Macaques with object recognition memory deficits display hyperactivity in the CA3 region of the hippocampus that is associated with fewer somatostatin(SOM)-positive inhibitory interneurons. Amanda Rodewald, Ivan Rudik, and Catherine Kling talk about the hazards of ozone pollution to birds. We thus show that, like human speech areas, macaque homologs in lateral frontal cortex support communicative articulation. Under this hypothesis, the efficacy of neural circuits in relatively close proximity might become similarly impacted by vascular aging. Although the evidence is still limited, a growing body of research suggests music may have beneficial effects for diseases such as Parkinson’s. Importantly, the number of a specific type of interneuron expressing the neuropeptide somatostatin was positively associated with memory function in aged rats (25). The rhesus monkey brain in stereotaxic coordinates (2000) Google Scholar 28. As ethical debates continue to surround this work, the time has come for scientists, physicians, caretakers, and policy makers to engage in a dialogue, both among themselves and with the general public, directed toward devising the best and most humane nonhuman primate research models to achieve the common goal of optimizing cognitive health throughout life. Nobody likes the idea of experimenting on animals. Thus, a potentially promising therapeutic avenue to attenuate the effects of central auditory system aging may be to focus on reducing calcium levels in this system. Human neuroimaging has revealed a specific network of brain regions—the default-mode network (DMN)—that reduces its activity during goal-directed behavior. Edited by Elizabeth A. Buffalo, University of Washington, Seattle, WA, and accepted by Editorial Board Member Tony Movshon July 5, 2019 (received for review March 19, 2019). One important translational implication of this work is the suggestion that age-related episodic memory decline may be alleviated by manipulating the function of specific interneuron subtypes to rebalance local network activity. (A) Proportion of correct responses made by adult and aged rhesus macaques performing a delayed nonmatching-to-sample task at different delays. As societies worldwide continue to achieve longer life expectancies, it is becoming more critical to devise strategies to maintain sensory and cognitive health to reduce the burden of declines in function for older individuals themselves, as well as the impact that this has on their families. (Bottom) Rats, on the other hand, have a drastically expanded LSO relative to humans and macaques, as well as a significantly reduced MSO. Their brain systems, when it comes to movement, are similar to people. Note that lower values indicate better function for both auditory measures. The calcium hypothesis suggests that rebalancing intracellular calcium levels, and perhaps hyperexcitability, by increasing inhibition to control excess neural activity may rebalance circuit activity and help preserve memory function in aging. It can be used as 486 coronal, 346 horizontal, or 191 parasagittal 150-um thick 'sections'. Among those who do evade the pathological hallmarks of neurodegenerative disease, it is also of interest to determine why there remains significant individual variation in the quality of cognitive or sensory function across age. These observations indicate that neurochemical changes occur within the central auditory system in response to a reduced acoustic drive from the periphery. ), suggesting that RRRs are conserved among mammalian species. Additionally, both within and between brain regions, aged neurons can exhibit striking differences in excitability. These anatomical differences between species are thought to reflect the drastically different acoustic sensitivities of primates and rodents. Anatomical studies in aging macaques have provided substantial evidence that the total number of neurons in the prefrontal cortex (28⇓–30) and medial temporal lobe (31⇓–33) does not change across the lifespan in the absence of neurodegenerative disease. and F31 AG055263 (to D.T.G.) Regardless, there was a strong negative correlation between the density of somatostatin-positive CA3 interneurons and principal neuron firing rates (Fig. In particular, this review will highlight studies that have utilized aged macaques to gain network-level and regional insights into age-related episodic memory decline and hearing loss, which are 2 of the most commonly experienced alterations in brain function experienced by older individuals. An absolute must for all neuroscientists navigating the rhesus monkey brain."--Dr. Once the stimulation was turned off, the macaques returned to an unconscious state. Other studies conducted in the rat hippocampus suggest that a neuronal change that may contribute to this is altered calcium homeostasis in older neurons (18). The brains were extracted and … Both of these points emphasize how nonhuman primates can provide a fundamental link between nonprimate laboratory animals and humans. The 23 species of macaques inhabit ranges throughout Asia, North Africa, and Gibraltar. These findings indicate that aging can lead to a disruption in the activity of circuits within the hippocampus that negatively impacts mnemonic processing. Shapeshifting designs could have wide-ranging pharmaceutical and biomedical applications in coming years. The animals with better discrimination abilities and measures of medial temporal lobe tract fractional anisotropy also had higher auditory processing capacities (Fig. Neuroscientists had previously pegged the central lateral thalamus as an NCC, but this latest research adds more credence to the claim. Brain atlases, and particularly those based on magnetic resonance imaging (MRI), have become important tools for understanding normal brain structure, and for identifying structural abnormalities resulting from disease states, exposures, and/or aging. Author contributions: D.T.G. Nonhuman primates, in particular, have been central and arguably irreplaceable to cognitive aging research due to several critical features unique to these animals. More recently, the impact that hearing loss, in particular, has on cognition has reemerged as a topic of research interest. Copyright © 2021 