The Human Brain : From Neurone to Nervous System

NEURONAL PROCESSING IN THE CEREBRAL CORTEX


  1. The cerebral cortex is divided into areas concerned with specific functions such as touch, vision, hearing and movement. Cortical neurones are organised as layers of cells according to size and shape; they are also grouped together into functional columns that process particular aspects of their inputs.

  2. Cortical columns process different features of a sensory input simultaneously. For example, visual inputs are simultaneously processed by columns that process shape, colour, movement, light intensity, and depth of the visual field.

  3. Parallel processing is a term used to refer to the simultaneous processing of signals in different ways in adjacent cortical areas.

  4. The primary sensory receiving areas send information to many areas of the association cortex.

  5. The parietal lobe, situated between the primary somatosensory and visual cortices is concerned with spatial awareness - the integration of cutaneous, proprioceptive and visual cues as to the position of objects in near space.

  6. The output of the visual cortex is also used to direct eye movements using areas of the frontal lobe, and to recognise faces, and the emotions expressed by them using areas of the temporal lobe.

  7. Other areas of the temporal lobe are concerned with spatial navigation through complex environments, which utilise all senses - somatosensory, visual, auditory and olfactory.

  8. This chapter attempts to bring together the location and function of neurones concerned with higher functions of the central nervous system, including
    • Facial recognition (temporal lobe)
    • Emotion (limbic system)
    • Spatial Navigation (entorhinal cortex)
    • Memory (hippocampus)
    • Attention (prefrontal cortex)
    • Empathy (insula)

  9. Cortical neurones degenerate in patients with Alzheimer's disease and other dementias, resulting in disconnection of areas concerned with different cerebral functions. This disintegration of the neural networks of the cerebral hemispheres can be devastating.

  10. Key Words: Cortical layers and columns; parallel processing. Specialised areas for memory (hippocampus) emotion (limbic system) and empathath and compassion (insula).









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