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Terms in this set (227)
Explain how angiography works
Catheter inserted via an external artery & guided close to the site of entry of arterial supply of the brain (e.g., internal carotid); Contrasting dye is injected (doesn't let x-rays through easily)
Explain what an angiography is used for
Diagnostic use - aneurysms, tumors w/ new vasculature, vascular shifting due to lesions or degeneration of brain tissue; Visualize cerebral vasculature (blood vessels in the brain)
How in general does an MRI work?
Applies powerful magnetic field to create image; Magnetic field aligns axes of the natural spin or rotation of atoms in water molecules; Radiofrequency signal causes all aligned axes to spin Termination of radiofrequency signal causes nuclear atoms to return to original state, releasing electromagnetic energy in the process; Released energy is measured & used to visualize the structure of the brain
What are the advantages of MRIs?
No radiation, cheap, have become increasingly accessible in the past 20 years, high image resolution
What are the disadvantages of MRIs?
Because MRIs use powerful magnetic fields, not everyone can take one (i.e., if you have metal in your body - pacemaker, shunt; or if you have too many tattoos bc they use heavy metals for coloring). You must lie still. Loud, long.
What types of things can be measured with MRIs, and how can it be used in research?
Uses powerful magnetic field; Takes multiple pictures; measures - Released electromagnetic energy; Applicable to any body organ and does not use radiation, high image resolution, cheap
Reveals the level of activity, size, & appearance of particular brain region/structure(s); Differences in gray matter volume b/w adolescents w/ & w/o substance problems; Subcortical shapes b/w recreational marijuana users
Explain what DTIs can image, and in what types of disorders this is interesting information. What descriptive research can be done with DTIs?
Explain what DTIs can image, and in what types of disorders this is interesting information.
Shows preferred direction of diffusion, visualization of directional fibers, visible white matter tracts; Diffusion tractography uses such diffusion tensor information to build an image of probable white-matter tracts; disorders - TBI (e.g., concussions), MS (multiple sclerosis - demyelinating disorder, attacks oligodendrocytes)
What descriptive research can be done with DTIs?
What does an fMRI measure?
Oxygen consumption and levels of (deoxygenated) blood; When oxygen consumption ↑, level of deoxygenated blood ↑
How does fMRI work in general?
Use oxygen consumption in the brain to create moving (dynamic) image
what does subtraction have to do with fMRI?
Used to ensure that a given task/stimulus is responsible for the activity detected in a particular area of the brain; Subtracts resting state activity from task activity
Blood Oxygen Level Dependent
Calculates regional blood flow; Part of brain that is active - increase in oxygen rich blood
What process is used to visualize brain processing via BOLD imaging?
What is difficult about an fMRI for patients, and what effect does this have for ability to use fMRI?
What different things are revealed by task-based and resting-state research approaches?
tasked-based approaches: Activation levels while performing task and Multivoxel pattern analysis (MVPA); resting state - Different networks active during rest
What are the various fMRI research approaches?
resting state approaches and tasked based approaches
How is looking at activation levels different from MVPA (in general)?
Analyze pattern of activity (e.g., level of activation when looking at an object all activate a common region of visual cortex, category of object associated w/ a unique pattern of activation)
Resting state approaches take a shorter amount of time than measuring for task-based approaches do. This could allow more groups of people to be included in this type of research, such as those who are claustrophobic, the elderly, or those with an intellectual disability.
Why do resting state approaches allow for testing of different groups of people?
Why would brain connectivity be of interest to researchers?
Connectivity b/w brain regions may influence cognitive processes; See if one brain region is related to activation of other areas
How does a PET work?
Records emission of radioactivity from injected radioactive chemicals to produce a high-resolution image; Uses radioactively labelled glucose or (now) radio labelled neurotransmitter-related substances
What is PET used for?
Showing where in brain blood supply is being used - shows function; Used if suspicion of tumor (glucose); Used to look at dopamine function across the brain (neurotransmitter)
Diagnosis or research of Alzheimer's disease - can image amyloid beta, which builds up in Alzheimer's
What are the advantages of PET?
Best measure of metabolic activity in the brain - rate of O2 consumption, glucose metabolism; Insights into neurotransmitter function in the brain
What are the disadvantages of PET
Not used for brain activity research that much; Superceded by fMRI
What is it that PET does that fMRIs do better?
fMRIs have better resolution and no radioactivity
Which two types of PET imaging are used in research for Alzheimer's disease?
