Substantia nigraThe substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement. Substantia nigra is Latin for "black substance", reflecting the fact that parts of the substantia nigra appear darker than neighboring areas due to high levels of neuromelanin in dopaminergic neurons. Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta.
Pars reticulataThe pars reticulata (SNpr) is a portion of the substantia nigra and is located lateral to the pars compacta. Most of the neurons that project out of the pars reticulata are inhibitory GABAergic neurons (i.e., these neurons release GABA, which is an inhibitory neurotransmitter). Neurons in the pars reticulata are much less densely packed than those in the pars compacta (they were sometimes named pars diffusa). They are smaller and thinner than the dopaminergic neurons and conversely identical and morphologically similar to the pallidal neurons (see primate basal ganglia).
Spinocerebellar ataxia type 1Spinocerebellar ataxia type 1 (SCA1) is a rare autosomal dominant disorder, which, like other spinocerebellar ataxias, is characterized by neurological symptoms including dysarthria, hypermetric saccades, and ataxia of gait and stance. This cerebellar dysfunction is progressive and permanent. First onset of symptoms is normally between 30 and 40 years of age, though juvenile onset can occur. Death typically occurs within 10 to 30 years from onset.
Basal gangliaThe basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an external and internal region, and in the division of the striatum. The basal ganglia are situated at the base of the forebrain and top of the midbrain. Basal ganglia are strongly interconnected with the cerebral cortex, thalamus, and brainstem, as well as several other brain areas.
Human brainThe human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head.
Pars compactaThe pars compacta (SNpc) is one of two subdivisions of the substantia nigra of the midbrain (the other being the pars reticulata); it is situated medial to the pars reticulata. It is formed by dopaminergic neurons. It projects to the striatum and portions of the cerebral cortex. It is functionally involved in fine motor control. Parkinson's disease is characterized by the death of dopaminergic neurons in this region. In humans, the nerve cell bodies of the pars compacta are coloured black by the pigment neuromelanin.
BrainA brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons.
NeuromelaninNeuromelanin (NM) is a dark pigment found in the brain which is structurally related to melanin. It is a polymer of 5,6-dihydroxyindole monomers. Neuromelanin is found in large quantities in catecholaminergic cells of the substantia nigra pars compacta and locus coeruleus, giving a dark color to the structures. Neuromelanin gives specific brain sections, such as the substantia nigra or the locus coeruleus, distinct color. It is a type of melanin and similar to other forms of peripheral melanin.
Spinocerebellar ataxiaSpinocerebellar ataxia (SCA) is a progressive, degenerative, genetic disease with multiple types, each of which could be considered a neurological condition in its own right. An estimated 150,000 people in the United States have a diagnosis of spinocerebellar ataxia at any given time. SCA is hereditary, progressive, degenerative, and often fatal. There is no known effective treatment or cure. SCA can affect anyone of any age. The disease is caused by either a recessive or dominant gene.
Polyglutamine tractA polyglutamine tract or polyQ tract is a portion of a protein consisting of a sequence of several glutamine units. A tract typically consists of about 10 to a few hundred such units. A multitude of genes, in various eukaryotic species (including humans), contain a number of repetitions of the nucleotide triplet CAG or CAA. When the gene is translated into a protein, each of these triplets gives rise to a glutamine unit, resulting in a polyglutamine tract.
PutamenThe putamen (pjutˈeɪmən; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal nuclei. Through various pathways, the putamen is connected to the substantia nigra, the globus pallidus, the claustrum, and the thalamus, in addition to many regions of the cerebral cortex. A primary function of the putamen is to regulate movements at various stages (e.
Pedunculopontine nucleusThe pedunculopontine nucleus (PPN) or pedunculopontine tegmental nucleus (PPT or PPTg) is a collection of neurons located in the upper pons in the brainstem. It lies caudal to the substantia nigra and adjacent to the superior cerebellar peduncle. It has two divisions of subnuclei; the pars compacta containing mainly cholinergic neurons, and the pars dissipata containing mainly glutamatergic neurons and some non-cholinergic neurons. The pedunculopontine nucleus is one of the main components of the reticular activating system.
Huntington's diseaseHuntington's disease (HD), also known as Huntington's chorea, is an incurable neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental/ psychiatric abilities. A general lack of coordination and an unsteady gait often follow. It is also a basal ganglia disease causing a hyperkinetic movement disorder known as chorea. As the disease advances, uncoordinated, involuntary body movements of chorea become more apparent.
Brain simulationBrain simulation is the concept of creating a functioning computer model of a brain or part of a brain. Brain simulation projects intend to contribute to a complete understanding of the brain, and eventually also assist the process of treating and diagnosing brain diseases. Various simulations from around the world have been fully or partially released as open source software, such as C. elegans, and the Blue Brain Project Showcase.
Split-brainSplit-brain or callosal syndrome is a type of disconnection syndrome when the corpus callosum connecting the two hemispheres of the brain is severed to some degree. It is an association of symptoms produced by disruption of, or interference with, the connection between the hemispheres of the brain. The surgical operation to produce this condition (corpus callosotomy) involves transection of the corpus callosum, and is usually a last resort to treat refractory epilepsy.
Neurodegenerative diseaseA neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic lateral sclerosis, multiple sclerosis, Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple system atrophy, and prion diseases. Neurodegeneration can be found in the brain at many different levels of neuronal circuitry, ranging from molecular to systemic.
Viral vectorViral vectors are tools commonly used by molecular biologists to deliver genetic material into cells. This process can be performed inside a living organism (in vivo) or in cell culture (in vitro). Viruses have evolved specialized molecular mechanisms to efficiently transport their genomes inside the cells they infect. Delivery of genes or other genetic material by a vector is termed transduction and the infected cells are described as transduced. Molecular biologists first harnessed this machinery in the 1970s.
Brain tumorA brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and secondary tumors, which most commonly have spread from tumors located outside the brain, known as brain metastasis tumors. All types of brain tumors may produce symptoms that vary depending on the size of the tumor and the part of the brain that is involved.
HyperkinesiaHyperkinesia refers to an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both. Hyperkinesia is a state of excessive restlessness which is featured in a large variety of disorders that affect the ability to control motor movement, such as Huntington's disease. It is the opposite of hypokinesia, which refers to decreased bodily movement, as commonly manifested in Parkinson's disease.
Lewy bodyLewy bodies are the inclusion bodies – abnormal aggregations of protein – that develop inside nerve cells affected by Parkinson's disease (PD), the Lewy body dementias (Parkinson's disease dementia and dementia with Lewy bodies (DLB)), and some other disorders. They are also seen in cases of multiple system atrophy, particularly the parkinsonian variant (MSA-P). Lewy bodies appear as spherical masses in the cytoplasm that displace other cell components. For instance, some Lewy bodies tend to displace the nucleus to one side of the cell.
