We then placed the animal into the MRI, acquiring functional volumes while alternating between microstimulation on and microstimulation off conditions every 24 s while the monkey fixated on a dot in the center of a gray screen. In both monkeys, microstimulation elicited strong activation throughout the OTS, as well as in an anatomically discontinuous region in the medial parahippocampal gyrus, which we term the medial place patch (MPP) for reasons discussed below. As with LPP, histological studies differ in their region labels for the area in which this activation resides, terming it TLO (Blatt and Rosene, 1998 and Blatt et al., 2003), TFO (Saleem et al., 2007), or VTF (Boussaoud et al., 1991). Erastin purchase Additional

microstimulation-evoked activation was observed in extrastriate Roxadustat visual areas V4V and putative DP and in the inferior branch of the posterior middle temporal sulcus (PMTS) (Figure 3). These areas are a subset

of the areas identified by tracing studies of the vicinity of LPP, which have shown reciprocal connectivity with medial parahippocampal areas, as well as extrastriate visual areas V3A, V3V, V4, FST, MST, LIP, and 7a; area TPO; retrosplenial cortex; and hippocampal subfield CA1 (Blatt and Rosene, 1998, Blatt et al., 2003 and Distler et al., 1993). Of the regions activated by microstimulation, we were particularly interested in the activation in the medial parahippocampal gyrus (MPP). Because this site is putatively located within parahippocampal cortex, it is well suited to carry scene information to the hippocampus, and, like LPP, it is potentially homologous to the human PPA. Furthermore, the region was also weakly activated by the place localizer in one hemisphere of M3, suggesting that it might respond to passive viewing of scenes (Figure S1C). We targeted this medial parahippocampal region as MTMR9 activated by microstimulation in monkey M1 (Figures S4A and S4B) and recorded a large proportion of scene-selective

single units (Figure 4A). Twenty-seven percent of visually responsive units (31/113) exhibited a scene selectivity index greater than one-third (median = 0.16; Figure 4B). While LPP and MPP exhibited similar latencies (LPP: 120 ± 42 ms; MPP: 123 ± 63 ms; p = 0.33, unequal variance t test), the duration of the neural response was nearly twice as long in LPP as compared to MPP (LPP: 155 ± 76 ms; MPP: 90 ± 70 ms; p < 10−14, unequal variance t test; Figure S4C). Additionally, none of 24 units recorded from grid holes between MPP and LPP were visually responsive, a significant difference from results in both regions (both p < 0.003, Fisher’s exact test; Figures S4D–S4G). These results indicate that MPP and LPP are distinct functional regions. To ensure that the scene selectivity observed in single units in LPP and MPP was not present throughout all ventral visual areas, we also recorded from 41 single units in a region 3 mm posterior to LPP (Figures 4 and S4H).