Chapter 2 Pt. 2

lesioning

• have an already damaged brain, stick an electrode (insulated wire), and destroy tissue

• can see what processes are disrupted

electric stimulation of the brain (ESB)

• does not damage the neurons

• make the neurons act as if they received a message

deep brain stimulation (DBS) - [Invasive or noninvasive]

• electrodes are placed deep in the brain and are connected to an impulse generator under the collarbone which sends stimulus to that are that the electrode is in

• invasive

optogenetics

• uses light rather than electricity to activate neurons

• uses the light to modify their activity

transcranial magnetic stimulation (TMS) [Invasive or noninvasive]

• noninvasive

• sends magnetic pulses to the cortex (outside of the brain) to stimulate the neurons

• can be repetitive

  • rTMS

• noninvasive

transcranial direct current stimulation (tDCS) - [Invasive or noninvasive]

• uses scalp electrodes to send a low current to the brain to change the excitability of the neurons under the electrodes

• noninvasive

Computed Tomography (CT) scan - [Structure or function]

• shows a not very detailed image of a horizontal cut/slice of the brain

• computer uses numerous x-ray beams to form pictures

• typically used for skull fractures and metal in the brain

• maps structure

magnetic resonance imaging (MRI) - [maps structure or function]

• a more detailed image

• powerful magnetic field sends radio pulses at a particular frequency and direction to align hydrogen atoms (which are usually spinning everywhere) in the brain tissue

• during the time they are lined up a picture is taken

• maps structure and function

gray matter

unmyelinated axons on the outer region of the brain

white matter

myelinated axons in the inside

MRI spectroscopy

helps estimate the concentration of chemicals and neurotransmitters in the brain

diffusion tensor imaging (DTI)

• uses MRI technology to measure connectivity in the brain by looking at white matter

• used to learn about normal function

electroencephalogram (EEG) [Structure or function]

• function

  • can’t directly identify areas of brain activation because it just shows the waves on paper (if it goes completely crazy it’ll look different)

    • distorts the location because mixes with other parts of the brain

• records electrical activity of the cortex to study the activity of the living brain

• forms waves that indicate certain things (alpha waves means relaxation)

• use scalp electrodes

event-related potentials

• type of EEG

• multiple stimuli are measured and remove normal variations to see how the brain reacts to that specific stimulus itself

magnetoencephalography (MEG)

• can identify areas of brain activation

  • passes through tissue which doesn’t distort the location

• detects small magnetic fields generated by the electrical activity of neurons

positron emission tomography (PET) scan

• person is injected with radioactive glucose and see which parts of the brain are using the sugar

• can do different tasks and see which parts of the brain are working

• maps function

single photon emission computed tomography (SPECT)

measures brain blood flow

functional MRI (fMRI)

• computer tracks changes of Oxygen levels of the blood

• shows brain function

• clearer than PET

• can put the image made by a fMRI (that shows the Oxygen levels) on top of a brain structure to see what parts of the brain are most active

near-infrared spectroscopy (NRIS) or AKA fNRIS

• uses near-infrared light to see cortical changes when there is oxygenated and deoxygenated blood

• can only see slightly in depth

  • not whole brain like fMRI