Magnocellular and parvocellular visual pathways have different blood oxygen level-dependent signal time courses in human primary visual cortex.
AJNR Am J Neuroradiol
; 27(8): 1628-34, 2006 Sep.
Article
em En
| MEDLINE
| ID: mdl-16971600
ABSTRACT
PURPOSE:
The magnocellular and parvocellular pathways (M and P pathways) are the major pathways of the visual system, with distinct histologic and physiologic properties that may also have different metabolic characteristics. We hypothesize that the differences of the 2 visual pathways would also manifest as differences in the signal time course of blood oxygen level-dependent functional MR imaging (BOLD fMRI). The differences in BOLD signal time course may provide insight into the metabolic requirements of the 2 pathways.METHODS:
Eleven fMRI sessions on 6 subjects were performed using stimuli that preferentially activated the 2 pathways. Regions commonly activated by both the M and P stimuli in the primary visual cortex (V1) were determined, and the contrast elicited by the stimulus, time-to-peak (TTP), and the full width at half maximum (FWHM) of the BOLD signal time course were measured.RESULTS:
The functional stimuli activated cortical regions described previously in the literature, such as V1, V4, and V5. Within V1, the TTP of the signal time course of the 2 stimuli were statistically different, with the P stimulus generating TTPs that were on average 12% faster than the M stimulus (P = .0037).CONCLUSION:
We have demonstrated the ability to functionally differentiate the M and P stimuli in a commonly activated anatomic region. Because the BOLD response is dependent on the ratio of oxyhemoglobin and deoxyhemoglobin in the blood, the difference in the BOLD time course between the 2 stimuli suggests that the oxygen demand of the 2 pathways may be different.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oxigênio
/
Reconhecimento Visual de Modelos
/
Retina
/
Córtex Visual
/
Vias Visuais
/
Processamento de Imagem Assistida por Computador
/
Imageamento por Ressonância Magnética
/
Sensibilidades de Contraste
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Metabolismo Energético
/
Corpos Geniculados
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
AJNR Am J Neuroradiol
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Estados Unidos