Permanent Lesions
What are the two subcategories of permanent lesions?
Injury and articficial
What category do mechanical, aspiration, and transection fall under?
All are mechanical
What are the 2 subcategories of temporary lesions?
Chemical and TMS (transcranial magnetic stimulation)
Transient lesions are ________
Reversible
What are the main disadvantages of drawing conclusions from case studies?
There is higher variability with multiple subjects, cannot be generalized to greater population, and can't be replicated
What are the advantages and disadvantages of electrical and chemical lesions?
A: highest spatial resolution, most precise
D: extremely tedious
How to transient chemical lesions work?
Suppressing action potentials of local neurons; need to use stereotaxic frame
How long do the lesions last in chemical versus TMS?
20-40 min vs 10 seconds
What is an example of a case study that had a permanent injury lesion?
Phineas Gage; railroad working accident; became first case study on frontal lobe function (altered personality)
What is the main differnece between a stereotaxic frame for humans vs animals?
Human frames are more invasive
What are the two common chemicals used in transient chemical lesions?
Scopolamine and muscimol
How is the spatial resolution for TMS?
What are the main advantages of of artificial lesions? (2)
More control (less variability), can create lesions in as many animals as you want
Holds the head in place for chemical and electrical lesions; creates "coordinates" so needle can be positioned accurately. Also can do MRI scans and CT scans while performing surgery
What are the characteristics of a chemical transient lesion?
Lesion lasts for 20-40 min, full recovery, must be used with a stereotaxic frame. Same procedure as using chemicals for permanent lesions.
What are the main advantages of TMS?
What are the 5 types of artificial lesion methods?
Mechanical (cutting out region or trauma), aspiration (using suction), Transection (taking entire brain regions out), electrical (overcharging), chemical (killing off cells with acid)
What are the disadvantages of permanent artificial lesions?
Systematic side effects, can't be easily generalized to human brains from animal models
How does TMS work?
The neurons become over-activated with magnetic stimulation and become non-functional for around 10 seconds.
What are the main disadvantages of TMS?
Short time frame, bad spatial resolution