neuronal oscillations lecture 10

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Questions and Answers

What frequency range is associated with slow oscillations as mentioned in the content?

1 – 4 Hz

0.5 – 1 Hz (correct)

0.1 – 0.5 Hz

4 – 8 Hz

What role do slow oscillations likely play in cognitive processes according to the studies mentioned?

Consolidation of memory (correct)

Enhancing motor skills

Visual processing

Emotion regulation

What was the purpose of applying so-tDCS in patients with mild cognitive impairment?

To improve motor coordination

To stimulate emotional responses

To enhance sensory perception

To improve cognitive function (correct)

In the study, how was the stimulation (so-tDCS or sham) administered to the patients?

During stage 2 sleep Signup and view all the answers

Which frequency band is measured in the EEG along with slow oscillations according to the content?

Spindles (8 – 12 Hz) Signup and view all the answers

Which of the following tasks is implied to benefit from the application of slow oscillations?

Spatial memory tasks Signup and view all the answers

What does the term 'sham stimulation' refer to in this context?

A placebo treatment with no active effect Signup and view all the answers

How did the researchers measure the EEG activity following the stimulation?

By analyzing power in defined frequency bands Signup and view all the answers

What is the role of the hippocampus in learning?

It serves as the fast learning store. Signup and view all the answers

What characterizes the 'down state' during slow wave sleep?

Hyperpolarization of neurons. Signup and view all the answers

How does boosting slow oscillations during sleep affect memory performance?

It enhances declarative memory performance. Signup and view all the answers

What frequency was identified as most effective for stimulating slow oscillations to enhance memory?

0.75 Hz Signup and view all the answers

Which area of the brain is associated with the slow learning store?

Neocortex Signup and view all the answers

During which phase does reactivation occur as a result of slow wave sleep?

Deep sleep Signup and view all the answers

What measurement can be used to assess the difference between learning and recall performance?

Declarative memory testing Signup and view all the answers

What is the main impact of slow wave sleep on the learning process?

It enhances recall of previously learned material. Signup and view all the answers

What EEG frequency band is most associated with sleep spindles, crucial for memory?

Theta waves Signup and view all the answers

During which stage of sleep do slow wave sleep (SWS) predominantly occur?

Stage 3 and 4 Signup and view all the answers

Which frequency range is considered slow oscillations during sleep?

< 1 Hz Signup and view all the answers

What is a critical function of sleep as per the two-stage model of memory consolidation?

Reacting newly encoded memory traces Signup and view all the answers

Which of the following is NOT a characteristic of REM sleep?

High levels of delta waves Signup and view all the answers

What effect did stimulating the brain at gamma frequency have on beta amyloid pathology?

It had no significant effect Signup and view all the answers

How do changes in sleep patterns relate to diseases such as Alzheimer's?

Changes in sleep indicate progression of the disease Signup and view all the answers

What frequency range of fast sleep spindles is critical for memory?

12-15 Hz Signup and view all the answers

What role does the prefrontal cortex (PFC) play in cognitive functions?

Executive functions such as memory and attention Signup and view all the answers

What is necessary for the normal function of the hippocampus and the prefrontal cortex?

Coherent communication between the two regions Signup and view all the answers

What identifies coherent excitability changes in neuronal groups?

Action potentials being timed at peak excitability Signup and view all the answers

What effect does cell damage have on cognitive function?

Loss of synchrony leading to cognitive impairment Signup and view all the answers

What type of oscillations are suggested to play a critical role in learning tasks?

Beta/gamma coupling during task learning Signup and view all the answers

Which frequency band is primarily associated with memory functions in the hippocampus?

Gamma frequency oscillations during learning and memory Signup and view all the answers

What is the relationship between local field potentials and cognitive tasks?

They reflect the synaptic activities during cognitive processing Signup and view all the answers

What aspect of spatial memory tasks involves the hippocampus?

The encoding and retrieval of spatial information Signup and view all the answers

What frequency range is classified as theta rhythms in EEG?

3 - 7 Hz Signup and view all the answers

Which EEG frequency is primarily associated with alert wakefulness?

Beta Signup and view all the answers

In the context of spatial memory tasks, when does increased theta activity occur?

