Biographical Memoirs Volume 65 (1994) / Chapter Skim
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9. David P. C. Lloyd
9. David P. C. Lloyd
Pages 196-209
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From page 197... ...
by the use of micropipette electrodes to measure membrane potentials of motoneurons subjected to controlled afferent inputs. A refinement of this technique utilizes computerizect averaging of membrane potential transients that permits one to assess the influence of single filter inputs.
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From page 198... ...
While his contributions never received the acclaim of a Nobel award, it can scarcely be denied that his detailed functional mapping of the intricate reciprocal reflex patterns of the lumbar cord and his identification of the peripheral sources and central connections of afferent fibers of different sizes constituted a critically essential connecting link between the two eras and one without which the third era could not easily have been prosecuted. in fact it may be that the "rules of the game" that Lloyd laid down were so clear and reasonable that subsequent investigators routinely employing them in designing experiments often took them for granted and forgot how dependent they were on his revelations.
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From page 199... ...
At that time the institute was the mecca of electrophysiology of the nervous system. Gasser's own interests were mainly in peripheral nerves but he gathered together a group including Lloyd, Birdsey Renshaw, Harry Grundfest, Lorente de No, and others who were interested in using the institute's available electronic gear to explore the spinal cord.
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From page 200... ...
, which innervate the primary endings of muscle spindles and proved that the monosynaptic ventral root discharge is destined exclusively for the fibers of the muscle from which the afferent volley arose. Conditioning-testing techniques established that the afferent volley facilitates but does not normally discharge the motoneurons supplying muscles that are synergists of the muscle from which the afferent volley arises and that it depresses the motoneurons supplying antagonistic muscles.
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From page 201... ...
C LLOYD 20 reflex described by Sherrington that there could be little doubt that they were one and the same, a likelihood that I~Ioy(1 subsequently prove(1 conclusively by showing that the central clelay of the earliest ventral root discharge elicited by a brief muscle stretch was too short to allow for more that one synaptic delay.
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From page 202... ...
The stained stump was then driest and the transection completed with a sharp knife neatly and cleanly exposing the unstained tracts that had been spared by the guillotine blade. In 1943 Lloyd, concerned about the uninviting prospects of raising his two chiTciren in a New York City apartment, left the institute to accept a faculty position in John Fulton's department at Yale Medical School.
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From page 203... ...
Almost immediately he produced two major publications, in one of which he sought to determine the time course of facilitation en cl inhibition using, in the first instance, a Group Ta conditioning ant! test volleys synergistic in nerve supplying muscle, and in the latter in nerves supplying antagonistic muscles.
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From page 204... ...
Quickly correcting this error so that the stimulus returned to a moderate repetition rate of one per second, he watched with amazement as the evoked reflexes grew to overfill the scope face and for a matter of some minutes remained at supranormal size. This persistent po
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From page 205... ...
as a consequence of a persistent hyperpolarization of the tetanizect terminals leading to increased transmitter potential of the presynaptic spike. The phenomenon can be used to bring out responses to small afferent volleys that otherwise escape detection.
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From page 206... ...
He could not bear the thought of being wrong and he insisted on excellence, precision, and neatness. Before giving a paper, he always carefully polished his slides for he hart nothing but contempt for the unfastidious speaker who displayed sli(les a(lorned with finger prints.
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From page 207... ...
6:111-19. Neuron patterns controlling the transmission of ipsilateral hind limb reflexes in cat.
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From page 208... ...
Nature and significance of the reflex connections established by large afferent fibers of muscle origin.
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From page 209... ...
Functional organization in the terminal segments of the spinal cord with a consideration of central excitatory and inhibitory latencies in monosynaptic reflex systems.
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