Temporal lobe
Researchers have also found that individuals experiencing PTA show accelerated forgetting. This contrasts with the normal forgetting observed by patients with normal amnesia related to brain damage. The temporal lobes are often the most vulnerable to the diffuse (widely distributed) and focal (more specifically localized) effects of TBI and it is possible that temporal lobe lesions may account for the accelerated forgetting observed in patients with PTA. These predictions were supported by the finding that most of the patients who showed rapid forgetting also had lesions to the temporal lobe. Bilateral damage to the temporal lobes also causes severe anterograde amnesia, making it likely that lesions to this area would be involved in PTA. Patients exhibit a temporal gradient with memory loss, meaning that older memories are preserved at the expense of newer memories. Temporal lobe damage has been linked to a temporal gradient of this sort, because older memories are less dependent on the hippocampus and thus are less influenced by its damage.