During goal-directed navigation Signup and view all the answers

What characterizes the local field potential signal?

Average behavior of a large number of interacting neurons Signup and view all the answers

In a virtual water maze task, what is primarily measured to assess navigation skills?

Path length and escape latency Signup and view all the answers

Which frequency band is associated with delta rhythms?

0.5 - 4 Hz Signup and view all the answers

What are gamma oscillations in EEG generally associated with?

Cognitive function and memory processes Signup and view all the answers

Which EEG frequency range is typically indicative of strong mental engagement?

60 - 80 Hz Signup and view all the answers

Study Notes

Power Spectra and EEG Signals

Fourier transform reveals frequency components of brain activity.
Different EEG signals categorized into frequency ranges:
- Slow waves: < 1 Hz
- Delta rhythms: 0.5 - 4 Hz (associated with deep sleep)
- Theta: 3 - 7 Hz
- Alpha: 9 - 11 Hz
- Spindles: 8 - 15 Hz
- Beta: 15 - 30 Hz (indicates alert awake state)
- Low Gamma: 30 – 60-80 Hz
- High Gamma: > 60/80-150 Hz
- Ultrafast: > 100 Hz
All frequencies play roles in memory functions.

Spatial Memory in Humans

MEG study on virtual water maze task assesses spatial navigation.
Participants navigate to a hidden platform using visual cues.
Path length and escape latency measured for cognitive mapping.

Increased theta oscillations (4-8 Hz) observed in the hippocampus during goal-directed navigation.
No significant change in other frequency bands noted during navigation tasks.

Local Field Potential and EEG Generation

Local mean field potential reflects activity from numerous interacting neurons.
Distinctions made between declarative tasks (facts/events) and procedural tasks (motor skills).

Slow Oscillations and Cognitive Function

EEG shows two key bands: slow oscillations (0.5 – 1 Hz) and spindles (8-12 Hz).
Increased activity in these bands during stimulation supports their role in consolidation.

Improving Cognition

Slow transcranial direct current stimulation (so-tDCS) explored in patients with mild cognitive impairment (MCI).
Stimulation delivered during stage 2 sleep to evaluate cognitive improvement effects.

The Prefrontal Cortex (PFC)

PFC is crucial for executive functions including memory, attention, and planning.
Human version is termed dorsolateral PFC; in rodents, medial PFC performs similar functions.

The Hippocampus

Central for memory functions in both humans and animals.
Effective communication between the hippocampus and PFC is essential for normal cognitive function.

Neuronal Synchrony and Learning

Spike timing control enhances neuronal communication, critical for cognitive function.
Loss of synchrony due to cell damage leads to cognitive impairments.

Gamma Frequency Oscillations and Learning

Beta/gamma coupling between entorhinal cortex and hippocampus increases during learning tasks.
Absence of learning results in decreased coupling.

Slow Wave Sleep and Memory

Reactivation of memory during slow wave sleep (SWS) enhances learning.
Slow oscillations (0.5 - 1 Hz) play a key role in memory consolidation during SWS.

Restoring Gamma Oscillations

Studies focus on stimulating gamma frequency in transgenic AD mice to address beta amyloid pathology.
Current findings indicate the debate is ongoing regarding the efficacy of this approach.

Sleep Architecture

Human sleep characterized by light sleep (stages 1 and 2), slow wave sleep (stages 3 and 4), and REM/non-REM stages.
Early sleep predominantly consists of SWS, transitioning to REM in later periods.

Importance of Sleep for Memory

Normal sleep rhythms are critical for cognitive functioning, with notable changes in diseases such as Alzheimer's.
Spindles (8-15 Hz, fast spindles at 12-15 Hz) and slow oscillations (< 1 Hz) critical for memory processes.

Memory Consolidation Model

"Two stage model" proposed for memory consolidation aligning fast learning store with slow learning store for reactive memory traces.

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Description

This quiz explores the concepts of power spectra and the Fourier transform, focusing on how frequency components of activity can be derived. Delve into the implications of these techniques in cognitive trends as outlined by Ward. Test your understanding of these fundamental concepts in signal analysis.