Short-Term vs. Long-Term memory problems

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Horus
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27 Sep 2010, 4:44 pm

As i've stated numerous times on WP, I strongly believe I have severe memory problems which I do not have any objective confirmation for. I have undergone six full neuropsychological evaulations in my life and NONE have indicated that most aspects my memory are subnormal in any way. The one exception would be my visual memory and my VS deficits are supposedly fairly mild. Visual memory deficits are common among those with AS/NVLD, so this in itself is hardly unusual.


Nonetheless....I do believe I have severe memory problems which are not commonly associated with AS/NVLD and may not be associated these disorders at all...at least in my case. Aside from problems with visual memory....people with AS/NVLD and autistic spectrum disorders in general often complain of deficits in short-term memory (especially working memory) if they complain of any issues with memory at all. OTOH....most seem to claim their long-term memory is normal or better and quite a few even claim to have an eidetic memory.

For some time now....i've assumed the memory deficits i'm referring to are long-term memory problems. More specfically.....problems with semantic, episodic and procedural long-term memory. One major reason for this is that the memory tests used in the typical clinical setting seem at least comparatively reliable when it comes assessing short-term memory as opposed to long-term memory. If this is indeed the case and I see no reason why it wouldn't be, it is likely because the consolidation of long-term memory is not limited to the 30-minute time delay on most memory tests used in the average clinical settings.

Psychologists once believed said consolidation was limited to this time frame (more or less) and now that view appears to be incorrect. In other words....i've assumed my own memory problems are long-term memory problems since I score within the normal ranges (again...with the exception of visual memory) on all the conventional neuropsychological memory tests. I can think of no reason why these tests wouldn't be reliable in terms of capturing any short-term memory problems I have.


One thing has recently forced me to call this assumption into question though. I have also shown impairment in certain neuropsychological tests like the Halstead-Reitan. To be clear....i've scored within the impaired ranges on certain parts of the H-R and other neuropsych tests. I scored in the <1st percentile on the Category Test for example. The Category Test is one of 8 or 9 (don't recall exactly how many subtests are on H-R off the top of my head) subtests on the Halstead-Reitan. It is considered to be one of the most sensitive measures in terms of detecting brain damage. Also....I have read (in credible book on neuropsychologly) that those who perform poorly on the Category Test frequently complain of "memory problems" though the book didn't specify what kind of memory problems. Based upon my performance on this test and likely several others, the neuropsychologists who've evaluated me believe I likely have frontal lobe deficits. They cannot tell me much in regards to the exact origin/s, nature and extent of these deficits though.




Therefore....assuming I do have some frontal lobe deficits.....i'm wondering if my short-term memory could be impaired and if so, i'm wondering why such impairments would elude detection on the neuropsychological memory tests i've taken. The frontal lobe region is largely, if not entirely, responsible for short-term memory. Likewise....long-term memory is critically dependent on short-term memory for transference. This raises a further question. It would seem that many people with AS have impairments in short-term memory (and said impairments may not be limited to problems with working memory) and therefore it might be safe to assume i'm hardly the only person with AS/NVLD with frontal lobe deficits. If that's the case.....then why do few, if any, others with AS/NVLD complain of memory problems similar to my own? Perhaps I just have some very rare impairments in specific regions of my frontal lobes involved in transferring short memory into long-term memory? Perhaps others with AS/NVLD have frontal lobe deficits which only impact working memory while leaving other aspects of short-term memory (not to mention long-term memory) intact? I could engage in endless speculation about all this...but i'll just stop here for now.


Also....another poster (who is studying cognitive science or something similar at uni) has claimed that there's good evidence to suggest that people with ASDs exhibit deficits in PROCEDURAL memory in disproportionate numbers to the NT population. I haven't been able to verify these claims yet, though I do believe the poster in question knows what they're talking about. I also believe I have significant problems with procedural memory which may or may not have anything to do with *my* AS/NVLD.


Anyway.....I welcome everyone's thoughts about all this. Especially those of you who know more about human memory and neuropsychology in general than I do.



