Function of Cerebral Cortex

This answer is oriented to dentistry students.

Physiological anatomy of the cerebral cortex

 * Total area of 0.25 m2, giri, sulci, fissures
 * Approximately >1010 neurons
 * Pyramidal neurons
 * Largest cortical cells
 * Dendrites in different layers
 * Projecting neurons
 * Excitatory (Glutamate, Aspartate NTs)
 * Stellate (granule) neurons
 * Local circuit neurons
 * Often send a projecting axon
 * Spiny stellate neurons → Excitatory
 * Smooth stellate neurons → Inhibitory (GABA)
 * Fusiform cells
 * Elongated cell
 * Local circuit neurons

Stratification of the cerebral cortex

 * Most incoming specific sensory signals terminate in layer IV
 * Most of output signals leave the cortex from neurons in
 * Layers II & III (corticocortical)
 * Layer V (to brainstem, striatum and the spinal cord)
 * Layer VI (corticothalamic)
 * Layers I, II and III perform most of the intracortical association functions
 * Cortical columns
 * Neurons along a line perpendicular to the cortical surface have similar response properties and receptive fields

Sensory cortex → IV (mainly)

Primary motor → V, VI (mainly)

Association cortex → in between sensory & primary

Function of specific cortical areas

 * Primary sensory areas
 * Somatic
 * Visual
 * Auditory
 * For experience of sensation
 * Secondary sensory areas
 * Corticocortical input
 * Make sense out of the specific sensory signals (interpreting the shape, texture of a object, stimulating the cutaneous receptors; light intensity or color; combination and sequence of tones)
 * Primary motor area
 * Connected with specific muscles
 * Secondary motor area
 * Programming of the motor action
 * Collaboration with basal ganglia & cerebellum

The association cortex

 * Most of the cortex is association cortex
 * Cortical areas that receive and analyze signals from multiple regions of the cortex and from some subcortical structures

Parieto-occipito-temporal association area

 * Polymodal sensory high level analysis and interpretation of signals (visual, auditory and somatosensoric inputs)
 * Memory functions
 * Interpretation of sensory information for conscious perception and language
 * Functions
 * Spatial coordinates
 * Of the body and surroundings (lesion – loss of the recognition, orientation over one’s own body – contralateral neglect
 * Language comprehension
 * Auditory processing of words (Wernicke’s area) + intelligence
 * Visual processing of written words
 * Lesion → dyslexia, word blindness)
 * Naming of objects
 * Auditory input (names)
 * Visual input (nature of the object)

The prefrontal association area
Works in close association with the motor cortex
 * Information on the spatial coordinates of the body
 * Planning of effective movements
 * Neuronal circuitry for word formation

The Limbic Association

 * Behavior
 * Emotions
 * Motivation

The specialization of hemispheres
Functions that require extensive intracortical connectivity may become lateralized (the capacity of interhemispheric connections is much lower)
 * Left hemisphere specialized on the
 * Precise motor movements of hands
 * Word formation and language
 * Logical interpretation of the processed information
 * Rational and analytical thinking
 * Mathematical amplitude
 * Right hemisphere is specialized on the
 * Complex and parallel procession of information
 * Nonverbal auditory experience
 * Non verbal visual
 * Non verbal communication
 * Emotional, nonverbal, intuitive thinking
 * Evidence of hemispheric asymmetry at birth
 * Physical structure of the brain
 * Hand preference
 * Responses to visual auditory stimuli
 * In infancy, different stimuli seem to activate one hemisphere only, or at least one hemisphere more that the other
 * Corpus callosum is structurally and functionally incomplete until around two years of age
 * The process of hemisphere specialization ends around the age of 12 years.
 * Functional specialization of hemispheres (lateralization) coincides with the period of higher plasticity of neuronal circuits

Planum Temporale

 * A section of the temporal cortex that is larger in the left hemisphere in approximately 65% of the population. This difference in size is apparent at age 3 months in humans
 * Children with the biggest ratio of left to right planum temporale performed better in language tests