Topic 3 - Research Methods Flashcards
What do staining techniques tell you about?
Type / structure of cells in that area
Pathways and networking of cells
3 stains
- Axon stain
- axons and dendrites - H & E stain
- cell bodies - Golgi silver stain
- entire neuron
3 sectioning techniques
- Spinalize
- Decerebrate
- Deafferent
Spinalize sectioning technique
Cut SC just below brain stem
If fxn no longer works, it means it was happening in brain stem and above
Decerebrate sectioning technique
Cut at top of brain stem
Separates higher order centers of the cerebral hemispheres from lower order structures of spinal cord and brain stem
If task no longer works, mean it was being completed by cerebral hemispheres
Cat could still walk bc cerebellum and brain stem was still in tact
Deafferent sextioning technique
Cut all dorsal roots
- this removes source of somatosensory info
Ian watterman
- had to re learn how to walk and do many movements bc he had no somatosensory info
2 types of structural brain imaging
- Computerized tomography (CT)
2. Magnetic resonance imaging (MRI)
Magnetic resonance imaging (MRI)
Magnetic field aligns rotation of specific molecules
Turn off mag feild causes disalignment/ degradation
Rate of degradation allows for you to know molecular composition
Composition allows to construct images
Provides images of intact & damaged structures
PET & SPECT
INDIRECT AND INVASIVE
pump radioactive molecules (glucose) into blood
Highest concentration of energy released from molecules is in area of brain that is most active during a task
Measuring metabolic byproduce (indirect)
fMRI
INDIRECT AND NON - INVASIVE
Works on BOLD principle
- blood oxygenation level dependant
Oxygenated blood produces a better MRI signal so active areas of the brain will take up more oxygenated blood and therefore produced stronger MRI sigal
Greatest signal is greatest activity
EEG AND MEG
DIRECT AND NON-INVASIVE
record electrical or magentic activity of a large group of neurons
- wave analysis
- evoked potentials
MEG has better spatial location/resolution than EEG
Wave analysis
Done with EEG or MEG
Longer period of time
Tracks frequency of oscillation shjch realtes to underlying neural activty (different frequencies when you’re awake vs asleep)
Evoked potentials
Short term collection
Track transfer of information throughout brain on a millisecond basis (up to 1 sec)
Which techniques have best spatial resolution?
MRI
CT
(Structural brain imaging techniques)
Which techniques have the best temporal resolution?
EEG and MEG
Bc they’re direct, they don’t use a metabolic by product
Single neuron recording
DIRECT AND INVASIVE
put a probe within neurons to directly record electrical activity
Highly selective
- even if you sample multiple neurons, you’re really only studying a low proportion within a region of the brain
Use rastor plots to show APs
Difference between Transcranial Electrical Stimulation (TES) and Transcranial Magnetic Stimulation (TMS)
TES stimulates descending oyramidal neurons didectly (alpha motorneurons) and TMS synapses with a cortical interneuron first
Peripheral Stimulation
Gives indication of integrity and excitability of the spinal circuit ans perioheral nerve
TES
gives indication of integrity and excitability of contralaterak spinal motor pathway
Cervicomeduary stimulation
Gives purest indication of integrity and excitability of spinal motor pathway bc the electrical current is applied to cervicomedullary jxn-> where brainstem ends and SC begins
- this is bc inhibition and excitation from cortex will not influence response in spinal motor pathway
What has shorter latency, TES or CMS
CMS bc stimulus has less to travel bc with CMS stimulus is applied to cervicomedullary jxn rather than motor cortex
TMS
Gives indication of integrity and excitability of entire contralateral corticospinal motor pathway
- remember corticospinal bc it activistes cortico interneurons whereas TES does not… TES directly activates pyramidsal nuerons
Sexindary useful effects of TMS
- Single pulse
Temporary brain lesion for 30-60 milliseconds
Increases neural noise which prevents area of the brain from performing purposeful activity
- Repeitive TMS
a. Low frequency (<1Hz) less than 1x/sec
Decreases excitability (overall efect is inhibitory)
b. High frequency (<5Hz) more than 5x/sec
Increases excitability (oversll effect is excitatory)
4 Stimulation Techniques
- TES
- CMS
- TMS
- Peripheral stimulation