One more thing:


Keep in mind that I also have no objective confirmation of any other neurological anomalies aside from the frontal lobe deficits the neuropsycholgists believe I have based on the tests they've given me. That is....if their claims here can even be legitimately defined as "objective confirmation". In other words....I have no clinical evidence of any abnormalities in my Hippocampus or other regions associated with memory. I suppose such abnormalities may only be determined via neuroimaging scans and I have no access to any at present. Perhaps an EEG or some other neurological/neuropsychological diagnostic tool/s can offer some indication of such abnormalities, but I doubt that.



Mama_to_Grace
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27 Sep 2010, 5:24 pm

I am interested in this as well. My daughter is dx AS and in her neuropsych workup they determined that she has exceptional (99.9%) strength in short term verbal memory. However, on that same test she scored 18th percentile on Visual and Verbal memory. She was not able to complete the test in Working memory so did not score in that area.

However, I have noticed exceptional memory skills with my daughter that are far from typical. She remembers dreams for YEARS as if they just happened. She also once was watching a tv show, stopped it and rewound to a bookcase in a library scene and stated where exactly she had seen one of the obscure books on the shelf. She also notices (strangely) when people wear a piece of clothing they have never worn before.

I am confused about these profound memory skills and yet her below average and nonexistent functioning in working memory and the other subtest. It doesn't make any sense to me that someone could have profound almost eidetic memory in some things and lack the ability to use those memories in working memory. I would be interested in replies to this post. Thanks for posting this topic.



pgd
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27 Sep 2010, 6:21 pm

Short-Term vs. Long-Term memory problems

Words

Absence (Petit mal, complex partial, TLE, and so on)
ADHD Inattentive
Brain injury / concussion
http://www.sportsconcussions.org
Dyslexia
Encephalitis (side-effect of)

Other

http://www.rsna.org/rsna/media/pr2005/Coffee.cfm (Short-term memory)
http://www.coffeescience.org/alert (Mental alertness)

http://en.wikipedia.org/wiki/Alertness
http://en.wikipedia.org/wiki/Attention

The whole area of memory has so very many aspects to it.

http://en.wikipedia.org/wiki/Music_and_the_brain
http://en.wikipedia.org/wiki/Neuroanatomy_of_memory

The most insightful book about memory I recall reading is a How To (understand) Hyperactivity book (1981) about ADHD Inattentive by C. Thomas Wild. Wild reported a temporary, very clear improvement to memory (not a cure) from using a FDA approved alertness aid (Tirend - contains caffeine - 100 mg - plus 14 other ingredients).

More words

Paying Attention
Concentration
Focus
Hearing
http://www.ericdigests.org/2003-5/auditory.htm
Memory
Perception of Motion/Movement
Sustained Attention
Vision

http://www.waiting.com/glossarya.html (Paying attention)
http://www.waiting.com/glossarym.html (Memory)

Modern brain scans are good but still imperfect and are unable to see the underlying causes of memory challenges in all cases. Also, computer/written memory tests are known to be imperfect and simply cannot easily detect all the subtle memory glitches some persons have.

That's my understanding.

Of course, the standard line is pretty close to brain scans see everything and memory tests are all perfect (which is simply a fib - my view today).

Memory challenges in older adults (say 65 and older) are often categorized as:

Dementia
Dementias
Alzheimer
http://www.ninds.nih.gov/disorders/alzh ... isease.htm

and so on.

Again, a huge topic - so many aspects. For many, no easy answers.



Horus
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27 Sep 2010, 7:19 pm

Thanks to both of you for your very interesting and informative replies. It is a very complicated topic which even professionals don't have all the answers for. Therefore...anything I say about it usually requires a considerable amount of time and that's something I don't have the moment. I will reply to both you ASAP, maybe even as early as later tonight. I am bound and determined to get to the bottom of these memory problems I believe I have. That said....I greatly appreciate any comments, questions and insights anyone has about this topic. They can only help to solve this mystery rather than reinforce it.



Mdyar
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27 Sep 2010, 9:17 pm

One fundamental aspect with memory is the cholinergic system, whether long or short term.

Acetycholine plays a significant role in in cognition.

There are several ways to boost levels of acetylcholine:

1) lecithin ------------------- (contraindicated with bipolar disorder).
2) cdp choline
3) choline bitartrate
4) Acetyl l Carnitine
5) piracetam or other acetams. --------( available online in U.S without script).
6) centrophenoxine----------------------- """"""""""

And the list goes on, but a safe bet is one of the top 4 would produce something tangible.

