Section 3 - Quantifying Cogntion; Neuropsychology, Neuroimaging & Neuromodulation Flashcards
What’s Unilateral Neglect?
When patients have impaired attention to the side contra-lateral to their lesion
Posner & Cohen (1984)
Exogenolis orienting - occurs when attention is guided by goals of the perceiver
What’s Spotlight Theory of Attention?
impaired disengagment
What’s the Biased Competition Model?
A consequence of attention orientating to the ipsilesional side
What’s the Extension disorder of attention?
When bloody supply around the Arteria cerebra median are often affected due to posterior parietal injury
What’s Perceptual Grouping (Reducing method of extinction)?
Process of determining which regions & parts of the visual scene belong together as parts of higher order perceptual units such as objects/patterns.
What’s Spotlight Metaphor of Attention?
Disengage -> move -> engage
What’s Premotor Theory of Attention?
Consequence of activation of the motor system, shifts pf attention are by goal-directed actions
What’s TES?
Refers to techniques that involve passing weak currents through the skull for the purposing of stimulating the brain
tDCS (direct)
Current of fixed magnitude is passed from one electrode to another
tACS (alternating)
Strength of current is varied at a particular frequency
o-tDCS (oscillatory)
Current ranges from 0-2 at the anode & -0 - -2 at the cathode
tRNS(transcranil random noise)
Intensity is varied randomly over time rather than constant or varying at a set frequency
What are the results of TES?
Neurones become more/less likely to fire, doesn’t trigger action potential and prolongs stimulation overtime
EPSP
An active presynaptic cell releases neurotransmitters into the synapse. Some bind to the receptors on the postsynaptic cell. Ion channels activated. Post synaptic excitation or inhibition
Association
Damage to single brain region = multiple deficits
Dissociation
Damage = impaired performance in task A but B is normal
What is Electrocephalography?
It measures the electrical brain activity at the post synaptic potentials by large populations of the neurones firing together. (must be spatially aligned)
What’s Cognitive Neuroscience?
Understanding the biological basis of consciousness & the mental processes by which we perceive, act, learn and remember
What are the 5 experimental disciplines that cognitive neuroscience emerged from?
Anatomy, embryology, physiology, pharmacology and psychology
H.M
Lesions, 1953. Had a surgical resection of medical temporal lobes (removed hippocampus) which resulted in anterograde amnesia
What does a PET do?
Detects a ‘tracer’ that’s introduced onto the body on a biologically active molecule. The concentrations of the tracer give the metabolic activity
What are the pros of a PET?
Excellent spatial resolution
What are the cons of a PET?
Poor temporal resolution, radiation exposure, very expensive
What does a TMS do?
Can either excite cortex or temporally disturb cortical features
What are the pros of a TMS?
Virtual lesion may be better defined, reduces plasticity, temporal resolution in millisecond range
What are the cons of TMS?
Discomfort, only one area, requires anatomical images, difficult to model path of current
What are the cons of FmRI
Poor temporal resolution, no movement, noise, confined space and expensive
What are the pros of FmRI?
Excellent spatial resolution, all brain accessible, measures change, no radiation exposure
What is a FmRI?
Looks at the Blood Oxygen Level Dependent EFFECT = Basics of a functional MRimaging
What’s a structured MRI?
Provides a high resolution structural image, high contrast between soft tissues, no exposure to radiation, high fixed strength magnets
What’s the Haemodynamic Response?
When active neurones use energy the blood releases oxygen to activate neurones which causes a change of the relative levels of oxyhemoglobin & deoxyhemoglobin. This then have different magnetic properties.
