Most theories of second language acquisition, like those in the field of general education, are based on two schools of thought: the behavioral, or the cognitive school of thought.
The behavioral school of thought affirms that learning occurs through habit formation and pattern practice, classical conditioning, and reinforcement. The cognitive school of thought, in contrast, cites developmental and psychological processes as innate tools that help produce the skills that are needed to achieve second language learning.
The neurofunctional theory of SLA is different than most behavioral and cognitive theories because the premise is that language acquisition is a product of internal processes and sub-processes taking place in the brain; the left hemisphere is associated with the comprehension and analytical use of language, while the right hemisphere is associated with general language comprehension and the detection of patterns in usage.
The basis of the Neurofunctional theory of SLA is the scientific research that shows how brain-based factors that affect learning in general also bound to also affect language learning. These factors include age, exposure, practice,etc. Hence, theoretically speaking, if brain issues affect the process of learning, then the process of language acquisition must be a brain-based process as well.
This does not mean that environmental and psychological issues do not affect at all the SLA process, according to this theory. What it means is that, like with any learning process, the proper elements must be in place, however, the Neurofunctional theory will place more weight in brain capacity and activity rather than in the interaction of teaching and learning alone. One of the forefathers of the neurofunctional theory of SLA is Joseph Lamendella, who proposed this theory in the article "The Neurofunctional Basis of Pattern Practice" (1979) inTESOL Quarterly.