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Pedunculopontine Nucleus
The pedunculopontine nucleus (PPN) or pedunculopontine tegmental nucleus (PPT or PPTg) is a collection of neurons located in the upper pons in the brainstem. It is involved in voluntary movements, arousal, and provides sensory feedback to the cerebral cortex and one of the main components of the ascending reticular activating system. It is a potential target for deep brain stimulation treatment for Parkinson's disease. It was first described in 1909 by Louis Jacobsohn-Lask, a German neuroanatomist. Structure and projections The pedunculopontine nucleus lies below the red nucleus, 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. Its neurons project axons to a wide range of areas in the brain, particularly parts of the basal ganglia such as the subthalamic nuc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pons
The pons (from Latin , "bridge") is part of the brainstem that in humans and other mammals, lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of Varolius"), after the Italian anatomist and surgeon Costanzo Varolio (1543–75). This region of the brainstem includes neural pathways and tracts that conduct signals from the brain down to the cerebellum and medulla, and tracts that carry the sensory signals up into the thalamus. Structure The pons in humans measures about in length. It is the part of the brainstem situated between the midbrain and the medulla oblongata. The horizontal ''medullopontine sulcus'' demarcates the boundary between the pons and medulla oblongata on the ventral aspect of the brainstem, and the roots of cranial nerves VI/VII/VIII emerge from the brainstem along this groove. The junction of pons, medulla oblongata, and cerebellum forms the cerebellopontine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substantia Nigra Pars Compacta
The pars compacta (SNpc, SNc) 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. Anatomy In humans, the nerve cell bodies of the ''pars compacta'' are coloured black by the pigment neuromelanin. The degree of pigmentation increases with age. This pigmentation is visible as a distinctive black stripe in brain sections and is the origin of the name given to this volume of the brain. Microanatomy The neurons have particularly long and thick dendrites. The ventral dendrites, particularly, go down deeply in the pars reticulata. Other similar neurons are more sparsely distributed in the midbrain and constitute "groups" with no well-de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reward System
The reward system (the mesocorticolimbic circuit) is a group of neural structures responsible for incentive salience (i.e., "wanting"; desire or craving for a reward and motivation), associative learning (primarily positive reinforcement and classical conditioning), and positively-valenced emotions, particularly ones involving pleasure as a core component (e.g., joy, euphoria and ecstasy). Reward is the attractive and motivational property of a stimulus that induces appetitive behavior, also known as approach behavior, and consummatory behavior. A rewarding stimulus has been described as "any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward". In operant conditioning, rewarding stimuli function as positive reinforcers; however, the converse statement also holds true: positive reinforcers are rewarding. The reward system motivates animals to approach stimuli or engage in behaviour that increase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Learning
Learning is the process of acquiring new understanding, knowledge, behaviors, skills, value (personal and cultural), values, Attitude (psychology), attitudes, and preferences. The ability to learn is possessed by humans, non-human animals, and some machine learning, machines; there is also evidence for some kind of learning in certain plants. Some learning is immediate, induced by a single event (e.g. being burned by a Heat, hot stove), but much skill and knowledge accumulate from repeated experiences. The changes induced by learning often last a lifetime, and it is hard to distinguish learned material that seems to be "lost" from that which cannot be retrieved. Human learning starts at birth (it might even start before) and continues until death as a consequence of ongoing interactions between people and their environment. The nature and processes involved in learning are studied in many established fields (including educational psychology, neuropsychology, experimental psycho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attention
Attention or focus, is the concentration of awareness on some phenomenon to the exclusion of other stimuli. It is the selective concentration on discrete information, either subjectively or objectively. William James (1890) wrote that "Attention is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration, of consciousness are of its essence." Attention has also been described as the allocation of limited cognitive processing resources. Attention is manifested by an attentional bottleneck, in terms of the amount of data the brain can process each second; for example, in human vision, less than 1% of the visual input data stream of 1MByte/sec can enter the bottleneck, leading to inattentional blindness. Attention remains a crucial area of investigation within education, psychology, neuroscience, cognitive neuroscience, and neuropsychology. Areas of activ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arousal
