Function of Cerebral Cortex

This answer is oriented to dentistry students.

Physiological anatomy of the cerebral cortex[edit | edit source]

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

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

A== 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 areaa4
- Programming of the motor action
- Collaboration with basal ganglia & cerebellum

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

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)

Works in close association with the motor cortex

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

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

Prof. Jaroslav Pokorný