and H.M, who have medial temporal damage and anterograde amnesia, still have perceptual priming. Priming was accomplished in many different experiments of amnesia, and it was found that the patients can be primed; they have no conscious recall of the event, but the response is there. Those patients did well in the word fragment completion task. There is some evidence that non-declarative memory can be held onto in the form of motor skills. This idea was disputed, though, because it is argued that motor skills require both declarative and non-declarative information. Causes
There are three generalized categories in which amnesia could be acquired by a person. The three categories are head trauma (example: head injuries), traumatic events (example: seeing something devastating to the mind), or physical deficiencies (example: atrophy of the hippocampus). The majority of amnesia and related memory issues derive from the first two categories as these are more common and the third could be considered a subcategory of the first. Head trauma is a very broad range as it deals with any kind of injury or active action toward the brain which might cause amnesia. Retrograde and anterograde amnesia is more often seen from events like this, an exact example of a cause of the two would be electroconvulsive therapy, which would cause both briefly for the receiving patient. Traumatic events are more subjective. What is traumatic is dependent on what the person finds to be traumatic.
Treating alcoholism and preventing alcohol and illicit drug use can prevent further damage, but in most cases will not recover lost memory.Although improvements occur when patients receive certain treatments, there is still no actual cure remedy for amnesia so far. To what extent the patient recovers and how long the amnesia will continue depends on the type and severity of the lesion. History
French psychologist Theodule-Armand Ribot was among the first scientists to study amnesia. He proposed Ribots Law which states that there is a time gradient in retrograde amnesia. The law follows a logical progression of memory loss due to disease. First, a patient loses the recent memories, then personal memories, and finally intellectual memories. He implied that the most recent memories were lost first.Case studies have played a large role in the discovery of amnesia and the parts of the brain that were affected. The studies gave important insight into how amnesia affects the brain. The studies also gave scientists the resources into improving their knowledge about amnesia and insight into a cure or prevention. There are several extremely important case studies: Henry Molaison, R.B, and G.D.

Henry Molaison
Henry Molaison, formerly known as H.M., changed the way people thought of memory. The case was first reported in a paper by William Beecher Scoville and Brenda Milner in 1957. He was a patient who had  severe epilepsy attributed to a bicycle accident at the age of nine.