Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Human ocular following responses are plastic: evidence for control by temporal frequency-dependent cortical adaptation (1992)
    Springer
    Experimental brain research 91 (1992), S. 525-538 
    Details
    ISSN: 1432-1106
    Keywords: Ocular following ; Eye movements ; Optokinetic nystagmus ; Visual stabilization ; Smooth pursuit ; Motion adaptation ; Motion aftereffects ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Optokinetic nystagmus (OKN) induced by wide-field visual stimulation was measured with and without prior adaptation to moving sinusoidal gratings. Under unadapted conditions the mean gains of the slow phases of OKN in the first 500 ms were 0.5–0.8, and the eye velocities and amplitudes had rise times with time constants of 0.1–0.2 s. By contrast, following adaptation to as little as 1 s of image motion, the magnitude of the initial gains fell and the rise times of the velocities and amplitudes increased markedly. The degree of adaptation depended on the adapting temporal frequency, the optimum adaptive frequencies being 1.7–3.4 Hz. In this range of temporal frequencies, the initial gains fell to 0.1–0.3 and the rise times for velocity and amplitude ranged from 0.4 to 7.0 s, depending on the length of the adapting period. Thus the observed changes in the time constant were up to 70-fold. Neither spatial frequency or image velocity had any marked influence on the level of adaptation. The dependence on temporal frequency rather than image velocity suggests that the motion detectors feeding the adaptive system respond to local motion-related changes in luminance. The adaptive effects were direction-selective, showing that this must also be the case for the motion detectors. The adaptive effects were observed both when the drift temporal frequency on the retina was established by artificially maintaining a fixed gaze or when the adapting temporal frequency was induced by retinal slip during OKN. Time constants for recovery from adaptation were similar to motion aftereffects measured by psychophysical and physiological methods. The results suggest a link between cortical motion adaptation and adaptive mechanisms effecting the oculomotor system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227849
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The effects of adaptation to visual stimuli on the velocity of subsequent ocular following responses (1994)
    Springer
    Experimental brain research 99 (1994), S. 148-154 
    Details
    ISSN: 1432-1106
    Keywords: Motion after-effects ; Ocular following ; Optokinetic nystagmus ; Smooth pursuit ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined the effect of prior adaptation to moving and flickering stimuli on the velocity of subsequent ocular following responses in man. Experiments consisted of two phases: an adaptation phase in which moving or flickering stimuli were presented while the eyes fixated a small spot and a test phase in which ocular following responses were free to occur. The effects resulting from prior adaptation were characterized by determining the mean initial eye velocities in the period 200–500 ms after the onset of the test stimulus. It was found that 8 s of prior exposure to a grating pattern moving at between 1.5 and 4 cycles·s-1 significantly reduced initial eye velocities in all subjects. Prior exposure to a flickering stimulus (temporal frequency 3.2 cycles·s-1) also attenuated the velocities of initial eye movements, but to a far lesser extent. These results suggest that a motion-dependent and a weaker flicker-dependent process have an adaptive influence on the generation of ocular following responses. Initial eye velocities were measured as a function of the contrast of the prior adapting gratings. The velocities were found to decrease with increasing adapting contrast. The reductions in eye velocity were well described by a decaying exponential function. The motion-dependent adaptive effect showed significant inter-ocular transfer and had the same temporal tuning when transferred (i.e. optimum adaptation at between 1.5 and 4 cycles·s-1). The flicker-dependent effect did not show inter-ocular transfer. There is a distinct similarity between the adaptive process that causes attenuation of ocular following velocities and the adaptive mechanism that induces perceptual motion after-ef-fects. This similarity is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241419
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...