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Current Opinion in Neurobiology Feb 1998The vertebrate forebrain is derived from the anterior neural plate, where anteroposterior, dorsoventral and local patterning mechanisms specify regional identify. The... (Review)
Review
The vertebrate forebrain is derived from the anterior neural plate, where anteroposterior, dorsoventral and local patterning mechanisms specify regional identify. The recent identification of genetic regulators of these processes has opened the way to elucidating how the major forebrain regions (i.e. cerebral cortex, basal ganglia, thalamus, and hypothalamus) are formed, and how molecular lesions in these processes cause human birth defects.
Topics: Animals; Female; Humans; Pregnancy; Prosencephalon; Signal Transduction
PubMed: 9568388
DOI: 10.1016/s0959-4388(98)80004-4 -
Nature Jul 1999
Topics: Animals; Chemotaxis; Drosophila Proteins; Mice; Nerve Tissue Proteins; Neurons; Olfactory Bulb; Prosencephalon
PubMed: 10432106
DOI: 10.1038/22427 -
Brain Research Bulletin Sep 2005Pax6 is a highly conserved transcription factor essential for the development of the eyes in vertebrate and invertebrate species. It is also required for normal... (Review)
Review
Pax6 is a highly conserved transcription factor essential for the development of the eyes in vertebrate and invertebrate species. It is also required for normal development of many regions of the central nervous system, including the mammalian forebrain, hindbrain and spinal cord. In the forebrain, it is expressed in a gradient in the dorsal telencephalon, where it is required for the expression of genes that confer dorsal characteristics and where it might play a role in regionalization of the cerebral cortex. It is expressed in the diencephalon, where it is essential for the specification of its derivatives. While the ancestral function of Pax6 may have been to specify a structure sensitive to light, it has been co-opted into the regulation of a broader range of processes in development of the vertebrate nervous system.
Topics: Animals; Eye Proteins; Gene Expression Regulation, Developmental; Homeodomain Proteins; Humans; PAX6 Transcription Factor; Paired Box Transcription Factors; Prosencephalon; Repressor Proteins
PubMed: 16144620
DOI: 10.1016/j.brainresbull.2005.02.006 -
Journal of Cerebral Blood Flow and... Jan 2006The recent identification of endogenous neural stem cells and persistent neuronal production in the adult brain suggests a previously unrecognized capacity for... (Review)
Review
The recent identification of endogenous neural stem cells and persistent neuronal production in the adult brain suggests a previously unrecognized capacity for self-repair after brain injury. Neurogenesis not only continues in discrete regions of the adult mammalian brain, but new evidence also suggests that neural progenitors form new neurons that integrate into existing circuitry after certain forms of brain injury in the adult. Experimental stroke in adult rodents and primates increases neurogenesis in the persistent forebrain subventricular and hippocampal dentate gyrus germinative zones. Of greater relevance for regenerative potential, ischemic insults stimulate endogenous neural progenitors to migrate to areas of damage and form neurons in otherwise dormant forebrain regions, such as the neostriatum and hippocampal pyramidal cell layer, of the mature brain. This review summarizes the current understanding of adult neurogenesis and its regulation in vivo, and describes evidence for stroke-induced neurogenesis and neuronal replacement in the adult. Current strategies used to modify endogenous neurogenesis after ischemic brain injury also will be discussed, as well as future research directions with potential for achieving regeneration after stroke and other brain insults.
