Lecture 1 -History of the Brain

Question 1

Why are animals used as models for studying human brain functions and diseases?

Answer 1

Animals have behaviors, cellular properties, and brain anatomy similar to humans and respond similarly to external substances.

Question 1

What is trepanation, and why was it practiced?

Answer 1

Trepanation is the intentional drilling of holes in the skull to treat conditions like head trauma or to release “evil spirits.”

Question 2

What is the Edwin Smith Surgical Papyrus, and why is it significant in medical history?

Answer 2

It’s an ancient Egyptian surgery guide that explains how to treat head injuries, showing early knowledge of brain injuires and treatment methods

Question 3

What did ancient Egyptians believe about the heart and the brain?

Answer 3

They believed the heart was responsible for the soul and memories, even though they recognized the brain’s role in physical trauma.

Question 4

What did Hippocrates believe about the brain?

Answer 4

He believed the brain was the organ of sensation.

Question 5

How did Aristotle view the brain’s role in the body?

Answer 5

He thought the brain acted as a radiator (cool down the blood and regualte body temperature) and that the heart was the center of intellect (thinking and emotions)

Question 6

What did Galen discover about the cerebrum and cerebellum?

Answer 6

He found that the soft cerebrum was for sensation, while the hard cerebellum controlled movement through animal dissections.

Question 7

What were Galen’s key discoveries and beliefs about the brain and bodily functions? (3)

Answer 7

1. Discovered brain ventricles containing cerebrospinal fluid
2. Believed in bodily “humors”
3. Thought sensation was caused by humors moving through nerves

Question 8

What did Descartes’ fluid-mechanical theory suggest about how the brain functions?

Answer 8

It suggested that the brain works like a machine, using fluid to control movements and bodily functions.

Question 9

What inspired Descartes to develop his fluid-mechanical theory of the brain?

Answer 9

He was inspired by hydraulic statues that moved using water pressure, leading him to think the brain might work similarly.

Question 10

How did Descartes think the mind interacted with the physical body?

Answer 10

He believed the mind communicated with the body through the brain’s ventricles, using fluid mechanisms.

Question 11

How did Descartes view the relationship between the mind and the body?

Answer 11

He believed the mind was a distinct, non-physical entity separate from the physical brain and body.

Question 12

What is the “mind-brain problem” that Descartes addressed?

Answer 12

It is the question of how the non-physical mind interacts with the physical brain and body.

Question 13

What role did Descartes attribute to the pineal gland?

Answer 13

He believed the pineal gland acted as a conduit, or connection point, where the mind interacted with the physical brain.

Question 14

What is the difference between gray matter and white matter in the brain?

Answer 14

Gray matter consists of neuronal cell bodies and short dendrites that communicate with nearby neurons. White matter is made of long axons covered in fatty tissue, transmitting impulses to distant brain and spinal cord regions.

Question 15

What are gyri and sulci in the brain?

Answer 15

Gyri are the “bumps” on the brain, and sulci (or fissures) are the “grooves” between them.

Question 16

What does the consistent organization of gyri and sulci between individuals suggest?

Answer 16

It suggests cerebral localization, where different brain areas are specialized for specific functions.

Question 17

What is phrenology, who developed it, and what did it claim about personality and skull shape?

Answer 17

Phrenology, developed by Franz Joseph Gall, is the belief that the shape and size of different areas of the skull reflect personality traits and mental abilities.

Question 18

What lasting idea did phrenology contribute to, despite being debunked?

Answer 18

Phrenology contributed to the understanding that the brain, not the heart or soul, is responsible for mental functions, emphasizing the brain’s role in governing behavior.

Question 19

How did Gall relate skull size and shape to behavioral traits and brain development?

Answer 19

Gall claimed that larger skull areas indicated stronger traits, and bumps or indentations revealed which brain regions were more developed, supposedly reflecting personality traits.

Question 20

What is Broca’s area, and where is it located?

Answer 20

Broca’s area is in the left frontal lobe and is crucial for speech production, named after Paul Broca.

Question 21

What did Paul Broca prove about brain function?

Answer 21

Paul Broca showed that specific brain areas are responsible for specific functions, proving localization of function.

Question 22

What did Broca learn from the patient “Tan”?

Answer 22

Broca studied a patient called “Tan,” who could understand language but could only say the word “Tan.” This was due to damage in Broca’s area, showing the link between this brain region and speech production.

Question 23

Who opened a new field of experimental ablation studies?

Answer 23

Early scientists, including Broca and Flourens, opened a new field of experimental ablation studies, which involve destroying brain structures using lesion techniques to study their functions.

Question 24

What did Flourens demonstrate about the cerebellum?

Answer 24

Flourens showed that the cerebellum coordinates movement, by removing parts of it in animals, which caused severe coordination and balance problems, proving that specific brain areas have distinct roles.

Question 25

What happened to Phineas Gage, and what did it reveal about the frontal cortex?

Answer 25

Phineas Gage’s frontal cortex was damaged by a tamping rod, causing drastic personality change (impulsive and aggressive). This showed that the frontal cortex is crucial for personality and behavior regulation.

