Lecture 4 - the anatomy of brain function

Question 1

What are the basic statistics about the brain’s weight, blood flow and energy consumption?

Answer 1

The brain is approximately 2% of body weight, receives about 20% of the blood pumped from the heart, and consumes about 20% of the body’s energy. It contains around 100 billion neurons and 1,000,000 billion synapses.

Question 2

Describe the main parts of the brain

Answer 2

• cerebrum (Cerebral Hemispheres)
• cerebellum (Hindbrain)
• brain stem

Question 3

What is the cerebral cortex, and what are its characteristics?

Answer 3

The cerebral cortex is the outermost surface layer of the cerebrum, also known as grey matter. It is 2mm to 4mm thick, contains the cell bodies of the brain’s neurons, and is highly folded to maximize surface area. The white matter underneath consists of axons connecting to the spinal cord and other area of the cortex.

Question 4

What are the main functions of the frontal lobe?

Answer 4

• executive functions: reasoning, planning, problem-solving, inhibitory control, working memory
• motor functions: motor planning (premotor cortex) and execution (primary motor cortex)
• speech production (Broca’s area)

Question 5

What are the main functions of the parietal lobe?

Answer 5

• perception of touch (primary somatosensory cortex)
• sense of space and location relative to body position
• spatial attention and linking vision to action

Question 6

What are the main functions of the occipital lobe?

Answer 6

The occipital lobe is responsible for visual perception, including processing shape, color, orientation, and motion (primary visual cortex and higher visual areas)

Question 7

What are the main functions of the temporal lobe?

Answer 7

• perception of sound (primary auditory cortex)
• language comprehension (Wernicke’s area)
• Learning and memory (limbic system: amygdala and hippocampus)

Question 8

What roles do the amygdala and hippocampus play in the limbic system?

Answer 8

The amygdala is involved in fear and arousal, responding to threats and danger.
The hippocampus is crucial for forming new episodic memories; damage to it can cause anterograde amnesia

Question 9

What is the function of the corpus callosum?

Answer 9

The corpus callosum consists of neuron connection between the left and right hemispheres, allowing communication between them. In “split-brain” patients, the two hemispheres cannot communicate.

Question 10

What was significant about Phineas Gage’s accident?

Answer 10

Phineas Gage’s accident involved an iron rod passing through his frontal lobes, which led to profound changes in his personality, highlighting the role of the frontal love in executive control of behavior

Question 11

What are the characteristics of Broca’s aphasia and Wernicke’s aphasia?

Answer 11

• Broca’s aphasia: Slow, non-fluent speech with difficulty finding words, but comprehension is mostly unaffected
• Wernicke’s aphasia: Fluent speech with normal but lacking meaning, resulting in nonsense speech and deficits in language comprehension

Question 12

What did Wilder Penfield’s research contribute to our understanding of the brain?

Answer 12

Wilder Penfield mapped the motor and sensory cortices by stimulating the brain with electrical probes during surgery, showing how different areas correspond to specific functions

Question 13

Differentiate between the central and peripheral nervous systems

Answer 13

• central nervous system (CNS): includes the brain and spinal cord
• peripheral nervous system (PNS): Includes the;
  
  • somatic nervous system (voluntary motor and sensory functions)
  • the autonomic nervous system (involuntary functions like heart rate, respiration)

Question 14

What are the two divisions of the autonomic nervous system, and what are their functions?

Answer 14

• sympathetic nervous system: handles emotional arousal, stress, and the “fight-or-flight” response, increasing heart rate and respiration
• parasympathetic nervous system: promotes “rest and digest” activities, lowering heart rate and respiration, and increasing digestive activity

Question 15

Compare “persistent vegetative state” and “locked-in” syndrome

Answer 15

persistent vegetative state:
- severe damage to the upper brain while the brainstem functions remain, resulting in no conscious awareness
locked-in syndrome:
- intact cerebrum and brainstem but disconnected from the spinal cord, leading to full consciousness and awareness without the ability to move

Question 16

What is the role of the cerebellum in motor control?

Answer 16

The cerebellum, or “little brain”, helps maintain balance and coordinate complex movements. It also aids in motor learning by fine-tuning movements based on feedback

Question 17

Explain the concept of “motor programs” in movement

Answer 17

Movements are planned and “programmed” in the brain before initiation, similar to a computer program. The brain retrieves these programs for learned skilled actions like signing a signature or performing a tennis swing

Question 18

How does feedback control of movement work?

Answer 18

• planned actions are compared with feedback from actual actions performed (e.g. vision, sensation, proprioception). The brain computes the difference and rapidly corrects actions, learning for future movements.