Divisions of the Central Nervous System & Cortical Regions

Historical Perspectives

• Galen (2nd Century): Proposed early ideas on the connection between brain behavior through his concept "Cerebrum Animalis Facvltatis Fons," which indicates that the brain serves as the source of animal capabilities. He emphasized the crucial role of the brain in controlling bodily functions.

Continuity in Study

• Historical Span: Nearly 1700 years later, discussions on the relationship between brain function and behavior persist, showing the evolving understanding of the brain's role in various functions.

Modern Views

• Golgi & Cajal: These scientists furthered the understanding of the nervous system as comprising distinct cells. Golgi's work involved staining techniques that revealed cell architecture in neural tissue, while Cajal utilized these findings to propose the neuron doctrine, emphasizing the individuality of neurons.

Neuron Doctrine

• Ross Harrison & Sanford Palay: Their contributions were pivotal in establishing the neuron doctrine, which posits that neurons are the fundamental building blocks of the nervous system and establishes key principles in neuroscience regarding neuron communication.

19th Century Theories

• Franz Joseph Gall (1800s): Although his theories were often dismissed as nonsense, they included early explorations into phrenology, suggesting that specific brain areas are linked to personality traits and behaviors, thereby hinting at localized brain functions.

Anatomical Terminology

• Navigational Terms: Understanding of anatomical positions is crucial.

  • Rostral-Caudal: Refers to head-tail regions.

  • Dorsal-Ventral Axes: Refers to structures situated above (dorsal) and below (ventral).

  • Medial-Lateral Axis: Describes the movement and relationship of body segments, distinguishing between midline (medial) and sides (lateral).

  • Section Planes: Important planes include Horizontal (transverse), Coronal (frontal), and Sagittal, each providing unique views of brain structures.

Central Nervous System Divisions

• Seven Main Parts: The central nervous system is divided into seven crucial parts:

  • Cerebrum

  • Diencephalon

  • Midbrain

  • Cerebellum

  • Pons

  • Medulla Oblongata

  • Spinal Cord

• Organizational Structure: These components can be further categorized into forebrain, midbrain, and hindbrain, each with specific functions including sensory processing and motor control.

Functional Regions of the Brain

• Cerebrum Lobe Classification: The cerebrum is divided into four major lobes:

  • Frontal Lobe: Involved in reasoning, planning, speech production, and movement.

  • Temporal Lobe: Responsible for auditory perception and memory.

  • Parietal Lobe: Processes sensory information and spatial orientation.

  • Occipital Lobe: Handles visual processing.

• Structural Features: Key features include the central sulcus (separates frontal and parietal lobes) and lateral sulci.

Lateralization of Cortical Function

• Left Hemisphere: Predominantly responsible for language processing, mathematical functions, and logical operations.

• Right Hemisphere: Engages in visual-spatial skills, intuition, emotional processing, and artistic and musical abilities.

• Interhemispheric Communication: Achieved through fiber tracts such as the corpus callosum, allowing speedy information exchange between hemispheres.

Functional Areas of the Cerebral Cortex

• Motor Areas: Include the primary motor cortex (initiating voluntary movement), premotor cortex (planning movement), and Broca's area (speech production).

• Sensory Areas: Comprise the primary somatosensory cortex (processing touch), and areas for taste, vision, and hearing.

• Multimodal Association Areas: Integrate sensory inputs and support higher cognitive tasks such as reasoning and problem-solving.

Brain's Functional Regions Overview

• Medial View Anatomy: Highlights structures such as the cingulate gyrus (involved in emotional regulation), corpus callosum (connecting hemispheres), and lobes including parietal, occipital, and temporal, aiding in various cognitive functions.

Five Lobes of Cerebral Hemispheres

• Components: Note additional structures like the insula which plays a role in emotional perception and interoceptive awareness alongside important cerebral features including central sulcus and gyri, particularly in the frontal and temporal regions.

Basal Ganglia Overview

• Subcortical and Deep Cortical Regions: Provides details of the basal ganglia components – notably the caudate nucleus and putamen, which are crucial for voluntary motor control and procedural learning, as well as their connections with other brain structures.

Ventricles of the Brain

• Cerebrospinal Fluid (CSF): The ventricles serve as reservoirs filled with CSF, lined with ependymal cells, and connected through a series of channels and apertures, playing a key role in cushioning the brain and maintaining homeostasis.

Imaging of Brain Structures

• Visualization Techniques: Advanced imaging techniques such as MRI and CT allow for detailed visualization of cortical and subcortical regions in living individuals, aiding in the diagnosis of neurological conditions and research.

Localization of Cognitive Abilities

• Language Disorders: Research links studies of brain damage to the localization of cognitive functions related to speech and language, underscoring critical areas like Broca's and Wernicke's areas, which are essential for language comprehension and production.

Functional Areas Classification

• Cerebral Cortex Classification: In the early 20th century, the human cerebral cortex was classified into 52 distinct functional areas to identify specialized roles, enhancing the understanding of brain function.

Common Language Processing Areas

• Deaf Signers vs. Hearing Individuals: Research shows that both groups utilize similar language processing areas, illustrating the brain's adaptability and its capability to process language through various modalities, including sign language.