Question 26

How did the case of Patient H.M. contribute to our understanding of memory?

Answer 26

Patient H.M. had his hippocampus removed to treat epilepsy, and he could no longer form new memories, though he retained old ones. This proved that the hippocampus is essential for making new memories but not for keeping older ones.

Question 27

What is the concept of “Nerves as Wires,” and how does it differ from earlier beliefs?

Answer 27

The concept of “Nerves as Wires” established that nerves transmit electrical signals, not fluid, changing the previous understanding of how the nervous system communicates with the body.

Question 28

What did Luigi Galvani’s frog experiments reveal about nerve function?

Answer 28

Galvani’s experiment involved dissecting a frog and exposing its leg muscles and nerves. He then applied electrical currents to the nerves, causing the muscles to twitch.
- This demonstrated that nerves transmit electrical impulses, not fluids, and provided evidence that electrical signals control muscle movement.

Question 29

What did Bell and Magendie discover about the spinal cord and nerve communication?

Answer 29

Bell and Magendie discovered that the spinal cord has separate paths for sensory and motor signals. Cutting these nerves disrupts sensation and movement, proving that nerve signals travel in specific directions.

Question 30

How are the pathways of the spinal cord organized, and what functions do they serve?

Answer 30

The spinal cord has two main pathways:

1. Ventral Root (Front): Carries motor signals from the spinal cord to the muscles, causing movement
2. Dorsal Root (Back): Carries sensory information from the body to the spinal cord.

Question 31

What was the key method used by José Delgado to control a bull’s behavior in his experiment?

Answer 31

Delgado implanted electrodes in the bull’s brain and used radio signals to disrupt normal neuron firing, allowing him to control the bull’s aggressive behavior

Question 32

What did Delgado’s experiment reveal about the relationship between the brain and behavior?

Answer 32

The experiment showed that manipulating neuronal signals can alter or control behavior, demonstrating that the brain has direct control over actions.

Question 33

Who was Santiago Ramón y Cajal, and what was his major contribution to neuroscience?

Answer 33

Ramon y Cajal proposed the Neuron Doctrine, which established that the nervous system is made up of individual, distinct cells called neurons that transmit information in one direction

Question 34

How did Cajal’s work lay the foundation for understanding synapses?

Answer 34

By proving neurons are separate, he implied the need for specialized communication points, leading to the concept of synapses.

Question 35

What scientific disagreement did Cajal have with Camillo Golgi?

Answer 35

Cajal believed neurons were separate units (Neuron Doctrine), while Golgi argued for the Reticular Theory, suggesting the nervous system was a continuous network.

Question 36

What are Type I and Type II synapses, and how do they differ?

Answer 36

Type I Synapses

1. Excitatory: Promote the firing of the post-synaptic neuron
2. Shape: Spherical
3. Vesicles: Contain neurotransmitters that excite the post-synaptic neuron (e.g., glutamate)

Type II Synapses
1. Inhibitory: Suppress the firing of the post-synaptic neuron
2. Shape: Flattened
3. Vesicles: Contain neurotransmitters that inhibit the post-synaptic neuron (e.g., GABA)

Question 37

How do asymmetrical and symmetrical synapses differ?

Answer 37

Asymmetrical synapses are usually inhibitory, like GABA synapses. Symmetrical synapses are usually excitatory, promoting neuron activation.

Question 38

What evidence supports the Neuron Doctrine?

Answer 38

The Neuron Doctrine is supported by the presence of two types of synapses: Type I (excitatory) and Type II (inhibitory). These distinct synapses show nervous system is made up of separate, individual cells called neurons, not a continuous network.

Question 39

What happens at the pre-synaptic and post-synaptic sides?

Answer 39

The pre-synaptic side releases neurotransmitters into the synaptic cleft. These neurotransmitters bind to receptors on the post-synaptic side, causing a response, with scaffolding proteins helping to organize the receptors.

Question 40

Steps of Chemical Synapse Communication

Answer 40

1. Synthesis of neurotransmitter
2. Packaging of neurotransmitter
3. Delivery to presynaptic terminal (if synthesized in cell body)
4. Arrival of action potential to presynaptic terminal
5. Influx of Ca2+ into presynaptic terminal
6. Fusion of synaptic vesicles with presynaptic membrane
7. Release of neurotransmitter
8. Binding to receptor on postsynaptic membrane
9. Response of postsynaptic membrane/cell

Question 41

Structure and Function of Cerebellar Purkinje cells:

Answer 41

1. Structure:
   Large, complex branching dendritic tree.
2. Function:
   Receives many inputs to coordinate precise body movements.

Question 42

What is the function of projection neurons?

Answer 42

Projection neurons send long-range axonal signals outside their local brain area.

Question 43

What distinguishes interneurons from projection neurons?

Answer 43

Interneurons project locally with smaller axons and typically inhibit the firing of postsynaptic cells.

Question 44

What is the role of glial cells?

Answer 44

Glial cells provide maintenance, repair functions, and support neural plasticity.