Cortical Connections to Area TE in Monkey: Hybrid Modular and Distributed Organization

Abstract

To investigate the fine anatomical organization of cortical inputs to visual association area TE, 2–3 small injections of retrograde tracers were made in macaque monkeys. Injections were made as a terminal procedure, after optical imaging and electrophysiological recording, and targeted to patches physiologically identified as object-selective. Retrogradely labeled neurons occurred in several unimodal visual areas, the superior temporal sulcus, intraparietal sulcus (IPS), and prefrontal cortex (PFC), consistent with previous studies. Despite the small injection size (<0.5 mm wide), the projection foci in visual areas, but not in IPS or PFC, were spatially widespread (4–6 mm in extent), and predominantly consisted of neurons labeled by only one of the injections. This can be seen as a quasi-modular organization. In addition, within each projection focus, there were scattered neurons projecting to one of the other injections, together with some double-labeled (DL) neurons, in a more distributed pattern. Finally, projection foci included smaller “hotspots,” consisting of intermixed neurons, single-labeled by the different injections, and DL neurons. DL neurons are likely the result of axons having extended, spatially separated terminal arbors, as demonstrated by anterograde experiments. These results suggest a complex, hybrid connectivity architecture, with both modular and distributed components.

Synchronization between the end stages of the dorsal and the ventral visual stream

“…Such top-down information could be useful for AIP in contexts in which familiar objects need to be grasped or when grasping perceptually ambiguous objects that are disambiguated through contextual information. Our findings (i.e., the spike-field coherence, GC, and phase differences between neural signals), together with the known anatomical connections between IT and AIP (Borra et al 2008(Borra et al , 2010, suggest the possibility that the beta activity is relayed through AIP to IT. Alternatively, the synchronized beta activity between IT and AIP could be due to common input arriving earlier in AIP.…”

“…In addition, neurons in the anterior intraparietal area AIP, the end stage of the dorsal visual stream, also exhibit selectivity for disparity-defined 3D shapes (Srivastava et al 2009;Verhoef et al 2010). Furthermore, recent anatomical tracer studies have found direct reciprocal connections between 3D-shape selective areas IT (area TEs) and AIP (Borra et al 2008(Borra et al , 2010. Accordingly, several authors have hypothesized that these anatomical connections are used to facilitate 3D-shape perception (Chinellato and Del Pobil 2009;Orban et al 2006).…”

Subjective visual perception: from local processing to emergent phenomena of brain activity

“…However, these temporal areas are not the final processing stage in the ventral visual stream that is involved in object perception [47]. Temporal cortical regions are reciprocally connected through monosynaptic connections with visually modulated areas of the lateral prefrontal cortex (LPFC) [48][49][50][51] where single units respond to faces and complex visual objects similarly to cells recorded in the temporal cortex [52][53][54]. Therefore, an intriguing question is whether the content of conscious perception is represented with the same magnitude in the LPFC.…”

Anatomical Evidence for the Involvement of the Macaque Ventrolateral Prefrontal Area 12r in Controlling Goal-Directed Actions

“…First, after tracer injections in the location of area TEa/m (Saleem et al, 2008) or in the inferotemporal convexity cortex (Webster et al, 1994;Saleem et al, 2008;Borra et al, 2010b), the prefrontal labeling involved the caudal and intermediate parts, but not the rostral part, of area 12r. Second, after injections in F5a or AIP (Borra et al, 2008), the labeling in area 12r was confined to the intermediate part.…”