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  • 1
    Electronic Resource
    Electronic Resource
    Engagement of visual fixation suppresses sensory responsiveness and multisensory integration in the primate superior colliculus (2003)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 18 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neurons in the intermediate and deep layers of the superior colliculus (SC) often exhibit sensory-related activity in addition to discharging for saccadic eye movements. These two patterns of activity can combine so that modifications of the sensory response can lead to changes in orienting behaviour. Can behavioural factors, however, influence sensory activity? In this study of rhesus monkeys, we isolate one behavioural factor, the state of visual fixation, and examine its influences on sensory processing and multisensory integration in the primate SC. Two interleaved fixation conditions were used: a FIX condition requiring exogenous fixation of a visible fixation point; and a FIX-BLINK condition, requiring endogenous fixation in the absence of a visible fixation point. Neurons of the SC were influenced by fixation state, exhibiting both lower levels of sensory activity and reduced multisensory interactions when fixation was exogenously engaged on a visible fixation point. These results are consistent with active visual fixation suppressing responses to extraneous stimuli, and thus demonstrate that sensory processing and multisensory responses in the SC are not dependent solely on the physical properties of the sensory environment, but are also dynamically influenced by the behavioural state of the animal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2003.02976.x
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  • 2
    Electronic Resource
    Electronic Resource
    Compensatory eye and head movements generated by the cat following stimulation-induced perturbations in gaze position (1989)
    Springer
    Experimental brain research 78 (1989), S. 654-658 
    Details
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Electrical stimulation ; Compensation ; Head-free cat ; Saccade ; Gaze control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It is thought that saccades are controlled by signals representing target and instantaneous eye positions coded with respect to the head. To determine the frame of reference relevant to gaze (= eye + head) control, we extended to the cat whose head is unrestrained the original study of Mays and Sparks (Mays and Sparks 1980). We stimulated the superior colliculus (SC) to perturb initial gaze position before the onset of a gaze shift made in the dark to a flashed target. Gaze shifts compensated for this perturbation and reached the target with normal accuracy, despite the absence of visual feedback. This result indicates that gaze shifts were coded in either a body-centered or spatial frame but we could not distinguish between these two alternatives because the cat's body was fixed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230255
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  • 3
    Electronic Resource
    Electronic Resource
    Age-related performance of human subjects on saccadic eye movement tasks (1998)
    Springer
    Experimental brain research 121 (1998), S. 391-400 
    Details
    ISSN: 1432-1106
    Keywords: Key words Saccade ; Visual fixation ; Anti-saccade ; Reaction times ; Express saccade ; Frontal cortex ; Aging ; Senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We measured saccadic eye movements in 168 normal human subjects, ranging in age from 5 to 79 years, to determine age-related changes in saccadic task performance. Subjects were instructed to look either toward (pro-saccade task) or away from (anti-saccade task) an eccentric target under different conditions of fixation. We quantified the percentage of direction errors, the time to onset of the eye movement (saccadic reaction time: SRT), and the metrics and dynamics of the movement itself (amplitude, peak velocity, duration) for subjects in different age groups. Young children (5–8 years of age) had slow SRTs, great intra-subject variance in SRT, and the most direction errors in the anti-saccade task. Young adults (20–30 years of age) typically had the fastest SRTs and lowest intra-subject variance in SRT. Elderly subjects (60–79 years of age) had slower SRTs and longer duration saccades than other subject groups. These results demonstrate very strong age-related effects in subject performance, which may reflect different stages of normal development and degeneration in the nervous system. We attribute the dramatic improvement in performance in the anti-saccade task that occurs between the ages of 5–15 years to delayed maturation of the frontal lobes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050473
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    Paper (German National Licenses)
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