Overview
This lecture covered the structure and functional organization of the brain, focusing on the cerebral hemispheres, sensory and motor areas, association regions, and speech centers.
Major Divisions of the Brain
- The brain is divided into the cerebral hemispheres (cerebrum), diencephalon (thalamus and hypothalamus), brainstem (midbrain, pons, medulla oblongata), and cerebellum.
- Cerebral hemispheres are divided by the longitudinal fissure and connected by the corpus callosum.
Protective Layers of the Brain
- From inside out: pia mater (inner), arachnoid mater, dura mater (outermost; two layers in brain).
- The dura mater contains dural sinuses for cerebrospinal fluid circulation.
- Skull provides bony protection.
Cerebral Cortex Organization
- Raised areas are called gyri; shallow grooves are sulci; deep grooves are fissures.
- The central sulcus separates sensory (posterior) and motor (anterior) regions.
- The cerebral cortex is the major site for conscious decision-making.
Sensory Areas of the Cerebral Cortex
- The postcentral gyrus (behind central sulcus) is the primary somatosensory area (touch, pain, temperature).
- Sensory cortex is spatially organized (different body parts map to specific neurons).
- Primary sensory areas:
- Visual (occipital lobe),
- Auditory (temporal lobe),
- Olfactory (smell),
- Gustatory (taste),
- Vestibular (balance).
Association Areas
- Association areas process and integrate raw sensory data with memory and emotion to give context.
- Examples:
- Somatosensory association area,
- Visual association area,
- Auditory association area.
- Integration leads to individual interpretation and response.
Motor Areas of the Cerebral Cortex
- The precentral gyrus (in front of central sulcus) is the primary motor cortex, initiating voluntary movements.
- Motor cortex organization is spatial (specific neuron groups control specific muscles).
- Premotor cortex plans movements and signals the primary motor cortex.
- Prefrontal cortex is responsible for higher intellect, executive function, and decision-making ("Ready, Set, Go": prefrontal, premotor, primary motor).
Speech Areas
- Wernicke's area (sensory, behind auditory area): comprehends and gives context to language.
- Broca's area (motor, in front of auditory area): controls muscles for speech production.
Key Terms & Definitions
- Cerebrum — largest part of the brain, divided into right and left hemispheres.
- Corpus Callosum — fiber bundle connecting the two cerebral hemispheres.
- Gyri — raised folds on the brain surface.
- Sulci — shallow grooves on the brain surface.
- Fissures — deep grooves separating major brain regions.
- Primary Somatosensory Area — region receiving body sensations.
- Association Area — brain region integrating sensory input with memory and emotion.
- Primary Motor Cortex — area initiating voluntary motor activity.
- Premotor Cortex — plans complex movements.
- Prefrontal Cortex — involved in planning, decision-making, and executive functions.
- Wernicke’s Area — interprets language meaning.
- Broca’s Area — controls speech production.
Action Items / Next Steps
- Review class PowerPoints and textbook for brain region functions.
- Focus on being able to describe the main responsibilities of each area discussed.
- No need to memorize excessive detail if not covered in lecture.