Elizabeth Gould (psychologist)
Encyclopedia
Elizabeth Gould is an American neuroscientist
Neuroscience
Neuroscience is the scientific study of the nervous system. Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics,...

. She is a professor of psychology at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....

's Department of Psychology. She was one of the first to find evidence of adult neurogenesis in the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

. Her research, in reviving the idea of neurogenesis
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...

, was instrumental in setting off a frenzy of research resulting in neurogenesis being currently one of the hottest topics in neuroscience.

Gould discovered evidence of
OF
OF may refer to:* Oxygen fluorides* Air Finland IATA airline designator* Old Firm, a term that refers to Glasgow-based association football clubs Celtic F.C...

 adult neurogenesis in the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 and olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...

 of rats
RATS
RATS may refer to:* RATS , Regression Analysis of Time Series, a statistical package* Rough Auditing Tool for Security, a computer program...

, marmosets  and macaque monkeys
Macaque
The macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. - Description :Aside from humans , the macaques are the most widespread primate genus, ranging from Japan to Afghanistan and, in the case of the barbary macaque, to North Africa...

. In her early studies, she laid the groundwork for understanding the relationship between stress and adult neurogenesis.

Her work has shown some evidence of neurogenesis in the adult neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...

. A study by Dr. Gould, http://serendip.brynmawr.edu/bb/neuro/neuro00/web1/Wall.html#11 et al., was published in the October 15, 1999 issue of Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

, investigating neurogenesis in the adult primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

 neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...

. Gould and the researchers reported new neurons in adult macaque monkeys are added to three neocortical association areas important in cognitive function: the prefrontal
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...

, inferior temporal and posterior parietal cortex
Posterior parietal cortex
The posterior parietal cortex plays an important role in producing planned movements. Before an effective movement can be initiated, the nervous system must know the original positions of the body parts that are to be moved, and the positions of any external objects with which the body is going to...

. The new neurons appeared to originate in the subventricular zone
Subventricular zone
The subventricular zone is a paired brain structure situated throughout the lateral walls of the lateral ventricles. It has been associated with having four distinct layers of variable thickness and cell density, as well as cellular composition....

, where stem cells giving rise to other cell types are located. They then migrate through the white matter to the neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...

, extending axons. Continual addition of neurons in adulthood apparently contributes to association neocortex functions.

Education and path to discovery

Gould received her Ph.D.
Ph.D.
A Ph.D. is a Doctor of Philosophy, an academic degree.Ph.D. may also refer to:* Ph.D. , a 1980s British group*Piled Higher and Deeper, a web comic strip*PhD: Phantasy Degree, a Korean comic series* PhD Docbook renderer, an XML renderer...

 in behavioral neuroscience
Behavioral neuroscience
Behavioral neuroscience, also known as biological psychology, biopsychology, or psychobiology is the application of the principles of biology , to the study of physiological, genetic, and developmental mechanisms of behavior in human and non-human animals...

 in 1988 at UCLA. In 1989, she was a young post-doc working in the lab of Bruce McEwen at Rockefeller University
Bruce McEwen
Bruce McEwen is the Alfred E. Mirsky professor of neuroscience and runs the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at Rockefeller University.-Career:...

, investigating the effect of stress hormone
Stress hormone
Stress hormones such as cortisol, GH and norepinephrine are released at periods of high stress. The hormone regulating system is known as the endocrine system...

s on rat brains
Laboratory rat
A laboratory rat is a rat of the species Rattus norvegicus which is bred and kept for scientific research. Laboratory rats have served as an important animal model for research in psychology, medicine, and other fields.- Origins :...

