Final answer:
The replacement diagnosis for several learning-related disorders in the DSM IV is Specific Learning Disorder, which is predominantly a neurological impairment affecting cognition.
Step-by-step explanation:
The diagnosis that replaced Reading disorder, Mathematics Disorder, Written Expression Disorder, and Learning Disorder NOS from the DSM IV is Specific Learning Disorder. A learning disability, as defined in the question, is predominantly a neurological disorder, which manifests as cognitive disorders affecting different areas of cognition, particularly language and reading. It is important to understand that learning disabilities are specific neurological impairments and should not be confused with global intellectual or developmental disabilities.