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CARPENTER: D., A. LUNDBERG and U. NORRSELL. Primary afferent depolarization evoked from the sensorimotor cortex. Acta physiol. scand. 1963. 59. 126-142. -Stimulation of the sensorimotor cortex evokes dorsal root potentials (DRP) in the lumbo-sacral cord. Primary afferent depolarization is evoked in group I b and group I1 muscle afferents and cutaneous afferents but not in Ia afferents. The effects are mediated by the pyramidal tract. There is spatial facilitation between the paths from primary afferents and cortex. It is concluded that the pyramidal tract acts on primary afferents by giving excitatory action to interneiirones of spinal reflex arcs to primary afferents. Activity in the pyramidal tract causes widespread activation of interneurones in the dorsal horn and intermediary region (LLOYD 1941, LUNDBERG, NORRSELL And VOORHOEVE 1962. A recent detailed analysis has revealcd facilitation from the pyramidal tract of interneurones transmitting actions to motorneiirones from Ia, I b and flexor reflex afferents (FRA) . Findings during this investigation gave rise to the question whether tlie pyramidal tract also had effect on primary afferents or on the spinal refkx paths to primary afferents. The reults of a systematic investigation of this problem will be presented below-. A basis for the present work has been tlie recent analysis of spinal reflex paths to primary afferents: Ia afferents are depolarized by volleys in Ia and Ib afferents mainly from flexors (ECCLES. MAGNI and WILLIS 1962 a), I b afferents are depolarized by 111 vollqs from flexor and extensor muscles (ECCLES, SCHMIDT and WILLIS I962 d j uhereas 1 Prrscnt address: Harvard Medical School, Bobton 15.I26

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Bilateral removal of the cerebral cortex was made in cats neonatally. Spontaneous and imposed behaviour was studied while they were growing up and after they had become adult. Special emphasis was put on the utilization of visual cues and on learning. The cats ate, drank and groomed themselves adequately. Adequate maternal and female sexual behaviour was observed. They utilized the visual and haptic senses with respect to external space. Two cats were trained to perform visual discrimination if a T-maze. The adequacy of the behaviour of these cats is compared to that of animals with similar lesions made at maturity.

LUNDBERG, A., U. NORRSELL and P. VOORHOEVE. Pyramidal effects on lurnbo-sacral interneurones activated by somatic afferents. Acta physiol. scand. 1962. 56. 220-229. -Intracellular recording was made from 23 interneurones in the dorsal horn and intermediate region. Stimulation of the sensorimotor cortex evoked excitatory postsynaptic potentials in interneurones receiving excitatory action from: 1) group I muscle afferents, 2) flexor reflex afferents, 3) cu-