cerebellum and speculation

I was listening to Lecture 9 from Prof. Gerald Schneider’s course from MIT Open Courseware on Neuroscience & Behaviour . He made a comment to the effect that the cerebellum (which deals with learnt action routines) receives input from all the different senses (with the possible exception of olfaction) and receives input from proprioceptive systems aswell (which makes sense, if the cerebellum is going to control action then it needs to know where the body is in space).

This is fascinating; the cerebellum has sensory input and memory that is apparently completely independent of the cortex!

A number of my colleague are interested in the question of why do objects (& images & smells) stimulate memory when talking does not and why do objects stimulate memory in people with dementia?

In ‘Introducing Mind and Brain’ (Gelatly & Zarate, 1998) there is an image of “the distribution and severity of degeneration of the brain in an average Alzheimer case” (p100). I appreciate that I need to learn more about Alzheimers and that there are varieties of dementias and Alzheimers but it is striking that, in the image, there is no damage in the cerebellum.

The brain is a deeply modular structure and, reflecting that, memory appears to be multi-faceted (memory of sound, of vision, of touch, of movement, of smell, of emotion, of events). But, if memory is multi-faceted, how are the facets co-ordinated? As other authors have pointed out, the brain may be modular but we experience seamlessly. There would seem to be 2 options either the different bits of the brain that deal with different aspects of experience also store the memories there and somehow these are co-ordinated centrally, or the memory is stored centrally but stimulates the appropriate centres as necessary. But then the comment from Schreider suggests that memory for learnt process is utterly independent of memory for anything else. (But it can’t be utterly independent if the memory of process provokes other memories.)

Digression – I think it was mentioned in the ‘In Our Time’ programme – researchers did an experiment on a man in a long-term vegetative state where they put him in an MRI scanner and then asked him to imagine himself doing various things. Quite shockingly, the brain showed that he responded to this request; furthermore the measurements showed that when he imagined playing tennis, all the motor control centres that would be needed to play tennis were activated only at a level too low to stimulate his muscles. What can we learn from this?

My feeling is that, when we try to talk to an older person about memory, it’s like we are trying to knock on the front door of memory. But, the problem is that, for some older people, the front door has been bricked up. But, when we give them an object or put them in a period setting, it’s like we’re going via a side door, which is still functioning.

Digression – I was chatting to an artist / health worker a couple of days ago. He recalled an instance where he was able to encourage an older person with dementia to do a drawing. The drawing showed a man by a boat. It turned out that the man doing the drawing used to be a sailor. Strangely, the artist said that the man could not recall his working life verbally but could produce drawings that linked to it. This needs looking at more deeply – can the hands draw on a memory that cannot be voiced?

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About Bruce Davenport

Museum educator and researcher.
This entry was posted in dementia, memory, Perception. Bookmark the permalink.

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