The Cebidae are one of the five families of New World monkeys now recognised. Extant members are the capuchin and squirrel monkeys. These species are found throughout tropical and subtropical South and Central America.
The motor cortex is the region of the cerebral cortex involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately anterior to the central sulcus.
Dizocilpine (INN), also known as MK-801, is a pore blocker of the NMDA receptor, a glutamate receptor, discovered by a team at Merck in 1982. Glutamate is the brain's primary excitatory neurotransmitter. The channel is normally blocked with a magnesium ion and requires depolarization of the neuron to remove the magnesium and allow the glutamate to open the channel, causing an influx of calcium, which then leads to subsequent depolarization. Dizocilpine binds inside the ion channel of the receptor at several of PCP's binding sites thus preventing the flow of ions, including calcium (Ca2+), through the channel. Dizocilpine blocks NMDA receptors in a use- and voltage-dependent manner, since the channel must open for the drug to bind inside it. The drug acts as a potent anti-convulsant and probably has dissociative anesthetic properties, but it is not used clinically for this purpose because of the discovery of brain lesions, called Olney's lesions (see below), in laboratory rats. Dizocilpine is also associated with a number of negative side effects, including cognitive disruption and psychotic-spectrum reactions. It inhibits the induction of long term potentiation and has been found to impair the acquisition of difficult, but not easy, learning tasks in rats and primates. Because of these effects of dizocilpine, the NMDA receptor pore blocker ketamine is used instead as a dissociative anesthetic in human medical procedures. While ketamine may also trigger temporary psychosis in certain individuals, its short half-life and lower potency make it a much safer clinical option. However, dizocilpine is the most frequently used uncompetitive NMDA receptor antagonist in animal models to mimic psychosis for experimental purposes.
Squirrel monkeys are New World monkeys of the genus Saimiri. Saimiri is the only genus in the subfamily Saimirinae. The name of the genus is of Tupi origin and was also used as an English name by early researchers.
The common marmoset, also called white-tufted marmoset or white-tufted-ear marmoset, is a New World monkey. It originally lived on the northeastern coast of Brazil, in the states of Piaui, Paraiba, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, and Bahia. Through release of captive individuals, it has expanded its range since the 1920s to Southeast Brazil, where it became an invasive species, raising concerns about genetic pollution of similar species, such as the buffy-tufted marmoset, and predation upon bird nestlings and eggs.
A stereotypy is a repetitive or ritualistic movement, posture, or utterance. Stereotypies may be simple movements such as body rocking, or complex, such as self-caressing, crossing and uncrossing of legs, and marching in place. They are found especially in people with autism spectrum disorders, visually impaired children, and are also found in intellectual disabilities, tardive dyskinesia and stereotypic movement disorder, yet may also be encountered in neurotypical individuals as well. Studies have shown stereotypies to be associated with some types of schizophrenia. Frontotemporal dementia is also a common neurological cause of repetitive behaviors and stereotypies. A number of causes have been hypothesized for stereotypy, and several treatment options are available.
Common squirrel monkey is the traditional common name for several small squirrel monkey species native to the tropical areas of South America. The term common squirrel monkey had been used as the common name for Saimiri sciureus before genetic research by Jessica Lynch Alfaro and others indicated S. scuireus covered at least three and possibly four species: the Guianan squirrel monkey, Humboldt's squirrel monkey and Collins' squirrel monkey. The Ecuadorian squirrel monkey, generally regarded as a subspecies of Humboldt's squirrel monkey, had also been sometimes proposed as a separate species that had originally been included within the term "common squirrel monkey."
The black squirrel monkey, also known as the blackish squirrel monkey or black-headed squirrel monkey, is a small New World primate, endemic to the central Amazon in Brazil. It largely resembles the female of the far more common Bolivian squirrel monkey, though the latter lacks the black central back.
The black-capped squirrel monkey is a species of New-World monkey native to the upper Amazon basin in Bolivia, western Brazil and eastern Peru. They weigh between 365 and 1,135 g and measure, from the head to the base of the tail, between 225 and 370 mm. Black-capped squirrel monkeys are primarily tree-dwelling and are found in both native and plantation forests as well as some farmed areas near running water. Their diet is omnivorous and mostly consists of flowers, fruit, leaves, nuts, seeds, insects, arachnids, eggs and small vertebrates. They mostly live in female-dominated troops of around 40 to 75 monkeys, with males having been observed to disperse to live in all-male troops after reaching sexual maturation. Their current conservation status according to the IUCN is 'Least Concern'. The species belongs to the genus Saimiri and has two subspecies, S. b. boliviensis and S. b. peruviensis.
The Central American squirrel monkey, also known as the red-backed squirrel monkey, is a squirrel monkey species from the Pacific coast of Costa Rica and Panama. It is restricted to the northwestern tip of Panama near the border with Costa Rica, and the central and southern Pacific coast of Costa Rica, primarily in Manuel Antonio and Corcovado National Parks.
