Class 4 - Animal Research - History of the Neuron Flashcards
Exam ques 100% =
How did we take 2 ideas (visualization + nerve impulse) and then neuroscience happen?
Or
How did visualization + nerve impulse lead to neuroscience?
Or
What was the impact of biological methods on neuroscience?
Consilience (the way in which we show how science builds on one another)….
Consilience means – that different areas of science connect and support each other. – It shows how new discoveries build on past knowledge.
Explain the attached image.
Around the 13th century, eyeglasses were invented to help people see better. – This led to the idea of the telescope. – Later, Robert Hooke experimented – with light and oil, – leading to the invention of the microscope. – Like Darwin’s theory of evolution, these discoveries opened new ways to study the world.
Why are we talking about microscopes? I thought this was about Neuron?
We discuss microscopes led to the discovery of cells, – which are essential to understanding neurons.
Robert Hook – coined the term “cells” – by noting that cork under the microscope looked like it had cells.
He created a book full of insects pictures called “micrographia” to share his discoveries with the world. – This new found term “micro world” sparked intense cursity.
Explain the attached image. Who was Anton Leeuwenhoek?
Anton Leeuwenhoek, who was a drapist, – invented – a powerful single-lens microscope to improve the way he wrapped drapes. – His microscope lense was much better than Hook’s – He made observations of his own
blood, skin, hair cells… among other things…– He drew the first images of red blood cells, protists, and spermatozoa.
Who invented microtome?
J.E Purkyne
Explain attached image.
The discovery of microorganisms sparked a scientific revolution, leading to a boom in microbiology. – Jan Evangelista Purkyne advanced the field by inventing the microtome, allowing thin tissue slices for detailed microscopic study.
He discovered heart has different cells (Purkinje fibers), showing that different cells have unique functions.
This pre-Darwin era focused on DESCRIBING cell types, fueling excitement in microbiology.
A scientific race began to explore the microscopic world, as more scientists gained access to microscopes.
Meanwhile, what did Europe embrace?
Romanticism
What did Romanticism, emphasized?
- Nature
- Individuality
- Harmony
Meanwhile, Europe embraced Romanticism, emphasizing nature, individuality, and harmony. – This shift inspired a new view of biology—seeing the body as a unified system, much like WHAT?
- As Darwin came up with Evolution.
- Newton transformed physics.
Explain the image.
A scientific race began to explore the microscopic world, as more scientists gained access to microscopes.
Meanwhile, Europe embraced Romanticism, emphasizing nature, individuality, and harmony. – This shift inspired a new view of biology—seeing the body as a unified system, much like how Darwin revolutionized Evolution or Newton transformed physics.
Explain image. don’t need to memorize these 1,2,3 points. Make sure you have an idea though as it connects to further slides.
Studying plant and animal cells – led to – Cell theory:
- All living things are made of one or more cells.
- The cell is the basic unit of life
- All cells come from pre-existing cells.
This raised questions – about how different cells function,– like why kidney and heart cells look and work differently.
What were the 2 major things that happened in neuroscience or what led to the emergence of neuroscience?
- Nerve Impulse
- Visualization
The timeline splits for a few years, then quickly comes back together when neuroscience begins.
Who challenged the idea that: nerve cells –worked together – because of supernatural forces, – not biology?
- Du Bois-Reymond
- Helmholtz
How did Du Bois-Reymond and Helmholtz challenge the following idea:
nerve cells worked together because of supernatural forces not biology?
They took a frog leg, – attached it to electrodes, – and sent an electrical impulse, – making the leg move. – Since this was the first time it was done, there was no standardization at that time. —- Later, they tested rapid stimulation – and noticed a delay before the leg moved again. – They thought the battery had died, – so they switched batteries which showed the nerve needed time to recover (refractory period).
They discovered that nerve impulses caused a drop – in electrical potential, which du Bois-Reymond called “negative variation“—now known as the action potential. – Helmholtz found that the impulse traveled at different speeds.
Before Du Bois-Reymond and Helmholtz WHO saw , frog leg react to electricity, but his work was dismissed because of unstable equipment before reliable batteries were invented?
Galvani
Explain the attached image.
Many people once believed – nerve cells –worked together – because of supernatural forces, – not biology. Du Bois-Reymond and Helmholtz challenged this idea.
They took a frog leg, – attached it to electrodes, – and sent an electrical impulse, – making the leg move. – Since this was the first time it was done, there was no standardization at that time. —- Later, they tested rapid stimulation – and noticed a delay before the leg moved again. – They thought the battery had died, – so they switched batteries which showed the nerve needed time to recover (refractory period).
They discovered that nerve impulses caused a drop – in electrical potential, which du Bois-Reymond called “negative variation“—now known as the action potential. – Helmholtz found that the impulse traveled at different speeds.
When was the first dye introduced and
who introduced it and
what was it called?
In 1820
by Turpin
called Carmine dye
What was the first dye used for?
To improve microscope contrast.
When was Hematoxylin dye, introduce and
who introduced it and
what did it enhance?
In 1865
by Böhmer
to enhance brain tissue visibility
Why did scientist use Contrast dye?
– Scientists used contrast dyes—one light to highlight unwanted tissue — and one dark to focus on key structures/elements–—making neurons easier to see.
What did the use of Contrast dye led to belief, yet what did other argue about?
That neurons formed a continuous network, —- but others argued – tiny gaps existed between them.
Explain the image.
