Placing Reactions, Concluding With A Demonstration Of The Development Of Corticofugal Inhibition

 

1. Surg. Forum 11: 381-383, 1960.

Conclusions included that occasional appearance of paw contact placing after hemispherectomy suggests placing does not require neocortex; rather, there is a subcortical locus of the neuronal circuits managing placing , and these are subject to corticofugal regulation. (click here for complete text).

2. Science 135: 309, 1962.

Chin contact placing slowly recovers after hemispherectomy in cats but not the paw contact placing. The latter does recover, albeit clumsily, after a second operation: removal of the remaining (contralateral) frontal lobe. It is concluded that placing is managed subcortically, subject to ipsilateral corticofugal inhibition as well as contralateral corticofugal (motor) facilitation. [See original article for figures showing data on 3 cats and a longer discussion.]

3. Fed. Proc. 22: 456, 1963.

Recovery Time for Placing Following Unilateral Ablations in Cats. Bogen, J.E., Campbell, B.

Placing refers to certain movement sequences of an animal in which a paw is lifted up, moved forward and set down on a surface. In the cat, placing of a forelimb in response to chin contact on the edge of a table is the most easily elicited. Contact of the dorsum of the forepaw with the table edge is less regularly elicited in the normal cat and less apt to recover following brain lesions. Loss of chin contact placing was reported to follow hemidecortication (Rademaker) or sensori-motor cortex ablation (Bard). We have found that the complete loss which follows a frontal lobe removal is succeeded by gradual reacquisition of chin contact placing so that in 8 - 12 weeks the majority showed responses hardly distinguishable from that of the unaffected limb. Following hemispherectomy on one side, the chin contact placing reaction recovers in fewer animals and, for full recovery requires a longer period than with the more restricted cortical lesion. We have previously noted that contralateral removals my accelerate recover from hemispherectomy. (Science, 135, 309, 1962).

4. Bull. L.A. Neurol. Soc. 37: 152, 1972.

Placing Reactions as a Model for "Stroke". Bogen,J.E..

Primary sensori-motor corticectomy, or hemispherectomy, is followed by the loss of various forms of placing in the contralateral forelimb of the cat (Bard, 1933). Placing to chin contact slowly returns, especially after the smaller ablation. However, placing to paw contact returns poorly if at all. The placing to paw contact does return, often dramatically, after a second ablation on the other side (Bogen and Campbell, 1962). This finding, plus the fact that placing can occur in decorticate cats given amphetamine (Meyers, et al, 1962), shows that the primary ablation does not destroy the capacity for placing. Rather, it removes contralateral corticofugal facilitation thus suppressing the placing behavior. In this view, the second operation removes ipsilateral inhibition permitting the behavioral return. Ontogenesis of the corticofugal influences has been studied in kittens. It has been found that the inhibition has a different developmental time course from the facilitation, suggesting a different neural origin. To the extent that forelimb placing is homologous with distal limb function in the human after cortical injury, these results offer a new approach to the active treatment of stroke with hemiplegia.

5. Bogen, J.E. (1974). Hemispherectomy and the placing reactions in cat. In Kinsbourne, M. and Smith, W.L. (eds.), Hemisphere Disconnection and Cerebral Function. C.C. Thomas, Springfield.

Extensive review of hemispherectomy in experimental animals. Also, additional data in four more cats showing return of paw contact placing after a second operation. Also some discussion of methodology problems including "halter inhibition" (via trigeminal stimulation) produced by blindfolds. Also shows ages at which visual, chin contact ,and paw contact placing appear in kitten (See figure 5.1). Also has pic of development of corticofugal inhibition in kitten (see 7. below for this picture).

Figure 5.1

6. J. Neurobiol. 6: 125-127 (1975).

Cats decerebrated just above the hypothalamus walk unassisted but with forepaws doubled under, and do not show paw contact placing. The placing reappears, however, when the cats are given large caffeine injections. (click here for complete text).

7. Proc. Soc. Neurosci. 3: 100, 1977.

Delayed Disappearance of Placing After Hemispherectomy in the Kitten.

Bogen, J.E., Campbell, B. and Suzuki, M.

After sensorimotor corticectomy, frontal lobectomy ,or hemispherectomy there is an immediate and enduring loss of paw contact placing in the contralateral limb. A second ablation (of the remaining frontal lobe) results in immediate return of placing (Bogen & Campbell, Science 135: 309-310., 1962) suggesting that the previous loss was due to unbalanced, tonic, ipsilateral inhibition. The cortical origin of this inhibition is indicated by subsequent experiments in which hemispherectomy of kittens 10-12 days old is followed by loss of contralateral paw contact placing only after a five week delay. During this delay, chin contact placing and visual placing appear, before subsiding gradually rather than abruptly as in the adult cat. This experiment exposes the ontogenesis of corticofugal influences on a behavior whose essential features appear to be organized subcortically.

Figure 7.1

Legend for the Figure:

All open symbols (circles, squares, and triangles) represent function of the paw contralateral to the right hemispherectomy. All solid symbols indicate function of the forepaw ipsilateral to the hemispherectomy.

These data show how hemispherectomy in infancy can unmask the development of corticofugal facilitation and inhibition. At the time of the operation (12th post-partum day) paw-contact placing was well-established bilaterally but there was no chin contact placing or visual placing. Toward the end of the fourth week both of the latter appeared bilaterally. Between the 30th and 33rd days all three forms of placing were brisk bilaterally. All three forms of placing then progressively disappeared from the limb contralateral to the hemispherectomy, reflecting the development of ipsilateral descending inhibition from the maturing frontal cortex.