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The organization and evolution of dorsal stream multisensory motor pathways in primates.

Kaas JH, Gharbawie OA, Stepniewska I - Front Neuroanat (2011)

Bottom Line: Each functional zone receives a different pattern of visual and somatosensory inputs, and projects preferentially to functionally matched parts of motor and premotor cortex.As PPC is a relatively small portion of cortex in most mammals, including the close relatives of primates, we suggest that a larger, more significant PPC emerged with the first primates as a region where several ethologically relevant behaviors could be initiated by sensory and intrinsic signals, and mediated via connections with premotor and motor cortex.While several classes of PPC modules appear to be retained by all primates, elaboration and differentiation of these modules likely occurred in some primates, especially humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Vanderbilt University Nashville, TN, USA.

ABSTRACT
In Prosimian primates, New World monkeys, and Old World monkeys microstimulation with half second trains of electrical pulses identifies separate zones in posterior parietal cortex (PPC) where reaching, defensive, grasping, and other complex movements can be evoked. Each functional zone receives a different pattern of visual and somatosensory inputs, and projects preferentially to functionally matched parts of motor and premotor cortex. As PPC is a relatively small portion of cortex in most mammals, including the close relatives of primates, we suggest that a larger, more significant PPC emerged with the first primates as a region where several ethologically relevant behaviors could be initiated by sensory and intrinsic signals, and mediated via connections with premotor and motor cortex. While several classes of PPC modules appear to be retained by all primates, elaboration and differentiation of these modules likely occurred in some primates, especially humans.

No MeSH data available.


Sensorimotor cortical pathways of tree shrews. The extent of posterior parietal cortex is very limited, and most visual and somatosensory information reaches motor cortex (M1) directly from somatosensory and visual areas. The caudal somatosensory area, SC, is a likely homolog of area 1–2 of galagos. TP, TD, and TA are proposed posterior, dorsal, and anterior temporal visual areas. S1 and S2, primary and secondary somatosensory areas. PV, the parietal ventral somatosensory area. Aud, auditory cortex. PM, premotor cortex. Arrows depict some of the relevant cortical connections. Based on Remple et al. (2006).
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Figure 6: Sensorimotor cortical pathways of tree shrews. The extent of posterior parietal cortex is very limited, and most visual and somatosensory information reaches motor cortex (M1) directly from somatosensory and visual areas. The caudal somatosensory area, SC, is a likely homolog of area 1–2 of galagos. TP, TD, and TA are proposed posterior, dorsal, and anterior temporal visual areas. S1 and S2, primary and secondary somatosensory areas. PV, the parietal ventral somatosensory area. Aud, auditory cortex. PM, premotor cortex. Arrows depict some of the relevant cortical connections. Based on Remple et al. (2006).

Mentions: Cortical organization in tree shrews has been extensively studied in an effort to infer the organization of cortex in the immediate ancestors of primates. Both tree shrews and early primates adapted to a greater reliance on vision by expanding visual cortex so that temporal and occipital regions of cortex were enlarged. Present-day tree shrews have a number of visual areas (Lyon et al., 1998), and other regions of visual cortex that have not yet been characterized (Figure 6). An auditory region may contain several areas. SC includes a primary area S1 or area 3b, a narrow area 3a just rostral to S1, and a narrow band of SC just caudal to S1 in the position of area 1 or area 1–2 of primates (Remple et al., 2006, 2007). Only a narrow band of cortex posterior to caudal SC can be reasonably defined as PPC, as it has a mixture of somatosensory and visual inputs, and projects to frontal motor cortex. However, some of the higher-order visual areas project directly to motor and frontal cortex, as do somatosensory areas. Thus, motor cortex functions are more directly guided by visual and somatosensory information in tree shrews than in primates. Since PPC is only a small part of cortex, it likely has a much more limited role. Rodents such as rats and squirrels also have proportionately little PPC and have direct visual and somatosensory inputs into motor and premotor cortex. Thus, an expanded PPC, with separate modules and connections with motor and premotor cortex form parallel networks that support different actions. Those networks evolved as early primates emerged, and their basic components have been retained in most or all extant primates. This is not to say that an expanded and functionally important PPC did not evolve independently in other branches of mammalian evolution, in carnivores for example, but this did not happen in other Euarchontoglires.


