Talk:Aftereffects in touch
Thank you for this very complete report on the aftereffects on touch.
While the authors speak well of the many aftereffects, this reader feels that that the contain does not address adequately the purpose of a scholarpedia entry. It is recommended that such articles should not be exhaustive, but instead explain things (Scholarpedia articles are at their best when they are concise but not abstruse; when they are accessible to advanced undergraduates familiar with the area, as well as to graduate students in adjacent fields.) Specifically the entry is missing a good definition of what is an aftereffect. The introductory paragraph does not do that. It mentions the waterfall illusion as an example of adaptation to motion but it is not obvious at all why it should cause an aftereffect. What seems obvious to the authors isn't for the reader. This reader in fact would suggest that adaptation to illumination would be a much better introductory example. On one hand, everyone including kids know it well, and on the other hand, most people, even non-scientists feel that there is something good about it: it's annoying for a minute or two but then you can see better in a dark room (or bight outdoors) even if most people are unable to explain why that is. It is then the job of the scientist to explain it especially for the purposes of an encyclopedia (see Shapley and Enroth-Cugell, 1984. for a nicely made encyclopedia entry). [R. Shapley and C. Enroth-Cugell. "Visual adaptation and retinal gain controls." Progress in retinal research 3 (1984): 263-346.]
Authors' response: We have added a definition to the introduction: An aftereffect is the change in the perception of a (test) stimulus after prolonged stimulation with an (adaptation) stimulus. Usually, this change is in negative direction, that is, in a direction opposite to that of the adaptation stimulus. Aftereffects are often fast and strong. As for the example, we have chosen to keep our own, because we think it is a more clear example.
In fact the introductory section should mention some more theoretical ideas. There is abundant literature on the time-scales, and information processing advantages showing that adaptation mediates a tradeoff between detection and discrimination performance including the neural correlates of such mechanism. This would justify the universal nature of adaptation and its consequences, among which one finds aftereffects.
Authors' response: This article is about aftereffects. Adaptation in general is beyond the scope of this article.
At the end of the section "Aftereffect of size" there is paragraph on comparing sizes of objects held in two hands. This reader found this paragraph very hard to read. In particular the last sentence "This showed that non-perceived somatosensory information is still processed by the brain." Firstly it not recommend to use the pronoun "This" as the subject of a sentence because it is ambiguous, we don't know what "this" stands for. Second, it would seem that the authors mean "unconsciously perceived" rather than "non-perceived". For example the phenomenon of Blindsight is described as visual perception of which the person is unaware. It seems that's what the authors mean here.
Authors' response: We have changed the text as follows: Although this patient did not consciously perceive the sphere presented to his left hand, the size of this sphere influenced the perception of the size of the sphere presented to his right hand. The occurrence of the aftereffect showed that somatosensory information that is not consciously perceived is still processed by the brain.
As a rule, this reader believes that the section titles are not properly formed. The common practice is to write "Size Aftereffet" "Motion Aftereffect" etc. etc. not "Aftereffet of Size" "Aftereffect os Motion" etc. At least that is the way 99% of the scientific literature calls these effects. Moreover,sSome of these aftereffects are so pervasive that they have very often received contractions such as MAE preceded by a letter to indicate the modality a vMAE or aMAE or tMAE. An encyclopedia reader should be made aware of that practice.
Authors' response: We have changed Aftereffect of temperature to Temperature aftereffect etc. However, we have not used the abbreviations, because they are less informative.
Another comment aimed at improving the text, in the section "Aftereffect of tactile motion" it is said that "Because of this insensitivity to direction, the authors conclude that this aftereffect has to be of central origin, as peripheral afferents are direction sensitive." This is a rather perplexing statement that needs clarification.
Authors' response: We have changed the text to read: As peripheral afferents are direction sensitive, this independence of direction suggests that adaptation of these afferents cannot be the cause of the aftereffect: adaptation in their preferred direction should cause stronger adaptation and as a consequence, a direction sensitive aftereffect. As this was clearly not the case, the authors conclude that this aftereffect has to be of central origin.
Similarly in the Section "Aftereffect of roughness" is hard to make any logical link between the phenomenology and the conclusion that "adaptation originates in the somatosensory cortex." given that they least three stages of neural processing between the peripheral sensing units and area 3b in the cortex, at least without some explanatory details.
Authors' response: Nevertheless, this is what is hypothesized in the cited article.
Another point that needs attention, is the abundant use the the word kinesthetic (and other variants of this root). The authors must explain what is meant by that since its use is extremely inconsistent through disciplines and through time. The use of this word throughout the entry is somewhat obfuscating. Perhaps the authors should avoid it or rest on some other discussion, ie. http://www.annualreviews.org/doi/pdf/10.1146/annurev.ne.05.030182.001201
Authors' response: The term is used four times in one section and once in another, which can hardly be called 'abundant'. It is used only when the cited authors do so; it would be strange to use another term then. With the first use, the experimental task is explained, so the meaning of the term is made clear. We do not think further explanation is necessary.
Finally, referring back to the introductory comment, this reader feels the need to provide to future readers more indications about the mechanisms at plat. For example is adaptation to temperature similar to adaptation to motion? (mechanism often attributed to the 'fatigue' of rival channels, etc., or motion processing taking place in MT in an amodal fashion, and so on)
Authors' response: Not enough data are available to make firm assertions about the mechanisms involved. Speculation about this would not befit an encyclopedia article.