Anterograde amnesia
[1] One extensively studied anterograde amnesiac patient, codenamed H.M., demonstrated that despite his amnesia preventing him from learning new declarative information, procedural memory consolidation was still possible, albeit severely reduced in power.
[3] This disorder is usually acquired in one of four ways: One cause is benzodiazepine drugs such as midazolam, flunitrazepam, lorazepam, temazepam, nitrazepam, triazolam, clonazepam, alprazolam, diazepam, and nimetazepam.
This has also been recorded in non-benzodiazepine sedatives or "z-drugs" which act on the same set of receptors, such as zolpidem (also known as Ambien), eszopiclone (also known as Lunesta), and zopiclone (also known by brand names Imovane and Zimovane).
Damage to specific areas can result in reduced or eliminated ability to encode new explicit memories, giving rise to anterograde amnesia.
Although later the complications can be much more widespread and strongly impair cognitive processes, at the initial stage of Alzheimer's the changes observed can be restricted to anterograde amnesia and a mild deficit in retaining newly learnt sequences.
This is explained by the fact that the disease is initiated within the medial temporal lobe and first affects the entorhinal cortex that directly sends and receives information from the hippocampal formation.
The MTL memory system includes the hippocampal formation (CA fields, dentate gyrus, subicular complex), perirhinal, entorhinal, and parahippocampal cortices.
[1] However, conflicting data in another primate study points to the observation that the amount of tissue damaged does not necessarily correlate with the severity of the memory loss.
[1] An important finding in amnesic patients with MTL damage is the impairment of memory in all sensory modalities – sound, touch, smell, taste, and sight.
Anterograde amnesics without combined retrograde disorders (localized damage to the MTL system) have memories prior to the traumatic event.
Easton and Parker also reported MRI scans of patients with severe anterograde amnesia showed damage beyond to cortical areas around the hippocampus and amygdala (a region of brain involved in emotions) and to surrounding white matter.
A case report describing a patient who had two lobectomies – in the first, doctors removed part of her right MTL first because of seizures originating from the region, and later her left because she developed a tumor – demonstrates this.
[16] Approaches used to treat those with anterograde amnesia often use interventions which focus on compensatory techniques, such as beepers, written notes, diaries or through intensive training programs involving the active participation of the individual concerned, along with their supporting network of family and friends.
[18] In moderately or severely injured individuals, effective interventions are those appealing to external aids, such as reminders in order to facilitate particular knowledge or skill acquisition.
[20] One patient, known by the codename "Gene", was involved in a motorcycle accident that damaged significant portions of his frontal and temporal lobes, including his left hippocampus.
[citation needed] In stark contrast, a woman whose temporal lobes were damaged in the front due to encephalitis lost her semantic memory.
[citation needed] Vicari et al. describe that it remains unclear whether neural circuits involved in semantic and episodic memory overlap partially or completely, and this case seems to suggest that the two systems are independent.
[22] Poreh et al.[23] describe a case study of patient A.D., whose damage to the fornix rendered the hippocampus useless, but spared adjacent cortical areas – a fairly rare injury.
[26] A similar case involved Clive Wearing, an accomplished musicologist who contracted a cold sore virus that attacked his brain, causing herpes simplex encephalitis.
[28] Another case in the literature is Eugene Pauly,[29] known as E.P., a severely amnesic patient, owing to viral encephalitis,[29] who was able to learn three-word sentences.
Notable examples include Lucy Whitmore in 50 First Dates, Joseph Gordon-Levitt in The Lookout, Kaori Fujimiya in One Week Friends, Chihiro Shindou in Ef: A Fairy Tale of the Two, Christine Lucas in Before I Go to Sleep, Gus in Remember Sunday.
Christopher Nolan's psychological crime film Memento (2000) contains a distinguished depiction of anterograde amnesia, in that the memory-impaired protagonist Leonard Shelby is trying to identify and kill the man who raped and murdered his wife, and does so through a system of writing crucial details related to the search on his body and on the blank spaces of Polaroid photographs.
[32] Ghajini (2008), a Hindi language film from India based on Memento, in which the main protagonist Sanjay Singhania played by Amir Khan has short-term memory loss, a variant of amnesia.
The disorder has also been portrayed in music by English musician the Caretaker in Theoretically Pure Anterograde Amnesia (2005) and Additional Amnesiac Memories (2006).
[35] In the 1964 film 36 Hours, Rod Taylor plays Nazi Major Walter Gerber, a psychiatrist who has developed an effective method for treating German soldiers with what is now known as PTSD – and for painlessly extracting information from Allied prisoners.
The technique involves convincing patients that years have passed, the war is over, and that they have anterograde amnesia, which supposedly can be cured with talk therapy.
After teaming up with the perverted "Ultimate Secret Agent" Yuto Kamishiro in an attempt to discover the perpetrator behind the Tragedy, Ryoko learns that she herself was personally involved in the event as the true Junko.
In the 2016 video game Phoenix Wright: Ace Attorney – Spirit of Justice, the character Sorin Sprocket is eventually revealed to have anterograde amnesia, which he developed after unintentionally causing a car accident which killed his sister.
[37] The episode also deals with legal issues concerning the disorder, when it is debated during Ellen Wyatt's trial as to whether Sorin's journal can be considered a proper substitution to his memories for the sake of viable witness testimony.
Dangers imposed by this also come into play when it is revealed that a page in Sorin's journal had been altered by someone, which causes him to go into a mental collapse, afraid that any of his other memories and thoughts could also have arisen from someone else's manipulation.
