Several studies have suggested that it might be easier to identify a letter when its replication ... more Several studies have suggested that it might be easier to identify a letter when its replication is simultaneously presented in the visual display. We have measured identification accuracy for a memorized target letter that was shown in the peripheral field in two conditions in which a letter either identical or different in shape was flashed simultaneously at fixation. The results of three forced‐choice experiments showed that, contrary to Geiger and Lettvin's (1986) previous findings, an identity prime did not improve the visibility of a temporally backward masked target letter. However, the foveal prime letter could apparently bias the subject's decision so that he/she was much more ready to report the more visible prime letter as the peripheral target.
The lateral part of area 7, area 7b, of alert, behaving macaque monkeys was investigated using tr... more The lateral part of area 7, area 7b, of alert, behaving macaque monkeys was investigated using transdural microelectrode recording technique. Two hundred twenty-eight cells from five hemispheres of four monkeys were isolated and studied. The functional properties of 2% of the cells isolated remained unidentified. Functions of the identified cells were prominently related to the spatial control of arm movements. Of the cells 70% responded to somatosensory (40%) or visual (16%) or both somatosensory and visual (14%) stimulation. The receptive fields of these passively drivable cells were large, covering e.g., the arm or leg or chest or even the skin of the whole body. Most of the visually drivable cells responded to stimuli in both halves of the visual field. Of the cells responding to sensory stimulation 80% were activated by stimuli moving in a certain direction. Of the directionally selective cells 25% received information through more than one sensory channel. The complex stimulus-response relationships of these "convergence" cells revealed the existence of an integrative system which analyzes the direction of a stimulus moving in one sensory system using an other sensory system as a reference. Of all the cells isolated 28% discharged only during active movements of the arms (25%) or eyes (3%). Firing of these neurons was related to contraction of a functionally uniform group of muscles and not individual muscles. Some previous investigations of the parietal association cortex, conducted mainly in area 7a, have shown that most cells were active only when the monkey himself moves his eyes or arms. In our study on area 7b most cells responded to passive stimulation. The discrepancy between the results indicates functional differentiation within area 7.
Several studies have suggested that it might be easier to identify a letter when its replication ... more Several studies have suggested that it might be easier to identify a letter when its replication is simultaneously presented in the visual display. We have measured identification accuracy for a memorized target letter that was shown in the peripheral field in two conditions in which a letter either identical or different in shape was flashed simultaneously at fixation. The results of three forced‐choice experiments showed that, contrary to Geiger and Lettvin's (1986) previous findings, an identity prime did not improve the visibility of a temporally backward masked target letter. However, the foveal prime letter could apparently bias the subject's decision so that he/she was much more ready to report the more visible prime letter as the peripheral target.
The lateral part of area 7, area 7b, of alert, behaving macaque monkeys was investigated using tr... more The lateral part of area 7, area 7b, of alert, behaving macaque monkeys was investigated using transdural microelectrode recording technique. Two hundred twenty-eight cells from five hemispheres of four monkeys were isolated and studied. The functional properties of 2% of the cells isolated remained unidentified. Functions of the identified cells were prominently related to the spatial control of arm movements. Of the cells 70% responded to somatosensory (40%) or visual (16%) or both somatosensory and visual (14%) stimulation. The receptive fields of these passively drivable cells were large, covering e.g., the arm or leg or chest or even the skin of the whole body. Most of the visually drivable cells responded to stimuli in both halves of the visual field. Of the cells responding to sensory stimulation 80% were activated by stimuli moving in a certain direction. Of the directionally selective cells 25% received information through more than one sensory channel. The complex stimulus-response relationships of these "convergence" cells revealed the existence of an integrative system which analyzes the direction of a stimulus moving in one sensory system using an other sensory system as a reference. Of all the cells isolated 28% discharged only during active movements of the arms (25%) or eyes (3%). Firing of these neurons was related to contraction of a functionally uniform group of muscles and not individual muscles. Some previous investigations of the parietal association cortex, conducted mainly in area 7a, have shown that most cells were active only when the monkey himself moves his eyes or arms. In our study on area 7b most cells responded to passive stimulation. The discrepancy between the results indicates functional differentiation within area 7.
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Papers by Gote Nyman