NH_4 - Neuroscience Methods

BOLD signal

blood oxygen level dependent

Advantages of ECT

1. 70% people with depression who don't respond to other treatments get relief with ECT 2. improvement in symptoms much more rapid than with antidepressants 3. Credited with saving many from suicide

Combining types of scans

1. PET and fMRI better at providing information about brain regions involved in cognitive activity 2. EEG better at providing info about precise sequence of events as info is processed 3. MEG can measure both time course and underlying neural substrate directly 4. NO ONE TECHNIQUE for studying large populations of neurons that has BOTH high temporal and high spatial resolution

Disadvantages of ECT

1. Prolonged and excessive use causes brain damage, resulting in long-lasting impairments in memory 2. high relapse rate

Event-related fMRI

1. able to measure BOLD signal associated with individual rapid occurring neural events 2. participants shown pictures as either they have seen, familiar, or never seen at all; correlated it with brain activity; indicates that parahippocampus and right dorsolateral prefrontal for encoding

Electroencephalogram (EEG)

1. electrodes attached to skull 2. only picks up surface level activity 3. coordinated activity seen as oscillatory waves at different frequencies 4. useful for diagnosing epilepsy and tumors 5. most widespread and least expensive technique for studying electrical activity of a large population of neurons

Repetitive Transcranial Magnetic Stimulation (rTMS)

1. intense pulse of magnetic energy sent through coil placed on surface resulting in the electrical firing of neurons beneath the scalp 2. can briefly enhance or disrupt neural activity 3. applied to left pFC reduces symptoms of depression without any side effects in about 30-40% of patients with depression; may energize brain's left frontal lobe which is relatively inactive during depression 4. FDA approved for treatment of OCD

Optogenetics

1. involves inserting opsin genes into neurons 2. causes neuron to manufacture light-sensitive opsin proteins and incorporate them into the membrane 3. opsin proteins become part of ion channels in cell membrane that control whether neuron fires or not 4. neuron can be activated by particular wavelength of light 5. opsin proteins can cause neuron to produce a flash of light of a particular wavelength when activated

Beta waves

1. irregular, low amplitude waves of 12-25 Hz 2. associated with state of arousal or alertness; focused on a task 3. most evident in frontal lobe and usually seen on both sides of brain

Magnetoencephalography (MEG)

1. large number of magnetically sensitive sensors place on scalp 2. measures magnetic fields created by brain's electrical activity 3. allows for finer spatial resolution than EEGs 4. less susceptible to distortions from skull than EEGs 5. very expensive because need to block out earth's magnetic field 6. currently used in medical diagnosis

Delta waves

1. low frequency, high-amplitude waves of less than 4 Hz 2. occurs during deepest stages of sleep and loss of consciousness

Hallucinations in mice using optogenetics

1. mice shown pictures of vertical or horizontal stripes; trained to lick pipe only if they saw vertical stripe 2. researchers found neurons in visual cortex that switched on in response to vertical stripes 3. turned off monitor and leaving mice in darkness 4. used light to switch on neurons for vertical stripes and mice responded by licking the pipe

Single Cell Recordings

1. microelectrode placed close to an individual neuron to record discharge of action potentials 2. used to identify neurons that respond to particular stimuli 3. discovery of mirror neurons; only done in animals

Deep brain stimulation

1. neurosurgical procedure involving placement of a neurostimulator (brain pacemaker) 2. sends electrical impulses, through implanted electrodes, to specific targets in the brain

Quantitative Electroencephalography (qEEG)

1. new variant of EEG that processes recorded EEG using computer algorithms 2. digital data is statistically analyzed, sometimes comparing values with "normative" database reference values 3. commonly converted into color maps of brain functioning called "brain maps"

Problems with Neuroimaging Data

1. noise in system when voxel large 2. everyone's brain slightly different

event related potentials (ERPs)

1. provoked by specific stimulus 2. very fine temporal resolution but low spatial resolutions

CAT scan

1. series of x-ray photographs taken from different angles and combined into a composite representation of a slice through the brain 2. more structure rather than function (EEG)

Theta waves

1. synchronous waves of 3.5-7.5 Hz 2. transition between sleep and wakefulness 3. associated with deep meditation, hypnagogic state, creativity, and memory retrieval

Alpha waves

1. synchronous waves of 7.5-13 Hz 2. associated with relaxed awake state 3. brain switches to this wave when watching TV

Implanting false memories in mice using optogenetics

1. tagged neurons associated with certain memory like fear of shock 2. using light, they induced those neurons to fire to make new associations with events and environments even though they are false

Electroconvulsive Therapy (ECT)

1. treatment for major depression 2. person anesthetize and given a drug which paralyzes the muscles 3. electrodes placed on scalp and jolt of electricity is applied for 1/25th of a second, triggering a brief seizure 4. consists of 3 treatments per week for 2-4 weeks 5. may work by increasing release of norepinephrine or by calming neural centers that are overactive in depression 6. potentially stimulates neurogenesis and new synaptic connections within the hippocampus and amygdala

Magnetic Resonance Imaging (MRI)

1. uses magnetic fields and radio waves to produce computer generated images 2. used to determine different types of tissue; allows us to see structures within the brain

Vowel Based Morphometry (VBM)

1. uses structural MRI scans to reveal differences between groups regional brain volume and tissue concentration 2. one of the first well known studies was showing a larger posterior hippocampus of London taxicab drivers

Functional MRI (FMRI)

1. variant of MRI that measures level of activity in different parts of the brain 2. superseded PET in many domains 3. oxygenated and deoxygenated blood respond differently to the magnetic field; can detect changes in blood oxygen to determine blood flow and cognitive activity

Gamma waves

1. very high frequency waves 26-42 Hz 2. state of consciousness or during REM 3. highest recorded by long-term super meditators 4. signal active exchange of information between cortical and other areas of brain

PET scan

1. visual display of brain activity that shows where a radioactive form of glucose goes while brain does a task 2. there may be all sorts of activity going on in brain; filter out by starting with a baseline scan then subtract from task activity

Removing noise in system

1. vowel is 3D version of pixel 2. smaller voxel yields higher spatial resolution but lower signal strength; often necessary to increase voxel size to capture small fluctuations in BOLD signal 3. increasing voxel size increases range of different types of brain tissue occurring in each voxel which can distort signal

Transcranial direct current stimulation (tDCS)

1. weak current is applied to the scalp on the left side of dorsolateral prefrontal 2. safer than ECT

Penfield Studies

electrical stimulation of association areas of brain during open brain surgery while patient is fully conscious

Mapping the Brain's Electrical Activity

identifying the networks of anatomical activity; measuring electrical activity is a good index of activity in neurons because when neurons fire they generate electricity