FURTHER INVESTIGATIONS ON DIENCEPHALIC-CORTICAL RELATIONS AND THEIR SIGNIFICANCE FOR THE PROBLEM OF EMOTION

Abstract

The relation between the various areas of the cortex of the brain and diencephalic nuclei was investigated by local application of strychnine to the cortex and exploration of the forebrain nuclei for strychnine spikes as well as by injn. of the latter with strychnine and exploration of other forebrain nuclei and the cortex for convulsive potentials. The results were as follows: Injn. of strychnine into the hypothalamus causes first "firing" of the dorsomedial thalamic nucleus and later of the cortex. This may be followed by the appearance of spikes in the contralateral hypothalamus, the dorsomedial nucleus, and the cortex. The ventrolateral thalamic nucleus remains constantly negative under these conditions. Strych-ninization of the dorsomedial nucleus causes "firing" in the ipsilateral and then in the contralateral cortex. In addition, with repeated injection, or after a sufficient interval of time, the ipsi- and contralateral hypothalamus and the ventrolateral thalamic nuclei as well as the contralateral dorsomedial nucleus show strychnine spikes. A study of the cortical potentials and their comparison with the potentials in the nuclei which initiated the strychnine "firing" indicates that the discharge in the cortex is sustained and may show a convulsive activity many times greater than that found in the forebrain nucleus. Strychninization of the ventrolateral thalamic nucleus causes "firing," in the hypothalamus and dorsomedial thalamic nucleus on both sides as well as in the contralateral ventrolateral thalamic nucleus. The "firing" of the cortex as described by Dusser de Barenne was confirmed. Strychninization of various cortical areas (gyrus proreus of the prefrontal lobe, the sensorimotor cortex, the primary acoustic area and the gyrus cinguli) causes the appearance of spikes in the anterior and posterior hypothalamus, the dorsomedial and the ventrolateral thalamic nuclei. In these, as well as in all other expts., the ipsilateral discharges appeared earlier and showed greater intensity than contralateral spiking. Simultaneous recordings of the resting potentials from the cortex and forebrain nuclei show the appearance of "Dial" bursts not only in the dorsomedial thalamic nucleus as found by Morison, Findley and Lothrop, but also in the hypothalamus and ventrolateral thalamic nuclei. These observations suggest the hypothalamus as a site of origin of these grouped potentials.