The neural and sensory mechanisms underlying appropriate muscle recruitment in response to balance challenges remains elusive. We asked whether the decerebrate cat preparation might be employed for further investigation of postural mechanisms. First, we evaluated the muscular activation patterns and three-dimensional whole limb forces generated by a modified premammillary decerebrated cat. We hypothesized that directionally appropriate muscle activation does not require the cerebral cortices. Furthermore, we hypothesized that the muscle responses would generate functionally appropriate and constrained force responses similar to those reported in the intact animal. Data confirmed both of our hypotheses and suggested important roles for the brainstem and spinal cord in mediating directionally appropriate muscular activation. Second, we investigated how individual muscle activation is translated to functional ground reaction forces. We hypothesized that muscles are selectively activated based upon their potential counteractive endpoint force. Data demonstrated that the endpoint force generated by each muscle through stimulation was directed oppositely to the principal direction of each muscle's EMG tuning curve. Further, muscles that have variable tuning curves were found to have variable endpoint forces in the XY plane. We further hypothesized that the biomechanical constraints of individual muscle actions generate the constrained ground reaction forces created in response to support surface perturbations. We found that there was a lack of muscles with strong medial-lateral actions in the XY plane. This was further exaggerated at long stance conditions, which corresponds to the increased force constraint present in the intact animal under the same conditions. Third, we investigated how loss of cutaneous feedback from the footpads affects the muscle recruitment in response to support surface perturbations. We utilized our decerebrate cat model as it allows 1) isolation of the proprioceptive system (cutaneous and muscle receptor) and 2) observation of the cutaneous loss before significant compensation by the animal. We hypothesized that muscle spindles drive directionally sensitive muscle activation during postural disturbances. Therefore, we expected that loss of cutaneous feedback from the foot soles would not alter the directional properties of muscle activation. While background activity was significantly diminished, the directionally sensitive muscular activation remained intact. Due to fixation of the head, the decerebrate cat additionally does not have access to vestibular or visual inputs. Therefore, this result strongly implicates muscle receptors as the primary source of directional feedback. Finally to confirm that muscle receptors, specifically muscle spindles, are capable of generating feedback to drive the directionally tuning, we investigated the response properties of muscle spindles to horizontal support surface perturbations in the anesthetized cat. As previously stated, we hypothesized that muscle spindles provide the feedback necessary for properly directed muscular responses. We further hypothesized that muscle spindles can relay feedback about the perturbation parameters such as velocity and the initial stance condtion. Results confirmed that muscle spindle generate activation patterns remarkably similar to muscular activation patterns generated in the intact cat. This information, along the knowledge that cutaneous feedback does not substantially eliminate directional tuning, strongly suggests that muscle spindles contribute the critical directional feedback to drive muscular activation in response to support surface perturbations.

<p><p><em>Transforming the Brute</em> addresses the ethical acceptability of creating painless animals for usage in biomedical experimentation.  In recent decades the possibility of creating genetically decerebrate animals or AMLs for human ends has been discussed in scientific, academic, and corporate communities.  While the ability to create animals that cannot feel, experience, and are more plant than animal remains science fiction, biomedicine may now be able to eliminate or significantly reduce the capacity to feel pain and nociception through genetic engineering.  With this new technology comes the opportunity to vastly increase the welfare of animals used in biomedical experimentation, yet this possibility has largely been ignored by the scientific and academic community.  This work seeks to reveal the moral necessity of creating painless animals for usage in biomedical experimentation for animal welfare ends.  Intrinsic objections relating to animal integrity, rights, companionship, the alteration of telos, humility and virtue are considered.  The benefit of eliminating nociceptive pain in experimental animals is addressed, and differences are examined between biomedical experimentation and other usage of animals for human ends which makes the proposed creation of painless animals ethically unique.  Finally, an argument is presented for the moral necessity of replacing normal animals with painless animals in biomedical experimentation with consideration given to genetically decerebrate animals.</p></p>

Transforming the Brute addresses the ethical acceptability of creating painless animals for usage in biomedical experimentation.  In recent decades the possibility of creating genetically decerebrate animals or AMLs for human ends has been discussed in scientific, academic, and corporate communities.  While the ability to create animals that cannot feel, experience, and are more plant than animal remains science fiction, biomedicine may now be able to eliminate or significantly reduce the capacity to feel pain and nociception through genetic engineering.  With this new technology comes the opportunity to vastly increase the welfare of animals used in biomedical experimentation, yet this possibility has largely been ignored by the scientific and academic community.  This work seeks to reveal the moral necessity of creating painless animals for usage in biomedical experimentation for animal welfare ends.  Intrinsic objections relating to animal integrity, rights, companionship, the alteration of telos, humility and virtue are considered.  The benefit of eliminating nociceptive pain in experimental animals is addressed, and differences are examined between biomedical experimentation and other usage of animals for human ends which makes the proposed creation of painless animals ethically unique.  Finally, an argument is presented for the moral necessity of replacing normal animals with painless animals in biomedical experimentation with consideration given to genetically decerebrate animals.