Hi Peter,
In terms of interpreting SPM activations pragmatically, there is a good
correlation in visual cortex between single cell spiking activity and BOLD
contrast, although the details of the mechanistic link remain uncertain.
Our paper demonstrates this for V5/MT:
Rees G, Friston KJ, Koch C. A direct quantitative relationship between the
functional properties of human and macaque V5. Nature Neuroscience, 3,
716-23 (2000) {See also News & Views}
...and the accompanying N&V by David Heeger shows that contrast response
functions in V1 follow the same pattern. So the linear relationship between
spiking and BOLD appears to hold for two different types of stimuli in two
different cortical areas. There's no guarantee that holds outside visual
cortex, of course, but it's a start.
Best wishes,
Geraint
___________________________________________
***NOTE NEW ADDRESS FROM 28TH FEB***
Institute of Cognitive Neuroscience
University College London
Alexandra House
17 Queen Square
London WC1N 3BG
voice +44-(0)20-7679-5496
fax +44-(0)20-7813-2835
email [log in to unmask]
web http://www.klab.caltech.edu/~geraint
____________________________________________
> Dear List
> When someone undergos a particular cognitive activation task (eg a verbal
> fluency test for sake of argument) and SPM finds 'activations' and
> 'deactivations' relative to a control condition, what are the principle
> contributors at the cellular and synaptic level to this increase or decrease
> in
> metabolic requirements in the region identified?
>
> For example, is it mainly the metabolic requirements related to
> glutamate/other EAAs release and reuptake or are other identified
> neurotransmitters equally or more important etc etc. Are the relevant
> contributions of neuronal vs glial metablism known?
>
> And am I even right to assume that the 'activation' represents mainly synaptic
> activity as opposed to, say, cell body metabolism?
>
> While the question is not completely SPM-related, I'd be grateful for any info
> or to be pointed towards relevant references.
>
> Thanks in advance.
>
> Peter Talbot
> ----------------------
> Dr Peter Talbot
> Department of Mental Health
> Queens University Belfast
> Whitla Medical Building
> Lisburn Road
> Belfast BT9 7BL,
> NORTHERN IRELAND, U.K.
>
> Phone: +44 (0)28 9027 2166
> Phone: +44 (0)28 9033 5791
>
> Fax: +44 (0)28 9032 4543
> Email: [log in to unmask]
>
