EB - Psychoactive Drugs Flashcards
What are the characteristics of Human imaging techniques? (5)
- Non-invasive
- Longitudinal
- No intervention studies – hard to get to mechanisms
- Can see effect of drugs
- Certain types of information only
What is CT (2), MRI (3) and DTI (1)?
CT - Computed tomography
- Spatial resolution: several mm
- E.g. ventricular size
MRI and fMRI - Magnetic resonance imaging
- Resolution less than 1 mm
- Reveals patterns of activity in the intact brain
Activity utilises oxygen – microvasculature increases blood flow to active regions
oxyhb:deoxyhb ratio increased
DTI - Diffusion tensor imaging
- Mapping pathways and investigating aberrant connectivity
What are PET and SPECT?
PET is positron emission tomography
SPECT is single photon positron emission tomography (main advantage does not require on site cyclotron)
How are unstable positron emission isotopes created for PET? (3)
- Created in a cyclotron (e.g., O15 with a half-life of 2 min)
- Isotopes are injected and distribute according to the relative activity of brain regions
- Can estimate receptor levels
What are the non-invasive techniques for monitoring brain activity? (2)
EEG: Electroencephalography
MEG: Magnetoencephalography
What are indirect markers for changes in neurotransmitter function?
Levels of neurotransmitters/metabolites in:
1) Cerebrospinal fluid (very invasive)
2) Plasma
3) Urine (e.g., decreased DA and metabolites like HVA in Parkinson’s disease)
4) Binding to platelets
What is measured during postmortem brain analysis? (3)
Imaging and biochemistry
- Includes analysis of protein (e.g. receptor) levels
- RNA levels
- Localisation of proteins/RNA
What are the limitations of postmortem brain analysis? (5)
- Endpoint analysis only
- Time post-death to freeze/fix/analyze
- Variability between samples
- Cause of death
- Possible medication effects
What are the applications of human tissue culture and electrophysiological analysis?
1) Provides insights into cellular functions
- The potential of induced pluripotent stem cells
2) Can study genetic changes associated with disease development
What are some animal model animal organisms? (5)
- Drosophila
- C.elegans
- Mice
- Rats
- Primates
What are the advantages (3) and disadvantages (1) of using animal models in research?
Advantages
- Malleable
- Drug screening
- Can do studies with multiple time points, interventions
Disadvantages
- Mimic some but not all human
What are psychotomimetic drugs?
Cause profound changes in perception, mood, and behavior
What are 3 examples of hallucinogens?
- Ayahuasca (active ingredient: harmaline)
- Peyote (active ingredient: mescaline)
- Magic mushrooms (active ingredient: psilocybin)
Compare the potency and effects of natural vs. synthetic hallucinogens
Natural:
- Psilocybin:
Dose - 250 µg/kg,
Duration - 3 hrs - Mescaline:
Dose - 15 mg/kg,
Duration - 12 hrs
Synthetic:
- LSD:
Dose - 3 µg/kg,
Duration - 10 hrs (most potent)
What was the original purpose of synthesizing LSD? (2)
- Derived from ergotism (gangrene, psychosis) caused by contaminated rye bread
- Aimed to treat hemorrhage using substances similar to ergot alkaloids