Topics: Animals; Brain Ischemia; Dentate Gyrus; Humans; Lateral Ventricles; Models, Neurological; Neurons; Prosencephalon; Regeneration
PubMed: 15959458
DOI: 10.1038/sj.jcbfm.9600170 -
Neuroscience Dec 2013In this review we discuss recent advances in the understanding of the development of forebrain projections attending to their origin, fate determination, and axon... (Review)
Review
In this review we discuss recent advances in the understanding of the development of forebrain projections attending to their origin, fate determination, and axon guidance. Major forebrain connections include callosal, corticospinal, corticothalamic and thalamocortical projections. Although distinct transcriptional programs specify these subpopulations of projecting neurons, the mechanisms involved in their axonal development are similar. Guidance by short- and long-range molecular cues, interaction with intermediate target populations and activity-dependent mechanisms contribute to their development. Moreover, some of these connections interact with each other showing that the development of these axonal tracts is a well-orchestrated event. Finally, we will recapitulate recent discoveries that challenge the field of neural wiring that show that these forebrain connections can be changed once formed. The field of reprogramming has arrived to postmitotic cortical neurons and has showed us that forebrain connectivity is not immutable and might be changed by manipulations in the transcriptional program of matured cells.
Topics: Animals; Axons; Cerebral Cortex; Humans; Nerve Net; Prosencephalon
PubMed: 24042037
DOI: 10.1016/j.neuroscience.2013.08.070 -
Trends in Endocrinology and Metabolism:... 2005Gonadotropin-releasing hormone (GnRH) is an essential decapeptide, with both endocrine and neuromodulatory functions in vertebrates. GnRH-containing cells of the... (Review)
Review
Gonadotropin-releasing hormone (GnRH) is an essential decapeptide, with both endocrine and neuromodulatory functions in vertebrates. GnRH-containing cells of the forebrain were thought to originate in the olfactory placode and migrate to their central nervous system destinations, and those of the midbrain to arise locally from the neural tube. Here, the embryonic origins of GnRH cells are re-examined in light of recent data suggesting that forebrain GnRH cells arise from the anterior pituitary placode and cranial neural crest, from where they migrate to their final destinations. The emerging picture suggests that GnRH cells do not originate from the olfactory placodes, but arise from multiple embryonic origins, and transiently associate with the developing olfactory system as they migrate to ventral forebrain locations.
Topics: Animals; Cell Movement; Embryonic Development; Gonadotropin-Releasing Hormone; Growth; Humans; Hypothalamus; Mesencephalon; Neurons; Prosencephalon; Telencephalon
PubMed: 15860410
DOI: 10.1016/j.tem.2005.03.005 -
Annals of the New York Academy of... Apr 2003The basal forebrain is a confluence of systems that are crucial to understanding some of the most important functions of the brain, including reward and punishment,... (Review)
Review
The basal forebrain is a confluence of systems that are crucial to understanding some of the most important functions of the brain, including reward and punishment, learning and cognition, and feeding and reproduction. Basic to understanding this broad spectrum of behavior is untangling the interwoven functional systems in basal forebrain. This has been grounded by the appreciation that the major nearby structures, that is, amygdala and basal ganglia, provide a context for interpreting basal forebrain areas that are best viewed as extensions of either of these larger regions. The components of basal forebrain, the ventral striatopallidal system and the medial and central divisions of extended amygdala, are subcortical relays for information garnered from brain stem, thalamus, and cortical areas. With respect to the classically defined amygdala of the temporal lobe, the lateral-basolateral complex, and the superficial amygdaloid nuclei may tentatively be viewed as specialized cortical regions. Their output targets both the striatopallidal complex and the extended amygdala, with some of the most massive basal forebrain efferents originating in the basolateral amygdaloid complex. The subcortical projections of the basolateral nucleus, at least in the rat, appear to be dichotomous, with anterior (or magnocellular) portions of the nucleus preferentially targeting striatum and ventral striatum (including the core of the nucleus accumbens), while the posterior (small-celled) portions of the basolateral nucleus target the extended amygdala as well as the shell of the nucleus accumbens. This divergence represents a particular opportunity for behavioral neuroscientists analyzing basal forebrain functions. Studies exploiting the dual subcortical projection of basolateral amygdala indicate distinct functional roles for striatum versus extended amygdala. These reinforce the identification of extended amygdala as a functional-anatomical entity distinct from the striatopallidal system.