Arousal is the physiology, physiological and psychology, psychological state of being awoken or of Five senses, sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the human brain, brain, which mediates wakefulness, the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, desire, mobility, and reactivity. Arousal is mediated by several neural systems. Wakefulness is regulated by the ARAS, which is composed of projections from five major neurotransmitter systems that originate in the brainstem and form connections extending throughout the Cerebral cortex, cortex; activity within the ARAS is regulated by neurons that release the neurotransmitters norepinephrine, acetylcholine, dopamine, serotonin and histamine. Activation of these neurons produces an increase in cortical activity and subsequently alertness. Arousal is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substantia Nigra Pars Reticulata
The 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). Anatomy 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). Their dendrites as well as the pallidal are preferentially perpendicular to the striatal afferents. The massive striatal afferents correspond to the medial end of the nigrostriatal bundle. Nigral neurons have the same peculiar synaptology with the striatal axonal endings. They make connections with the dopamine neurons of the pars compacta whose long dendrites plunge deeply in the pars reticulata. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motor Cortex
The motor cortex is the region of the cerebral cortex involved in the planning, motor control, 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. Components The motor cortex can be divided into three areas: 1. The primary motor cortex is the main contributor to generating neural impulses that pass down to the spinal cord and control the execution of movement. However, some of the other motor areas in the brain also play a role in this function. It is located on the anterior paracentral lobule on the medial surface. 2. The premotor cortex is responsible for some aspects of motor control, possibly including the preparation for movement, the sensory guidance of movement, the spatial guidance of reaching, or the direct control of some movements with an emphasis on control of proximal and trunk muscles of the body. Located anterior to the primary mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somatosensory Cortex
The somatosensory system, or somatic sensory system is a subset of the sensory nervous system. The main functions of the somatosensory system are the perception of external stimuli, the perception of internal stimuli, and the regulation of body position and balance (proprioception). It is believed to act as a pathway between the different sensory modalities within the body. As of 2024 debate continued on the underlying mechanisms, correctness and validity of the somatosensory system model, and whether it impacts emotions in the body. The somatosensory system has been thought of as having two subdivisions; *one for the detection of mechanosensory information related to touch. Mechanosensory information includes that of light touch, vibration, pressure and tension in the skin. Much of this information belongs to the sense of touch which is a general somatic sense in contrast to the special senses of sight, smell, taste, hearing, and balance. * one for the nociception detect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supplementary Motor Area
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 (anterior to) 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. For the discovery of the SMA and its relationship to other motor cortical areas, see the main article on the motor cortex. Subre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The six-layered neocortex makes up approximately 90% of the Cortex (anatomy), cortex, with the allocortex making up the remainder. The cortex is divided into left and right parts by the longitudinal fissure, which separates the two cerebral hemispheres that are joined beneath the cortex by the corpus callosum and other commissural fibers. In most mammals, apart from small mammals that have small brains, the cerebral cortex is folded, providing a greater surface area in the confined volume of the neurocranium, cranium. Apart from minimising brain and cranial volume, gyrification, cortical folding is crucial for the Neural circuit, brain circuitry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal Forebrain
Part of the human brain, the basal forebrain structures are located in the forebrain to the front of and below the striatum. They include the ventral basal ganglia (including nucleus accumbens and ventral pallidum), nucleus basalis, diagonal band of Broca, substantia innominata, and the medial septal nucleus. These structures are important in the production of acetylcholine, which is then distributed widely throughout the brain. The basal forebrain is considered to be the major cholinergic output of the central nervous system (CNS) centred on the output of the nucleus basalis. The presence of non-cholinergic neurons projecting to the cortex have been found to act with the cholinergic neurons to dynamically modulate activity in the cortex. Function Acetylcholine is known to promote wakefulness in the basal forebrain. Stimulating the basal forebrain gives rise to acetylcholine release, which induces wakefulness and REM sleep, whereas inhibition of acetylcholine release in the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
