Pseudo-random procedures for rapid presentation rates using optical imaging and spectroscopy.
Optical imaging of rat barrel cortex has provided detailed spatio-temporal maps of functional cortical architecture. We describe an event-related procedure (ERP) for optical imaging based on selective signal averaging as reported by Burock et al., using an anti-correlative pseudo-random event sequence. The sequence used 1 s vibrissal stimulation at 5 Hz, with an interevent interval of 2 s. This rapid presentation rate allows for greater statistical power per unit time, and allows for direct comparison of event-related studies with other imaging modalities. The spatio-temporal characteristics of single wavelength and spectrographic results were found to be comparable with those obtained by standard techniques, although a general lessening of haemodynamic response function (HRF) was noted. We also describe a method of locating barrel activity by spectral analysis of summed event data. Using this technique, the power spectrum of remitted light from the barrel region was found to peak within +/- 0.12 Hz of the inter-event interval frequency.
Department of Academic Radiology, University of Sheffield, UK.
J
J
Martindale
J
J
Berwick
D
D
Johnston
M
M
Jones
Y
Y
Zheng
P
P
Coffey
M
M
Paley
J
J
Mayhew
D000465:Algorithms; D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D010108:Oxyhemoglobins / Q000378:metabolism; D051381:Rats; D011930:Reaction Time; D013053:Spectrophotometry / Q000379:methods; D014738:Vibrissae / Q000294:innervation*
D006454:Hemoglobins; D010108:Oxyhemoglobins