Fig. 4.

HD cells in AD lost all of their directional firing properties in response to BLs of LMN. The directional tuning curves of each HD cell are plotted before (solid lines) and immediately after (broken lines) the BLs. Notice that HD cells did not fall silent after BLs but fired spontaneously in a nondirectional manner (see Results). Gray shading indicates the extent of the lesion in each case, as in Figure 2. PMD, Dorsal premammillary nucleus;LH, lateral hypothalamic area; PMV, ventral premammillary area; VTA, ventral tegmental area;SuM, supramammillary nucleus; ML, medial mammillary nucleus (lateral division); MM, medial mammillary nucleus (medial division); Arc, arcuate hypothalamic nucleus.