Posterior zone: Comprises the posterior parietal cortex, which includes areas PE, PF, and PG.
Somatosensory Cortex
Organization:
Structured into body maps known as the homunculus:
Adjacent skin areas correspond to adjacent brain areas.
Certain skin areas occupy disproportionately large brain regions.
Experience and Adaptation:
The cortical representation can increase with experience.
Example: Violin players show greater cortical representation for their left-hand fingers (Elbert et al., 1995).
Pathways from the Parietal Lobes
Three key pathways:
To Premotor Cortex:
Serves as the "how" pathway, involved in movement planning.
To Prefrontal Cortex:
Associated with visuospatial working memory.
To Medial Temporal Regions (Hippocampus):
Important for spatial navigation.
Functions and Disorders of the Parietal Lobes
Anosognosia:
A condition characterized by unawareness of one's illness or deficits.
Balint's Syndrome:
Includes symptoms such as simultagnosia (inability to perceive more than one object at a time) and optic ataxia (difficulty with visually guided movements).
Neglect Syndrome:
Patients ignore one side of their body or space.
Gerstmann Syndrome:
Involves dysgraphia (writing difficulties), dyscalculia (math difficulties), and issues with right-left discrimination.
Apraxia:
Loss of skilled movement due to brain function, not muscle weakness.
Sensoriomotor Transformation Problems:
The posterior parietal region integrates bodily movements with sensory feedback.
Efference Copy:
Refers to the internal copy of motor commands that helps to inhibit relevant sensory responses during self-initiated movements (like in self-tickling).
Corollary Discharge:
This is the term for the inhibition of sensory responses during execution of a motor task that prevents interference from the sensory feedback from the planned action.