Cerebral Cortex and Brain Functions

Cerebral Cortex

• The cerebral cortex is the outermost layer of the cerebrum, responsible for processing sensory information, controlling movement, and managing higher-level cognitive functions.

External Features

• The cerebral cortex has distinct poles (frontal, occipital, and temporal), surfaces (superolateral, medial, and inferior), and borders (superomedial, inferolateral, and medial).

Sulci and Gyri

• The cerebral cortex has numerous sulci (fissures) and gyri (folds) that increase its surface area, allowing for more neurons and a greater capacity for processing information.
• The surface area of the cortex is approximately 2200 cm².

Lobes of the Cerebral Hemispheres

• The cerebral hemispheres are divided into four lobes: frontal (motor), parietal (sensory), temporal (auditory), and occipital (visual).

Cortical Functional Areas

• The cortical functional areas are categorized into motor, sensory, auditory, and visual areas, each with distinct Brodmann areas.
• The primary motor area (4) is responsible for controlling voluntary movements, while the premotor area (6) is involved in planning and coordinating movements.
• The primary sensory area (3, 1, 2) receives and processes sensory information, while the secondary sensory area processes more complex sensory information.
• The auditory area (41, 42) is responsible for processing sound, while the visual area (17, 18, 19) processes visual information.

Important Points

• Afferent fibers from specific nuclei of the thalamus project to laminae I-IV, while afferent fibers from non-specific nuclei of the thalamus and the ascending reticular formation project to all laminae.
• Laminae II & IV are concerned with sensorial modalities, while laminae III-V are involved in somatomotor and visceromotor activities.

Types of Neocortex

• There are five types of neocortex: agranular (type I), frontal (type II), parietal (type III), polar (type IV), and granular (type V).
• Each type of neocortex has distinct characteristics, such as the presence or absence of granule cells, pyramidal cells, and layer II & III.

Frontal Lobe

• The frontal lobe is responsible for motor control, including voluntary movements, speech, and other higher-level cognitive functions.
• The precentral cortex (4) is the primary motor area, while the prefrontal cortex (44, 45) is involved in planning and decision-making.

Parietal Lobe

• The parietal lobe is responsible for processing sensory information, including touch, pressure, and proprioception.
• The primary sensory area (3, 1, 2) receives and processes sensory information, while the secondary sensory area processes more complex sensory information.

Temporal Lobe

• The temporal lobe is responsible for processing auditory information, including sound localization and speech recognition.
• The primary auditory area (41) receives and processes sound, while the auditory association area (42) processes more complex auditory information.

Applied Aspects

• Unilateral removal of the temporal lobe can result in Temporal Lobe Syndrome, characterized by difficulties with language processing, memory, and other higher-level cognitive functions.