Primate

About: Primate is a research topic. Over the lifetime, 1250 publications have been published within this topic receiving 67388 citations. The topic is also known as: the primate order & primates.

Sexual Attractiveness and Receptivity in Rhesus Monkeys

Abstract: THE catarrhine monkeys and the apes alone among animals have a clearly defined menstruation with a cycle lasting about 30 days. They do not show well-circumscribed periods of oestrus (heat), but will copulate throughout the cycle. This has led to the idea that the great development of neocortical mechanisms in the primate has resulted in an emancipation of its brain from the influence of gonadal steroids1. Earlier work in both the rhesus monkey2,3 and the chimpanzee4–6, however, has indicated that the level of sexual interaction shows some variation with the phases of the menstrual cycle. Furthermore, studies of the rhesus monkey7,8 have shown that well marked rhythms of mounting behaviour by males occur in relation to the menstrual cycles of their female partners. These rhythms are abolished by bilateral ovariectomy, and so endocrine mechanisms in primate sexual behaviour seem to have been underestimated9.

Cortical neuron response properties are related to lesion extent and behavioral recovery after sensory loss from spinal cord injury in monkeys.

Abstract: Lesions of the dorsal columns at a mid-cervical level render the hand representation of the contralateral primary somatosensory cortex (area 3b) unresponsive. Over weeks of recovery, most of this cortex becomes responsive to touch on the hand. Determining functional properties of neurons within the hand representation is critical to understanding the neural basis of this adaptive plasticity. Here, we recorded neural activity across the hand representation of area 3b with a 100-electrode array and compared results from owl monkeys and squirrel monkeys 5–10 weeks after lesions with controls. Even after extensive lesions, performance on reach-to-grasp tasks returned to prelesion levels, and hand touches activated territories mainly within expected cortical locations. However, some digit representations were abnormal, such that receptive fields of presumably reactivated neurons were larger and more often involved discontinuous parts of the hand compared with controls. Hand stimulation evoked similar neuronal firing rates in lesion and control monkeys. By assessing the same monkeys with multiple measures, we determined that properties of neurons in area 3b were highly correlated with both the lesion severity and the impairment of hand use. We propose that the reactivation of neurons with near-normal response properties and the recovery of near-normal somatotopy likely supported the recovery of hand use. Given the near-completeness of the more extensive dorsal column lesions we studied, we suggest that alternate spinal afferents, in addition to the few spared primary axon afferents in the dorsal columns, likely have a major role in the reactivation pattern and return of function.

Primate homeland: forests and the evolution of primates during the Tertiary and Quaternary in Asia

Abstract: Primates evolved in the tropical forests of the Late Paleocene or Early Eocene. The cognitive, locomotor and life-history characteristics that define primates evolved under the equable and generally non-seasonal conditions that distinguish such forests. All primates since have carried the biological imprint of this original association with tropical forests. In Asia, the persistence of tropical forests in Indonesia from the Eocene onward has permitted tarsiers to endure and evolve, while other Eocene primates became extinct on their home continents. Following a disastrous decline in tropical forest distribution and primate diversity at the Late Eocene/Oligocene boundary, forests and primates rebounded during the Late Oligocene and Miocene. The dominant Old World primates of most of the Neogene were hominoids, which inhabited large tracts of woodlands and forests throughout Africa and Eurasia. These relatively large, frugivorous animals were quadrupedal, but many were capable of undertaking bridging postures that allowed them to stretch between arboreal substrates. Hominoids reached the apex of their evolutionary success in the Middle Miocene, then declined—as a result of the slow disappearance of their forest homes—in the Late Miocene, especially after 10 Ma. The extirpation of apes at this time can be traced to their inability to live in more seasonal and open habitats. Old World monkeys originated in forest biomes, but became the dominant primate of the late Neogene because of their ability to live in environments ranging from closed, non-seasonal rainforests to open savannahs and alpine meadows. This adaptability can be traced to their slightly faster life histories and their ability to thrive on a wide range of both high- and low-quality foods.

Growth/differentiation factor 7 is preferentially expressed in the primary motor area of the monkey neocortex

Abstract: We applied a differential display PCR technique to isolate molecules that are area-specific in expression in the primate neocortex, and found that growth/differentiation factor 7 (GDF7), a member of the bone morphogenetic protein (BMP)/transforming growth factor (TGF) beta super-family, is preferentially expressed in the primary motor area of African green monkeys (Cercopithecus aethiops). We proved that GDF7 is 10 times more abundant in the motor cortex than in the visual cortex by northern blotting and quantitative RT-PCR. When we examined the neocortex of closely related rhesus monkeys (Macaca mulatta), GDF7 was also most abundant in the motor cortex, although the regional difference was reduced to 3-fold. This differential expression pattern was observed in both newborn and infant rhesus monkeys. We found that several type I/II receptors of BMP, candidates of the receptors for GDF7, are uniformly expressed in the mature neocortex. The unique expression pattern of GDF7 suggests that it may play an active role in the motor area of the primate neocortex.

Vitamin C deficiency in captive nonhuman primates fed commercial primate diet.

Abstract: Scurvy was diagnosed in 19 rhesus monkeys (Macaca mulatta) and four squirrel monkeys (Saimiri sciureus) from a colony of nonhuman primates maintained on a commercial diet. Signs of weakness, reluctance to move, gingival hemorrhage, bruising, proximal and distal metaphyseal fractures, weight loss and anemia appeared in juvenile and young adult rhesus monkeys over a 2 week period. Clinical signs subsided after 5 days of vitamin C therapy. At the same time, cephalohematomas and weakness developed in squirrel monkeys, which failed to respond to treatment. These cases were associated with manufacturer's admitted error in preparation of the commercially prepared monkey diet.