77 Questions
Which imaging technique reveals the static physical characteristics of the brain?
Structural imaging
What does the BOLD signal measure in fMRI?
Changes in brain physiology
What triggers an increase in blood flow to a region in the brain?
Neural activity
Which imaging technique measures relative changes in neural activity?
Functional imaging
What is the HRF in fMRI?
Haemodynamic response function
What does the BOLD signal in fMRI correlate with?
Cognitive function
Which imaging technique measures changes in the amount of deoxyhaemoglobin in a region of the brain?
Functional imaging
What is the main function of brain rhythms?
All of the above
During which sleep state does the main neurotransmitter modulation come from histamine?
Non-REM
Which imaging technique provides better discrimination between white and grey matter?
MRI scan
What is the main difference between PET and fMRI?
PET measures blood flow, fMRI measures blood oxygen concentration
What is the main purpose of the external magnetic field in MRI scans?
To align the protons in the brain
What is the relationship between metabolic activity of neurons and blood supply to the region?
Metabolic activity of neurons increases blood supply to the region
Which sleep state is characterized by reduced motor activity and decreased response to stimulation?
Non-REM
Which neurotransmitter provides the main modulation during REM sleep?
Acetylcholine
What is the main purpose of brain rhythms?
All of the above
Which imaging technique provides dynamic maps of the brain's moment-to-moment characteristics?
fMRI scan
Which imaging technique measures the physiological signals of the brain and is commonly used to study brain function?
fMRI
What does EEG measure?
Brain rhythms
Which structure in the brain is involved in the generation of synchronous brain rhythms?
Thalamus
What is the main requirement for signal detection in EEG?
A whole population of neurons must be active in synchrony
Which imaging technique provides detailed structural information about the brain?
MRI
Which of the following is NOT a brain rhythm measured by EEG?
Gamma
Which imaging technique measures changes in blood flow and oxygenation levels in the brain?
fMRI
Which of the following is NOT a method of imaging the living brain?
EEG
How do brain rhythms relate to the environment?
They are influenced by day and night cycles
Which part of the brain acts as the pacemaker during sleep?
Brainstem
What is the purpose of the hand clapping mechanism in brain activity coordination?
To maintain signals
What type of brain waves are observed during slow wave sleep?
Delta waves
What is the main function of brain rhythms?
Unknown
Which technique can be used to study the activity of large populations of neurons?
Electroencephalography (EEG)
What are the three topics discussed in the presentation?
Brain rhythms, sleep cycle, imaging techniques
Which imaging technique provides dynamic maps of the brain's moment-to-moment characteristics?
Functional Magnetic Resonance Imaging (fMRI)
What is the main purpose of brain rhythms?
To generate synchronous brain activity
What is the main factor that determines the amplitude of an EEG signal?
The number of active cells
What type of neurons are primarily recorded in an EEG signal?
Pyramidal neurons
Which sleep stage is characterized by reduced motor activity and decreased response to stimulation?
Stage 3 sleep
What is the main purpose of brain rhythms?
To synchronize activity across different brain regions
Which neurotransmitter is the main modulator of REM sleep?
Acetylcholine
Which neurotransmitter is responsible for keeping us alert and attentive?
Noradrenaline
Which sleep state is characterized by reduced motor activity and decreased response to stimulation?
Stage 2 non-REM sleep
Which brain adaptation allows dolphins and seals to sleep while keeping half of their brain awake?
Asynchronous brain activity
What is the main purpose of the gel used in EEG?
To improve the conductance of the electrodes
What is the main requirement for signal detection in EEG?
Large populations of synchronously firing neurons
What type of brain activity can EEG only record?
Massive synchronous firing of pyramidal neurons directly below the EEG electrode
What is the purpose of the wires connected to the EEG electrodes?
To safely transport the signal to devices for filtering and amplification
During non-REM sleep, what happens to the synchronization and amplitude of neuronal activity as we progress from stage 1 to stage 4?
Synchronization increases and amplitude increases
Which brain rhythm is typically observed during REM sleep?
Beta rhythm
What is the main difference between the generation of synchronous brain rhythms and asynchronous brain rhythms?
Synchronous brain rhythms are generated by a pacemaker, while asynchronous brain rhythms are generated through feedback and improvisation
What is the purpose of the spindle feature in the thalamus?
To activate calcium channels and send a signal to the cortex
During REM sleep, the main neurotransmitter modulation is provided by which neurotransmitter?
Histamine
Which sleep state is somewhere in between awake and REM sleep in terms of levels of neurotransmitter modulation?
Non-REM sleep
Which sleep states have high levels of activation?
Awake and REM sleep
Which sleep states have entirely different neurotransmitter modulation compared to each other?
Awake and REM sleep
Which sleep states have entirely different information sources compared to each other?
Awake and REM sleep
Which sleep states are the most opposite ones in terms of neurotransmitter modulation and information source?
Awake and REM sleep
During REM sleep the main neurotransmitter modulation is provided by:
Acetylcholine
Four basic EEG phenomena: The alpha rhythm, 8-13Hz, awake subjects with eyes closed The beta rhythm, 14-60 Hz, indicates mental activity and attention, eyes open Theta waves, 4-7 Hz, indicates drowsiness and sleep or a pathological condition. Delta waves, <4 Hz, as in 3.