The Catecholamines play a role in cognition, but when there are severe impairments the implication is heavily loaded on the cholinergic side.

Much anecdotal evidence here, not much to lose.

See CERI or Cognitive Enhancement Research Institute.



Horus
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29 Sep 2010, 10:17 pm

Mama_to_Grace wrote:
I am interested in this as well. My daughter is dx AS and in her neuropsych workup they determined that she has exceptional (99.9%) strength in short term verbal memory. However, on that same test she scored 18th percentile on Visual and Verbal memory. She was not able to complete the test in Working memory so did not score in that area.

However, I have noticed exceptional memory skills with my daughter that are far from typical. She remembers dreams for YEARS as if they just happened. She also once was watching a tv show, stopped it and rewound to a bookcase in a library scene and stated where exactly she had seen one of the obscure books on the shelf. She also notices (strangely) when people wear a piece of clothing they have never worn before.



I am confused about these profound memory skills and yet her below average and nonexistent functioning in working memory and the other subtest. It doesn't make any sense to me that someone could have profound almost eidetic memory in some things and lack the ability to use those memories in working memory. I would be interested in replies to this post. Thanks for posting this topic.


Do you know the name of the memory tests your daughter had? If they were the Weschler memory tests (WMS), i'm familiar with those since i've taken them several times. Verbal memory (both ST and LT) seems pretty good in most people with AS. There are limitations in terms of what can be determined about long-term memory from the standard neuropsych memory tests. I believe the measures of short-term memory are much better, but they may not be perfect either. Visual memory is often deficient in those with AS/NLD. I'm not sure what you mean when you say her verbal memory was in the 18th percentile on the same test though. Perhaps her score in the 18th percentile on verbal memory was on a 30-minute delay subtest and her verbal memory score in the 99.9%-tile was on the immediate subtest? :?

Why wasn't she able to complete the working memory test? It's not really surprising that she didn't...since people with ASD's often have problems with working memory as well. Working memory can also be determined via tests like the arithmetic subtest on the Verbal IQ section of WAIS/WISC. I think subtests like digit span are also designed to assess working memory.

It sounds like she has a pretty good long-term memory (at least in terms of episodic memory), but it's hard to tell if her abilities in this area are universal. For example, she may remember her old dreams quite well, but other things which happened long ago may not be as readily accessible to her memory. The same may be true for information and facts (semantic memory) and "hands-on" procedures (procedural memory.) It sounds like her tests of visual memory might not tell the whole story there either. I'd say she has some pretty impressive visual memory skills if she can recall the exact location of obscure books on a shelf and realize that people haven't worn a particular piece of clothing before.

Anyway....this is how memory often works and these strange incongruities in memory aren't exclusive to people with ASD's.
Generally speaking....it seems like people with ASD's often have problems with working memory and maybe to a lesser extent, short-term memory in general. People with AS/NVLD specifically often have problems with visual memory.

There is also some evidence to suggest that those with ASD's may be inclined to have more difficulties with procedural memory (which would involve bodily-kinesthetic skills for one thing), but I don't think there's anything approaching a consensus on that.

Those with ASD's tend to have pretty good long-term memories when it comes to episodic (autobiographical) memory and semantic (memory for facts, information) memory, but this is probably not always the case either. Some may have a good LT memory for things that interest them while remembering virtually nothing about subjects they have no interest in. IOW...there are a million stories in the "naked city" when it comes to human memory.



Horus
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29 Sep 2010, 10:45 pm

Quote:
pgd wrote:
Short-Term vs. Long-Term memory problems

Words

Absence (Petit mal, complex partial, TLE, and so on)
ADHD Inattentive
Brain injury / concussion
http://www.sportsconcussions.org
Dyslexia
Encephalitis (side-effect of)

Other

http://www.rsna.org/rsna/media/pr2005/Coffee.cfm (Short-term memory)
http://www.coffeescience.org/alert (Mental alertness)

http://en.wikipedia.org/wiki/Alertness
http://en.wikipedia.org/wiki/Attention

The whole area of memory has so very many aspects to it.

http://en.wikipedia.org/wiki/Music_and_the_brain
http://en.wikipedia.org/wiki/Neuroanatomy_of_memory

The most insightful book about memory I recall reading is a How To (understand) Hyperactivity book (1981) about ADHD Inattentive by C. Thomas Wild. Wild reported a temporary, very clear improvement to memory (not a cure) from using a FDA approved alertness aid (Tirend - contains caffeine - 100 mg - plus 14 other ingredients).

