Electrophysiological evidence for an L-shaped interhemispheric connection in the cat

Cukiert, A; Timo-Iaria, C.

doi:10.1590/S0004-282X1989000400001

Abstracts

Transcallosal potentials evoked by electrical stimulation with rectangular pulses of 1 ms, 5 c/s and variable intensity were recorded from the cortical surface in cats anesthetized with ketamine hydrochloride. Sites of stimulation and recording were selected by means of a cartesian map of most of the neocortex. In addition to the well known transcallosal projection pattern it was found that stimulation of a restricted posterior area evokes low voltage potentials over the contralateral symmetric area while high voltage potentials are recorded from a few sites located at the ipsilateral anterior cortex and from the area symmetric as to the latter. This L-shaped transcallosal connection may be involved in complex cortical processes and is compatible with effective results of partial anterior callosotomies in patients with multifocal epilepsy and frontal bisynchronism.

Foram obtidos potenciais evocados transcalosos por aplicação de pulsos quadrados de 1 ms, 5 c/s e intensidade variável e registro sobre a corticalidade de gatos anestesiados com quetamina. Os locais de estimulação e registro eram selecionados através de mapa cartesiano de grande parte do neocórtex. Além das bem conhecidas projeções calosas, foram discriminadas áreas posteriores cuja estimulação evocava potenciais de baixa amplitude em sua área homóloga e potenciais de grande amplitude em regiões mais anteriores, ipsi- e contralateralmente. Esta conexão transcalosa em forma de 'L' pode estar envolvida em processos corticais complexos e é compatível aos bons resultados obtidos por calosotomias parciais anteriores em pacientes com epilepsia multifocal e bissincronia frontal.

Electrophysiological evidence for an L-shaped interhemispheric connection in the cat

Evidência eletrofisiológica da presença de uma conexão inter-hemisférica em forma de 'L' no gato

A. Cukiert; C. Timo-Iaria

Laboratories of Functional Neurosurgery and Clinical Physiology, School of Medicine, University of São Paulo, Brazil

SUMMARY

Transcallosal potentials evoked by electrical stimulation with rectangular pulses of 1 ms, 5 c/s and variable intensity were recorded from the cortical surface in cats anesthetized with ketamine hydrochloride. Sites of stimulation and recording were selected by means of a cartesian map of most of the neocortex. In addition to the well known transcallosal projection pattern it was found that stimulation of a restricted posterior area evokes low voltage potentials over the contralateral symmetric area while high voltage potentials are recorded from a few sites located at the ipsilateral anterior cortex and from the area symmetric as to the latter. This L-shaped transcallosal connection may be involved in complex cortical processes and is compatible with effective results of partial anterior callosotomies in patients with multifocal epilepsy and frontal bisynchronism.

RESUMO

Foram obtidos potenciais evocados transcalosos por aplicação de pulsos quadrados de 1 ms, 5 c/s e intensidade variável e registro sobre a corticalidade de gatos anestesiados com quetamina. Os locais de estimulação e registro eram selecionados através de mapa cartesiano de grande parte do neocórtex. Além das bem conhecidas projeções calosas, foram discriminadas áreas posteriores cuja estimulação evocava potenciais de baixa amplitude em sua área homóloga e potenciais de grande amplitude em regiões mais anteriores, ipsi- e contralateralmente. Esta conexão transcalosa em forma de 'L' pode estar envolvida em processos corticais complexos e é compatível aos bons resultados obtidos por calosotomias parciais anteriores em pacientes com epilepsia multifocal e bissincronia frontal.

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This research was supported by FAPESP (84/1078-9 and 85/3531-5), FINEP (43.86.0222.00) and LIM Institute (LIM 74-45).

Dr. Arthur Cukiert - Rua Baltazar da Veiga 367 apto. 151 - 04510 São Paulo SP - Brasil.

