Fine detail of neurovascular coupling revealed by spatiotemporal analysis of the hemodynamic response to single whisker stimulation in rat barrel cortex.
The spatial resolution of hemodynamic-based neuroimaging techniques, including functional magnetic resonance imaging, is limited by the degree to which neurons regulate their blood supply on a fine scale. Here we investigated the spatial detail of neurovascular events with a combination of high spatiotemporal resolution two-dimensional spectroscopic optical imaging, multichannel electrode recordings and cytochrome oxidase histology in the rodent whisker barrel field. After mechanical stimulation of a single whisker, we found two spatially distinct cortical hemodynamic responses: a transient response in the "upstream" branches of surface arteries and a later highly localized increase in blood volume centered on the activated cortical column. Although the spatial representation of this localized response exceeded that of a single "barrel," the spread of hemodynamic activity accurately reflected the neural response in neighboring columns rather than being due to a passive "overspill." These data confirm hemodynamics are capable of providing accurate "single-condition" maps of neural activity.
Department of Psychology, University of Sheffield, Sheffield S10 2TN, UK. j.berwick@sheffield.ac.uk
J
J
Berwick
D
D
Johnston
M
M
Jones
J
J
Martindale
C
C
Martin
A J
AJ
Kennerley
P
P
Redgrave
J E W
JE
Mayhew
D000818:Animals; D001931:Brain Mapping; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D010812:Physical Stimulation / Q000379:methods; D051381:Rats; D011930:Reaction Time; D013003:Somatosensory Cortex / Q000098:blood supply* / Q000502:physiology*; D013997:Time Factors; D014738:Vibrissae / Q000294:innervation*