Comments on: Dateline Atlanta, SfN 2006: Hughlings Jackson vindicated again http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/ It's all around you Tue, 10 Nov 2009 19:34:56 +0000 http://wordpress.com/ hourly 1 By: peripersonalspace http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/#comment-12 peripersonalspace Sun, 22 Oct 2006 19:17:25 +0000 http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/#comment-12 Grant, most of the somatosensory plasticity work is in monkeys after finger fusion or amputation (Taub would be one reference), and a lot of the work in reorganization of primary visual cortex receptive fields after retinal lesions is in Charlie Gilbert's lab (seminal paper, invoking CaMKII mechanisms -- NMDAR related, right?; see Obata S, Obata J, Das A, Gilbert CD Molecular correlates of topographic reorganization in primary visual cortex following retinal lesions. CEREB CORTEX 1999 APR-MAY;9(3):238-248). Note in some of this work there are "long range horizontal connections" being altered, but these are clearly not as long range as the kind of thalamocortical circuits that must be present here for Pascual-Leone's reorganization to take place. The closest I know to an animal model is the rewiring of the ferret auditory cortex so it can "see" by Sur at MIT; there collicular inputs to cortex are damaged so that the rewiring can occur. Other than that I know of no suitable animal studies showing these duplicate inputs (by the way, spared inputs from the superior colliculus and maybe the pulvinar to V5 are said to be responsible for blindsight, so we have another human case, but notice this is still *within* a modality, so that's why these Pascual-Leone results are so cool!). Neil, as far as Hughlings Jackson, I suggest googling around. He was an amazing neurologist; the first to recognize the primary role of the right hemisphere in certain types visuospatial processing, back in the early 1870s or so, and he was also perfectly spot on in realizing the right hemisphere's role in both emotional processing and, critically, in inhibition. He was able to do all this by exceedingly careful observation (in the case of epilepsy he watched his wife's seizures) and brilliant induction. Grant, most of the somatosensory plasticity work is in monkeys after finger fusion or amputation (Taub would be one reference), and a lot of the work in reorganization of primary visual cortex receptive fields after retinal lesions is in Charlie Gilbert’s lab (seminal paper, invoking CaMKII mechanisms — NMDAR related, right?; see Obata S, Obata J, Das A, Gilbert CD Molecular correlates of topographic reorganization in primary visual cortex following retinal lesions. CEREB CORTEX 1999 APR-MAY;9(3):238-248). Note in some of this work there are “long range horizontal connections” being altered, but these are clearly not as long range as the kind of thalamocortical circuits that must be present here for Pascual-Leone’s reorganization to take place.

The closest I know to an animal model is the rewiring of the ferret auditory cortex so it can “see” by Sur at MIT; there collicular inputs to cortex are damaged so that the rewiring can occur. Other than that I know of no suitable animal studies showing these duplicate inputs (by the way, spared inputs from the superior colliculus and maybe the pulvinar to V5 are said to be responsible for blindsight, so we have another human case, but notice this is still *within* a modality, so that’s why these Pascual-Leone results are so cool!).

Neil, as far as Hughlings Jackson, I suggest googling around. He was an amazing neurologist; the first to recognize the primary role of the right hemisphere in certain types visuospatial processing, back in the early 1870s or so, and he was also perfectly spot on in realizing the right hemisphere’s role in both emotional processing and, critically, in inhibition. He was able to do all this by exceedingly careful observation (in the case of epilepsy he watched his wife’s seizures) and brilliant induction.

]]> By: Grant N. http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/#comment-11 Grant N. Sun, 22 Oct 2006 18:23:52 +0000 http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/#comment-11 First post on the schroppfy's blog! That's some cool stuff. Do you know if anyone has done similar studies in monkeys or other animals? I would be interested in mechanism. Presumably some sort of scaling mechanism resulting from deprivation could allow the somatosensory inputs to register above the noise. It would also be cool to see if those afferents were mostly silent (NMDAR only) before the shift and then changed, or if it's a more simple Hebbian-ish mechanism. First post on the schroppfy’s blog! That’s some cool stuff. Do you know if anyone has done similar studies in monkeys or other animals? I would be interested in mechanism. Presumably some sort of scaling mechanism resulting from deprivation could allow the somatosensory inputs to register above the noise. It would also be cool to see if those afferents were mostly silent (NMDAR only) before the shift and then changed, or if it’s a more simple Hebbian-ish mechanism.

]]> By: Neil H. http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/#comment-10 Neil H. Sun, 22 Oct 2006 18:07:55 +0000 http://peripersonalspace.wordpress.com/2006/10/14/john-hughlings-jackson-was-always-right/#comment-10 Do you happen to know of good sources for more info on Hughlings Jackson's work? It seems rather interesting. Do you happen to know of good sources for more info on Hughlings Jackson’s work? It seems rather interesting.

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