Turpin (1820) first used Carmine dye to improve microscope contrast, later refined by Johann Diedrich. – In 1865, Böhmer introduced Hematoxylin dye, which enhanced brain tissue visibility. – Scientists used contrast dyes—one light to highlight unwanted tissue and one dark to focus on key structures—making neurons easier to see. – This led to the belief that neurons formed a continuous network, —- but others argued – tiny gaps existed between them.
Read the text.
This led to a long feud between Golgi and Ramón y Cajal, – with scientists taking sides.
Golgi’s theory seemed simpler and more intuitive, – while Cajal’s made things more complex.
Explain the image.
Julius Bernstein knew – Na+ and K+ – were in the body – and tested a frog leg – with a voltmeter. – When the leg was damaged, the reading turned negative, revealing that ions moved across the membrane. —- This confirmed electrical charges within the membrane as the basis for neural transmission.
Who tested frog leg nerves in 3 experiments?
Charles Sherrington
What was Charles Sherrington 1st experiment and
what did it suggest?
- He found a few millisecond delay —- between stimulation – and muscle contraction, —- suggesting an underlying process.
Was was Charles Sherrington 2nd experiment and
what did it suggest?
- Stimulating one side caused movement, – but the other side didn’t, – showing nerve signals move in one direction.
Was was Charles Sherrington 3rd experiment and
which discovery did it lead to ?
- After a contraction, the muscle couldn’t contract again immediately – but worked after a short wait, – leading to the discovery of the refractory period.
What was the Prevailing theory?
That electricity traveled – between neurons.
Expalin this image, experiment.
The prevailing theory was that something traveled between neurons.
A researcher – placed 2 frog hearts– in separate beakers – artificial cerebrospinal fluid (aCSF).
A researcher took out 2 frog hearts and placed them in 2 **separate beakers that contained artificial cerebrospinal fluid (aCSF). Both hearts continued beating..
In Beaker 1, the vagus nerve that controlled the heartbeat was not removed. Stimulating the nerve slowed the heartbeat.
In Beaker 2, the vagus nerve that controlled the heartbeat was removed.
The aCSF from Beaker 1 was transferred to Beaker 2, which had no vagus nerve. The 2nd heart began to slow, and this is only possible if some chemical was released from heart 1 while it was being stimulated.
What did this experiment show?
That a chemical (later called a neurotransmitter) – was released from the first heart, – proving that neurons communicate – chemically, not just electrically.
How do the discoveries in neural transmission (frog leg experiments, neuron staining, and chemical signaling) demonstrate the principle of consilience in science?
Provide examples of how one experiment built upon another to advance our understanding of how neurons communicate.
Each experiment built on the last, showing how science connects across discoveries:
- Frog Leg Experiments (Galvani, Bernstein, Sherrington) → Confirmed electrical signals in neurons and the refractory period.
- Neuron Staining (Turpin, Böhmer) → Improved visualization, revealing neuron structures and connections.
-
Chemical Signaling (Vagus Nerve Experiment) → Proved neurotransmitters, not just electricity, transmit signals.
Together, these findings showed that neural communication involves both electrical and chemical processes, illustrating consilience—how different scientific fields connect to deepen understanding.
Provide examples of how one experiment (below) built upon another to advance our understanding of how neurons communicate.
neural transmission (frog leg experiments)
neuron staining, and
chemical signaling.
Together, these findings showed that – neural communication – involves both electrical and chemical processes, – illustrating consilience—how different scientific fields connect to deepen understanding.
Contemporary Neuroscience –from here on –
–from here on–
explain image
The voltage clamp – holds – a neuron – at a fixed voltage – to study – how neurons generate and transmit electrical signals.
It measures the current needed to maintain this voltage, and by dividing voltage by current, resistance is determined—representing ion channel activity.
explain the attached image.
Imagine inflating a balloon—over time, air escapes through tiny pores. – Higher pressure speeds up deflation. By using an inflator to adjust airflow, – we can keep pressure constant. The same amount of airrflow will be needed as much escapes, just like ionic flow in a voltage clamp.
What was created shortly after the voltage clamp?
Current clamp
What was discovered using Voltage clamp and current clamp?
1) Which ions are involved in an action potential.
2) The presence of ion channels allowing ionic travel.
3) The mathematical equation to calculate the action potential.
After the Voltage clamp and Current clamp and:
1) Which ions are involved in an **action potential **.
2) The presence of ion channels allowing ionic travel.
3) The mathematical equation to calculate the action potential.
What was next gigantic step towards Psychological research?
Patch clamp
explain image
Patch clamping – lets us isolate – a single neuron, – seal it with suction, and – record its baseline activity.
By adding Xanax (a GABA agonist), – we can measure how – the current changes—in this case, it increases.
read image
How can optogenetics be used to control neuron activity and modify animal behavior in real time?
Explaim image.
A virus carrying inhibitory or excitatory opsins – is inserted into a brain region, – along with a fiber-optic cable. – Light activation opens specific receptors, allowing real-time control of neuron activity. – This can alter behavior—for example, stopping a male mouse from wanting to mate by activating certain neural pathways.
How have Electrophysiology advanced our understanding of brain function, behavior, and neurological disorders?
Unveiling – action potential mechanisms – to deepen our understanding of psychological phenomena and neuroplasticity.
How have Optogenetics advanced our understanding of brain function, behavior, and neurological disorders?
- Exploring dopamine’s role in reward and addiction.
- Uncovering fear mechanisms – to better understand anxiety and panic.
- Restoring vision in blind mice, — paving the way for human treatments.
