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26 Cards in this Set
- Front
- Back
Neural circuits
Neural systems |
Neural circuits - neurons organized into ensembles that process specific kinds of information
Neural systems - circuits that process similar types of information that serve broader behavioral purposes Sensory system - acquire and process info on environment motor systems - generate movement and other behavior assosciational systems - mediate most complex brain functions |
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Direction of infomration flow (3 functional classes are basci constituents of all neural circuits)
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afferent - neurons carry info towards brain or SC
Efferent - neurons carry info away from brain or SC interneurons only participate in local aspects o f circuit |
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Major components of NS and functional relationship
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Somatic sensory system. what is critical 1st step in all sensory processing
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Sensory transduction - cricital 1st step in all sensory processing; energy of a stimulus is converted to an electrical signal in sensory neurons
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Somatotrophic order in human primary somatic sensory cortex
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ascending sensory pathway project ot cortical neurons in somatic sensory cortex. Mapping studies show that cortical area contains a complete disproportionate representation of body
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Somatic motor system
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neural control of striated muscle contraction is orchestrated by lower and upper motor neurons.
LMN (lower motor neuron)- spinal or brainstem motor neuron; directly innervates muscle (primary, alpha) UMN (upper motor neuron) - gives rise to descending projection that controls the activity of LMN in brainstem and SC (initiation of voluntary movements) |
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Topographic Map of Body Musculature in Primary motor cortex
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Electrical stimulation of motor cortex elicits contraction of muscles and the cortex contains a complete disproportionate represenation or map of body's masculature. Masculatur used in tasks requiring fine motor control occupies a greater amt of space in motor map.
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Visceral Motor system (read)
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controls involuntary functions mediated by activity of smooth muscle fibers, cardiac muscle fibers, and glands to maintain body homeostasis
sympathetic and parasympathetic NS sympathetic - prepare for emergency effectors are adrenergic ganglion cells located relatively far from end organ parasympatehtic -conserving and restoring energy effectors are cholinergic gangion cells located near target organs |
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Gray matter nad white matter of cerebral hemisphere
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gray matter - regions of CNS rich in neuronal cell bodies and neurophil
white matter - refers to large axon tracts in brain and SC |
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White Matter of cerebral hemisphere
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Commissural fibers - connect corresponding regions of 2 hemispheres
associational fibers - connect various cortical regions w/i same hemisphere projection fibers - afferent and efferent nerve fibers passing to and from brainstem to entire cortex |
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example of association connectivity in white matter
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ex: Arcuate fasciculus - neural pathway connecting Broca's to Wernicke's area. involved in generation and understanding of language
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Neuromodulator systems that have widespread diffuse projections.
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Ach, dopamine, NE and serotonin
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ACh system
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ACh system in brainstem and basal forebrain
ACh effects are generally excitatory and are thought to function in attention, memory and learning Central block of Ach causes delerium and memory deficit. Basal forebrain cholinergic systems are damaged in Alzheimer's disease |
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Dopamine system. What happens if Mesostriatal is damaged? What is mesolimbic involved in? Mesocortical?
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originate in substantia nigra and ventral tegmental area.
Mesostratial - damaged in Parkinson's disease Mesolimbic - involved in "positive" symptoms of schizophrenia (hallucination) Mesocortical - involved in congnitive deficits and "negative" symptoms of schizoprenia |
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NE system
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originates in locus coeruleus and lateral tegmental area. project to entire forebrain.
Functions in attenion, sleep-wake cycles, mood and sypathetic activities. NE and 5HT are important in mood disorders (ex: depression and manic depressive disorder, and in anxiety disorders including OCD) |
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Serotonin system
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originates in raphe nuclei; rostral raphe projects to entire forebrain; caudal raphe projects to cerebellum, medulla and spinal cord
involved in depression, anxiety, OCD, aggresive behaviour and some eating disorders. Caudal raphe functions in pain modulation |
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laminar organization and connectivity of cerebral cortex
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Synpatic integration and modulation basic network properties
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Feed-forward inhibition:
- ex: reflex loop - sensory neuron activates extensor motor neuron = kick but there's inhibitory neuron which inhibits flexor motor neuron = allows for kicking. Feed-back inhibition - product inhibits its own production Divergence - one neuron branches to give multiple isgnals Convergence - multiple neurons collectively create 1 signal |
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Signaling is organized same way in all neurons. Draw model neurons, sensory neurons, motor neurons, local interneurons, projection interneurons, neuroendocrine cells
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Sequence of neuronal signaling of reflex loop
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Sensory signal --> motor signal --> muscle signals
at each neuron receive input, integration, conduction, output (neurotransmitter release or behavior) more neurotransmitters = increase spike threshold = more frequent AP b/c takes longer time for AP to decrease to threshold |
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important Component of synapses
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mitochonidria*
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presynaptic neurotransmitte release (draw)
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Neuromusclular junction (draw)
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Clostridial toxins causes? Alpha-latrotoxin? alpha-neurotoxin? Curare? conotoxins
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causes botulism - preteases that cleave presynaptic vesicle proteins (BOTOX) that should be released in neuromuscular junction
Alpha latrotoxin - a protein found in venom of black widow spider cuases massive discharge of synpatic vesicles Alpha- neurotoxin - in cobra which blocks Ach receptors = paralyze Curare - in arrow heads to paralyze prey Conotoxin - fish hunting marine cone snail shoot venomous darts into prey which blocks Ca2+, Ach, glutamate, Na+ channels |
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Glial cells
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Oligodendrocytes - axon insulation to increase veocity of AP
Microglia - immune-competent cells of CNS Ependyma cells - line cavities of brain and central canal of SC. involved in production and secretion of CSF |
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Astrocyte functions
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Established, Probable, Emerging
1. Established - sequestration and/ or redistribution of K+ during neural activity removal of glutamate and GABA at synapses synthesis of precursor for glutamate and GABA production pathological - alexander disease, cytotoxic brain edema, glioma formation, failure of extracellular glutamate homeostasis 2. Probable providing eneryg substrate to neurons (lactate) sharing energy substrate deriving from glycogen w/ neurons brain water homeostasis influencing integrity of BBB regulation of extracellular pH Pathological - hepatic encephalopathy, modulation of stroke outcome 3. Emerging modulation of excitatory and inhibitory synpases regulation of synpatogenesis regulation of neurogenesis in adult brain detoxicification of brain free radical species pathological Trophic modulation of post-injury neural repair and axon regrowth release of cytokines and chemokines neuroinflammation |