The mechanism of vision. XIII. Cerebral function in discrimination of brightness when detail vision is controlled
✍ Scribed by K. S. Lashley
- Publisher
- John Wiley and Sons
- Year
- 1937
- Tongue
- English
- Weight
- 498 KB
- Volume
- 66
- Category
- Article
- ISSN
- 0021-9967
No coin nor oath required. For personal study only.
✦ Synopsis
I n various earlier experiments dealing with the neural basis of brightness discrimination in the rat a seemingly paradoxical situation has appeared. Animals trained in a reaction to light versus darkness in the Yerkes box lose the habit completely when the striate areas of the cerebral cortex are destroyed. No injury to any other cytoarchitectural area affects the habit. This indicates that the habit is dependent upon the visual cortex. But animals lacking the striate areas form the habit just as rapidly as do normal ones and animals which have lost the habit through removal of the striate areas relearn it with a normal amount of practice. I n the absence of the striate areas injury to the optic thalamus retards or prevents formation of the habit. These results indicate that the habit is a function of the optic thalamus or tectum.l
If the subcortical centers alone can mediate the habit, why do they not do so when the visual cortex is present? If the visual cortex plays an important part in the learning, why is learning not retarded in its absence?
The problem is further complicated by the experiments reported by Kreehevsky ('35) which indicate that the rate of learning is normal in the animal without striate arcas only when motivated by punishment for errors, but this faet is irrelevant for the present study.