People with retrograde amnesia cannot remember some or even all of their past.
Retrograde amnesia is loss of memory for events that occurred prior to the trauma. However, when presented the same puzzle several days in a row, although he did not remember having seen the puzzle before, his speed at solving it became faster each day (because of relearning) (Corkin, 1965, 1968). and then you left the room for a few minutes, he would not know you upon your return and would introduce himself to you again. He also could not remember people he had met after his surgery. would read the same magazine over and over, having no memory of ever reading it-it was always new to him. The brain damage caused by his surgery resulted in anterograde amnesia. Many people with this form of amnesia are unable to form new episodic or semantic memories, but are still able to form new procedural memories (Bayley & Squire, 2002). This suggests that damage to the brain has resulted in the inability to transfer information from short-term to long-term memory that is, the inability to consolidate memories. The hippocampus is usually affected (McLeod, 2011). With anterograde amnesia, you cannot remember new information, although you can remember information and events that happened prior to your injury. Anterograde amnesia is commonly caused by brain trauma, such as a blow to the head. The present finding implies that the sensitive PI effect in amnesic patients, such as aMCI and Alzheimer's Disease (AD), may be due to encoding deficit, and thus may contribute to the diagnosis and cognitive training of these patients.There are two common types of amnesia: anterograde amnesia and retrograde amnesia. Moreover, with SAC, the present findings suggested that the increased sensitivity of PI under midazolam, as compared with saline, may be due to the encoding impairment under midazolam. In conclusion, by using drug studies, we replicated and further demonstrated the susceptible PI effect in amnesic subjects. The output of the SAC model was fitted well with the experimental data. The similar pattern was also observed in list3, although not to be significant.
In list2, the list directly followed the injection, the PI effect was detected both under midazolam and saline, but the PI magnitude under midazolam was significantly higher than that under saline. It was found that, episodic memory was significantly reduced after midazolam injection, as contrast to saline injection.
An ANOVA statistical analysis was run on behavioral data and SAC (Source of Action Confusion) models were constructed accordingly. Three kinds of word pairs were designed, with control pairs studied on only one list, practice pairs practiced on all three lists, and interference pairs involved recombining cue and response terms from one list to the next. For each list, subjects were asked to remember 45 word pairs firstly, and then each word pair was tested twice. In each day, subjects went through 3 lists of word-pair associative learning tasks and a final cued-recall test. Subjects were required to participate the experiment twice, one week apart, under midazolam (0.03 mg/kg) or saline. 20 healthy adults (11 females) voluntarily participated in a double-blind, between-subject, placebo- controlled experiment, with a 2 (drug: midazolam, saline) × 3 (list: list1, list2, list3) × 3 (word pairs: control, interference, practice) factorial design. Based on the recent findings from amnesic mild cognitive impairments (aMCI) that encoding impairment and susceptible PI effect coexisted in aMCI, and susceptible PI effect still remained in the absence of response competition, we hypothesized that the susceptible PI effect in amnesic patients might be primarily due to encoding deficits. The present study focused on this issue by in combination using neuropsychopharmacological experiment and computational cognitive modeling technique. Moreover, the results from patient study may be confounded by the differences of age, gender, education level and intelligence between patients and controls. There were two competing theories proposed to account for the susceptible PI effect in amnesia patients, with one holds that PI occurs at encoding stage, and the other believes that PI occurs at retrieval stage, however, its underlying mechanism was still unclear. Increased sensitivity to proactive interference (PI) was widely observed in patients with memory impairment.
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