Neurons

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  • Created by: Gemma
  • Created on: 02-06-17 04:17

Measuring Cognition

They try and understand what is occuring in the brain broadly by measuring it.

But measuring cognition is not that simple- they use physiological signals as their measurement options.

Single neurons can be studied better due to advances in science including: the development of the microelectrode, discovering about chemical transmitters of the neuron. the electron microscope and developments in microbiology (structure, chemical composition and genetic advances).

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Neurons

Neurons and the chemicals they make and use are derived from genes.

Genes build the brain, regulate processes in neurons through life and up to 30% of the estimated 100,000 genes may be unique to the brain.

There are millions of neurons in the human body. They are the basic functional units of the brain.

There are typically 4 parts to a neuron-> the cell body, dendrites, axon and pre-synaptic terminals.

Two basic types of neurons: 

  • Principle neurons (golgi type I)
  • Interneurons (golgi type II)

Sensory neurons go from the sense organs to the CNS- afferent

Motor neurons go from the CNS/NS to muscles- efferent

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Neurons part II

Synapse is electrical and chemical

Gila- proliific in the brain, formation of myelin sheath on axons. Blood brain barrier function

Myelin- insulating fatty sheath for axon- It increases speed of conduction of the action potential- multiple sclerosis is an example of demyelinating disease.

Learning and memories causes new connections in neurons

Stem cells divide to form new cells- neurons

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Neurons part II

Synapse is electrical and chemical

Gila- proliific in the brain, formation of myelin sheath on axons. Blood brain barrier function

Myelin- insulating fatty sheath for axon- It increases speed of conduction of the action potential- multiple sclerosis is an example of demyelinating disease.

Learning and memories causes new connections in neurons

Stem cells divide to form new cells- neurons

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Parts of the brain

Cerrebellum- posture, movement, coordination, motor and learning motor skills, linked to vestibular system (balance)

Frontal lobe- personality, inhibition, exectuive control, social behaviour

Temporal lobe- auditory control, learning, memory, emotion

Occipital lobe- primarily vision processing, V1-5

Parietal- interpreation, sensory processing, spatial awareness

Lateralisation of the brain- Corpus callosum links the two halves of the brain

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Cognitive neuroscience

They focus on brain signals rather than behaviour

Limitations:

  • Correlation
  • Different methods measure different things
  • Data averaged
  • Lack of clear theoretical basis
  • Thresholds
  • Methodological considerations

Major techniques:

  • Single unit recordings
  • EEG/ERP
  • PET
  • MRI/fMRI
  • MEG
  • TMS
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Techniques

Single unit recording- micro-electrode measuring single neurons or mulitple neurons, its very sensitive

Limitations- only single cells of a small sample of cells, single cell recording in live human brain may be unethical

EEG- poor spatial resolution, useful when task is simple and time-locked

Positron emission tomography- based on detection of positrons, atomic particles emitted by some radioactive substances.- reasonable spatical resolution, poor temporal resolution, indirect measure of activity.

fMRI functional magnetic resonance imagine- structural- indirect measure of neural activity, some areas are hard to scane, scanner is noisy, claustrophobic, supine, experimental design difficulties

MEG- magneto-encephalography- expensive, comfort, artifact, signal dropoff

TMS- mechanism unclear, limited brain areas, specificity

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