Amyloid-PET scan, FDG-PET scan
What types of electrical recordings of brain activity are there (we mention 3)?
Single/multiple cell recording, electroencephalograph (EEG) recording, event related potential (ERP) recording
What is the general process in single cell recordings?
Electrode(s) inserted into brain, adjacent to neuron(s); Neuron's activity recorded (many can be recorded simultaneously); Record action potential(s)
Who is this process (single cell recordings) used with?
Animals, generally not humans
What is the general process in an EEG?
Records electrical potentials or "brain waves"; Reflects the collective & synchronous activity of neurons in the cortex
What can be studied with EEGs?
Sleep studies; Epilepsy diagnosis; Monitoring the depth of anesthesia (long procedures); Studying normal brain function
Event-Related Potential (AKA evoked potential)
how does ERP work?
Uses slow-wave EEG signal to measure response to a stimulus; Stimulus must be REPEATED many times
What is function of averaging in ERPs?
Allows someone to read a clear signal/response from a stimulus
How is that like the subtraction process in fMRIs?
It allows someone to measure what the true response to a stimulus is
Records magnetic potential produced by brain activity
Advantages of magnetoencephalography
Magnetic potentials do not weaken as they travel
Disadvantages of magnetoencephalography
Need magnetic proof room so other magnetic forces (i.e., Earth, equipment) do not interfere
What is it used for?
Clinical - location where epileptic seizure originates; Neurosurgery - identify where sensory cortices are
In which types of cases can this be used when fMRI cannot?
optical imaging - Information about source & time of neural activity, Light source used & optical sensor senses how much absorbed, reflected off brain; absorption - Allows you to ID oxygenated/deoxygenated blood; Light scattering - Provides info about the tissue
optic imaging VS fMRI
Noninvasive, can be done on children/babies
Transcranial Magnetic Stimulation
What in general is the process for TMS?
Apply intense magnetic fields to temporarily inactivate neurons (can also make neurons more active, but not as common as inactivating)
What is TMS used for?
Transcranial direct current stimulation
What is the tDCS process?
Stimulation beneath + (anode) electrode: ↑ in neuronal activity; Stimulation beneath - (cathode) electrode: ↓ in neuronal activity
What is tDCS used for
Clinical use: reduce craving & addiction, slow decline in Alzheimer's, reduce auditory hallucinations (Schizophrenia), increase attention
Structure; Diagnostic - aneurysms, tumors; visualize cerebral vasculature, vascular shifting due to lesions or degeneration of brain tissue
Magnetic Resonance Imaging (MRI)
Structure; Released electromagnetic energy Activity, size, & appearance of brain structures
Diffusion Tensor Imaging (DTI)
Structure; measures - Direction of diffusion; use/research - White matter
Function; O2 consumption, deoxygenated blood; Brain activity & connectivity (resting or w/ stimuli)
Positron Emission Tomography (PET)
Function; Emission of radioactivity Oxygen use, glucose metabolism, Alzheimer's - amyloid beta
Single Cell Recordings
Function; Single/group of cell's activity in specific location
Function; Records electrical potentials or "brain waves"; Measures electrical currents detectable off scalp; Reflects the collective & synchronous activity of neurons in the cortex; Sleep studies; Epilepsy diagnosis; Monitoring the depth of anesthesia (long procedures); Studying normal brain function
ERP (Event Related Potential AKA evoked potential)
Function; Uses slow-wave EEG signal to measure response to a stimulus
Str & Func; Record magnetic potential produced by brain activity; Clinical - location where epileptic seizure originates, neurosurgery - ID where sensory cortices are
Function; Amt of light absorbed or reflected off brain
Transcranial Magnetic Stimulation (TMS)
Temporarily inactivates neurons Electroconvulsive therapy - depression
Transcranial Direct Current Stimulation (tDCS)
Clinical use: reduce craving & addiction, slow decline in Alzheimer's, reduce auditory hallucinations (Schizophrenia), increase attention
Explain the distinction between epilepsy and seizures.
Seizures = symptom of epilepsy | Not all seizures are due to epilepsy
What is the prevalence of epilepsy?