More words

Paying Attention
Concentration
Focus
Hearing
http://www.ericdigests.org/2003-5/auditory.htm
Memory
Perception of Motion/Movement
Sustained Attention
Vision

http://www.waiting.com/glossarya.html (Paying attention)
http://www.waiting.com/glossarym.html (Memory)

Modern brain scans are good but still imperfect and are unable to see the underlying causes of memory challenges in all cases. Also, computer/written memory tests are known to be imperfect and simply cannot easily detect all the subtle memory glitches some persons have.

That's my understanding.

Of course, the standard line is pretty close to brain scans see everything and memory tests are all perfect (which is simply a fib - my view today).

Memory challenges in older adults (say 65 and older) are often categorized as:

Dementia
Dementias
Alzheimer
http://www.ninds.nih.gov/disorders/alzh ... isease.htm

and so on.



Based upon what the neuropsychologist who just evaluated me said, PET scans may be the best neuroimaging has to offer right now insofar as identifying neurological causes for memory problems. I suppose this has something to do with the PET scan's ability to detect detail at the molecular level.


"While some imaging scans such as CT and MRI isolate organic anatomic changes in the body, PET and SPECT are capable of detecting areas of molecular biology detail (even prior to anatomic change). PET scanning does this using radiolabelled molecular probes that have different rates of uptake depending on the type and function of tissue involved. Changing of regional blood flow in various anatomic structures (as a measure of the injected positron emitter) can be visualized and relatively quantified with a PET scan".

http://en.wikipedia.org/wiki/PET_scan#Applications

After reading the following...I can why PET scans might be more useful in determining the origin/nature of memory problems than other types of imaging like MRI.


"PET scan of the human brain.Neurology: PET neuroimaging is based on an assumption that areas of high radioactivity are associated with brain activity. What is actually measured indirectly is the flow of blood to different parts of the brain, which is generally believed to be correlated, and has been measured using the tracer oxygen-15. However, because of its 2-minute half-life O-15 must be piped directly from a medical cyclotron for such uses, and this is difficult. In practice, since the brain is normally a rapid user of glucose, and since brain pathologies such as Alzheimer's disease greatly decrease brain metabolism of both glucose and oxygen in tandem, standard FDG-PET of the brain, which measures regional glucose use, may also be successfully used to differentiate Alzheimer's disease from other dementing processes, and also to make early diagnosis of Alzheimer's disease. The advantage of FDG-PET for these uses is its much wider availability. PET imaging with FDG can also be used for localization of seizure focus: A seizure focus will appear as hypometabolic during an interictal scan. Several radiotracers (i.e. radioligands) have been developed for PET that are ligands for specific neuroreceptor subtypes such as [11C] raclopride and [18F] fallypride for dopamine D2/D3 receptors, [11C]McN 5652 and [11C]DASB for serotonin transporters, or enzyme substrates (e.g. 6-FDOPA for the AADC enzyme). These agents permit the visualization of neuroreceptor pools in the context of a plurality of neuropsychiatric and neurologic illnesses. A novel probe developed at the University of Pittsburgh termed PIB (Pittsburgh compound B) permits the visualization of amyloid plaques in the brains of Alzheimer's patients. This technology could assist clinicians in making a positive clinical diagnosis of AD pre-mortem and aid in the development of novel anti-amyloid therapies. [11C]PMP (N-[11C]methylpiperidin-4-yl propionate) is a novel radiopharmaceutical used in PET imaging to determine the activity of the acetylcholinergic neurotransmitter system by acting as a substrate for acetylcholinesterase. Post-mortem examination of AD patients have shown decreased levels of acetylcholinesterase. [11C]PMP is used to map the acetylcholinesterase activity in the brain which could allow for pre-mortem diagnosis of AD and help to monitor AD treatments.[10] Avid Radiopharmaceuticals of Philadelphia has developed a compound called 18F-AV-45 that uses the longer-lasting radionuclide fluorine-18 to detect amyloid plaques using PET scans.[11]



