biological approach

Label brain structure and functions.

Frontal: Cognitive skills

Parietal: Relates visual information to motor skills

in response to perception and sensation.

Occipital: Visual processing

Temporal: Memory ans auditory processing.

Cerebellum: Co-ordinates muscle activity and stores motor skills.

Limbic System: (hippocampus

hypothalamus

Striatum: Controls motivation.

Corpus Callosum: Connects the two hemispheres.

Describe fMRI scans.

Functional Magnetic Resonance Imaging.

A magnetic field causes oxygen in the brain to align

and the oxygen is shown on a computer screen as 'voxels'. More active areas have more oxygenated haemoglobin for respiring tissues.

Used to detect diseased tissue

monitor tumours and observe brain function.

Evaluate fMRI scans.

Advantages:

Shows brain function.

Non-invasive.

Low risk.

No radiation.

Produces images from every angle.

Disadvantages:

Expensive.

Any movement from patient can distort readings.

Cannot distinguish between tumour types.

Claustrophobic.

Readings susceptible to non-neural changes.

Describe CAT scans.

Computerised Axial Tomography.

X-rays used to create a detailed image of brain sructure

which can be layered together to produce a 3D image.

Used to detect infraction

tumour

Evaluate CAT scans.

Advantages:

Provides detailed images of structure.

Non-invasive.

Disadvantages:

Radiation risk.

Needs a 7 hour fast.

Specialist required.

Any movement from patient can distort reading.

Describe PET scans.

Positron Emission Tomography.

Used to show images of funtion and structure

as radioactive tracer (FDG) is injected which attaches to glucose and shows the most active areas of the brain

Evaluate PET scans.

Advantages:

Shows brain structure and function

(Relatively) non-invasive.

Disadvantages:

Injection required.

Radioactive tracer used.

Claustrophobic.

Risk to foetus for pregnant women.

Define: Neuron

A specialised cell for transmitting electrical nerve impulses.

Label a neuron.

A: Dendrite.

B: Cell Body.

C: Axon.

D: Axon Terminal.

E: Schwann Cell.

F: Myelin Sheath.

G: Nodes of Ranvier.

How to neurons work?

Neurons recieve electrical impulses in the dendrites from other cells.

A differentiation in ion voltage causes a wave of action potential to travel down the axon

insulated by the myelin sheath to the axon terminal.

The action potential causes neurotransmitters to be released into the synaptic cleft by the axon terminal.

Define: Neurotransmitters

A chemical that is stored in the axon terminal in vesicles

EG Serotonin

Dopamine

Define: Synapse

A junction between two neurons

Label a synapse.

Axon Terminal.

Vesicles containing neurotransmitter.

Synaptic cleft.

Neurotransmitter.

Receptor.

Dendrite.

How to synapses work?

Wave of action potential arrives at axon terminal

The rate of re-uptake regulates the amount of neurotransmitter in the synapse.

Describe Raine et al. (1997)

Aims:

To see if there was a difference in brain structure of murderer who pleaded not guilty by way of insanity

and non-murderers.

Procedure:

39 males

2 females

Participants injected with a FDG tracer

and completed a cognitive task.

After 32 of uptake of the tracer they had a PET scan.

Images produced via cortical peel and box techniques.

Results:

Low activity in frontal lobe (impulsivity

loss of self control

Low activity in left amygdala

higher activity in right amygdala (aggression).

Low activity in corpus callosum.

Low activity in parietal lobe.

More activity in occipital lobe.

Same activity in temporal lobe.

More activity in the thalamus.

Conclusion:

Violence can have biological causes.

Murderers pleading guilty by way of insanity do have different brain structure to non-murderers.

Areas of brain connected to aggression are bilateral prefrontal

posterior parietal and corpus callosum.

Abnormal activity in limbic system can cause aggression.

Evaluate Raine et al (1997).

Generalisability:

:( Gender bias.

:) Large sample.

:( Everyone's brain structure is different so affects people differently.

Reliability:

:) Standard procedures used.

:( PET scans need interpretation so there is some interpretation bias.

Application:

:) Can be used to determine whether someone should be imprisoned or rehabilitated for mental health as study shows limbic system

pre frontal

Validity:

:) Lab experiment

high control

:( Artificial setting

low ecological validity

:( Low internal validity because we don't know if the brain activity changed before or after the murder

so not sure if brain activity causes violence or vice versa.

:) PET scans are a scientific measure

so high internal validity.