Loss of consciousness & equilibrium, Tonic-clonic convulsions, Resulting hypoxia may cause brain damage
What types of seizures are these on the new classification?
Both grand mal and petit mal (absence seizure) are generalized seizures in the new classification
Petit mal (absence seizure)
Not associated w/ convulsions; Disruption of conscious; Cessation of ongoing behavior
What is the difference between a partial and generalized seizure?
partial - Does NOT involve the whole brain Involves the entire brain; generalized -
Where does partial seizure originate?
at seizure focus
where does generalized seizure originate
In which order are the brain lobes "epileptogenic"?
Most to least (capable of causing an epileptic attack): temporal, frontal, parietal/occipital
What is a secondarily generalized seizure and what is the "Jacksonian march"?
Secondarily generalized seizure
Begins in one place & spreads
Seizure "walks up" homunculus
What are the stages of an epileptic attack? What modalities can the aura be associated with?
Weird sensation, twinkling in vision, smell strange things, hearing, taste, emotion - depends which part of brain affected
What does tonic, clonic, atonic, and myotonic mean?
Lose all muscle tone
Rigidity followed by jerky muscles (e.g., grand mal)
Why is the diagnosis 'epilepsy' a lengthy process to establish? What are the differential diagnoses?
Careful history, seizure type, symptoms
Tests - EEG, blood work, scans
Decide on therapy
Narcolepsy - symptom = atonic
Migraines - auras
Panic disorder - weird sensations that could double as auras
What types of therapy were mentioned for epilepsy in class?
Medication, neurosurgery, ketogenic diet (no carbs)
Class 12 - Sleep
What types of recordings are part of a polysomnogram? What are they measuring, and why is this important?
Brain waves (e.g., ID sleep stage)
Electrical activity from the eye (e.g., ID REM sleep)
Muscle activity - usually chin, jaw, legs
What kind of waves during normal awake time on EEG? (amplitude, frequency, name)
What kind of waves during relaxation on EEG? (amplitude, frequency, name)
What 2 weird phenomena during stage 2 sleep on EEG?
Activity from thalamus
Early delta waves
What kind of waves during deeper sleep (3 & 4) on EEG? (amplitude, frequency, name)
Answers to 2-5:
Level of consciousness Amplitude Frequency
Normal awake time Low High
Relaxation/resting Increased Lower
Deep sleep (stage 3 & 4) High Low
What is NR3 or N3?
Stage 3 & 4
N3 is a stage during NREM sleep
During this stage it is the deepest stage of NREM and EEG's reveal a high amplitude (large) low frequency (slow) waves (Delta) and spindles
What is the general trend in the amplitude/frequency from awake to deep sleep?
Increase in amplitude, decrease in frequency.
How are the waves on an EEG during coma? How are they different from delta waves?
Coma Delta Waves
Explain the sleep cycles that one goes through in a normal night (both stages and REM/NREM alternation).
What is the trend for Slow wave sleep and REM sleep during the night? How many REM cycles during a 'normal' night?
Less slow wave sleep & longer REM as sleep progresses
How many REM cycles
What are the differences between REM and NREM sleep w.r.t. movement of body parts (eyes, limbs etc).
How does the % of REM sleep change during your lifespan? (infants, grandparents)
Decreases (babies 80%)
What is the circadian rhythm? Which sensory system acts on which part of the brain? What does the pineal gland have to do with the circadian rhythm? How does entrainment of the circadian system work (generally)?
Light → SCN → pineal gland
What is sleep pressure? What is it thought to be due to? How does caffeine work to inhibit sleep pressure temporarily?
When your body makes it difficult for you to resist sleep
Cause of sleep pressure
Adenosine levels rise & accumulate during day
Caffeine - how it works
Binds to adenosine receptors (prevent adenosine build up)
What did the movie suggest happens during sleep? During which type of sleep does this process happen?
The movie suggests that we replay problems during our sleep in our dreams (REM)
What did your instructor mention was the 'prelearning' value of sleep? What are the two processes in which consolidation of memories happens during sleep? What was the third way in which you improve 'knowledge' during sleep?
Pre-learning - you need to be well rested to be able to lay down memory traces and help encode
Memory consolidation - replay problem/scenario that was experienced and then store it
Integration - makes connections/associations between things
What are the three main views on the function of sleep? Are they exclusive of each other?
