Cutting edge Flashcards
What is the major difference between top down and bottom up functions?
Top Down: Directly stimulating the are of interest: rTMS, tDCS, DBS
Bottom up: Targeting cranial nerves to travel back up. VNS, Trigeminal Nerve Stimulation
What is rTMS and what are some of the issues with it?
repetitive Transcranial Magnetic Stimulation
Based on Faradays law of Electromagnetic induction.
Known since the 1980s, more popular now.
Use of figure 8 instrument:
1 HZ slow and inhibits
5HZ or more for Fast and Stimulating
Both depolarise the Neurons causing synaptic firing
Limitation:
Sweet spot at 0.5cm diameter:
Accuracy
Superficial penetrance
What is the neurological process that makes TMS work and what are some considerations?
The process is believed to cause synaptic changes:
Due to LTP and LTD via neuroplasticity
Due to gene expression
However it is noted that there is a distal effect that is not fully understood yet.
What has rTMS been used for most and how?
For depression:
Based on the under activation model: DLPFC, striatum, thalamus and ACC.
BUT: we can only activate DLPFC, Left side (pref_
What is the typical rTMS paradigm fro Depression?
10hz 4 seconds on, 26 seconds off. 30 m daily for 2-3 weeks?
But optimal not known
Is tTMS effective in depression?
Yes: Level A from European Expert Consensus
NICE guideline: Adequate
How is rTMS used in psychosis and is it useful?
Yes. Mainly for AVH.
Inhibition of Temporal Parietal junction at 1HZ for 15-30 Min. Daily for 4 weeks
Moderate but significant effect.
what is tDCS, how does it work and how is it administered currently?
Transcranial Direct Current Stimulation.
Direct current between nodes. 9v source 1-2ma battery. 20 minutes.
Doesn’t make neurons fire, just more likely to fire via enhanced plasticity.
Does tDCS work?
Used for Depression, AH and Cognition.
Mixed results other than Cognition.
What is VNS and does it work?
Vagal Nerve Stimulation:
Stimulating a cranial nerve to travel back up to the brain.
In particular VNS will activate noradrenaline and serotonin via the Locus Ceruleus and nucleus Raphe
Show via imaging to change PFC
NICE say inadequate, FDA disagree.
What is the protocol to use VNS?
Invasive surgery that implants watch battery size device connected to Vagus Nerve.
20-50hz for 30s and 5 Mins off at 1-4mA
Problem:
Used mainly on TR, so data is skewed
Double Blind Ethics-results were non-significant
What is TNS and how is it administered?
Trigeminal Nerve Stimulus- cranial nerve
Non-invasive: Electrodes on forehead: 120Hz 30s cycles
Shown to effect cortex.
However:
Open Label
Active intervention
Data exist, but methodology is weak
What is DBS and how is it administered?
Deep Brain Stimulation:
two electrodes implanted into brain and battery under clavicle.
Stimulated continuously
Used for TR depression (No results yet)
Parkinsons, and most useful for Tourettes
What are some of the issues with DBS?
Batteries need replacing every 5 years.
Where to put electrodes
Double Bind ethics
Side effects: Death
What are some of the ways that neuromodulation can and does differ and why?
Physiological Differences Schedule of delivery Duration of session Level of Stimulation Method of siting modality Diagnostic Issue of unitary phenomena
These protocols are based only on past research not biology
Lack of info on protocols in research
