week 3 (2&3) Flashcards
what are Phrenology and localisation of function in the brain?
mental function are localised in different areas in the brain
different areas activated will get different areas to budge (correlation between brain and size)
What does ablation mean?
Removal of section in the brain from brain injury or diseases.
three stages of localisation of function
Map out input/output stages
hope structure is modular
multiple converged methodologies
Broadmann (1868-1918) theory
Cytoarchitecture
Cytoarchitecture meaning
Structure and organisation of cells
Semir Zeki theory of localisation ?
Micro electrodes to measure single cells and create boundaries around different properties response
Blasdell And Salama (1986) theory of localisation?
Usea dyes that change with intensity
what happens in the hyper column ?
the cells receive the info from the same area in the visual fields
What is Spatiotopic mean?
Neighbouring hyper-column receive info from neighbouring region in the visual field.
What is retinotopic mapping?
the mapping of visual input from the retina to neurons
How does retinotpic mapping work?
Maintain same spatial relationship between adjacent points that is seen in the retina
The process of Retinotopic mapping
Fovea is focused on an area it appears in red
in cortex the central part of visual field is magnified relative to periphery
What is Cortical magnification factor?
refers to area of cortex that is stimulated by a target of a specified visual angle
What happens in cortical magnification ?
Foveal section enlarged in primary visual correct relative to the periphery
Forward pathways process?
Moving from the LGNd to higher cortical area
Connection from superficial layer of cortex to layer 4
feedback pathway process?
signals originate in superficial and deep layers and terminate in superficial and deep layers
What is the Corpus collosum fibre
Carry info about the retinal midline of the visual field
What are the visual responsive areas ?
not every area is connected to every other area. there are functional pathways
which side of the brain controls motion
LEft
Which side of the brain controls pattern or form?
Right
What does the dorsal pathway do?
Stronger Magno-cellular input
what does the Ventral pathway ?
Stronger Parvo-cellular input
What do the M & P pathways refer to?
The early visual pathway before signal reaches cortex
What does CAT scan stand for?
Computerised Axil Topography
What is the CAT scan capable of ?
Can only detect density difference (bone and brain)
what does fMRI stand for?
Functional Magnetic Resonance Imaging
What is the fMRI capable of ?
very strong magnet which detects oxygen
what does PET stand for?
Postion Emission Topography
What is PET scan capable of?
Detects location of radioactive isotopes carried in the blood
What can detect functional streams?
Transcranial magnetic stimulation
What can TMS do?
Uses magnetic pulses to stimulate neurons
what is Neuro-Phrenology
Different areas of the brain light up when performing tasks.
Whats the Classifier method?
A Correlation between brain response and behaviour.
How many pathways from the Retina to the Cortex?
five different pathways
What is LGN of the thalamus for?
Visual perception
What is the Pulvinar for?
Thalamic structure that response to motion and selection of stimuli
What is the pretectum of the midbrain for ?
Controls of eye movement
what is the suprachiasmatic nucleus of the hypothalamus for
Control of dinural rhythms and hormonal levels
Whats the size of a Hemianopia?
Half a field
What is the size of a Quadrantanopia?
quarter field
What is the size of Scotoma?
Small island
What can lesions cause?
Selective visual function losses
What is a scatoma?
Regions where the stimulus presence is not reported
What can people with lesions detect?
Huge changes in brightness,
can’t see the target but can localise them
Blindsight definition?
For a subject with clinically blind field defects detect, localise and discriminate visual stimuli of which the subject say they are completely unaware
What is Spared visual cortex ?
an island of normal cortex could support residual vision
What is scattered light?
Light scatters as it passes through the optical system
makes identification difficult
What is Criterion?
the willingness to say the target is present?
What is Signal detection theory?
The strength of the signal presented and the participants perceptual sensitivity
Is blindsight just a criterion change?
Sensitivity doesn’t change between Y/N and FC tasks but Criterion did change
Can the vision in blindsight be used?
Cant see target even if the image was correctly detected
what is the Best explanation for blindsight?
Direct pathway from LGN to hMT+ region
What does dMRI stand for?
Diffusion weighted MRI
What do Blindsight positive have?
Normal tract appearance at cortical end
What do blindsight negative have?
do not have a normal tract
What is the conclusion to a missing V1?
Need V1 for conscious vision, but other pathways support visual information when V1 is missing
