The neuronal basis of a sensory analyser, the acridid movement detector system. The data also strongly support the idea of functional specialization of areas MT and MST for motion processing. In addition, they provide evidence for the importance of behavioral training for functional recovery after cortical lesions. These results demonstrate the importance of areas MT and MST for the perception of motion direction, particularly in the presence of noise. On the other hand, deficits in the ability to extract motion from noisy stimuli and in the accuracy of direction discrimination persisted despite extensive behavioral training. These improvements were particularly pronounced for stimuli not masked by noise. Subsequent improvements in thresholds were seen with all motion stimuli, as behavioral training progressed, and these improvements occurred only with extensive behavioral testing in the lesioned visual field.
step sizes), suggesting an increase in spatial scale of the residual directional mechanism.
In addition, the accuracy of direction discrimination was reduced at smaller spatial displacements (i.e. At the start of behavioral testing, we found pronounced, motion-specific deficits in thresholds for all types of moving stimuli, including pronounced elevations in contrast thresholds and in signal-to-noise thresholds measured with moving gratings, as well as deficits in direction range thresholds and motion coherence measured with random-dot stimuli. Direction and orientation discrimination were assessed by measuring thresholds with gratings and random-dots placed in the intact or lesioned visual fields. The monkeys discriminated two stimuli that differed either in stimulus direction or orientation. Lesions were made by injecting ibotenic acid into the representation of the left visual field in two macaque monkeys. (1/3995)We examined the nature and the selectivity of the motion deficits produced by lesions of extrastriate areas MT and MST. Transient and permanent deficits in motion perception after lesions of cortical areas MT and MST in the macaque monkey.
0 kommentar(er)