Did you ever read any of the studies about developmental amnesia? You should check them out on Pubmed or something. The various case studies are interesting. It was once thought that individuals with DA usually exhibit impairments in episodic memory while their semantic memory intact. Many researchers now believe this may not be the case, at least in many instances. That is..many people with DA may also have some impairments in semantic memory which are subtle and weren't really detected until recently. Also..those with only episodic memory impairments may only have hippocampal abnormalties since it's believed the hippocampus is the "seat" of episodic memory. I believe semantic memory is associated with areas surrounding the hippocampus, but the hippocampus may still play a vital role in semantic memory.



Last edited by Horus on 29 Sep 2010, 10:55 pm, edited 2 times in total.

ScottyN
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29 Sep 2010, 10:50 pm

Based on what you have said in several posts, I am convinced that you do not have significant neurological impairments in your temporal lobes/and or hippocampus. I still think that a fMRI would show normal anatomical structures in those regions. Perhaps you do have some damage to your prefrontal cortex, an area that is important for memory processing. Perhaps information is being lost in the memory loop involving this structure. I do not know. 6 neuropsych evaluations turn out as you say, and yet you still have memory problems? A truly intriguing case.



Horus
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29 Sep 2010, 11:17 pm

ScottyN wrote:
Based on what you have said in several posts, I am convinced that you do not have significant neurological impairments in your temporal lobes/and or hippocampus. I still think that a fMRI would show normal anatomical structures in those regions. Perhaps you do have some damage to your prefrontal cortex, an area that is important for memory processing. Perhaps information is being lost in the memory loop involving this structure. I do not know. 6 neuropsych evaluations turn out as you say, and yet you still have memory problems? A truly intriguing case.



Can you be more specific in terms of why you don't believe I have any neurological impairments in my temporal lobes/hippocampus. AFAIK....the hippocampus has much, if not everything, to do with episodic memory and I do believe I have problems with this aspect of memory. I think the surrounding structures play more of a role in semantic memory and I believe problems are just as serious in that respect.

The prefrontal cortex is supposedly also more involved with episodic memory rather than semantic and keep in mind I DO have some objective evidence for frontal lobe deficits. So if indeed information is being lost in the memory loop involving the PFC, would this mean my short-term memory is not being properly transferred into long-term memory?

I am as "intrigued" as you believe me. Anyway.....there is ample reason to believe significant memory (particularily with long-term memory or mabye especially with VERY long-term memory) impairments can be overlooked entirely by the neuropsych memory tests used in most clincial
settings.

The neuropsychologist who just evaluated me in June confirmed my belief here and said belief was partially formulated from this article I read in the Oxford Journal of Neurology over a year ago.

http://www.ncbi.nlm.nih.gov/pubmed/9339303



Horus
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29 Sep 2010, 11:52 pm

Mdyar wrote:
One fundamental aspect with memory is the cholinergic system, whether long or short term.

Acetycholine plays a significant role in in cognition.

There are several ways to boost levels of acetylcholine:

1) lecithin ------------------- (contraindicated with bipolar disorder).
2) cdp choline
3) choline bitartrate
4) Acetyl l Carnitine
5) piracetam or other acetams. --------( available online in U.S without script).
6) centrophenoxine----------------------- """"""""""

And the list goes on, but a safe bet is one of the top 4 would produce something tangible.

The Catecholamines play a role in cognition, but when there are severe impairments the implication is heavily loaded on the cholinergic side.

Much anecdotal evidence here, not much to lose.

See CERI or Cognitive Enhancement Research Institute.



Right.....and I really don't know what, if anything, could determine any deficiencies I may have in the cholinergic system. I suppose I could just assume I have problems in this area and treat them accordingly I have never been dx-ed with bipolar disorder, so I doubt lecitin present a problem for me. Do you think I could get enough choline to significantly boost my levels of acetylcholine simply from the dietary sources which are rich in choline?

