Higher mental function Flashcards
Which area of the brain is the primary visual cortex?
Area 17
What cortex recognises where an object is?
Posterior parietal association cortex
What cortex recognises what an object is?
Inferotemporal association cortex
How is primary visual cortex connected to posterior parietal association cortex?
Superior longitudinal fasciculus
How is primary visual cortex connected to inferotemporal association cortex?
Inferior longitudinal fasciculus
What shape receptive fields do ganglion cells in the retina have?
Circular
What do you call ganglion cells with an excitatory centre?
On-centre cells
How do on centre ganglion cells respond if a spot of light is shone in the centre of their field?
They fire action potentials
What happens if a spot of light is shone on the surrounding region of on-centre cells?
Firing of action potentials is reduced?
What is the effect of diffuse light which illuminates both areas?
No effect
What do you call a ganglion cell with inhibitory centre and excitatory surround?
Off-centre, on-surround cell
What happens is light is shone on the centre of an off-centre, on-surround cell?
Firing of action potentials is inhibited
What happens if light is shone on surrounding region of off-centre, on-surround cell
Cell firing is increased
How do receptive fields in lateral geniculate nucleus appear?
Similar shape to those in the retina
What stimulation do cells in the primary visual cortex respond best to?
Binocular stimulation with bars or edges of a particular orientation: simple visual receptive field
In cells with simple receptive fields, what is the effect of bars of light having incorrect orientation?
Stimulates both excitatory and inhibitory so fails to excite cell
How can simple cells be formed by convergence of centre surround cells?
Particular set of afferents with circular receptive fields converge onto a cortical cell giving it a bar-shaped receptive field
How can a bar shaped receptive field anywhere within large area of retina be produced?
Particular set of cortical cells with bar shaped receptive fields converge onto another cortical cell
What information do complex cells have in terms of orientation and position?
Orientation information maintained: orientation specific
Position information discarded: position independent
What are V4 and V8 sensitive to?
Colour of objects
What are V3 cells sensitive to?
Movement of objects
What are V7 cells sensitive to?
Size of objects
What is meant by feature detection theory of visual perception
When an object is recognised, hierarchy of cells is active
V1 cells: edges and corners of object
Simultaneously active set of these cells feed into gnostic cells that responds to basic outline of shape
Where do the neurones that recognise colour size and movement have inputs into
Inferotemporal cortex
How is inferotemporal cortex involved in recognition of an object?
Activity of particular subset of neurone activates one or a small group of cells in inferotemporal cortex. This generates concious recognition of the object
What is meant by bottom up perceptual processing?
Information passing up through a hierarchy of neurones with ever-increasing specificity of receptive field to final cell(s) that represent consciousness
What is meant by the top down component of perception?
The brain can set thresholds for activations of cells in different hierarchies because it has a sense of expectation of what is will see
What part of the brain computes the separation of an object from its background, and the objects relative location?
Right posterior parietal association cortex
Name 5 symptoms of damage to right posterior parietal association cortex?
Piecemeal perception Constructional apraxia Optic apraxia Discalculi Contralateral disregard
What is piecemeal perception?
Inability to observe more than one object at a time
What is constructional apraxia?
Inability tto construct 3 dimentional objects using other objects
What is optic apraxia?
Clumsiness in searching for objects, inability to state relative size of objects
What is discalculi
Difficulty is counting objects
What is contralateral disregard?
Subject ignores left side of body
What is prosopagnosia and what is its most common cause?
Loss of ability to recognise faces
Bilateral damage to part of inferotemporal cortex
Neurons in what area of the brain are activation during facial recognition?
Fusiform gyrus
How to the brain work to recognise faces and put names to faces?
Right inferotemporal cortex identifies face, and information is sent to left inferotemporal cortex to put name to face
What is the main/ general function of the dorsolateral frontal association cortex?
Decision making systems
How is damage to dorsolateral frontal association cortex assessed?
loss of digit span memory (can you repeat back numbers)
ability to extract meaning from proverbs
Wisconsin card sorting test
