title: Effect of reading on blood flow changes in the posterior cerebral artery in early blind and sighted people--A transcranial Doppler study.
abstract: BACKGROUND
  Neuroimaging studies proved that Braille reading resulted in visual cortex activation in blind people, however, very few data are available about the measure of flow increase in these subjects. Therefore, we investigated the flow response in the posterior cerebral artery (PCA) of eleven early blind and ten sighted subjects induced by reading Braille and print, respectively.
  
  
  METHODS
  Two experimental protocols were used in both groups: PCA flow velocity during reading was compared to the resting phase and "NLC" phase (volunteers "read" non-lexical characters; e.g. .,-.:,-.:...,). The use of these experimental protocols allowed to investigate separately the effect of "light stimulus+print reading" versus "print reading alone" in sighted, and "hand/finger movement+Braille reading" versus "Braille reading alone" in blind subjects.
  
  
  RESULTS
  The flow response in the PCA evoked by "Braille reading alone" in blind (10.5±4.5%) and "print reading alone" in sighted subjects (8.1±3.5%) was similar. The flow increase induced by "hand/finger movement+Braille reading" and by "Braille reading alone" did not differ in blind people, however, "light stimulus+print reading" in sighted subjects caused higher PCA flow increase (25.9±6.9%) than "print reading alone" (8.1±3.5%).
  
  
  CONCLUSIONS
  The similar PCA flow response induced by Braille and print reading alone suggested a similar degree of occipital cortex activation in blind and sighted subjects. In sighted people, the 3-times higher flow velocity increase induced by "light stimulus+print reading" compared with "print reading alone" indicated that 2/3 of PCA flow increase during reading was due to the light stimulus and only 1/3 of flow response was caused by reading alone.
authors.affiliation: Department of Neurology, University of Debrecen, Moricz Zs. str. 22, H-4032 Debrecen, Hungary.
authors.forename: Sandor
authors.initials: S
authors.lastname: Viski
authors.affiliation: Department of Neurology, University of Debrecen, Moricz Zs. str. 22, H-4032 Debrecen, Hungary.
authors.forename: David
authors.initials: D
authors.lastname: Orgovan
authors.affiliation: Department of Neurology, University of Debrecen, Moricz Zs. str. 22, H-4032 Debrecen, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Szabo
authors.affiliation: Department of Neurology, University of Giessen, Giessen, Amsteg 14, Giessen D-35385, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Rosengarten
authors.affiliation: Department of Neurology, University of Debrecen, Moricz Zs. str. 22, H-4032 Debrecen, Hungary.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Csiba
authors.affiliation: Department of Neurology, University of Debrecen, Moricz Zs. str. 22, H-4032 Debrecen, Hungary. Electronic address: olah@med.unideb.hu.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Olah
mesh_terms: D000293:Adolescent; D000328:Adult; D001766:Blindness / Q000175:diagnosis / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D020769:Posterior Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D011932:Reading; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Blind subjects; Cerebral blood flow; Cortical activation; Neurovascular coupling; Transcranial Doppler