Describe basic principles and advantages (disadvantages) of the method:

Все методы различаются по параметрам: 1) temporal resolution – how well in time we can differentiate different stages of decision making. 2) spatial resolution – how well in space we can differentiate different neuron populations of decision making. Combination is the best

Lesions (повреждение) – trauma leads to changes (case with prefrontal cortex trauma which leads to emotional unstable and social risky behavior -> optimal decision making, emotional learning) Design: group of normal people vs group of patients with the same lesions

Advantages: lesions bring important insights into ne, specific area in the brain associated with specific change in behavior. show the casual role of the brain region

Disadvantages: often rare, usually not focal, consequences are long-term, can be compensated by brain plasticity, a possibility of fuzzy interpretations(doesn’t mean that this area is directly involved in processes it interferes)

Electrical stimulation of the brain

Adapted on animals. Stimulation of the monkey’s brain while perceptual decisions task change their performance

Advantages: can stimulate specific neurons in the brain, investigates rapid changes in decision making

Disadvantages: Short-term effects, Invasive (damages tissues) , Normally can not be applied to humans, Relatively not-focal, i.e. you could unintentionally stimulate many regions at the same time, possible fuzzy interpretations (similar to lesions study)

Transcranial Magnetic Stimulation – TMS

TMS - rapidly changing magnetic fields (electromagnetic induction) induce weak electric currents in the brain, i.e. affect neurons.

Repetitive TMS (rTMS) – repetitive TMS pulses. rTMS produce longer lasting changes.

Coil produces very focused magnetic field, this stimulation temporarily blocks some areas of the brain. Studies mostly cortex, one of the most promising methods of NE

Advantages: noninvasive, investigate how stimulation changes decision making processes, can temporarily and quickly disturb of inhibit certain brain area, we can influence our decisions. Transient or long-term effects, shows causal neural mechanisms

Disadvantages: Difficult to stimulate deep brain areas, there are medical limits for MF exposure, produces loud sounds and muscles, constructions.A mild risk of epileptic seizures

Electrophysiology (cell recordings)

• Single cell record

An electrode put into one neuron or few neurons to record action potential rate. This method ivasive thus applied to animals. Usually they forced to perform some task or to pay attention to the screen. The activity of neurons is recorded and analysed.

Advantages: the only direct measure of neuronal activity

Disadvantages: Invasive, limited to few neurons, unclear information code

Both EEG and MEG do not reflect to action potential! Only synaptic potential!!

• Electroencephalography (EEG) is the recording of electrical activity along the scalp produced by the firing of neurons within the brain.

Advantages: cheap, Perfect time resolution

Disadvantages: noisy, you need many trials to get average rate and filter out noise, relatively bad spatial resolution

• Magnetoencephalography (MEG) measures the magnetic fields produced by electrical activity in the brain.

Advantages: perfect time resolution, detect activity of exact neurons

Disadvantages: quite expensive,relatively bad spatial resolution

functional Magnetic Resonance Imaging – fMRI

A functional neuroimaging procedure using MRI technology that measures brain activity by detecting associated changes in blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases.

In sum, when neurons are more active they consume oxygen that triggers originated blood inflow.

−neural activity _ ­ blood flow _ ­ oxyhemoglobin _ ­ T2* _ ­ MR signal

There structural and functional MRI. Structural provides 3D atlas of the brain, functional provides information about changes in BOLD signal. Thus we have data to further statistical analysis by means of which we get information about which area were activated while performing activity(BOLD signal in certain voxel).

Advantages: Noninvasive, able to record brain structure and activity, good 3D resolution

Disadvantages: Indirect (measures BOLD response), bad timing (few seconds time resolution),noisy,has restrictions for subjects, bad temporal resolution,

temporal resolution

spatial resolution