 |
||||
|
||||
|
||||
|
||||
Electronic Letters to:
- BehavioralSystemsCognitive:
Stefan Klöppel, Anna Vongerichten, Thilo van Eimeren, Richard S. J. Frackowiak, and Hartwig R. Siebner- Can Left-Handedness be Switched? Insights from an Early Switch of Handwriting
J. Neurosci. 2007; 27: 7847-7853[Abstract] [Full text] [PDF]
eLetters: Submit a response to this article
Electronic letters published:
laterality of motor control revisited, an update
- iraj derakhshan (3 September 2007)
laterality of motor control revisited, an update 3 September 2007 
iraj derakhshan,
neurologist, private practice
415 morris st, suite 401, charleston, wv 25301Send letter to journal:
Re: laterality of motor control revisited, an update
idneuro{at}hotmail.com iraj derakhshan
In answering the question of immutability of the circuitry underpinning handedness, the following observations are critical:
1. Clinically, ~ 15 % and 50 % of right and left handers (respectively) become aphasic with paralysis of their nondominant side of the body (Goodglass and Quadfasel, 1954; Mohr et al, 1980).
2. Experimentally, a closely similar percentage of right and left handers display a longer simple reaction time on their avowed dominant side compared to the other (Shen and Franz, 2005). The reason is that behavioral handedness bespeaks of the choice made by us as to the laterality of our favorite hand at an early age (an event long forgotten but by a few). Neural handedness (brainedness), on the other hand, bespeaks of the laterality of the command center (the hemisphere of speech) which is closer to the neurally dominant side by a callosal-width. This makes the reaction time of the neurally dominant side shorter by an interval equal to the interhemispheric transfer time (IHTT) (Derakhshan, 2006). As shown by Hoshiyama and Kakigi (1999), moving the neurally nondominant side is associated with the appearance of a movement related cortical potential in both hemispheres, beginning with the major and going to the minor hemisphere, with an interval equal to IHTT.
3. Thus, as shown in an earlier study by the authors, moving the neurally dominant side of the body is associated with activation of both hemispheres, whereas moving the dominant side implicate the contralateral hemisphere alone. This immutability was acknowledged by the authors (Kloppel et al, 2007).
References:
Derakhshan I (2006) Crossed-uncrossed difference (CUD) in a new light: anatomy of the negative CUD in Poffenberger's paradigm. Acta Neurologica Scandinavica 113:203-208.
Goodglass H, Quadfasel FA (1954) Language laterality in left-handed aphasics. Brain 4:521-548.
Hoshiyama M, Kakigi R (1999) Changes of somatosensory evoked potentials during writing with the dominant and non-dominant hands. Brain Research 833:10-19.
Kloppel S, Vongerichten A, van Eimeren T, Frackowiak RS, Siebner HR (2007) Can left-handedness be switched? Insights from an early switch of handwriting. Journal of Neuroscience 27:7847-7853.
Mohr JP, Weiss GH, Caveness WF, Dillon JD, Kistler JP, Meirowsky AM, Rish BL (1980) Language and motor disorders after penetrating head injury in Viet Nam. Neurology 30:1273-1279.
Shen YC, Franz EA (2005) Hemispheric competition in left-handers on bimanual reaction time tasks. Journal of Motor Behavior 37:3-9.
|
|
|
|
 |
|