How to study the brain

• What is a stroke?

  blood clot in the brain which causes damage, may lead to impairments in specific regions such as language
• What is Alzheimer's disease?

  Neurodegenerative disorder that consists of damage in the temporal lobe, including the hippocampus
• What is Parkinson's disease?

  Neurodegenerative disorder consisting of muscle deficits due to degeneration of neurons in the substantia nigra
• Who was patient LeBorgne?

  A man who had a stroke causing damage in later discovered Broca's area, lead to deficits in speech production where the only word he could say was 'tan'
• Who was Phineas Gage?

  A man who had severe damage to frontal cortex lead to behavioural and personality changes
• Who was patient HM?

  A man who had surgical resection of mainly hippocampus to stop seizures, found that he had impairments in specific memory such as spatial and declarative, however cognitive and memory functions were largely unaffected
• How are behavioural studies used to study the brain?

  Observing patients with particular brain damage to find out role of brain region in behaviour
• How are manipulations of brain function used to study the brain?

  can confirm roles of brain structures by specifically manipulating them, however this is not ethically possible in humans so use animals such as rats
• How is neuroanatomy and histology used to study the brain?

  asks why does this region have this role? what parts is it connected to? and examining it further by observing electrical activity
• How is imaging used to study the brain?

  MRI, PET scans are the main ways of scanning the brain
• How are computational models used to study the brain?

  used to build models of brain circuits and their functions, helps to test is theories are correct
• In what way is studying the brain multidisciplinary?

  understanding of brain-behaviour relations requires a combination of many of these methodological approaches, and combines views from chemistry, physics, biology etc
• What is declarative (explicit) memory?

  memory of facts and events, coordinated by diencephalon
• What is nondeclarative (implicit) memory?

  procedural memory, priming, classical conditioning, nonassocative learning
• What are experimentally induced lesions?

  selective destructions of specific brain sites (via mechanical, electrolytic, neurotoxic methods) using stereotactic brain surgery
• How else can lesions be induced?

  can use temporary pharmacological manipulations via pre-implanted micro-cannula to switch neurons or specific receptors on and off
• What is optogenetics

  manipulating specific neurons in the brain the make them light sensitive, shining light can then activate or inhibit neuron
• What is Trans-cranial magnetic stimulation (TMS)?

  Non-invasive brain stimulation which induces a magnetic field around the brain disrupting neurons
• Why do we test hippocampal lesions in rats?

  problem with using rats for memory experiments is we cant verbally test their memory, but we can test spatial memory
• How do we test hippocampal lesions in rats?

  • put rats in a water maze and they get faster to escape every time, showing spatial memory
  • when rats given a lesion in hippocampus, their memory is impaired and they take longer to escape the maze
• What is neuronal tract tracing?

  • mapping neural connections
  • using a tract tracer injected into brain region, this compound travels with action potential or against an action potential
  • we can track where is ends up to examine how brain systems link
• What is diffusion magnetic resonance imaging?

  can highlight white fibres tracts and main connection in human brain, helps confirm findings from rat studies
• Polymodal sensory input to the hippocampus...

  the hippocampus is connected to many other brain regions, this allows us to form multimodal models of memory
• What is electrophysiology?

  the process of recording the electrical activity of the brain using electrodes
• What are single unit recordings in electrophysiology?

  • record the electrical activity of single neurons
  • O´Keefe (2014)- found neurons in rats fired only when in specific locations, e.g. when in top left corner of box only certain neurons fire, may offer explanation of how hippocampus builds spatial memory
• What are local field potential recordings in electrophysiology?

  • recording electrical potentials generated by many neurons
  • specific neurons of fields help differentiate between processes such as different stages of sleep
• Electrophysiology in humans...

  Invasive single unit and LFP recordings only conducted in rare cases for the pre-surgical evaluation of epilepsy patients (allows them to do as little damage as possible when operating on brain)
• What is a surface EEG?

  putting electrodes on surface of scalp, weaker but more widely used as non invasive, spontaneous and event-related
• What is a magnetencephalography (MEG)?

  measures small magnetic field changes accompanying electrical voltage changes due to brain activity, better spatial resolution then EEG
• What is magnetic resonance imaging (MRI)?

  images generated from magnetic resonance signal that comes from hydrogen nuclei in brain tissue when they are aligned by a strong magnetic field then excited by a magnetic pulse
• What is a structutal MRI?

  non-invasive imaging of brain structure based on MRI contrast between different tissue types due to different densities of H nuclei
• What is a functional MRI?

  non-invasive imaging of brain ‘activity’ based on MR signal changes associated with metabolic and cerebral-blood-flow changes
• What is a Positron Emission Tomography (PET) scan?

  • involves injection of radioactive tracers that resemble compounds of biological interest
  • using dedicated detectors around the head, these tracers can be followed in the brain, for example to monitor metabolic activation