Journal of Cerebral Blood Flow & Metabolism (2010), 1–2                                                             & 2010...
Commentary2            rapidly map individual eloquent cortical areas                 Hahnloser RHR, Kozhevnikov AA, Fee M...
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Feature commentary-jcbfm-nature-publishing-2011

  1. 1. Journal of Cerebral Blood Flow & Metabolism (2010), 1–2 & 2010 ISCBFM All rights reserved 0271-678X/10 $32.00 www.jcbfm.comFeature Article CommentaryA new technique for functional imagingin songbirds and beyondHenning U VossPre-Clinical Imaging Division, Citigroup Biomedical Imaging Center, Weill Cornell Medical College,New York, New York, USAJournal of Cerebral Blood Flow & Metabolism advance online publication, 20 October 2010; doi:10.1038/jcbfm.2010.190Keywords: functional MRI; functional optical imaging; hemodynamics; songbirdsThe quantitative study of cerebral hemodynamics information to more classical methods of birdsongrequires measurement methods with high spatial and research based on electrical recordings or functionaltemporal resolution. In the best case, these methods MRI by virtue of its quantitative nature. For example,are noninvasive or even contact free. Mottin et al could it be used to get a better picture of how the(2010, this issue) propose picosecond optical tomo- song system works as a network of connected songgraphy, or POT, to quantitatively image hemody- nuclei by quantitatively analyzing the hemodynamicnamics in a contact-free way. POT relies on white response dynamics?laser light spectral absorption in the near-infrared Besides further applications in songbird research,measured with a streak camera. The tens-of- these advantages could also play out in functionalfemtosecond temporal resolution of the streak cam- studies of neurovascular plasticity, as has beenera enables depth-specific imaging of oxy- and observed for example after focal cerebral injurydeoxy-hemoglobin concentration with submillimeter (Whitaker et al, 2007), or in neurovascular repairresolution. The authors validate their technique on a mechanisms after induction of small-scale corticalsongbird model of auditory perception and show vascular lesions (Nishimura et al, 2006) that areresults consistent with previous findings that were believed to have a function in aging-related cognitiveobtained using functional magnetic resonance ima- decline. As they point out at the end of the article,ging (MRI). Furthermore, they shed new light onto this is a field worth studying for Mottin et al too, bybrain oxygen recoupling in these tachymetabolic using their technology to investigate a proposed linkanimals, results that would be difficult to obtain with between brain aging and changes in vascular reac-conventional functional MRI. tivity found by functional MRI. However, it remains The songbird model is an interesting choice for to be seen if POT can compete with the very powerfuldemonstrating the validity of POT, as songbirds imaging techniques already used in this field, suchprovide a versatile model for studying neuronal as multiphoton microscopy and voltage sensitive dyeplasticity (Brenowitz, 2004). This includes the ability imaging (Brown et al, 2009).to generate a significant amount of new neurons in Finally, the authors propose a way to expand POTadult life (Nottebohm, 2002), as well as the rare trait into a true two-dimensional imaging method (so farof vocal learning (Mooney, 2009). Songbirds produce it can only image line segments) by sweepingbehavioral patterns of high complexity (song) that the optical field over the sample. In the longcan be precisely recorded and related to neuronal term, functional imaging methods like this could,dynamics from time scales of milliseconds to a time once developed for human applications, becomespanning several generations (Hahnloser et al, 2002; more relevant clinically (Prakash et al, 2009). AsFeher et al, 2009). It might be possible that POT adds functional MRI maps of the human cortex display a considerable amount of interindividual variability, it is necessary to map, for example, eloquent sensor-Correspondence: Dr HU Voss, Pre-Clinical Imaging Division, imotor areas before or during brain tumor surgery.Citigroup Biomedical Imaging Center, Weill Cornell Medical Often, a combination of electrocortical stimulationCollege, 516 E 72nd Street, New York, NY 10021, USA. mapping on the exposed brain and functional MRI isE-mail: hev2006@med.cornell.eduThis study was supported by NSF award 0956306 and Nancy M used to identify eloquent sensorimotor areasand Samuel C Fleming Research Scholar Award in Intercampus and thus to reduce surgical risks (Holodny, 2008). ItCollaborations, Cornell University. can be envisioned that optical imaging methodsReceived 30 September 2010; accepted 30 September 2010 based on POT could be used in the operating room to
  2. 2. Commentary2 rapidly map individual eloquent cortical areas Hahnloser RHR, Kozhevnikov AA, Fee MS (2002) An ultra- during surgery. sparse code underlies the generation of neural se- quences in a songbird. Nature 419:65–70 Holodny AI (2008) Functional Neuroimaging—A Clinical Disclosure/conflict of interest Approach. New York: Informa Healthcare Mooney R (2009) Neural mechanisms for learned birdsong. The author declares no conflict of interest. Learn Mem 16:655–69 Mottin S, Montcel B, de Chatellus HG, Ramstein S (2010) Functional white laser imaging to study brain oxygen uncoupling/recoupling in songbirds. J Cereb Blood Flow References Metab (this issue) Nishimura N, Schaffer CB, Friedman B, Tsai PS, Lyden PD, Brenowitz EA (2004) Plasticity of the adult avian Kleinfeld D (2006) Targeted insult to subsurface cortical song control system. Behav Neurobiol Birdsong 1016: blood vessels using ultrashort laser pulses: three models 560–85 of stroke. Nat Methods 3:99–108 Brown CE, Aminoltejari K, Erb H, Winship IR, Murphy TH Nottebohm F (2002) Why are some neurons replaced in (2009) In vivo voltage-sensitive dye imaging in adult adult brain? J Neurosci 22:624–8 mice reveals that somatosensory maps lost to stroke are Prakash N, Uhlemann F, Sheth SA, Bookheimer S, Martin N, replaced over weeks by new structural and functional Toga AW (2009) Current trends in intraoperative optical circuits with prolonged modes of activation within both imaging for functional brain mapping and delineation of the peri-infarct zone and distant sites. J Neurosci lesions of language cortex. Neuroimage 47:T116–26 29:1719–34 Whitaker VR, Cui L, Miller S, Yu SP, Wei L (2007) Whisker Feher O, Wang HB, Saar S, Mitra PP, Tchernichovski O stimulation enhances angiogenesis in the barrel cortex (2009) De novo establishment of wild-type song culture following focal ischemia in mice. J Cereb Blood Flow in the zebra finch. Nature 459:564–8 Metab 27:57–68Journal of Cerebral Blood Flow & Metabolism (2010), 1–2