PHYSL 371: In-Vitro Approaches to Studying Neuronal and Network Function

what is the fundamental goal of modern neuroscience

to understand behaviour in terms of the fundamental molecular, cellular, and synaptic (connectivity) properties of individual neurons and glial cells in the CNS

what does behaviour refer to in the goal of neuroscience

everything including the simplest reflexes, complex movements, critical hemostatic functions (like breathing and blood pressure control), complex cognitive functions (memory formation and recall), production of emotion and morality

what is the fundamental goal of modern neuroscience clinically

to understand the fundamental molecular, cellular, and synaptic mechanisms of brain and nervous system disorders and translate that knowledge into effective methods for diagnosing, preventing, and treating them in humans

what is the genetic framework

1. describe behaviour

2. motor behaviour

3. motorneurons

4. localize brain region

5. connectivity

6. molecular, cellular, and synaptic properties

7. manipulation

8. reconstruction modeling

what is the mechanistic hypothesis testing of core question

4. localize brain region

5. connectivity

6. molecular, cellular, and synaptic properties

7. manipulation

8. reconstruction modeling

what methods is best for studying behaviour

in vivo: observation- minor manipulation, correlative data

what methods is best for studying motor behaviour

in vivo: observation- EMGs, ENGs, minor manipulation, largely correlative data

what methods is best for studying motorneurons

in vivo or in vitro- EMGs, ENGs, some single cell measurements, manipulations (motor neurons shape behaviour but are not the source)

what methods is best for studying localized brain regions

in vivo or in vitro- hypothesis testing about core question

what methods is best for studying connectivity

in vivo for long and short range, in vitro for short range

what methods is best for studying molecular, cellular, and synaptic properties

in vivo or in vitro (in vitro is best suited)

what methods is best for studying manipulation

in vivo and in vitro (but must verify with in vivo if you use in vitro)

what methods is best for studying reconstruction/modelling

in vivo, vitro, and silico (computer model) combined to make models, predictions, test those predictions, revise the models, verify findings with both methods

what does picking the right animal model depend on

1. long-term goal of research (fundamental mechanism or apply clinically)

2. the question and the tools applicable for that model

3. ethics

4. budget

what is the best subject model to pick if the goal is to be used clinically to detect, treat, or prevent

human models are the best

what are the limitations of human models

ethical constraints

what are in vivo research techniques we can use on human models

postmortem materia, imaging (PET, fMRI, fNIRs, CT), neurophysiology (EEG, brainstem stimulation)

what type of data do in vivo human models provide

correlative data (cannot assume cause and effect)

what are in vitro research techniques we can use on human models

surgically cut out brain tissue, cell lines in culture, iPSCs, organoids

what are the benefits and drawbacks of in vitro techniques on humans

they can provide mechanistic insight but rarely define causation

what are some things to consider when using animal models

your research question and social values/ethics

what are the primary animal models used now

rodents, rats, and mice

why are rodents good animal models

they are mammals therefore similar to humans in many ways and share 99% of genes

why are rats good animal models

they are larger than mice therefore better suited for some surguries, implantations, headhunts,etc

why are mice good animal models

cost (much cheaper than rats) and are the primary model now

what level do cellular neuroscientists mainly ask their questions at

the molecular, cellular, and synaptic property level

what approaches are mainly used at the molecular, cellular, and synaptic property level

a diverse amount of in vitro approaches

what is the common advantage among all in vitro methods

greater experimental control compared to in vivo (lots of uncontrolled variability)

what are some examples of greater experimental control that in vitro methods offer

mechanical stability, precise control over ionic environment, ability to make lesions/injections/transections, increased drug access without the BBB, single cell recordings to study channel properties, multicellular recording, functional imaging, more data being but through a system

what is the biggest challenge for all in vitro approaches

interpreting the relevance of in vitro data to physiology (which includes knowing the functional indents of the cells and synapses under study) which has the potential to vary from real physiological conditions with increased time