L3 - Brain Basics

Question 1

Label the brians according to what specie(s) they belong to:

Answer 1

A. Bird

B. Mammal

C. Reptile

D. Bony Fish

E. Amphibian

F. Shark

G. Lamprey

Question 2

Why do regions of the brain vary in size?

Answer 2

Neuron-rich system are energetically costly

• e.g. In humans: 20% of blood flow goes to the brain, and consumes 20% of the oxygen your body uses. (despite being only c. 2% of your body weight)
• basically use it or lose it

Question 3

Lable this embryonic vertibrate brain

Answer 3

Top to bottom:

1. Forbrain
2. Midbrain
3. Hindbrain

Question 4

What are the cerebral “cortices” of mammals?

Answer 4

• The outer layers of the cerebral hemispheres
• singular - “cortex”

Question 5

What does DECORTICATE** mean?

Answer 5

The cortices are surgically removed

Question 6

What does DECEREBRATE** mean?

Answer 6

The entire cerebral hemispheres are surgically removed

Question 7

What does VOLUNTARY mean?

Answer 7

In humans

• feels like we mke a decision

Also

• action can be initiated, delayed or withheld altogether based on context (often thanks to learning)
• action can be modified part-way through if not succeeding (use of feedback)
• action can be abandoned part-way through if not working (ditto)
• action can be modified over time with learning

Question 8

Lable the diagram

Answer 8

Question 9

What part of the brain is responsible for decision-making, learning, and use of feedback?

Answer 9

Forebrain - Telencephalon

Question 10

What does UNVOLUNTARY mean?

Answer 10

In humans

• Feels like we do not make a decision: just happens

Also

• context does not weather or when an action is performed: happens in a ‘stimulus-response’ automatic manner
• action cannot be modified part-way through if not succeeding (no use of feedback)
• action cannot be abandoned part-way through if not working (ditto)
• action cannot be modified over time with learning
• e.g. startle reflexes

Question 11

What is the function the MEDULLA?

Answer 11

• coordinates some unlearnt reflex actions (e.g. swallowing, vomiting, sneezing)
• also contains ‘vital centres’ that control heart -beat and breathing (also blood pressure)

Question 12

What is the function of the PONS?

Answer 12

• mediates other unlearnt, reflex actions like startle, grasping

Question 13

Some actions can be voluntary OR involuntary.

True or False?

Answer 13

True

• Some functions like swallowing, breathing,stepping, swimming, ect can be both
• Most of these functions are controlled by the medulla and/or spine and/ or midbrain (optic tectum) BUT can be ‘commanded’ by the forebrain too

Question 14

What are some characteristics of “Anencephalic” babies lacking a cerebrum?

Answer 14

• They can still swallow, yawn, show grasp reflexes; have facial expressions; eyes may even follow moving objects
• all these actions are involuntary due to the fact there is no fore-brain to allow these actions to become voluntary.

Question 15

“DECEREBRATE” dogs/cats can still…

Question 16

A lamprey needs a froebrain to be able to swim.

True or False?

Answer 16

False

A lamprey actually doesn’t need a brain at all in order to swim

Question 17

What are the cortical areas relevant to voluntary motor control?

Answer 17

• Premotor cortex
• Supplementary cortex motor area
• Primary motor cortex
• Posterior parietal cortex

Question 18

Sensory cortices and pre-frontak cortex send information processing via ___________?

Answer 18

via the basal ganglia

Question 19

What are the 3 main types of CORTICO-BASAL CIRCUITS?

Answer 19

1. A motivation circuit that assesses and determines the rate and persistence required
2. A sensorimotor circuit that starts and ends at the motor and sensorimoter cortices, mainly passing through the putamen
3. A cognitive cirvuit that starts and ends at several cortical regions including the prefrontal cortex and parietal cortex, mainly passing through the caudate

Question 20

What is the PUTAMEN?

Answer 20

• The outer part of the lentiform nucleus of the brain.
• involved in learning and motor control, including speech articulation, and language functions, reward, cognitive functioning, and addiction

Question 21

What is the CAUDATE?

Answer 21

• a paired, “C”-shaped subcortical structure which lies deep inside the brain near the thalamus
• It plays a critical role in various higher neurological functions
• The caudate works with the putamen to receive the input from cerebral cortex. Collectively, they can be considered the “entrance” to the basal ganglia. Projections from the putamen reach the caudate directly via the caudolenticular grey bridges.

Question 22

What are the 4 main types of voluntary movent control?

Answer 22

1. High level decisions about what to do
2. How to do it I: the individual actions required
3. How to do it II: smooth speedy sequences
4. How to do it III: the rate and persistence required

Question 23

What are some facts about the ASSOCIATIVE REGIONS of the prefrontal cortex?

Answer 23

• It acts via the cognitive circuit that starts and ends at several cortical regions including the prefrontal cortex, mainly passing through the caudate
• In charge of:
  
  • impulse control
    
    • stop and think, then act
  • supervision and planning
  • moderating ‘impulsivity’ & distractibility
    
    • preference for immediate small rewards over delayed bigger rewards
    • THIS CIRCUIT FUNCTIONS POORLY IN JUVENILES AND STRESSED INDIVIDUALS

Question 24

What role does the cerebellum play in motor coordination with practice?

Answer 24

• it receives input from the motor cortex and sends signals back
• programs final voluntary muscle control so that: muscles are more coordinated, muscle memory can start to occur.

Question 25

The forebrain develops similarly in all vertibrates except who?

Answer 25

Bony fish

Question 26

Regional size of the brain reflects functional improtance in vertibrates

True or False?

Answer 26

True

Question 27

True or False

The brain and spinal chord are designed to automatically produce some reflexes and simple actions (with no volition or forebrain input)

Answer 27

True

Question 28

True or False?

Voluntary behavior is not controlled by three major cortice-basal ganglia circuits

Answer 28

False

Voluntary behavior is controlled by three major cortice-basal ganglia circuits; and regional allocation within the motor cortex reflects functional importance

Question 29

Sequences of voluntary behavior is smoothed and integrated with practice thats to what region of the brain?

Answer 29

The cerebellum

Question 30

Brain comparison

Answer 30