Ways of studying the brain

ways to study the brain

1. Scanning techniques (fMRI)

2. EEGs

3. ERPs

4. Post-mortem examinations

Spatial resolution

the capacity of a technique to tell the researcher exactly which area of the brain is active (identifying localisation of function)

Temporal resolution

the capacity of a technique to tell the researcher when the activation in the brain occurred

functional magnetic resonance imaging (fMRI)

• uses magnetic field and radio waves to measure blood flow in a particular area of the brain when a person forms a particular task or is exposed to a stimulus

• Produce 3 dimensional images

How fRMI works

1. Increased blood flow means increase in neural activity

2. Area becomes more active, so more demand for oxygen in that area (oxygenation)

3. Brain responds in increasing blood flow and delivering oxygen in red blood cells to the area of heightened neural activity (haemodynamic response)

4. Results of changes in blood flow causes images to be produced, which show which areas of brain are being used when engaged in certain tasks

Common uses of fMRI

• cognitive neuroscience

• Clinical applications

• Neuromarketing

• Neuroplasticity

Cognitive neuroscience

understanding brain regions involved in memory, language, and decision-making and other cognitive processes

clinical applications

diagnosing brain disorders like, Alzheimer’s, as well as tumours and strokes

neuromarketing

under consumer behaviour and product preferences

neuroplasticity

studying how the brain changes over time

fMRI temporal resolution

• low

• Images show activity approximately around 1-4 seconds

• Researchers are unable to predict, with high degrees of accuracy, the onset of the brain activity observed

fMRI spatial resolution

• high

• Images thought to be accurate within 1-2mm

• Has developed our understanding of localisation of function

Electroencephalogram (EEGs)

• measure electrical activity caused by brain cell activity

• Achieved via electrodes attached to the scalp (skull cap)

• Detect electrical charges which result from activity in thousands of brain cells

• Shows overall brain activity

Amplitude

intensity or size of the activity

frequency

the speed or quantity of activity

EGG patterns

two distinctive states

• synchronised

• Desynchronised

Synchronised pattern

recognisable waveform (alpha, beta, delta and theta)

Alpha waves

associated with relaxation and light sleep

beta waves

shown when a person is physiologically aroused, also shown in REM sleep. Focusing, exercising

theta/delta waves

associated with deeper sleep

uses of EGG

• detect various brain disorder

  • Eg. Epilepsy (patients show spikes of brain activity)

• Used to diagnose disorders that influence brain activity

  • Alzheimers

• Have been used in sleep research which helped to identify the sleep cycle and diagnose sleep disorders

Event-related potentials (ERP)

• researchers have developed way to use EEG data and filter all extraneous brain activity through a statistical averaging technique

• Only brain activity that relates to presentation of specific stimulus or performance of specific task is left

Latency

time or interval between the presentation of the stimulus and the brain response is referred to as latency

what are ERPs

small chargers in the brain triggered by a specific event/stimulus

Eg. Processing a specific stimulus

ERP diagram

• used to visualise the electrical activity of the brain in response to specific stimulus

• Each peak represents different components of the brain’s response

Types of ERPs at certain times

sensory ERPs - within 100 milliseconds

Cognitive ERPs - after 100 milliseconds

Horizontal axis

• time axis

• Represents the time elapsed from the presentation of the stimulus

Y-axis

• amplitude of the electrical signal

• Amplitude is measured in microvolts (µV)

EEG and ERP temporal resolution

• high

• Show activity ever millisecond, recording activity in (nearly) real time

EEG and ERP spatial resolution

• low

• Only detect activity in superficial, general areas of the brain

• Not activity in particular parts of the brain

Similarities of EGG and ERP