Good sources would include eggs and wheat germ for example.


Or do you feel that acetyl l Carnitine would be my best bet in this regard?

The U.S. institute of medicine has the adequate intake of choline for the average male is 550 mg per day. This amount could easily be obtained from dietary sources alone, but i'm not sure if it's enough to significantly increase the levels of acetylcholine.

I'm glad you mentioned the Catecholamines and they role they play in cognition. Catechol-O-methyl transferase is one of the enzymes that degrades the catecholamines. There are several drugs which specifically target the COMT. Considering that I have been dx-ed with either schizoptypal or schizoid personality disorder on five out of the six neuropsych evals i've had, i'm wondering I have an inherited variant of the COMT gene. I say this because some psycholgists believe both these cluster A "odd" or "eccentric" personality disorders are a "schizophrenic spectrum"...if there truly is such a thing. The evidence about all this is insufficient at present though, so again i'm just engaging in speculation here. COMT can have a negative impact on the catecholamines and therefore, cognition itself may be negatively impacted. I'm not sure if memory itself would be affected in any substantial fashion though.

Anyway...still doing my research....very slowly....but very surely. Thanks again for the info here and I will be in touch via pm ASAP. Most likely not long after I return home on Tues, Oct 5th. :)



ScottyN
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30 Sep 2010, 12:39 am

If you have damage to your prefrontal cortex, the ability to separate events in time will be impaired. This can have an impact on how the information is "dumped" into the hippocampus for long term memory processing. You may then of course have trouble retrieving the chronology of events in your long-term memory. If, however, as you believe: there is actual temporal lobe damage, then amnesia of varying degrees can be expected. Hippocampal damage would be particularily devastating. You would be impaired at any kind of learning task in which there is a delay between presentation and recall. Most of your posts are lucid, and you are highly intelligent. I see little or no global amnesia in regards to response to others, and your ability to answer posts in response to chronological order is not impaired. There might be a defects in your temporal lobe anatomy, but they are probably subtle and not severe. At least this is my interpretation. I do not know enough about your situation, so only you can determine how impaired you feel. But in 6 neuropsych exams, if a person had serious temporal lobe damage, then the amnesia would show up in the results. Since you state the exams were normal, then your impairment in these brain regions must probably be minor.



pgd
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30 Sep 2010, 4:24 am

Horus wrote:
Quote:
pgd wrote:
Short-Term vs. Long-Term memory problems

Words

Absence (Petit mal, complex partial, TLE, and so on)
ADHD Inattentive
Brain injury / concussion
http://www.sportsconcussions.org
Dyslexia
Encephalitis (side-effect of)

Other

http://www.rsna.org/rsna/media/pr2005/Coffee.cfm (Short-term memory)
http://www.coffeescience.org/alert (Mental alertness)

http://en.wikipedia.org/wiki/Alertness
http://en.wikipedia.org/wiki/Attention

The whole area of memory has so very many aspects to it.

http://en.wikipedia.org/wiki/Music_and_the_brain
http://en.wikipedia.org/wiki/Neuroanatomy_of_memory

The most insightful book about memory I recall reading is a How To (understand) Hyperactivity book (1981) about ADHD Inattentive by C. Thomas Wild. Wild reported a temporary, very clear improvement to memory (not a cure) from using a FDA approved alertness aid (Tirend - contains caffeine - 100 mg - plus 14 other ingredients).

More words

Paying Attention
Concentration
Focus
Hearing
http://www.ericdigests.org/2003-5/auditory.htm
Memory
Perception of Motion/Movement
Sustained Attention
Vision

http://www.waiting.com/glossarya.html (Paying attention)
http://www.waiting.com/glossarym.html (Memory)

Modern brain scans are good but still imperfect and are unable to see the underlying causes of memory challenges in all cases. Also, computer/written memory tests are known to be imperfect and simply cannot easily detect all the subtle memory glitches some persons have.

That's my understanding.

Of course, the standard line is pretty close to brain scans see everything and memory tests are all perfect (which is simply a fib - my view today).

Memory challenges in older adults (say 65 and older) are often categorized as:

Dementia
Dementias
Alzheimer
http://www.ninds.nih.gov/disorders/alzh ... isease.htm

and so on.



