PMID- 30656446
OWN - NLM
STAT- MEDLINE
DCOM- 20190830
LR  - 20190830
IS  - 1863-2661 (Electronic)
IS  - 1863-2653 (Linking)
VI  - 224
IP  - 3
DP  - 2019 Apr
TI  - Categorical laterality indices in fMRI: a parallel with classic similarity 
      indices.
PG  - 1377-1383
LID - 10.1007/s00429-019-01833-9 [doi]
AB  - FMRI-based laterality index (LI) is widely used to assess relative left-right 
      differences in brain function. Here we investigated objective ways to generate 
      categorical LI. By defining left and right hemisphere contributions as discrete 
      random variables, it was possible to depict the probability mass function of LI. 
      Its distribution has a shape of a symmetrical truncated exponential function. We 
      demonstrate that LI = +/- 0.2 is an objective cut-off to categorize classification 
      of hemispheric dominance. We then searched for parallels between LI and classic 
      similarity or association indices. A parallel between LI and Sorensen-Dice index 
      can be established under maximal voxel-wise overlap between left and right 
      hemispheres. To redefine LI as a proper distance metric, we suggest instead to 
      relate LI to Jaccard-Tanimoto similarity index. Accordingly, a new LI formula can 
      be derived: LI(new) = LH-RH/max(LH,RH). Using this new formula, all LI(new) 
      values follow a uniform-like distribution, and optimal categorization of 
      hemispheric dominance can be achieved at cut-off LI(new) = +/- 1/3. Overall, this 
      study investigated some statistical properties of LI and revealed interesting 
      parallels with classic similarity indices in taxonomy. The theoretical 
      distribution of LI should be taken into account when quantifying any existing 
      bias in empirical distributions of lateralization in healthy or clinical 
      populations.
FAU - Seghier, Mohamed L
AU  - Seghier ML
AD  - Cognitive Neuroimaging Unit, Emirates College for Advanced Education, PO Box: 
      126662, Abu Dhabi, United Arab Emirates. mseghier@gmail.com.
LA  - eng
PT  - Journal Article
DEP - 20190117
PL  - Germany
TA  - Brain Struct Funct
JT  - Brain structure & function
JID - 101282001
RN  - S88TT14065 (Oxygen)
SB  - IM
MH  - Brain/*diagnostic imaging/physiology
MH  - *Brain Mapping
MH  - Female
MH  - Functional Laterality/*physiology
MH  - Humans
MH  - Image Processing, Computer-Assisted
MH  - *Magnetic Resonance Imaging
MH  - Male
MH  - Oxygen/blood
OTO - NOTNLM
OT  - Categorization cut-off
OT  - Dice index
OT  - Hemispheric dominance
OT  - Jaccard index
OT  - Lateralisation
OT  - Laterality index
OT  - Probability mass function
EDAT- 2019/01/19 06:00
MHDA- 2019/08/31 06:00
CRDT- 2019/01/19 06:00
PHST- 2018/09/27 00:00 [received]
PHST- 2019/01/08 00:00 [accepted]
PHST- 2019/01/19 06:00 [pubmed]
PHST- 2019/08/31 06:00 [medline]
PHST- 2019/01/19 06:00 [entrez]
AID - 10.1007/s00429-019-01833-9 [pii]
AID - 10.1007/s00429-019-01833-9 [doi]
PST - ppublish
SO  - Brain Struct Funct. 2019 Apr;224(3):1377-1383. doi: 10.1007/s00429-019-01833-9. 
      Epub 2019 Jan 17.