ECT and determination of laterality of motor control (cerebral dominance)
iraj derakhshan, mimicking man manually, inc.
2 July 2005
Dear Editor:
I read Dragocic's and colleagues atricle with interest [1]. They advocated use of fTCD in determining cerebral dominance in lieu of other techniques (tabulated in their table 1). What the respected authors did not address is the anatomy sustaining cerebral dominance codified as behavioral handedness; i.e. the laterality of the controlling moiety of a bilaterally distributed neuronal ensemble devoted to movements. The two moities are connected via an excitatory synapse by fibers traversing the callosum (anteriorly). This anatomy has been delineated conclusively elsewhere [2-5]. Thus, in neural right handers the directionality of callosal transfer is from left to right hemisphere. It is in the opposite direction in neural left handers. The laterality of motor control is dichotomous in nature. It has been shown that the relationship between neural (described above) to the behavioral handedness is statistical only. The two match in no more than 80 percent of occasions.
Thus, rather than using the methods described by the authors in table 1, the best way for determining a subject's laterality is to ascertain the reaction time of the subject by old-fashioned push-button technique as they respond to an stimulus. The side with the shorter response time is located opposite to the dominant hemisphere. Elsewhere, I have tabulated various implications of the above anatomy in humans (www.mimickingman.com). Thank you. I.Derakhshan, md, cbe; Neurologist
References:
1. Dragovic M, Allet L, Janca A.
Electroconvulsive therapy and determination of cerebral dominance. Ann Gen Hosp Psychiatry. 2004; 12;3:14. (electronic edition)
2. Derakhshan I. Laterality of motor control revisited: directionality of callosal traffic and
its rehabilitative implications. Top Stroke Rehabil. 2005;12:76-82.
3. Derakhshan I. Handedness and macular vision: laterality of motor control underpins both.
Neurol Res. 2004 ;26:331-337.
4.Derakhshan I, Franz EA, Rowse A. An exchange on Franz, Rowse, and Ballantine (2002). Handedness, neural versus behavioral: is there a measureable callosal difference? J Mot Behav. 2003;35:409-414.
5.Derakhshan I. Callosum and movement control: case reports. Neurol Res. 2003;25:538-542.
Annals of General Psychiatry
ECT and determination of laterality of motor control (cerebral dominance)
2 July 2005
Dear Editor:
I read Dragocic's and colleagues atricle with interest [1]. They advocated use of fTCD in determining cerebral dominance in lieu of other techniques (tabulated in their table 1). What the respected authors did not address is the anatomy sustaining cerebral dominance codified as behavioral handedness; i.e. the laterality of the controlling moiety of a bilaterally distributed neuronal ensemble devoted to movements. The two moities are connected via an excitatory synapse by fibers traversing the callosum (anteriorly). This anatomy has been delineated conclusively elsewhere [2-5]. Thus, in neural right handers the directionality of callosal transfer is from left to right hemisphere. It is in the opposite direction in neural left handers. The laterality of motor control is dichotomous in nature. It has been shown that the relationship between neural (described above) to the behavioral handedness is statistical only. The two match in no more than 80 percent of occasions.
Thus, rather than using the methods described by the authors in table 1, the best way for determining a subject's laterality is to ascertain the reaction time of the subject by old-fashioned push-button technique as they respond to an stimulus. The side with the shorter response time is located opposite to the dominant hemisphere. Elsewhere, I have tabulated various implications of the above anatomy in humans (www.mimickingman.com). Thank you. I.Derakhshan, md, cbe; Neurologist
References:
1. Dragovic M, Allet L, Janca A.
Electroconvulsive therapy and determination of cerebral dominance. Ann Gen Hosp Psychiatry. 2004; 12;3:14. (electronic edition)
2. Derakhshan I. Laterality of motor control revisited: directionality of callosal traffic and
its rehabilitative implications. Top Stroke Rehabil. 2005;12:76-82.
3. Derakhshan I. Handedness and macular vision: laterality of motor control underpins both.
Neurol Res. 2004 ;26:331-337.
4.Derakhshan I, Franz EA, Rowse A. An exchange on Franz, Rowse, and Ballantine (2002). Handedness, neural versus behavioral: is there a measureable callosal difference? J Mot Behav. 2003;35:409-414.
5.Derakhshan I. Callosum and movement control: case reports. Neurol Res. 2003;25:538-542.
Competing interests
none