Brain interventions

Reason for brain intervention

• Establish a causal relationship
• Medical treatment potential
• Treatment + Cogntive enhancment

Broad ways to intervine in the brain

1. Nuerochemical: alter level of nuerotransmitter(s)
2. Electrical - Increase or derace electrical signalling of nuerons
3. Anatomical- Intervine wiht the brain's structure
4. Genetics

Descrribe how the brain lesion approach is used

• Part of brain structure is altered (can be purposeful or accident)
• Can be groups given same lesion or case study
• Patients compared with matched controls on tasks that are relevant to hypothosised role

Double dissociation

When a brain lesion can demonstrate:

Lesion in area X:

• Impares Fuction a
• Leaves function B in tact

Lesion in area Y:

• Impares fuction B
• Leaves dunction A in tact

Double dissociation of the amgydala

Antondiates et al (2007)

• bilateral damage to the amgydela

Result:

• impaired fearful face processing
• Identity facial recognition intact
• able to draw expression for other emotion but not fear

Caveats of brain lesions

• Most of the time is small sample size

- Brain lesion happen for a reason (either accident or other exisitng brain issues), har to say if changes in funcitoning is because of damage to area or other reason

Patient HM's condition

Damage to:

• Medial temporal lobe
• Hppocampus
• amygdala

Impact:

• Unable to form code new episodic memeroies
• Could rember memories from before surgery

Describe the pharmachological approch for brain intervention

• direcly changethe nuerochemistry of a participant
• Find out the impact of a particular nuerotransmitted

Decribe how the pharmachological approch can be used

1. Increase availability of nuertrasmitted

• Reduce uptake
• Selective seratoninin reuptake inhibitors (SSRIs) treat depression

1. Decrease the avalibility of the nuero transmitted

• Can be done through diet by limmiting the amino acid precursor
  => tyrosime (seratonin)

Can imigigne be used to inform about nuerotransmitters

• Not really
• MRS (form og MRI) can be used to look at concetrations of GABA

Caveats of pharmachological approch for brain intervention

• Nuerotransmitters have very complex impacts
• Inverted U effect (too much may also cause worse preformce)
• Placibo effects
• Ethical considerations

Seretonin and ultumatim game experiment

Crockett et al (2008)

• Delpletion of seratonin
• Through limiting tyrosine (amino acid precursosr for seretonin)

Result:

• Reject more unfair deals (bevae more emotionally)

Decribe the genetic approch

• primiarly used in animals (currently)
• cahnge the genetics of a subject in order to see the impact of a particular gene or nuero
• example: optogenetics

Describe opto genetics

• Genetically modify genes to be photo senstive
• By taking DNA from chloroplants, turn light => enry
• In nuero, light energy => electrical energy, action potential
• Light shown on nuero causes it to fire

Decribe brain stimultaion

• Influence electrical activity of the brain
• Create "reversible" lesions

Name 4 types of brain stimulation

1. Deep Brain Stimulation (DBS)
2. Transcranial Magnetic stimulation (TMS)
3. Transcranimal Electric strimulation (TES)
4. Transcranimal Ultrasound Stimulation (TUS)

How does Deep Brain Stimulation (DBS) word

• electrodes are implanted on the surface of the brain (under the skull)
• Strimulates nucleus in specific areas
• resents nueral output such that the nueron cannot fire (creating reversible lesion)
• overides disruptive ossolations between brain network and nodes

How Deep brain stimulation (DBS) helps Parkinson's disease

Target area: SubThalamic Nucleus (STN) in the basial ganglia of the midbrain

Motor effect

• Reduce tremors
• Improve motor initiation
• Reduce ridgitity

Cogntive effect

• Reduce impulsivity
• Allows waiting for higher rewards => delayed gratification
• Wait in ultimatum games where there is a win/win

How Deep brain stimulation (DBS) helps Majior Depressive Dissorder

Target. area: SubGeneral anterior cingulate cortex (sgACC) in lymbic system, in forebrain

• shown to improve depresison where medicaiton has failed
• Mayberg et al (2005)

Advantages of Deep Brain Stimulation (DBS)

• Can target deep areas of brain
• Generally, can target specific areas

Disadvantages of Deep Brain Stimulation (DBS)

• Highly invasive
• Limited research, only able to test small population
• DBS actually spreads to areas so not very specific on area for research

Decribe how TMS works

Transcranial Magnetic Stimulation

• TMS magnetic coil generated magnetic feild is places over head
• Induces a secendry current perpendicular to magnetic feild
• Creates action potential in nueron, preventing it from fieing again

Desctibe the two types of TMS

Single Impulse TMS

• Used more in experimentaiton
• Shorter impact on specific area

Repetative TMS

• Used more for treatment
• Long impact (relating to number of impulses)

TMS on blind people experiment

• See if blind poeple use visual cortex when using tactile identificaiton of letters
• Not able to do so when visual cortex is stimulated

Decribe TES

Transcranial Electric Stimulation

• Two electrodes (anode and cathode) placed on scalp
• delivers electric impulse to excite cortex

Advantages of TMS and TES

• Non invase
• Temporary effects (good for experimentation)

Advantages of TES over TMS

• more comfortable
• Many people nto able to tell
  -Makes for better experiment

Disatavatges of TES

• Poor spacial resloution
• poor penatrability

Disadvantages of TMS and TES

• long term treatment requires repeated trip to hospital
• Not able to stiumlate deep aresa (only baout 3cm)

Decribe how TUS is used

Transcranial Ultrasound Strimulation

• Uses ultasound to stimulate areas of brain
• Can change activity for >1hr
• Mechnism is not fully understood

Advatages of TUS

• More comfortable than both TMS and TES (particiants cannot tell if being done to them)
• Can stimulate much more precise areas
• Can pentrate deeper in the brain

Disadvantages of TUS

• Very new and not yet fully understood
• Saftey parameters => Can damage brain

Stimulation outside of the brain

1. Vagus Nerve Stimulation

Describe how VNS works

Vagus Nerve Stimulation

• Electrical device implated in chest (most common)
• Electrodes place on ear (experimental conditions)
• Sends electrical impulse of vagus nerve (in neck)
• Mechanism not fully understood
• Could work by influencing noradrenaline system in locus coerules
• Used to treat epilepcy and some evidece for depression