Topics: Amygdala; Animals; Brain Mapping; Humans; Learning; Models, Neurological; Prosencephalon
PubMed: 12724159
DOI: 10.1111/j.1749-6632.2003.tb07082.x -
Journal of Neural Transmission (Vienna,... Dec 2009Since the late 1970s glycine has been considered an important inhibitory neurotransmitter in brain stem and medulla. The description of its involvement in the mechanism... (Review)
Review
Since the late 1970s glycine has been considered an important inhibitory neurotransmitter in brain stem and medulla. The description of its involvement in the mechanism of action of the potent neurotoxin strychnine pushed further the concept of inhibitory transmitter. The significant concentrations of glycine in forebrain motivated investigators to evaluate different aspects of glycinergic transmission under the ontogenetic, physiologic and pathologic standpoints. This review encompasses a few of these aspects as the role of the different glycine receptors (GlyRs) in intracellular chloride balance, glycine transporters, GABA/Glycine co-release, glycine/NMDA receptor interaction, glycine receptors in acute alcohol effects and advocates a more relevant role for glycine as a stimulatory transmitter in forebrain areas. Finally, the possible co-release of glycine and GABA is considered as an important process to understand the role of glycine in forebrain neural transmission.
Topics: Animals; Glycine; Humans; Neurotransmitter Agents; Prosencephalon
PubMed: 19826900
DOI: 10.1007/s00702-009-0326-6 -
Annals of the New York Academy of... Jun 2004The brain nuclei and pathways comprising the song system of oscine songbirds bear many similarities with circuits in other bird species and in mammals. This suggests... (Review)
Review
The brain nuclei and pathways comprising the song system of oscine songbirds bear many similarities with circuits in other bird species and in mammals. This suggests that the song system evolved as a specialization of pre-existing circuits and may retain fundamental properties in common with those of other taxa. Here we review evidence for these similarities, including electrophysiological, morphological, and neurochemical data for identifying specific cell types. In addition, we discuss connectional data, addressing similarities in axonal projections among nuclei across taxa. We focus primarily on the anterior forebrain pathway, a circuit essential for song learning and vocal plasticity, because the evidence is strongest that this circuit is homologous to mammalian circuits. These fundamental similarities highlight the importance of comparative approaches; for example, understanding the role the anterior forebrain pathway plays in song plasticity may shed light on general principles of basal ganglia function. In addition, understanding specializations of such circuits in songbirds may illuminate specific innovations critical for vocal learning.
Topics: Animals; Basal Ganglia; Biological Evolution; Mammals; Neural Pathways; Prosencephalon; Songbirds
PubMed: 15313803
DOI: 10.1196/annals.1298.039 -
Experimental Gerontology Aug 2017In the anterior forebrain, along the lateral wall of the lateral ventricles, a neurogenic stem cell niche is found in a region referred to as the... (Review)
Review
In the anterior forebrain, along the lateral wall of the lateral ventricles, a neurogenic stem cell niche is found in a region referred to as the ventricular-subventricular zone (V-SVZ). In rodents, robust V-SVZ neurogenesis provides new neurons to the olfactory bulb throughout adulthood; however, with increasing age stem cell numbers are reduced and neurogenic capacity is significantly diminished, but new olfactory bulb neurons continue to be produced even in old age. Humans, in contrast, show little to no new neurogenesis after two years of age and whether V-SVZ neural stem cells persist in the adult human brain remains unclear. Here, we review functional and organizational differences in the V-SVZ stem cell niche of mice and humans, and examine how aging affects the V-SVZ niche and its associated functions.
Topics: Age Factors; Aging; Animals; Cell Movement; Cell Proliferation; Humans; Lateral Ventricles; Neural Stem Cells; Neurogenesis; Olfactory Bulb; Prosencephalon; Species Specificity; Stem Cell Niche
PubMed: 27867091
DOI: 10.1016/j.exger.2016.11.007