National Academy of Sciences. Emergence of a powerful connection between sensory and cognitive functions across the adult life span: A new window to the study of cognitive aging? Some species, such as the crab-eating macaque, subsist on a diet of invertebrates and occasionally small vertebrates. From February 2001 through May 2019 colloquia were supported by a generous gift from The Dame Jillian and Dr. Arthur M. Sackler Foundation for the Arts, Sciences, & Humanities, in memory of Dame Sackler's husband, Arthur M. Sackler. Little Dog claims that the brain of a macaque monkey is closer to a human brain than any other living mammal, and he claims that the macaques are capable of critical thought and problem solving, and that they have the ability to recall past events. (E) CA3 SOM neuron density and CA3 firing rates showed weak associations with object recognition performance. Despite evidence dating back several decades to suggest that individuals with poorer sensory function are more likely to have cognitive problems later in life, the neurobiological processes responsible for these associations have not been a subject of intense research (79⇓⇓–82). In this study, we applied both histone demethylase Kdm4d mRNA and histone deacetylase inhibitor trichostatin A (TSA) to the cloning of macaque monkeys. Numerous studies, first in rodents (both rats and mice) and then in macaques, have demonstrated that the number of neurons expressing CaBPs changes across the lifespan at multiple levels of the ascending auditory pathway (58⇓⇓⇓⇓⇓⇓⇓–66). Importantly, this study also demonstrated that the extent of CA3/dentate gyrus hyperactivation was significantly associated with discrimination abilities in these participants, regardless of age (15). (C) Similarly, animals with higher right hemisphere fimbria-fornix FA had lower auditory brainstem response (ABR) thresholds. 105 (Springer Nature: The Mammalian Auditory Pathway: Neuroanatomy, Copyright 1992). NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. Over the past several decades, neuroscientists have teased apart the various regions and networks in the brain to better understand how they contribute to normal cognitive function, but huge questions remain about consciousness and which parts of the brain can be described as the neural correlates of consciousness (NCCs)—that is, the specific brain regions that allow us to experience the smell of burnt toast, the redness of a blooming rose, or the richness of our internal thoughts. 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George is a senior staff reporter at Gizmodo. These observations indicate that, like cognitive function, not all aspects of sensory function are equivalently impacted by the aging process in macaques. The acquisition of multiple estimates of cognitive and sensory function within the same group of monkeys allowed an assessment of whether specific cognitive and sensory domains changed independent of one another or in tandem (90). This suggests that the relationships between the fractional anisotropy of hippocampus-associated white matter tracts and hearing function were not due to general changes in white matter systems across the aging brain. A major goal within the field of the neuroscience of aging is to determine what factors allow certain individuals to evade neurodegenerative disease, while others succumb to them. Conversely, the domestic mouse cannot hear 60-dB tones below 2.3 kHz and can hear up to 85.5 kHz (71). This fascinating result is providing new clues about the brain and how it produces conscious awareness—insights that could potentially lead to therapies for patients trapped in a coma. May 21, 2012. Sensory functioning and intelligence in old age: A strong connection, The strong connection between sensory and cognitive performance in old age: Not due to sensory acuity reductions operating during cognitive assessment. We present a quadrature volume coil designed for brain imaging of a macaque monkey fixed in a sphinx position (facing down the bore) within a stereotactic frame at 3 T, where the position of the monkey and presence of the frame preclude use of existing coils. While fMRI technologies can detect broad changes in activity, they do not provide detailed circuit-level insights into such changes. When this happened, the primates behaved just as they would when awake. Together, these findings indicate that auditory function is specifically associated with the structural composition of medial temporal lobe-associated, but not frontal lobe-associated, white matter. With respect specifically to brain aging research, it will be critical to objectively determine whether the advantages associated with the novel experimental tools that marmoset research can provide outweigh the potential disadvantages of reduced gyral complexity and increased phylogenetic distance from humans (102). Several studies discussed here exemplify how nonhuman primate research has enriched our understanding of cognitive and sensory decline in the aging brain, as well as how this work has been important for translating mechanistic implications derived from experiments conducted in rodents to human brain aging research. We thank Michelle Albert for assistance with the graphics. Consequently, age-related deficits in human episodic memory are thought to largely result from structural and functional alterations in these structures, although the precise neurobiological mechanisms involved have been difficult to pinpoint. The brain remains the most mysterious organ in the human body. These observations indicate that the neurobiological processes driving functional changes in aged cognitive circuits (e.g., hyperexcitability) likely occur at subcellular levels. We showed that the TG monkeys carrying the huMCPH1 transgene did not manifest an enlarged brain size, implying that a single gene likely has a limited effect on neural progenitor pool proliferation during brain development. A few functional imaging studies in older humans have shown compensatory recruitment of certain auditory, frontal, and temporoparietal brain regions when older people listen to human speech, even in subjects with clinically normal hearing thresholds (85⇓⇓⇓–89). 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