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Volledige samenvatting van het boek The Students Guide To Cognitive Neuroscience. Er is niets overgeslagen, en bevat ook korte samenvattingen van de belangrijkste punten van alle artikelen in het boek€8,49
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Volledige samenvatting van het boek The Students Guide To Cognitive Neuroscience. Er is niets overgeslagen, en bevat ook korte samenvattingen van de belangrijkste punten van alle artikelen in het boek
De samenvatting bestaat uit de volgende hoofdstukken: 2, 3, 4, 7, 8, 9, 10, 14, 15, 16
Er is niets overgeslagen, en bevat ook korte samenvattingen van de belangrijkste punten van alle artikelen in het boek
Duidelijk onderscheid tussen begrippen (dikgedrukt) en uitleg
Structure and function of the neuron; 3 components
● Cell body
● Dendrites
● Axon
● Neuron: cell that makes up nervous system + supports cognitive function
Cell body
● Contains nucleus → contains genetic code for protein synthesis
Dendrites
● Branch from cell body
● Enable communication with other neurons
● Receive info from neurons close by
● Number and structure varies with place in the brain (type of neuron)
Axon
● Each neuron has 1 axon (may be divided into branches → collaterals
● Sends info to other neurons
● Transmits an action potential
Synapse; Pre- postsynaptic
● Disc-shaped, at the terminal of an axon
● Small gap between neurons, in which neurotransmitters(chemical signals) are released
● Two neurons forming the synapse
○ Presynaptic: before synapse
○ Postsynaptic: after synapse
○ Reflects direction of info flow
● Some synapses signal electrically not chemically
Axon hillock
● Start of an axon
● Electrical current is large enough: action potential initiated
Action potential
● Presynaptic neuron is active: action potential sent through axon
● When reaches axon terminal, neurotransmitters released into synaptic cleft
Neurotransmitters
● Bind to receptors on dendrites or cell body of postsynaptic neuron
● Create a synaptic potential → conducted passively (without creating action potential) through
dendrites of postsynaptic neuron
● Passive current strong enough at beginning of axon in postsynaptic neuron → action potential
triggered in this neuron
Passive/active conduction
● Passive conduction → short range. Electrical signal impeded by resistance of surrounding
matter
● Active conduction → long range, between neurons by action potentials
Cell membrane
● Barrier for certain chemicals
● Protein molecules act as gatekeepers; allow certain chemicals in/out under certain conditions
,Chemicals going in/out membrane + balance
● Charged sodium ion: Na+
● Charged potassium ions: K+
● Balance between these in/outside membrane: normally at resting potential of -70mV across
membrane (inside negative relative to outside)
Important for generation of an action potential
● Voltage gated ion channels: only found in axons, so only axon can produce an action potential
Sequence of events in generating action potential
1. Strong enough passive current across axon membrane: opens sodium (Na+) channels
2. Sodium enters cell, cell depolarizes → becomes less negative on inside
○ At -50mV: membrane becomes penetrable → charge on inside momentarily reverses →
sudden depolarization + following repolarization in membrane = action potential
3. Negative potential of cell restored via potassium flowing out and sodium not flowing back in
4. Brief period of hyperpolarization → inside more negative than when at rest: more difficult for axon
to depolarize + prevents AP from travelling backwards
How AP moves progressively down the axon
● AP in one part of axon opens adjacent Na+ channels, so it can move from cell body to axon
terminal
● Goes faster if axon is myelinated
Myelin
● Fat substance around axon of some cells (mostly those that carry motor signals)
● Blocks normal Na+/K+ transfer, so AP jumps via passive conduction down axon where there’s no
myelin (nodes of Ranvier)
● Destruction of myelin: MS
Protein receptors in membrane of postsynaptic neurons
● They bind to neurotransmitters
● Many set up a localised flow of Na+, K+ or chloride → creates the synaptic potential
Neurotransmitters inhibitory & excitatory effects on postsynaptic neuron
● Inhibitory effects → makes it less likely to fire
○ Achieved by making inside of neuron more negative than normal → harder to depolarize
● Excitatory effects → makes it more likely to fire
○ Synaptic potentials are then passively conducted
How neurons code info
● Size AP doesn’t vary, the number of AP’s per second does
● This ‘spiking rate’ (rate of responding) depends on info the neuron is carrying
○ Some may have high spiking rate in some situations: during speech, but not others (during
vision)
● Neurons responding to similar type of info often grouped together → specialization of brain
regions
Type of info a neuron carries
● Depends on input/output it receives/sends to other neurons
● Input/output determines function of a region
Gray + white matter
● Gray matter: neural cell bodies
● White matter: axons and support cells (glia)
● Folded sheet of grey matter: cerebral cortex
● Center of brain, grey matter subcortex: basal ganglia, limbic system, diencephalon
Association tracts + Commissures + Projection tracts
● Association tracts: white matter tracts project between different cortical regions in same
hemisphere
,● Commissures: white matter tracts project between different cortical regions in different
hemispheres
○ Most important commissure: corpus callosum
● projection tracts: white matter tracts project between cortical and subcortical structures
4 ventricles
● 2 lateral ventricles: in each hemisphere
● One around subcortical structures
● One in brainstem (hindbrain)
Directions for navigating the brain
● Anterior (rostral) → towards the front
● Posterior (caudal) → towards the back
● Superior (dorsal) → towards the top
● Inferior (ventral) → towards the bottom
● Lateral (medial) → outer part
● Medial → in/toward the middle
Central nervous system
Coronal cross-section
● Slice in vertical plane through both hemispheres
● Brain appears round
Sagittal section
● Slice in vertical plane through one of hemispheres
● When sagittal section is between hemispheres: called midline or medial section
Axial section
● In horizontal plane
Cerebral cortex
● Two folded sheets of grey matter; L/R hemisphere
, ● High surface area to volume ratio; efficient packaging
● 3mm thick + has different layers; reflect grouping of different cell types
● 6 main cortical layers: neocortex (new cortex)
3 different ways to divide regions of cerebral cortex
● Regions divided by pattern of gyri and sulci
○ Same pattern in everyone
● Regions divided by cytoarchitecture
○ Broadman’s areas: 52 areas (BA1-BA52), based in distribution of cell types across cortical
layers
● Regions divided by function
○ Only for primary sensory and motor areas
○ Higher cortical regions harder to ascribe unique functions to
Subcortex
● Collection of grey matter beneath cortical surface
● Divided in different systems
Basal ganglia
● Large round mass in each hemisphere
● Regulates motor activity, programming / termination of action
● Learning of rewards, skills, habits
● Disorders hypokinetic (poverty of movement) or hyperkinetic (excess of movement) -
Parkinson - Huntingtons
Basal ganglia main structures
● Caudate nucleus (tail-like structure)
● Putamen (lie more laterally)
● Globus pallidus (lie more medially)
Limbic system
● Region of subcortex involved in relating organism to its present and past environment
● Involved in detection/expression of emotional responses
● Include; amygdala, hippocampus, cingulate cortex, mammillary bodies
Amygdala
● Detection of fearful or threatening stimuli
Cingulate gyrus
● Detection of emotional and cognitive conflicts
Hippocampus
● For learning and memory
Mammillary bodies
● 2 small round projections(uitsteeksels) implicated in memory
Olfactory bulbs
● Under frontal lobes
● By connections to limbic system → importance of smell for stimuli and
● Influence on mood and memory
Diencephalon, 2 main structures
● Thalamus + hypothalamus
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