Memory processing, recuperation/cleaning, or adaption; no.
What are the findings with respect to the immune system and sleep?
A study found that between 2 groups, one where people received a normal amount of sleep and the other received 4 hours, the 4 hour group did not have as strong as a response to the flu vaccine.
What were the findings recently with respect to CSF circulation and sleep?
A study on mice found that glial cells shrink, leaving room between them, CSF washes away beta amyloid (the proteins that build up in Alzheimer's). This occurs during slow-wave sleep, which older people get less of. This is why Alzheimer's is thought to start progressing at this age.
Class 13 - Sleep
What are some of the cognitive effects of sleep deprivation? What are some physical effects of sleep deprivation?
Increased sleepiness & faster sleep onset, poor mood, poor vigilance, poor executive function
Temperature ↓, BP ↑, immune function ↓, hormonal changes (e.g., mess up glucose regulation, become prediabetic), metabolic changes
What two ways of classifying of insomnia were discussed in class? What are three types of insomnia based on how long they last? What are three sleep disturbance patterns that count as insomnia?
Ways of classifying
Length of time you have insomnia, by sleep disturbance pattern
3 types of insomnia
Transient (<1 week), acute (1 month), chronic (>1 month)
Falling asleep, staying sleep, waking up early & can't fall back asleep
What is the incidence of insomnia?
1 in 4 adults
What sleep hygiene measures were discussed in class? How does blue light have a poor effect on sleep?
Going to bed & waking up at regular time; room should be cold, dark, quiet; use bed only for sleep; relaxation; screens; magnesium for sleep.
Blue light inhibits melatonin production
What additional sleep hygiene measures were discussed in class?
What happens in sleep apnea (in general)? What is the prevalence of sleep apnea?
Disturbed breathing during sleep
How does obstructive sleep apnea 'work'? What is central sleep apnea?
How much of sleep apnea is obstructive as opposed to central?
What is the standard therapy for sleep apnea? What is the main problem with this therapy?
Tongue obstructs air flow, CO2 levels ↑ & O2 levels ↓ - hypoxia
Not enough deep wave & REM sleep
Brain stem not giving out orders to breathe
CPAP (continuous positive airway pressure) - delivered through a mask that pumps air into lungs
CON: uncomfortable to sleep with
How common is narcolepsy?
Very rare - 20-45/100,000
What are the symptoms of narcolepsy that were discussed in class?
Sleep attack, cataplexy, hypnagogic, hallucination, sleep paralysis
Explain the difference between cataplexy and sleep paralysis.
Cataplexy Sleep paralysis
Yes - person is fully conscious Yes - right after waking up/at edges of sleep
Both may be a symptom for narcolepsy
What types of drugs are used to treat narcolepsy?
Medications - REM inhibitors or stimulators. Same meds as those w/ ADHD/ADD.
What is REM behavior disorder, and with what disease does this often occur?
REM behavior disorder
Muscle suppression does not occur during sleep
How many layers can most parts of the cortex be divided into? What are thought to be the functions of these layers?
Can be divided into 6
Input layer Integration layers Output layers
IV I, II, III V, VI
What is Brodmann's division of the cortex into separate areas based on (i.e. why did he say these areas were different?)
Based on organization, structure, & distribution of cortical cells. These areas were different because you can distinguish the areas by how the cells are arranged.
Organization sensory systems
What are the three parts of all sensory systems?
Sensory receptors, neural relays, central representations in the neocortex
Explain what it means that receptors only respond to a range of stimuli.
Receptors are specific in the range that can be detected. For example, in humans, we can only the visible light within the electromagnetic wave spectrum.
What is transduction when you are talking about receptors? What is the "common language" that stimuli get transduced to?
Translating stimuli into a relay of actions that leads to an action potential
Explain how receptors locate events, detect change and constancy and help to distinguish internal from external stimuli.
How does receptor density determine the sensitivity?
↑ receptor density = ↑ sensitivity
Explain how stimulation of other types of receptors around a pain receptor can make pain appear less, and how this is an example of an interaction among different senses at the relay level.
Stimulation of another receptor/sensation will essentially "distract" from the stimulation of the other receptor.
What does it mean that sensory systems have multiple representations in the brain?
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