Techniques for Investigating the Ageing Brain Flashcards
What are the age-related constrains when using older participants?
- Timing: Longer experimental sessions
- Can your participants lie flat?
- Can they stay seated for long periods of time?
- Will they struggle to get in/out of low chairs?
- Do they have implants (e.g. metal joints)
- Are they taking any medication that will interfere with the aspects of neurobiology we’re interested in?
What are the different types of methods we have to work with: Neuroimaging
- Positron Emmission Tomography (PET)
- Magnetic Resonance Imaging (MRI)
- Diffusion Weighted Imaging (DWI)
- Functional MRI (fMRI)
- MAgnetic Resonance Spectroscopy (MRS)
What are the different types of methods we have to work with: Electrophysiology
- Electroencephalography (EEG)
- Magnetoencephalography (MEG)
What are the different types of methods we have to work with: Brain Stimulation
- Transcranial Magnetic Stimulation (TMS)
- Transcranial Electrical Stimulation (tES e.g. tDCS, tRNS, tACS)
What does Positron Emission Tomography (PET) measure?
Metabolism/energy consumption
What are the strengths of Positron Emission Tomography (PET)?
- Insight into chemical functioning
- Detection of certain proteins which can give us clinical applications
What are the weaknesses of Positron Emission Tomography (PET)
- Expensive and invasive
- Spatial and temporal resolution is bad
What does magnetic resonance imagine (MRI) measure?
Volume of brain tissue (grey matter, white matter, and cerebrospinal fluid)
What are the strengths of magnetic resonance imagine (MRI)?
- Non-invasive
- Spatial resolution is good
- Shows age-related structural change well
What are the weaknesses of magnetic resonance imagine (MRI)?
- Lack of temporal information
- Lack of insight into age-related functional change
What does diffusion weighted imaging (DWI) measure?
Status of axonal fibres/neural pathways
What are the strengths of diffusion weighted imaging (DWI)?
- Multiple measures of white matter integrity e.g. fractional anisotropy
- Perspectives on processing speed/structural connectivity
What are the weaknesses of diffusion weighted imaging (DWI)?
- Highly specialised, complex analysis
- Not a direct measure of myelin
- Issue of crossing fibres
What does fMRI measure?
- Oxygen consumption
- Blood Oxygen Dependent Signal (BOLD)
What are the strengths of fMRI?
- Shows age-related changes in brain activity
- Functional connectivity: task specific networks, resting state (DMN)
What are the weaknesses of fMRI?
- Temporal resolution is bad (speed of haemodynamic response function; hrf)
- Lack of causation
What does MR spectroscopy (MRS) measure?
Amount of neurotransmitters (e.g. GABA)
What are the strengths of MR spectroscopy?
- In vivo quantification
What are the weaknesses with MR spectroscopy?
- Complex acquisition
- Undetermined relation to synaptic activity
What does electroencephalography (EEG) measure?
Event-related potentials/brain oscillations
What are the strengths of electroencephalography (EEG)
- Direct relationship to neuronal activity
- Temporal resolution
- Less susceptible to motion artefacts (than fMRI)
What are the weaknesses of electroencephalography (EEG?
- Lack of structural image
- Spatial resolution is bad (particularly sub-cortical)
What does magnetoencephalography (MEG) measure?
- Evoked fields
- Brain oscillations
What are the strengths of magnetoencephalography (MEG)
- Direct relationship to neuronal activity
- Temporal resolution
- Lack of volume conduction (compared to EEG)
What are the weaknesses of magnetoencephalography (MEG)
- Spatial resolution (but better than EEG)
- Lack of structural image
What does transcranial magnetic stimulation (TMS) measure?
Nothing, it influences the way the brain behaves
What are the strengths of transcranial magnetic stimulation (TMS)
- Causal inference
- Temporal resolution (particularly ‘online’ single pulse methods)
What are the weaknesses of transcranial magnetic stimulation (TMS)
- Cortical regions only
- Unknown effects beyond hypotheses
- Blinding/’Sham’ options
What does transcranial electrical stimulation (tES) measure?
Nothing, it influences the way the brain behaves
What are the strengths of transcranial electrical stimulation (tES) measure
- Causal inference
- Altering plasticity
- Blinding/’Sham”
What are the weaknesses of transcranial electrical stimulation (tES) measure
- Restricted to superficial/cortical regions
- Unknown current pathway
- Focality