Based upon what the neuropsychologist who just evaluated me said, PET scans may be the best neuroimaging has to offer right now insofar as identifying neurological causes for memory problems. I suppose this has something to do with the PET scan's ability to detect detail at the molecular level.


"While some imaging scans such as CT and MRI isolate organic anatomic changes in the body, PET and SPECT are capable of detecting areas of molecular biology detail (even prior to anatomic change). PET scanning does this using radiolabelled molecular probes that have different rates of uptake depending on the type and function of tissue involved. Changing of regional blood flow in various anatomic structures (as a measure of the injected positron emitter) can be visualized and relatively quantified with a PET scan".

http://en.wikipedia.org/wiki/PET_scan#Applications

After reading the following...I can why PET scans might be more useful in determining the origin/nature of memory problems than other types of imaging like MRI.


"PET scan of the human brain.Neurology: PET neuroimaging is based on an assumption that areas of high radioactivity are associated with brain activity. What is actually measured indirectly is the flow of blood to different parts of the brain, which is generally believed to be correlated, and has been measured using the tracer oxygen-15. However, because of its 2-minute half-life O-15 must be piped directly from a medical cyclotron for such uses, and this is difficult. In practice, since the brain is normally a rapid user of glucose, and since brain pathologies such as Alzheimer's disease greatly decrease brain metabolism of both glucose and oxygen in tandem, standard FDG-PET of the brain, which measures regional glucose use, may also be successfully used to differentiate Alzheimer's disease from other dementing processes, and also to make early diagnosis of Alzheimer's disease. The advantage of FDG-PET for these uses is its much wider availability. PET imaging with FDG can also be used for localization of seizure focus: A seizure focus will appear as hypometabolic during an interictal scan. Several radiotracers (i.e. radioligands) have been developed for PET that are ligands for specific neuroreceptor subtypes such as [11C] raclopride and [18F] fallypride for dopamine D2/D3 receptors, [11C]McN 5652 and [11C]DASB for serotonin transporters, or enzyme substrates (e.g. 6-FDOPA for the AADC enzyme). These agents permit the visualization of neuroreceptor pools in the context of a plurality of neuropsychiatric and neurologic illnesses. A novel probe developed at the University of Pittsburgh termed PIB (Pittsburgh compound B) permits the visualization of amyloid plaques in the brains of Alzheimer's patients. This technology could assist clinicians in making a positive clinical diagnosis of AD pre-mortem and aid in the development of novel anti-amyloid therapies. [11C]PMP (N-[11C]methylpiperidin-4-yl propionate) is a novel radiopharmaceutical used in PET imaging to determine the activity of the acetylcholinergic neurotransmitter system by acting as a substrate for acetylcholinesterase. Post-mortem examination of AD patients have shown decreased levels of acetylcholinesterase. [11C]PMP is used to map the acetylcholinesterase activity in the brain which could allow for pre-mortem diagnosis of AD and help to monitor AD treatments.[10] Avid Radiopharmaceuticals of Philadelphia has developed a compound called 18F-AV-45 that uses the longer-lasting radionuclide fluorine-18 to detect amyloid plaques using PET scans.[11]



Did you ever read any of the studies about developmental amnesia? You should check them out on Pubmed or something. The various case studies are interesting. It was once thought that individuals with DA usually exhibit impairments in episodic memory while their semantic memory intact. Many researchers now believe this may not be the case, at least in many instances. That is..many people with DA may also have some impairments in semantic memory which are subtle and weren't really detected until recently. Also..those with only episodic memory impairments may only have hippocampal abnormalties since it's believed the hippocampus is the "seat" of episodic memory. I believe semantic memory is associated with areas surrounding the hippocampus, but the hippocampus may still play a vital role in semantic memory.


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Memory, Semantic - Memory for facts, usually learned through repetition.