What is the order of the waves from shortest to longest?
Delta waves, theta waves, alpha rhythm, the beta rhythm
What is a true statement regarding generation of small fields in pyramidal cells?
It takes many thousands of underlying neurons, activated together, to generate an EEG signal big enough to see at all.
What is NOT true regarding basic requirements for signal detection?
This population of neurons must be aligned in a parallel orientation so that they summate rather than cancel out.
The amplitude of the EEG signal partly depends on how synchronous the activity of the underlying neurons is. Number of active cells, total amount of excitation, timing of activity.
What is NOT true regarding Synchronous activity?
If the inputs are regular, their algebraic sum will have a small amplitude, as occurs in the waking state.
What is NOT true regarding generation of synchronous rhythms?
Brainstem nuclei modulate the rhythm of interactions between the medulla oblongata and the cortex.
A one neuron oscillator Thalamic cells have a set of voltage-gated ion channels that allow each cell to generate rhythmic, self-sustaining discharge patterns, even in the absence of external inputs. The rhythmic activity of each thalamic pacemaker neuron then becomes synchronised with many other thalamic cells via a hand-clapping kind of collective interaction.
What is NOT true regarding generation of synchronous rhythms?
Hyperpolarisation of the cell (by injecting current or stimulating the cholinergic reticular activation system) transforms the oscillatory activity into a tonically active mode.
What are EEG rhythms?
Window of the functional states of the brain
What is NOT a behavioural criteria for sleep?
Relatively hard reversibility
What is NOT a functional states of sleep
Sleep
Predatory animals, like humans, can indulge in long, uninterrupted periods of sleep. The animals that are prayed upon need to have constant vigilance, and usually sleep only a few minutes at a time (e.g. rabbits, giraffes). Dolphins and seals have come up with a particularly ingenious solution:
one hemisphere sleeps, while the other is awake.
What is NOT true regarding summary scheme of sleep-wake states?
In NON- REM sleep, activation is also high, the modulation is cholinergic, and the information source is internal.
What is NOT a function of Sleep and Dreaming
Release of metabolic energy
What is NOT true regarding Structural imaging?
Functional magnetic resonance imaging, fMRI
What is NOT true regarding functional imaging?
An example: Magnetic resonance imaging, MRI
What is NOT true regarding Imaging techniques?
Structural imaging always measures relative changes in activity (e.g. activity while performing a task vs. baseline or a control task).
What is NOT true regarding the BOLD signal?
Haemodynamic response function, describes the BOLD signal
What stages in the Non REM stage of sleep?
Stage 1: Theta Rhythms, Stage 2: Spindle and K complexes, Stage 3: Delta Rhythms, Stage 4: Delta Rhythms
In the awake stage of sleep, what rhythms are present?
Alpha and beta rhythms
In the REM sleep stage, what rhythms are present?
Beta rhythms
The neurons that control sleeping and waking are part of the diffuse modulatory neurotransmitter systems (brain stem). Those systems control the rhythmic behaviours of the thalamus, which in turn controls many of the EEG rhythms of the cortex. What is true regarding the diffuse modulatory neurotransmitter systems (brain stem)?
modulation is aminergic (NE (Locus coeruleus), 5-HT (raphe nuclei)), and the information source is external.Histamine-containing neurons in the tuberomammilary nucleus (TMN) of the hypothalamus are also involved (~ drowsiness as a side effect of an antihistamines which supress the TMN network).
Study Notes
Brain Activity and Imaging Techniques
- Presentation is for personal use only and not to be copied or used outside of BSMS Global Brain Activity
- Presentation covers activity of large populations of neurons, electroencephalography (EEG), brain rhythms, sleep cycle, and methods of imaging the brain
- Learning outcomes include understanding EEG, frequency bands, role of thalamus in brain rhythms, stages of sleep, and differences between structural and functional imaging techniques
- Brain rhythms are influenced by environmental factors and include sleeping and waking patterns, breathing cycles, and stages of night sleep
- EEG measures the synchronous activity of a population of neurons aligned in a parallel orientation, with amplitude depending on the synchrony of the neurons
- EEG and brain rhythms correlate with pathology and behavioral states
- Thalamic cells generate rhythmic, self-sustaining discharge patterns that synchronize with other thalamic cells to generate brain rhythms
- Sleep is characterized by reduced motor activity, decreased response to stimulation, stereotypic postures, and relatively easy reversibility
- Sleep has functions such as conservation of metabolic energy, cognition, thermoregulation, neural maturation, and mental health
- Structural imaging techniques include computerized tomography (CT) and magnetic resonance imaging (MRI), which provide static maps of brain tissue
- Functional imaging techniques include positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), which provide dynamic maps of brain activity associated with cognitive processing
- PET measures changes in blood flow, while fMRI is sensitive to the concentration of oxygen in the blood, both indirectly measuring neuronal activity
Test your knowledge on the activity of large populations of neurons, brain waves, sleep cycles, and imaging techniques such as EEG, CT, MRI, fMRI, and PET. This quiz is designed to enhance your understanding of neuroscience and behavior.
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