Question

John Doe had a stroke that left lesions in his thalamus. He found out that his vision, hearing, taste, and sense of touch has significantly diminished as a result of the stroke. Curiously, a neuropsychological examination reveals that his sense of smell appears to be intact. In fact, his sense of smell is still working at 100% capacity. what underlying mechanism might be responsible for these symptoms?

Answer 1

Dear Student,

Thalamus is the relaycenter for all sensory signals

Thalamus regulates the senses related to vision, hearing,taste and touch, etc. So, when there is a lesion in thalamus, all these senses are diminished.

But exceptionally sense of smell is the only sense that do not travel to the thalamus before accessing forebrain unlike the other mentioned senses, which first sends the impulses to the Thalamus first, from where the signals are forwarded to other areas of brain for proper perception.

This is the reason why the sense of smell is still working at 100% capacity despite of the stroke of Thalamus.

Hope you are clear...!