Question

Describe the hubs and spokes model of semantic memory. Why are lesions in the premotor/motor cortices more likely to produce categorical deficits for tools than animals? Why do lesions in the anterior temporal lobe produce deficits for a wider range of concepts?

Answer 1

The semantic memory is responsible for encoding information and it helps in decoding meaning of words, objects, people and different types of verbal and non-verbal stimuli in response to the world. It helps in determining the human behavior and helps in better understanding of all the abstract concepts existing in the world. The memories are created from real and actual experiences. The hubs and spokes model help in defining the semantic memory where the hubs mean abstract representations unified and these representations are present within the anterior temporal lobes of the brain. Through the hubs it helps in bringing together and integrating knowledge of different concepts. The spokes is basically modality specific information which is a combination of all the somatosensory information along with visual understanding, verbal features, sound, motor movements and olfaction.

The lesions within the premotor/motor cortices leads to production of defect in the tools rather than in animals because when there is a lesion in such areas, it makes one paralysis and impairs the motor movement and processing capacity. With such lesions, it makes it difficult for one to use their body parts efficiently and hence it impairs one’s ability to perform different voluntary functions. Hence, one is not able to use the movements they have learnt. Due to the lesions within the motor cortices, it impairs the ability for one to perform task that was learnt earlier.

The anterior temporal lobe is an important part of the brain which is responsible for causing and creating semantic memories which tends to enhance the knowledge of people, objects, world and understanding of facts. Hence when there is a lesion in the anterior temporal lobe, it is unable to create memories of many concepts and things and hence leads to the disruption of understanding of wider concept of things.