The organization and evolution of dorsal stream multisensory motor pathways in primates.

Kaas JH, Gharbawie OA, Stepniewska I - Front Neuroanat (2011)

Sensorimotor cortical pathways of tree shrews. The extent of posterior parietal cortex is very limited, and most visual and somatosensory information reaches motor cortex (M1) directly from somatosensory and visual areas. The caudal somatosensory area, SC, is a likely homolog of area 1–2 of galagos. TP, TD, and TA are proposed posterior, dorsal, and anterior temporal visual areas. S1 and S2, primary and secondary somatosensory areas. PV, the parietal ventral somatosensory area. Aud, auditory cortex. PM, premotor cortex. Arrows depict some of the relevant cortical connections. Based on Remple et al. (2006).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC3116136&req=5

Figure 6: Sensorimotor cortical pathways of tree shrews. The extent of posterior parietal cortex is very limited, and most visual and somatosensory information reaches motor cortex (M1) directly from somatosensory and visual areas. The caudal somatosensory area, SC, is a likely homolog of area 1–2 of galagos. TP, TD, and TA are proposed posterior, dorsal, and anterior temporal visual areas. S1 and S2, primary and secondary somatosensory areas. PV, the parietal ventral somatosensory area. Aud, auditory cortex. PM, premotor cortex. Arrows depict some of the relevant cortical connections. Based on Remple et al. (2006).
Mentions: Cortical organization in tree shrews has been extensively studied in an effort to infer the organization of cortex in the immediate ancestors of primates. Both tree shrews and early primates adapted to a greater reliance on vision by expanding visual cortex so that temporal and occipital regions of cortex were enlarged. Present-day tree shrews have a number of visual areas (Lyon et al., 1998), and other regions of visual cortex that have not yet been characterized (Figure 6). An auditory region may contain several areas. SC includes a primary area S1 or area 3b, a narrow area 3a just rostral to S1, and a narrow band of SC just caudal to S1 in the position of area 1 or area 1–2 of primates (Remple et al., 2006, 2007). Only a narrow band of cortex posterior to caudal SC can be reasonably defined as PPC, as it has a mixture of somatosensory and visual inputs, and projects to frontal motor cortex. However, some of the higher-order visual areas project directly to motor and frontal cortex, as do somatosensory areas. Thus, motor cortex functions are more directly guided by visual and somatosensory information in tree shrews than in primates. Since PPC is only a small part of cortex, it likely has a much more limited role. Rodents such as rats and squirrels also have proportionately little PPC and have direct visual and somatosensory inputs into motor and premotor cortex. Thus, an expanded PPC, with separate modules and connections with motor and premotor cortex form parallel networks that support different actions. Those networks evolved as early primates emerged, and their basic components have been retained in most or all extant primates. This is not to say that an expanded and functionally important PPC did not evolve independently in other branches of mammalian evolution, in carnivores for example, but this did not happen in other Euarchontoglires.

Bottom Line: Each functional zone receives a different pattern of visual and somatosensory inputs, and projects preferentially to functionally matched parts of motor and premotor cortex.As PPC is a relatively small portion of cortex in most mammals, including the close relatives of primates, we suggest that a larger, more significant PPC emerged with the first primates as a region where several ethologically relevant behaviors could be initiated by sensory and intrinsic signals, and mediated via connections with premotor and motor cortex.While several classes of PPC modules appear to be retained by all primates, elaboration and differentiation of these modules likely occurred in some primates, especially humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Vanderbilt University Nashville, TN, USA.

ABSTRACT
In Prosimian primates, New World monkeys, and Old World monkeys microstimulation with half second trains of electrical pulses identifies separate zones in posterior parietal cortex (PPC) where reaching, defensive, grasping, and other complex movements can be evoked. Each functional zone receives a different pattern of visual and somatosensory inputs, and projects preferentially to functionally matched parts of motor and premotor cortex. As PPC is a relatively small portion of cortex in most mammals, including the close relatives of primates, we suggest that a larger, more significant PPC emerged with the first primates as a region where several ethologically relevant behaviors could be initiated by sensory and intrinsic signals, and mediated via connections with premotor and motor cortex. While several classes of PPC modules appear to be retained by all primates, elaboration and differentiation of these modules likely occurred in some primates, especially humans.

No MeSH data available.