The thalamic connections of motor, premotor, and prefrontal areas of cortex in a prosimian primate (Otolemur garnetti)

Abstract

Connections of motor areas in the frontal cortex of prosimian galagos (Otolemur garnetti) were determined by injecting tracers into sites identified by microstimulation in the primary motor area (M1), dorsal premotor area (PMD), ventral premotor area (PMV), supplementary motor area (SMA), frontal eye field (FEF), and granular frontal cortex. Retrogradely labeled neurons for each injection were related to architectonically defined thalamic nuclei. Nissl, acetylcholinesterase, cytochrome oxidase, myelin, parvalbumin, calbindin, and Cat 301 preparations allowed the ventral anterior and ventral lateral thalamic regions, parvocellular and magnocellular subdivisions of ventral anterior nucleus, and anterior and posterior subdivisions of ventral lateral nucleus of monkeys to be identified. The results indicate that each cortical area receives inputs from several thalamic nuclei, but the proportions differ. M1 receives major inputs from the posterior subdivision of ventral lateral nucleus while premotor areas receive major inputs from anterior parts of ventral lateral nucleus (the anterior subdivision of ventral lateral nucleus and the anterior portion of posterior subdivision of ventral lateral nucleus). PMD and SMA have connections with more dorsal parts of the ventral lateral nucleus than PMV. The results suggest that galagos share many subdivisions of the motor thalamus and thalamocortical connection patterns with simian primates, while having less clearly differentiated subdivisions of the motor thalamus.

Thalamocortical Connections of Parietal Somatosensory Cortical Fields in Macaque Monkeys are Highly Divergent and Convergent

“…3) and have different patterns of interconnection with the neocortex. Thus, VLp (VPLo) has dense projections to motor and premotor areas and to area 3a (see Wiesendanger and Miles 1982; Macchi and Jones 1997; see Fang et al 2006 for review) while VPs has major projections to areas 2 and 5 (Pons and Kaas 1985b). For these reasons, it is more consistent with other nomenclature to refer to VPs and VLp as separate nuclei rather than as a shell of VP proper (Table 1).…”

Recollection and familiarity in the human thalamus

“…The lateral parvocellular portion of the MD (MDpc) has a completely different pattern of connectivity. Indeed, it is reciprocally connected to the dorsolateral regions of the frontal lobes (DLPFC) (Preuss and Goldman-Rakic, 1987;Fang et al, 2006;Ray and Price, 1993) and thus may influence the role played by the frontal lobes in memory (and when damaged presumably it presumably reflects the dysfunctional memory pattern observed following prefrontal damage). Indeed, the second assumption is that the DLPFC is particularly implicated in promoting relational memory (Blumenfeld et al, 2011;Mitchell and Johnson, 2009).…”

Multiple thalamo-cortical disconnections in anterior thalamic infarction: Implications for thalamic mechanisms of memory and language

“…Third, damage to the cellular component of the VA proper and the anterior portions of the VLa and VLp may lead to dysfunction of the lateral frontal cortices. These nuclei have abundant connections with the lateral frontal cortices (Fang, Stepniewska, & Kaas, 2006;Jones, 2007). …”