CEREBRAL CORTEX

Question 1

why is the white matter white?

Answer 1

becuase of the myelin surrounding the neuron axons

Question 2

what are association fibres?

Answer 2

connect areas within the same hemisphere

Question 3

what are commissural fibres?

Answer 3

connect left hemisphere to right hemisphere

eg corpus collosum

Question 4

what are projection fibres

Answer 4

connect cortex with lower brain structures (e.g. thalamus), brain stem and spinal cord

corticospinal tract

Question 5

what are the three types of fibres in white matter?

Answer 5

association
commissural
projection fibres

Question 6

what structures is the neocortex (main brain) arranged in?

Answer 6

layers (lamina) and collumns

Question 7

what are the functions the temporal lobe?

Answer 7

language, object recognition, memory, emotion

injury leads to agnosia, receptive aphasia

Question 8

what are the functions of the parietal lobe?

Answer 8

perception of space around you
posterior parietal association cortex creates spatial map of body in surroundings, from multi-modality information
injury may cause disorientation, inability to read map or understand spatial relationships, apraxia, hemispatial neglect

Question 9

what are the functions of the occipital lobe?

Answer 9

visual association cortex analyses different attributes of visual image in different places
form & colour analyzed along ventral pathway; spatial relationships & movement along dorsal pathway
lesions affect specific aspects of visual perception

Question 10

what are the functions of the frontal lobe?

Answer 10

judgement, foresight, personality, appreciation of self in relation to world
injury leads to deficits in planning and inappropriate behaviour

Question 11

what is the difference between the ventral and dorsal streams and where are these?

Answer 11

ventral-visual identification (what)
dorsal- location (where)

in the occipital lobe - primary visual cortex

Question 12

what can patients get with a stroke in the parietal cortex

Answer 12

hemispatial neglect

cant see a big chunk of a picture

Question 13

how might the brain function be tested?

Answer 13

Transcranial magnetic stimulation (TMS)

• The magnetic field induces an electric current in the cortex, causing neurons to fire.
• This can be used to test whether a specific brain area is responsible for a function, e.g. speech

transcranial direct current stimulation (TDCS)
-Recent research suggests that TDCS could be used to reduce motion sickness by suppressing the area of the cortex associated with processing vestibular information

Question 14

what methods for measuring and imaging the brain?

Answer 14

position emission tomography (PET)
-uses a radioactive tracer attached to a molecule to locate brain areas where that particular molecule, e.g. dopamine, is being absorbed in the brain. It is an expensive process but has good spatial resolution and specificity in terms of the underlying biology (i.e. it is the only way to identify brain regions absorbing particular substances).

Magnetoencephalography (MEG) and Electroencephalography (EEG)

• MEG: measures magnetic fields
• EEG: measures electric fields

functional magnetic resonance imaging (fMRI)
-measures brain activity by detecting changes associated with blood flow.
This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases