Semantic memory from perspective of neuropsychology and its theoretical models: An article review

Semantic memory is one kind of long-term memory as Tulving suggest in his theory of memory systems, it represent the cognitive encyclopedia owned by individual about what surrounds him\ her, and what he\ she learn, therefore most definitions of semantic memory focus on its importance in representing knowledge, the way of its expression, and retain them for a long periods of time.  The current review dealt with semantic memory definitions and the cause of differences among them, also included a review of the most important theoretical models that explain it and the developing of them. Starting from the network models, which has interpreted the representation of knowledge through spreading-activation of concepts across the nodes and pathways, then feature comparison models which focused on the role of primary features of each concept, and  hierarchy within each category when knowledge represented, and finally the levels of categorization models, which tried to avoid  disadvantages of the previous two models through  assumption of a rating certain categories helps to organize data and increases the speed of learning.  Knowledge representation associated with multiple brain areas, the most notably is temporal lobe and hippocampus, which activates in classifying and retain of objects, and prefrontal cortex which actives in selection and recall of information.
     The review concluded that most theoretical models focused on the representation of knowledge in verbal form only, while it can be represented in a visual form, too, as the problem of meanings specifically still need further research and interpretation, as well as the role of the brain regions in supporting or rejecting assumptions underlying theoretical models of semantic memory.