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P Sutton

Publications and source records attributed to P Sutton.

60 records · Page 4Linked to original sources
PubMed1970

The perceived spatial frequency shift: evidence for frequency-selective neurones in the human brain.

1. Prolonged observation of a high-contrast grating pattern causes an apparent shift in the spatial frequency of gratings subsequently viewed with the same retinal region. Gratings of higher and lower frequency than the adapting pattern seem, respectively, higher and lower than in fact they are.2. There is no significant after-effect at the adapting frequency itself nor at frequencies more than two octaves away.3. For very low adapting frequencies, the after-effect remains centred at about 3.0 c/deg and declines in strength as the adapting frequency is successively lowered.4. The magnitude of the after-effect increases with the contrast of the adapting grating and the length of time spent in adaptation. It takes several hours to recover completely from 30 min adaptation.5. The phenomenon is orientation-specific: a horizontal adapting grating has no effect on vertical test gratings. There is partial interocular transfer of the after-effect.6. These findings provide further evidence that the visual system of man, like those of the cat and the monkey, contains neurones selectively sensitive to the orientation and dimensions of retinal images, and that these adaptable cells are actually involved in the encoding and perception of the size of simple patterns.

Adaptation, Ocular↗
PubMed1969

Size adaptation: a new aftereffect.

If, after prolonged observation of a striped pattern, one views a grating of the same orientation with somewhat narrower bars, then the bars seem even thinner than in fact they are. Broader bars seem broader still. This finding implies a system of size-detecting channels in humnan vision. The phenomenon may underlie many of the classical figural aftereffects.

Adaptation, Ocular↗
PubMedDate not supplied

Comparison of the immune response elicited by a free peptide and a lipopeptide construct.

Among the synthetic peptides derived from the 28-kDa Schistosoma mansoni gluthatione-S-transferase (Sm28GST), the C-terminal peptide, comprising amino acid residues 190 to 211, represents a major T-cell epitope in both infected humans and Sm28GST-immunized mice. The aim of this study was to determine the nature of the immune response induced by the 190-211 peptide coupled to a fatty acid (lipopeptide construction) in comparison to the free form. We explored B- and T-cell responses elicited by these two peptidic constructions in three different mouse strains (BALB/c, CBA/N and C57B1/6). For all strains, the addition of a lipid chain to the 190-211 peptide greatly modified its immunogenicity. The lipopeptide, compared to the free form, induced a greatly reduced antibody response against the peptide, whereas the production of messenger for cytokines was greatly increased after immunization with the lipopeptide. Immunization with peptide led mainly to a Th1-type cytokine profile following antigenic restimulation in vitro, while lipopeptide, in general, induced a mixed profile, and that occurred most significantly with the production of messengers for the protective cytokines IFN-gamma and IL-2, even without antigenic restimulations. This modification of immunogenicity of a peptide by the addition of a lipid chain could be of value in the development of efficient peptide vaccines.

Animals↗