The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks. Different subregions of the premotor cortex have different properties and presumably emphasize different functions. Nerve signals generated in the premotor cortex cause much more complex patterns of movement than the discrete patterns generated in the primary motor cortex.
The basal ganglia form a major brain system in all species of vertebrates, but in primates there are special features that justify a separate consideration. As in other vertebrates, the primate basal ganglia can be divided into striatal, pallidal, nigral, and subthalamic components. In primates, however, there are two pallidal subdivisions called the external globus pallidus (GPe) and internal globus pallidus (GPi). Also in primates, the dorsal striatum is divided by a large tract called the internal capsule into two masses named the caudate nucleus and the putamen—in most other species no such division exists, and only the striatum as a whole is recognized. Beyond this, there is a complex circuitry of connections between the striatum and cortex that is specific to primates. This complexity reflects the difference in functioning of different cortical areas in the primate brain.
The supplementary motor area (SMA) is a part of the motor cortex of primates that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of the primary motor cortex leg representation. In monkeys the SMA contains a rough map of the body. In humans the body map is not apparent. Neurons in the SMA project directly to the spinal cord and may play a role in the direct control of movement. Possible functions attributed to the SMA include the postural stabilization of the body, the coordination of both sides of the body such as during bimanual action, the control of movements that are internally generated rather than triggered by sensory events, and the control of sequences of movements. All of these proposed functions remain hypotheses. The precise role or roles of the SMA is not yet known.
The Mauthner cells are a pair of big and easily identifiable neurons located in the rhombomere 4 of the hindbrain in fish and amphibians that are responsible for a very fast escape reflex. The cells are also notable for their unusual use of both chemical and electrical synapses.
Environmental enrichment is the stimulation of the brain by its physical and social surroundings. Brains in richer, more stimulating environments have higher rates of synaptogenesis and more complex dendrite arbors, leading to increased brain activity. This effect takes place primarily during neurodevelopment, but also during adulthood to a lesser degree. With extra synapses there is also increased synapse activity, leading to an increased size and number of glial energy-support cells. Environmental enrichment also enhances capillary vasculation, providing the neurons and glial cells with extra energy. The neuropil expands, thickening the cortex. Research on rodent brains suggests that environmental enrichment may also lead to an increased rate of neurogenesis.
Judith L. Hand is an American evolutionary biologist, animal behaviorist (ethologist) and a novelist. She writes on a variety of topics related to the science of animal and human behavior, including the biological and evolutionary roots of war, gender differences in conflict resolution, the empowerment of women, and the steps for ending war.
Brenda McCowan is a research behaviorist interested in evolutionary, biological, and ecological aspects of animal behavior and communication. Her work focuses on improving the health and welfare of domesticated production animals, captive species, and wildlife using applied animal behavior and bioacoustics. She received her BS in Animal Physiology from Cornell University in 1985, and her PhD in Biological Anthropology from Harvard University in 1994. Dr. McCowan is the Program Head of Primate Behavioral Management at California National Primate Research Center, a position she has held since 2004. Dr. McCowan has been on the faculty at the University of California – Davis since 1999, and is currently an Associate Adjunct Professor in the Department of Population Health and Reproduction at the UC Davis School of Veterinary Medicine. She also heads the McCowan Lab of Behavioral Management at UC Davis School of Veterinary Medicine. Dr. McCowan is also affiliated with the Alaska Whale Foundation, SETI Institute, Hubbs-Sea World Institute, and Santa Fe Institute.
Humboldt's squirrel monkey is a species of squirrel monkey from Brazil, Colombia, Ecuador, Peru and Venezuela. It had previously been considered a subspecies of the common squirrel monkey, S. scuireus, but was elevated to full species status based on a genetic study by Carretero-Pinzón in 2009. A genetic study by Jessica Lynch Alfaro, et al indicated that the Ecuadorian squirrel monkey may be synonymous with Saimiri cassiquiarensis. As of 2018, the Ecuadorian squirrel monkey is generally regarded as a subspecies of Humboldt's squirrel monkey, S. cassiquiarensis macrodon.
The Guianan squirrel monkey is a species of squirrel monkey from Guiana, Venezuela and Brazil. S. sciureus formerly applied to Humboldt's squirrel monkey and Collins' squirrel monkey, but genetic research in 2009 and 2015 revealed that these are distinct species.
The Ecuadorian squirrel monkey is a type of squirrel monkey. It had been considered a subspecies of the Guianan squirrel monkey, Saimiri sciureus, but was elevated to a full species, S. macrodon, based on a 2009 study by Carretero-Pinzón, et al. Based on subsequent genetic research by Jessica Lynch Alfaro, et al it was again reclassified as a subspecies of Humboldt's squirrel monkey.
