WK:1 The Cerebral Cortex

What are the two main tissue types in the cerebral cortex and what do they consist of?

1. Grey matter: Outer shell of cell bodies, dendrites, and glia

2. White matter: Inner mass of myelinated axonal tracts

How do the two cerebral hemispheres relate to body control and function?

• Contralateral control: Each hemisphere controls the opposite side of the body

• Connected via the corpus callosum

• Not symmetrical in structure or function

Name the four lobes of the cerebral cortex and one primary function of each.

1. Frontal lobe: Motor function, executive decisions

2. Parietal lobe: Somatosensory processing

3. Temporal lobe: Auditory processing, memory

4. Occipital lobe: Visual processing

Where is the primary somatosensory cortex located and what does it process?

• Located in the parietal lobe

• Processes touch, temperature, pain, and proprioception from the opposite side of the body

What is a sensory homunculus and what does it demonstrate?

• A cortical map of the body in the somatosensory cortex

• Demonstrates that cortical area is proportional to sensory sensitivity (e.g., large areas for lips, hands)

What is cortical plasticity in the somatosensory cortex?

• The brain’s ability to reorganize cortical maps based on use/disuse

• Example: A violinist’s finger representation expands with practice

Where is the primary motor cortex located and what is its main function?

• Located in the frontal lobe

• Responsible for planning, control, and execution of voluntary movements

What does the motor homunculus represent?

• A somatotopic map in the motor cortex showing which areas control specific body parts

• Contralateral control; more cortex devoted to fine-motor areas (fingers, face)

List three key brain regions that provide input to the motor cortex.

1. Basal ganglia – modulates movement

2. Cerebellum – coordinates movement

3. Thalamus – relays sensory and motor info

In what percentage of people is language primarily localized to the left hemisphere?

• ~90% of people (especially right-handed)

• Key areas: Broca’s area (speech production) and Wernicke’s area (comprehension)

Where is Broca’s area located and what is its function?

• Left frontal lobe

• Controls motor production of speech (articulation)

• Damage → Broca’s aphasia (non-fluent, effortful speech)

Where is Wernicke’s area located and what is its function?

• Left temporal lobe

• Responsible for language comprehension and coherent speech planning

• Damage → Wernicke’s aphasia (fluent but meaningless speech)

What are gyri and sulci, and why are they important?

• Gyri: Ridges on the cortical surface

• Sulci: Grooves between gyri

• Increase surface area for more neurons and processing power

What is the role of cortical association areas?

integrate information from multiple sensory modalities

• Involved in higher-order processing: perception, planning, reasoning

• Located near primary sensory/motor areas