| Title |
Visual acuity, contrast sensitivity and retinal magnification in a marsupial, the tammar wallaby (Macropus eugenii )
|
|---|---|
| Published in |
Journal of Comparative Physiology A, September 1998
|
| DOI | 10.1007/s003590050264 |
| Pubmed ID | |
| Authors |
J. M. Hemmi, R. F. Mark |
| Abstract |
The visual acuity of the tammar wallaby was estimated using a behavioural discrimination task. The wallabies were trained to discriminate a high-contrast (86%) square-wave grating from a grey field of equal luminance (1000-6000 cd m-2). Visual-evoked cortical potentials were used to measure the complete contrast sensitivity function. The stimulus was a sinusoidal phase reversal of a sinusoidally modulated grating of various spatial frequencies and contrasts with a mean luminance of 40 cd m-2). The behavioural acuity was estimated to be about 4.8 cycles/deg. The contrast sensitivity peaked at about 0.15 cycles/deg and declined towards both lower and higher spatial frequencies. The cut-off frequency of the contrast sensitivity function is slightly lower than the behaviourally measured acuity at about 2.7 cycles/deg. The retinal magnification factor was estimated anatomically from laser lesions to be about 0.16 mm/deg. Based on the known ganglion cell density and the retinal magnification factor, an anatomical upper limit to visual acuity of about 6 cycles/deg can be calculated. The differences in estimates of visual acuity between the behavioural and anatomical methods on the one side and physiology on the other side are discussed. |
Mendeley readers
The data shown below were compiled from readership statistics for 27 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Germany | 2 | 7% |
| Colombia | 1 | 4% |
| Unknown | 24 | 89% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Researcher | 6 | 22% |
| Student > Ph. D. Student | 5 | 19% |
| Student > Bachelor | 3 | 11% |
| Student > Master | 3 | 11% |
| Professor | 2 | 7% |
| Other | 4 | 15% |
| Unknown | 4 | 15% |
| Readers by discipline | Count | As % |
|---|---|---|
| Agricultural and Biological Sciences | 10 | 37% |
| Neuroscience | 4 | 15% |
| Psychology | 3 | 11% |
| Medicine and Dentistry | 2 | 7% |
| Chemistry | 1 | 4% |
| Other | 0 | 0% |
| Unknown | 7 | 26% |
Attention Score in Context
This research output has an Altmetric Attention Score of 3. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 12 January 2012.
All research outputs
#8,534,528
of 25,371,288 outputs
Outputs from Journal of Comparative Physiology A
#514
of 1,550 outputs
Outputs of similar age
#9,998
of 31,202 outputs
Outputs of similar age from Journal of Comparative Physiology A
#1
of 5 outputs
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