Module 2 - Visualizing the nervous system Flashcards
When was the cell theory introduced?
1838
Outline the cell theory
- All living organisms are composed of cells
- The cell is the basic unit of structure and organization in organisms
- All cells come from pre-existing cells
Did the reticular theory of the nervous system consider the cell theory?
No
What did the reticular theory of the nervous system believe?
The nervous system is made up of a single continuous network, not separate cells
When was the reticular theory introduced?
1861
Who were two strong proponents of the reticular theory?
Joseph von Gerlach and Camillo Golgi
What did Golgi (ironically) invent?
“La reazione nera ‘ or “the black reaction” AKA the Golgi stain
Outline the process of a Golgi stain.
Apply potassium dichromate and silver nitrate to fixed neurons
Randomly labels a subset of neurons in their entirety, permitting single cell tracing
Who was Santiago Ramon y Cajal?
A visionary histologist who studied a broad range of nervous system tissues.
Why Santiago Ramon y Cajal a significant figure in the understanding of the nervous system?
One of the first to see the great potential of the Golgi stain
Did seminal work that disproved the reticular theory in favour of the neuron theory (along with others)
Who introduced the neuron theory/doctrine?
Heinrich Waldeyer
Who generated the data that was used for formulating the neuron doctrine?
Ramon y Cajal and colleagues
Outline the tenets of the neuron doctrine (4)
- Neurons are the functional units of the nervous system
- Law of dynamic polarization
- Neurons communicate via synapses
- Dale’s Law
What is the law of dynamic polarization?
Nerve cells have a single axon that serves as an effector (i.e., passes information)
Dendrites and cell body serve as receptor surfaces
Information travels from dendrites to axons
Who put forward the concept of synaptic transmission?
Charles Scott Sherrington
What is Dale’s Law?
Single neurons utilize a single type of neurotransmitter
What are the 4 issues with the neuron doctrine?
Extensive gap junctions (electrical synapses) in the CNS encroach upon the reticular theory
Axons can acts as dendrites and vice versa
Signals can travel against polarity (e.g., from soma/axon to dendrites)
Some neurons can secrete more than one neurotransmitter type
What is a common theory about gaining insight about information flow in the nervous system?
Understanding nervous system structure and connectivity = understanding information flow in the nervous system
What is the analogy used to show why connectomics might not be adequate to understand information flow?
If you map the entire system of roadways in a city, would that be enough to understand all the traffic patterns that flow through it at different times of day?
How do fluorescent dyes work?
Have electrons that absorb light and emit fluorescence as they drop back down to lower energy orbitals