. Chronic stress is devastating to neurons, and Gould’s research focused on the death of cells in the hippocampus. (Pasko Rakic's declaration that there was no such thing as neurogenesis was entrenched dogma at that time.) The research was exciting because stress research was a booming field at that time also. However, it was extremely hard work necessitating killing her rats
Laboratory rat
A laboratory rat is a rat of the species Rattus norvegicus which is bred and kept for scientific research. Laboratory rats have served as an important animal model for research in psychology, medicine, and other fields.- Origins :...

 at various time points, pluck their tiny brains out of their cranial encasing, cut through their cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...

, slice the hippocampus thinner than a sheet of paper, and with great care count the dying neurons under a microscope. While Gould was documenting the degeneration of these brains, she happened upon something seemingly inexplicable. Evidence pointed to the idea that the brain might also heal itself. She explains, “At first, I assumed I must be counting [the neurons] incorrectly,” Gould said. “There were just too many cells.”

Uncovering earlier work in neurogenesis

Confused by this anomaly, Gould assumed she must have been making some simple experimental error, and she went to the Rockefeller library, hoping she could find explanation as to what she was doing wrong. (This all took place before the Internet.) She ended up looking through numerous dusty papers in the Rockefeller stacks. In one such science journal, buried there for 27 years, Gould found the explanation she needed, though not the one she was expecting. Several 1962 papers revealed the research at MIT by Joseph Altman
Joseph Altman
Joseph Altman discovered adult neurogenesis, the creation of new neurons in the adult brain, in the 1960s. As an independent investigator at MIT, his results were largely ignored. In the late 1990s, the fact that the brain can create new neurons even into adulthood was rediscovered, leading it to...

 claiming that adult rats, cats, and guinea pigs all formed new neurons. Altman’s results had been at first ridiculed, then ignored, and quickly forgotten. As a result, the field of neurogenesis had died before it could get started.

Further investigation by Gould revealed that a decade later Michael Kaplan, at the University of New Mexico
Michael Kaplan (biologist)
Michael S. Kaplan is an American biology researcher, medical professor, and clinical physician. A pioneer of neurogenesis research, his work was the first to refute the classic idea that no new nerve cells are born in the adult mammalian brain...

, had used an electron microscope
Electron microscope
An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...

 to image neurons giving birth. Kaplan had, he believed, discovered new neurons everywhere in the mammalian brain, including the cortex. Yet even with this visual evidence, science clung to Rakic's doctrine which denied the possibility of neurogenesis. Kaplan is reported as remembering Rakic telling him that “Those [cells] may look like neurons in New Mexico, but they don’t in New Haven
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...

.” Faced with the toxicity of this type of criticism, like Altman before him, Kaplan had abandoned his work in neurogenesis.

Confronting Rakic's data

Gould was more than intrigued. She would spend the next eight years quantifying endless numbers of radioactive rat hippocampii
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 in pursuit of neurogenesis
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...

. Eventually the painstaking manual labor bore fruit as Gould’s data caused a shift in the neuroscience
Neuroscience
Neuroscience is the scientific study of the nervous system. Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics,...

 paradigm and neurogenesis
Neurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...

 had finally become a real science. After having been worn down by the continual criticism of her data during her post-doc, Gould was eventually offered a job at Princeton. The very next year, in a series of landmark papers, Gould began documenting neurogenesis in primates, thus confronting Rakic’s data directly. She demonstrated that adult marmosets created new neurons in their brains, especially in the olfactory cortex and the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

. By 1999, even Rakic finally had to admit that neurogenesis was real. To that end he published a paper in the http://www.pnas.org/ Proceedings of the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...

that reported seeing new neurons in the hippocampus of macaques.

Current work

Gould's laboratory at Princeton studies the production of new neurons in the early postnatal
Postnatal
Postnatal is the period beginning immediately after the birth of a child and extending for about six weeks. Another term would be postpartum period, as it refers to the mother...

 and adult mammalian brain. Her laboratory explores issues related to the regulation of cell production and survival in three brain regions the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

, the olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...

 and the neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...

 in rodents and primates (marmosets and macaques).

