Effects from the Sensorimotor Cortex on Ascending Spinal Pathways

The effect of stimulation of the sensorimotor cortex on ascending spinal pathways was investigated in cats with recording of mass discharges, with intracellular recording from the cell bodies and with unit recording from the axons. Apart from effects caused by primary afferent depolarization there are marked effects from the sensorimotor cortex only on pathways influenced from the flevor reflex afferents (FKA). This holds true for the ventral spinocercbellar tract which is inhibited from the FRA and from cortex and for the ventral spinobulbar tract which is excited from the FRA and from cortex. The same parallelism betwerri actions from cortex and the FKA was found for the dorsal spinocerrbellar tract but not for the spinocervical tract which have FRA activated neurones that are not excited from the sensorimotor cortex.