1. Avila JO, Radvany J, Huck FR, Camargo CHP, Marino R Jr, Ragazzo PC, Riva D - Anterior callosotomy as a substitute for hemispherectomy. Acta Neurochir 30 (Suppl): 137, 1980.
2. Chang HT - Cortical response to activity of callosal neurons. J Neurophysiol 16: 117, 1953.
3. Chang HT - Interaction of evoked cortical potentials. J Neurophysiol 16: 133, 1953.
4. Cukiert A, Timo-Iaria C - An evoked potential mapping of transcallosal projections in the cat. Arq Neuro-Psiquiat (São Paulo) 47:1, 1989.
5. Curtis HJ - Intercortical connections of corpus callosum as indicated by evoked potentials. J Neurophysiol 3: 405, 1940.
6. Curtis HJ - An analysis of cortical potentials mediated by the corpus callosum. J Neurophysiol 3: 414, 1940.
7. Ebner FF, Myers RW - Distribution of corpus callosum and anterior commissure in cat and racoon. J Comp Neurol 124: 353, 1965.
8. Hubel DH, Wiesel TN - Cortical and callosal connections concerned with the vertical meridian of visual fields in the cat. J Neurophysiol 30: 1561, 1967.
9. Luessenhop AJ - Interhemispheric commissurotomy. Am Surg 36: 265, 1970.
10. Marcus EM, Watson CW - Bilateral synchronous spike and wave electrographic patterns in the cat. Arch Neurol 14: 601, 1966.
11. Poljak S - An experimental study of the association, callosal and projection fibers of the cerebral cortex of the cat. J Comp Neurol 44: 197, 1927.
12. Ptito M, Tassinari G, Antonini A - Electrophysiological evidence for interhemispheric connections in the anterior ectosylvian sulcus in the cat. Exp Brain Res 66: 90, 1987.
13. Tomasch J - Size, distribution and number of fibers in the human corpus callosum. Anat Rec 119: 119, 1954.

Publication Dates

Publication in this collection
01 June 2011
Date of issue
Dec 1989

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

[1] 1. Avila JO, Radvany J, Huck FR, Camargo CHP, Marino R Jr, Ragazzo PC, Riva D - Anterior callosotomy as a substitute for hemispherectomy. Acta Neurochir 30 (Suppl): 137, 1980.

[2] 2. Chang HT - Cortical response to activity of callosal neurons. J Neurophysiol 16: 117, 1953.

[3] 3. Chang HT - Interaction of evoked cortical potentials. J Neurophysiol 16: 133, 1953.

[4] 4. Cukiert A, Timo-Iaria C - An evoked potential mapping of transcallosal projections in the cat. Arq Neuro-Psiquiat (São Paulo) 47:1, 1989.

[5] 5. Curtis HJ - Intercortical connections of corpus callosum as indicated by evoked potentials. J Neurophysiol 3: 405, 1940.

[6] 6. Curtis HJ - An analysis of cortical potentials mediated by the corpus callosum. J Neurophysiol 3: 414, 1940.

[7] 7. Ebner FF, Myers RW - Distribution of corpus callosum and anterior commissure in cat and racoon. J Comp Neurol 124: 353, 1965.

[8] 8. Hubel DH, Wiesel TN - Cortical and callosal connections concerned with the vertical meridian of visual fields in the cat. J Neurophysiol 30: 1561, 1967.

[9] 9. Luessenhop AJ - Interhemispheric commissurotomy. Am Surg 36: 265, 1970.

[10] 10. Marcus EM, Watson CW - Bilateral synchronous spike and wave electrographic patterns in the cat. Arch Neurol 14: 601, 1966.

[11] 11. Poljak S - An experimental study of the association, callosal and projection fibers of the cerebral cortex of the cat. J Comp Neurol 44: 197, 1927.

[12] 12. Ptito M, Tassinari G, Antonini A - Electrophysiological evidence for interhemispheric connections in the anterior ectosylvian sulcus in the cat. Exp Brain Res 66: 90, 1987.

[13] 13. Tomasch J - Size, distribution and number of fibers in the human corpus callosum. Anat Rec 119: 119, 1954.