Memory Episodic - Memory for ongoing events in a person's life. More easily impaired than semantic memory, perhaps because rehearsal or repetition tends to be minimal.

http://www.waiting.com/glossarym.html

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Amnesia - Lack of memory about events occurring during a particular period of time. See also: anterograde amnesia, retrograde amnesia, post-traumatic amnesia.

http://www.waiting.com/glossarya.html



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30 Sep 2010, 4:35 am

Horus wrote:
ScottyN wrote:
Based on what you have said in several posts, I am convinced that you do not have significant neurological impairments in your temporal lobes/and or hippocampus. I still think that a fMRI would show normal anatomical structures in those regions. Perhaps you do have some damage to your prefrontal cortex, an area that is important for memory processing. Perhaps information is being lost in the memory loop involving this structure. I do not know. 6 neuropsych evaluations turn out as you say, and yet you still have memory problems? A truly intriguing case.



Can you be more specific in terms of why you don't believe I have any neurological impairments in my temporal lobes/hippocampus. AFAIK....the hippocampus has much, if not everything, to do with episodic memory and I do believe I have problems with this aspect of memory. I think the surrounding structures play more of a role in semantic memory and I believe problems are just as serious in that respect.

The prefrontal cortex is supposedly also more involved with episodic memory rather than semantic and keep in mind I DO have some objective evidence for frontal lobe deficits. So if indeed information is being lost in the memory loop involving the PFC, would this mean my short-term memory is not being properly transferred into long-term memory?

I am as "intrigued" as you believe me. Anyway.....there is ample reason to believe significant memory (particularily with long-term memory or mabye especially with VERY long-term memory) impairments can be overlooked entirely by the neuropsych memory tests used in most clincial
settings.

The neuropsychologist who just evaluated me in June confirmed my belief here and said belief was partially formulated from this article I read in the Oxford Journal of Neurology over a year ago.

http://www.ncbi.nlm.nih.gov/pubmed/9339303


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http://www.ncbi.nlm.nih.gov/pubmed/9339303 leads to: Brain Cogn. 1997 Oct;35(1):71-84.

Accelerated forgetting in association with temporal lobe epilepsy and
paraneoplastic encephalitis.

O'Connor M, Sieggreen MA, Ahern G, Schomer D, Mesulam M.

Memory Disorders Research Center, Boston University School of Medicine, MA, USA.

Abstract

The association between epilepsy and amnesia is studied in patient J.T. who
presented with a very unusual pattern of memory loss with retention of
information for hours to days but rapid forgetting of information that exceeded
this time frame. J.T.'s unusual memory profile was studied with several tests
administered over week-long intervals of time. There was evidence that his
retention decreased in conjunction with increased seizures. During a trial of
paraldehyde, a decrease in seizure frequency was associated with enhanced
memory. J.T.'s memory problem was unlike that described in prototypical cases of
amnesia. His day-long retention of new information alongside his absolute loss
of that information days later is consistent with the idea that consolidation is
a process that occurs over lengthy periods of time.

PMID: 9339303 [PubMed - indexed for MEDLINE]

Publication Types, MeSH Terms, Grant Support
LinkOut - more resources

http://www.ncbi.nlm.nih.gov/pubmed/9339303

...

(Source)

Short-Term vs. Long-Term memory problems

http://www.wrongplanet.net/postt138930.html

. . .

The above, accelerated forgetting in association with temporal lobe epilepsy and
paraneoplastic encephalitis, is interesting since it goes into ideas like:

- retention of information for hours and days
- then, rapid forgetting of information.

...

Memory/Learning

- Change in person's understanding or behavior due to experience or practice. Often thought of as acquisition of new information. For example, a person who learns quickly will likely remember an entire set of instructions after hearing them a single time. A patient with severely impaired learning ability will show little gain in recall after numerous repetitions. Learning and memory are interdependent. If immediate memory is poor, learning will be poor because only a portion of the information will be available for rehearsal/repetition. It is important to note that patients may have intact learning ability, but poor delayed memory. For example, a brain-injured patient may learn a set of instructions after several repetitions, but forget them the next day.

http://www.waiting.com/glossarym.html



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30 Sep 2010, 4:49 am

I'm beginning to suspect that I have some kind of memory disorder, but I cannot begin to grasp in what way.


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30 Sep 2010, 5:48 am

My very first thought is, because memory is essentially the extension of our senses, it should not not be considered as a whole independent part.

Horus, when somebody reminds you of what you think you have forgot, do you remember? If yes, it might be only when you try to tap into your memories that might be dysfunctional.


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