Gould and her colleagues believe the answer to the question, ‘What possible function could late-generated cells serve?’ could have immense significance in neuroscience and their investigations are guided mostly by this question. Gould and her team are also endeavoring to discover how hormones modulate the production of new neurons and how experience affects new cell production and if so, through what underlying mechanisms.

Representative studies of Gould and her colleagues' research

Hormonal regulation of cell production

Gould and her colleagues found that the ovarian steroid estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...

 enhances cell proliferation in the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...

 of the adult rat. This effect can be seen following ovariectomy and hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...

 replacement as well as under naturally occurring changes in hormone levels. They discovered that cell proliferation peaks during proestrus, a time when estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...

 levels are highest. Also and conversely, steroid hormone
Steroid hormone
A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into five groups by the receptors to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestogens...

s of the adrenal glands were found to inhibit cell proliferation in the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...

 but do so indirectly via an NMDA receptor
NMDA receptor
The NMDA receptor , a glutamate receptor, is the predominant molecular device for controlling synaptic plasticity and memory function....

-dependent mechanism.

Experience-dependent changes in neurogenesis

Gould’s research has shown that exposure of aversive stimuli results in a decrease in cell proliferation in the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...

 of adult rats, tree shrews and marmoset monkeys
Marmoset
Marmosets are the 22 New World monkey species of the genera Callithrix, Cebuella, Callibella, and Mico. All four genera are part of the biological family Callitrichidae. The term marmoset is also used in reference to the Goeldi's Monkey, Callimico goeldii, which is closely related.Most marmosets...

. Gould and her colleagues have shown that social stress inhibits cell production in these three species in a series of studies. Furthermore, they have discovered that exposure of adult rats to the odors of natural predators, but not other novel odors, suppresses the proliferation of cells in the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...

. This effect was found to be dependent on adrenal steroids because the prevention of the stress-induced rise in glucocorticoids (by adrenalectomy
Adrenalectomy
Adrenalectomy is the surgical removal of one or both adrenal glands. It is usually advised for patients with tumors of the adrenal glands. The procedure can be performed using an open incision or laparoscopic technique....

 and replacement with low-dose corticosterone
Corticosterone
Corticosterone is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands.-Roles:In many species, including amphibians, reptiles, rodents and birds, corticosterone is a main glucocorticoid, involved in regulation of fuel, immune reactions, and stress...

 in the drinking water) eliminated the inhibitory effect of fox odor on cell production.

The importance of complex environments
Gould’s team has observed that many new cells in the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 of adult rats and monkeys do not survive in animals living under standard laboratory conditions. In rodents, they discovered that these cells can be rescued by exposing the animals to more complex environments. These results they believe reflect the deprived laboratory conditions in which experimental animals live. This they also suspect is a phenomenon, that is probably, even more pronounced in primates with higher social needs than in rodents. The Gould team is continuing to explore this issue by examining the brains of adult rats living in a visible burrow
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...

 system and adult monkeys living in semi-naturalistic conditions with opportunities for foraging
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...

 and other natural activities.

The functional role of new neurons

Although the function of new neurons in the adult brain is as yet unknown Gould and her colleagues have begun to conjecture possibilities. So many new neurons are generated in the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 and these cells appear to be a sensitive to experience, therefore it seems likely to the Gould team that they participate in hippocampal function
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

. They are exploring the possibility that new neurons participate in two functions of the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

, learning and modulation of the stress response. They have shown that learning enhances the number of new neurons but only under certain conditions. Furthermore they have discovered, experimental depletion of new neurons is associated with impairment in certain types of learning but not others. A decrease in the number of new neurons following treatment with anti-mitotic drugs impairs trace eye blink conditioning but not spatial learning in a Morris water maze, both hippocampal-dependent tasks.

Honors and Awards

In 2009 she was awarded the Benjamin Franklin Medal by the Royal Society for the encouragement of Arts, Manufactures and Commerce (RSA) for her groundbreaking work on neurogenesis.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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