fMRI – “Pluripotentiality” vs. “Degeneracy” Based on Noppenney Friston and Price J. Anat. (2004) 205, pp433–442

Tasks apparently tapping different ‘cognitive functions’ activate the same regions Fig. 3. Peaks of activation in fronto-parietal areas associated with: (A) attention, (B) working memory, (C) episodic retrieval, and (D) conscious perception, extracted from the studies listed in Tables 1–4, respectively. Blank areas indicate the regions with highest level of common regional brain activity across functions, namely bilateral BA 7 and BA 40, left BA 6, and right BA 9. Only the peaks in (or adjacent to) these regions are shown. H.R. Naghavi, L. Nyberg / Consciousness and Cognition 14 (2005) 390–425

Pluripotentiality (one to many) Function 3 Structure A Function 2 State functions? Common processing stage? Or True pluripotentiality? Function 1 If pluripotentiality – at what level? Lobe? Region? Ansemble? Single neuron?

Degeneracy (many to one) Structure C Function 1 Structure B Structure A Different normal strategies? Normal anatomical variation?

Fig. 2 Normal activation patterns during a semantic paradigm Fig. 2 Normal activation patterns during a semantic paradigm. (a) Regions that were consistently activated across all 12 subjects (P < 0.05 corrected). (b,c) Single subject data to illustrate intersubject variability. Circles highlight activations that are specific to only one subject.

Level of description determines Pluripotent\Degenerate Structure: Multiple regions (network) Single regions Neuronal assemplies\populations Single neurons Function E.g. “sentence comprehension” vs. [word recognition; working memory; syntactic parsing…” The level of description determines whether we say there is degeneracy\pluripotentiality or not - for example, there may be a one to one relationship between a region and a function, but a many to one (degenerate) when considering assemblies. Like wise

Degenerate or not? קריאת מילים “orthographic” “phonology”

The spatial resolution Intrinsic resolution is determined by the physiology Precision depends on the voxel size + distrotions Distinguishing two foci is hindered by intersubject variability Neuronal adaptation technique