temporally compressed form.

replayed

Consolidation of a memory involves multiple stages that occur during __________ following learning.

sleep

In longer-term scenarios, multiple memory traces may exist in both the hippocampus and the cortex; retrieval of remote memories requires intact __________ and __________ plasticity.

cortex, synaptic

Episodic memories may remain dependent on the __________ while the cortex dominates more abstract semantic memories.

hippocampus

What is the role of the hippocampus in spatial navigation?

The hippocampus is crucial for the mapping and navigation of spatial environments.

What type of memory is primarily associated with the hippocampus?

The hippocampus is primarily associated with declarative memory, which includes episodic and semantic memory.

Describe the interaction between the hippocampus and the neocortex during memory retrieval.

During memory retrieval, the hippocampus provides contextual details while the neocortex stores more abstracted memories.

How does the hippocampus contribute to the process of consolidation?

The hippocampus helps consolidate memories by transferring them from short-term to long-term storage in the neocortex during sleep.

What are some neuroanatomical features of the hippocampus?

The hippocampus consists of regions such as the CA1, CA2, CA3, and dentate gyrus, each with distinct functions.

What type of pathological states can affect the hippocampus and impact memory?

Conditions such as Alzheimer's disease, stress, and traumatic brain injury can lead to hippocampal dysfunction.

What is the relationship between the hippocampus and neurogenesis?

The dentate gyrus of the hippocampus shows neurogenesis, the birth of new neurons, which is important for memory formation and learning.

How do emotions influence hippocampal function?

Emotions can enhance memory encoding and retrieval, with the amygdala interacting with the hippocampus to modulate these processes.

What experimental evidence supports the role of the hippocampus in memory?

Studies involving lesioning the hippocampus in animals show deficits in memory tasks, confirming its essential role.

What is cognitive mapping, and how does it relate to the hippocampus?

Cognitive mapping refers to the mental representation of spatial environments, which relies heavily on hippocampal function.

How do stress hormones affect the hippocampus?

Elevated levels of stress hormones like cortisol can impair hippocampal function and affect memory negatively.

What is the significance of place cells in the hippocampus?

Place cells are neurons in the hippocampus that become active when an animal is in a specific location, contributing to spatial memory.

What is the role of the entorhinal cortex in relation to the hippocampus?

The entorhinal cortex acts as a major input and output relay for information going to and from the hippocampus.

How might aging influence hippocampal function?

Aging can lead to structural and functional changes in the hippocampus, resulting in memory decline and cognitive impairments.

What techniques are used to study hippocampal function in humans?

Techniques such as fMRI, PET scans, and electrophysiological recordings are used to study hippocampal activity during memory tasks.