News Round-Up: February 2009 1st Edition

This is a remarkable week for two reasons. Firstly a group publishing in Nature Neuroscience have suggested that individual cells are capable of holding memories for short periods of time on the basis of their findings. If this proves correct, then it would represent a paradigm shift in the understanding of brain function and the formation of memories. The second piece of research which seems to have come from nowhere is the revival of an extinct species, the Pyrenean Ibex.  While this is not immediately relevant to psychiatry, this field of research has the potential to have far reaching implications.

Research in Dementia and Related Areas

Alan Johnson, Health Secretary, is unveiling a national dementia strategy to Parliament this week. The consultation document is here (STT1). A slightly abstract piece of research is one at the cellular level, but i’ve included it here as it has important implications for memory. Thus in Nature Neuroscience, Cooper and colleagues have used a patch-clamp recording technique on layer V Pyramidal cells in the Prefrontal Cortex and found that the cell’s depolarisation on receiving input from another cell continues for up to a minute even when the other synapsing neuron is no longer firing. As cocaine has an influence on working memory and also eliminated the depolarisation, the authors conclude that this cell was retaining a memory. Needless to say, the suggestion that it is not the synapses but the cells themselves that are storing the memories is quite staggering and runs 180 degrees to prevailing theory. In my opinion there will almost certainly still be a role for the synapses themselves and associated processes such as Long Term Potentiation. However, should these findings be reliably replicated then this would represent a paradigm shift and add a new perspective to theoretical models of dementia including interventional strategies (STT4). A study in healthy elderly (average age 60 years) volunteers showed an improvement in verbal memory with calorific restriction together with a reduction in C-Reactive Protein and Insulin levels. The results will need further replication but fit with a body of evidence emerging in the area of calorie-restriction. However, such approaches have potential to compromise the immune system and the Department of Health has given advice about not reducing calories during the winter months when infections are more prevalent. Larger and longer term studies will be required before any recommendations can be safely made (STT4).

Miscellaneous

A recently extinct species, the Pyrenean Ibex has been cloned (using DNA from skin samples) after the eggs were introduced into a goat. Unfortunately the infant died soon after birth. This is an astonishing piece of news and will surely trigger an ethical debate while at the same time offering an option unthinkable to conservationalists even a decade ago.

Responses

If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk

Disclaimer

The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

4 comments

  1. Sir, wiith all due respect Gary Lynch has been espousing fundatmental changes to the ‘spines’ of the dendrites for the past 10 years.

    Are you familiar with his work??

    So you are correct, the physiological/measurable change occurs in the receving neuron, and lasts. However, that doesn’t imply that a memory is storing in one neuron.

    As you probably know that brain has approximately 100 million neurons, with that times 1,000 number of synapses.

    http://www.latimes.com/news/nationworld/nation/la-na-memoryfirst19aug19,0,5913608.story

    Hth,

    Gary is at UC/Irvine.

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  2. Dear Hth,

    Thanks for your comments. I wasn’t familiar with his work prior to your comments. You’ve linked to a nice article that seems to capture something of what he is doing and how he does this. I’ve looked briefly at some of his articles and he seems to focus on elucidating the finer details of Long Term Potentiation particularly with intracellular structural changes involving actin as well as more recent articles on ampakines and trophic factors. The importance of LTP is difficult to dispute.

    However the authors of the current article have demonstrated a persistent depolarisation that lasts for up to a minute and is not influenced by further synaptic input. In the crudest sense this can be considered to represent a ‘bit’ of information. The researchers have further modified this response by the use of cocaine and they draw an analogy between the cellular behaviour in this regards and the interference that can also occur in working memory which is associated with the Prefrontal Cortex. This adds a further line of support to their central argument.

    As mentioned above such results would need further replication given their implications. Even though there are many more synapses than neurons, were such a phenomenon to prove correct then one could divide memory into a slower, larger memory store contained within synapses and an immediate but smaller memory store contained within cells. This is consistent with the small number of items that can be stored in working memory in comparison with long term memory. From an evolutionary perspective such a property of neurons would be expected to be conserved. Additionally there is a certain utility in a single neuron being able to store short term information as when neurons first originated, the single unit information store would surely improve the fitness of the organism. The alternative possibility is that a network of neurons with information contained within the synapses spontaneously arose. This in my opinion is much less likely

    Regards

    Justin

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  3. Justin,
    Bottom line is memory involved physical changes in the neuron, intuitive, but now provien. Whether that is within one neuron or betweeen connections of many neurons remains to be seen.
    I think DR. Lynch would argue that a single cell is not the likely component to contain the intracticies of changes that a memory would produce….but we shall see.

    Take care,
    Norm

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    • Hi Norman,

      Thanks for your comments. I’ve been a supporter of the LTP model of memory formation for a while now. With the new study there might now be two mechanisms. As you say, we should wait and see…

      Kind regards

      Justin

      Like

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