Editing Muscle memory (section)

== Impairment ==
It is difficult to display cases of "pure" motor memory impairment because the memory system is so widespread throughout the brain that damage is not often isolated to one specific type of memory.  Likewise,  diseases commonly associated with motor deficits, such as [[Huntington's]] and [[Parkinson's disease]], have a wide variety of symptoms and associated brain damage that make it impossible to pinpoint whether or not motor memory is in fact impaired.  Case studies have provided some examples of how motor memory has been implemented in patients with brain damage.

As Edward S. Casey notes in Remembering, Second Edition: A Phenomenological Study,  declarative memory, a process that involves an initial fragile learning period. "The activity of the past, in short, resides in its habitual enactment in the present."

=== Consolidation deficit ===
A recent issue in motor memory is whether or not it consolidates in a manner similar to declarative memory, a process that involves an initial fragile learning period that eventually becomes stable and less susceptible to damage over time.<ref name = "Krakauer" /> An example of stable motor memory consolidation in a patient with brain damage is the case of [[Clive Wearing]]. Clive has severe anterograde and retrograde amnesia owing to damage in his temporal lobes, frontal lobes, and hippocampi, which prevents him from storing any new memories and making him aware of only the present moment. However, Clive still retains access to his procedural memories, to be specific, the motor memories involved in playing the piano. This could be because motor memory is demonstrated through savings over several trials of learning, whereas declarative memory is demonstrated through recall of a single item.<ref name = "Krakauer" />  This suggests that lesions in certain brain areas normally associated with declarative memory would not affect motor memory for a well-learned skill.

=== Dysgraphia for the alphabet ===
Case study: 54-year-old man with known history of [[epilepsy]]
	
This patient was diagnosed with a pure form of [[dysgraphia]] of letters, meaning he had no other speech or reading impairments.<ref name="Kapur">{{cite journal |last1=Kapur |first1=N. |last2=Lawton |first2=N. F. |year=1983 |title=Dysgraphia for Letters: a Form of Motor Memory Deficit? |journal= Journal of Neurology, Neurosurgery & Psychiatry|volume=46 |issue=6 |pages=573–575 |doi=10.1136/jnnp.46.6.573 |pmid=6875593 |pmc=1027454 }}</ref> His impairment was specific to letters in the alphabet. He was able to copy letters from the alphabet, but he was not able to write these letters.<ref name = "Kapur" /> He had previously been rated average on the [[Wechsler Adult Intelligence Scale]]'s vocabulary subtest for writing ability comparative to his age before his diagnosis.<ref name="Kapur" /> His writing impairment consisted of difficulty remembering motor movements associated with the letters he was supposed to write.<ref name="Kapur" /> He was able to copy the letters, and also form images that were similar to the letters.<ref name="Kapur" /> This suggests that dysgraphia for letters is a deficit related to motor memory.<ref name="Kapur" /> Somehow there is a distinct process within the brain related to writing letters, which is dissociated from copying and drawing letter-like items.