brain anatomy & localisation of function

Question 1

which 2 categories is the brain separated into?

Answer 1

brain stem (posterior part continuous with spinal cord) - contrl over physiological and metabolic processes 
cerebral hemispheres

Question 2

what is the corpus callosum and what is its function?

Answer 2

white matter tracts

connecting the 2 hemispheres allowing them to communicate

Question 3

what is the cerebral cortex?

Answer 3

grey matter on the outer part of the brain and is made of bodies of neurons

Question 4

what is the difference between white and grey matter?

Answer 4

white matter (due to whiteness of myelin) - situated under grey matter and is made of long elongates part of neurons called axons

grey matter - outer part of the brain made up of the soma and dendrites of neurons (start and middle)

Question 5

what is the difference between a gyrus and a sulcus?

Answer 5

gyrus - outside of fold

sulcus - inside of fold and major ones referred to as fissures

Question 6

what is the function of the myelin sheath on axons?

Answer 6

made up of proteins and fatty substances and enables electrical impulses to travel quickly along the nerve cell

Question 7

what is intercallosal transfer?

Answer 7

refers to electrical impulses which travel from neurons in one hemisphere to the other via the corpus callosum

Question 8

what are the 3 major sulci/fissures and what do they separate?

Answer 8

1. central sulcus / fissure of Rolando - separates the frontal lobe and the parietal lobe & primary motor (frontal) and somatosensory (parietal) cortex
2. parieto-occipital sulcus
3. sylvian / lateral fissure - separates frontal and parietl lobe above from temporal lobe below

they separate the 4 lobes

Question 9

what are the coordinates and orientations for different parts of the brain?

Answer 9

coordinates:
(from side on with the front of brain on the left going clockwise) superior/dorsal to posterior/caudal to inferior/ventral to anterior/rostral

Question 10

what do medial superior and inferior refer to?

what does lateral refer to?

Answer 10

medial superior = near top middle
medial inferior = near bottom middle

lateral = either on the right or left hand side

Question 11

what are the 3 different brain slice orientations?

Answer 11

axial - view would be as if looking down on brain

coronal - view would be one half of brain from the front or back e.g cutting through middle

sagittal - view would be as if looking sideways at brain

Question 12

what does cytoarchitecture refer to?

Answer 12

a finding by Brodmann
that cortical regions vary in detailed cellular structure (types of neurons) and arrangement (number of layers, density)

and divided cortex into areas up to 52 in this way

Question 13

what are 3 specific groups of neurons and what do they do?

Answer 13

reticular formation - control of arousal and sleep (with Reticular Activating System determining level of alterness)

SCN - controls circadian rhythms

ventromedial nucleus - controls conversion of blood glucose into body fat

Question 14

what is phrenology?

Answer 14

school of thought that attempted to localise mental processesanatomically

Gall

Question 15

what is equipotentiality?

Answer 15

cognitive functions aren’t localised

but basic physiological regulation and motor functions are localised

Flourens

Question 16

what is the hierarchy of perception?

Answer 16

primary areas - where sensory info arrives e.g thalamus (occupy small area of cortex compared to other 2 parts)

secondary areas - perceptual info gets passed to them for more sophisticated processing

association areas - info from different modalities and of different types is intergrated

Question 17

which 2 pathways is visual processing separated into?

Answer 17

‘what’ including V1,2,4 and inferotemporal cortex

‘where’ including V1,2,3,5 and parietal cortex

Question 18

what is the specific function of the Fusiform gyrus?

Answer 18

specialises in facial recognition

so damage/ cell loss results in impaired face recognition (prosopagnosia)

Question 19

what is the hierarcy of motor control?

and which of Brodmann’s areas are responsible for motor control?

Answer 19

primary motor cortex - direct control over moevment (occupy small area of cortex compared to other 2 parts)

premotor and supplementary motor - planning of movement and intergration of motor beh. with other beh.

Brodmann areas of 4,6,8 are motor areas

Question 20

why does paralysis often occur after a stroke?

Answer 20

main artery runs past the primary motor cortex which is responsible for direct control over movement so if impaired =paralysis

Question 21

which region expanded more than any other in course of evolution in primates?

Answer 21

dorso-lateral prefrontal cortex but patients with lessions rarely show deficits

Question 22

what is an example of challenges in functional localisation?

Answer 22

Broca’s area is activated during 10% of studies not speech production related

could be that area isn’t specialised to specific function
or only a small area of Broca’s area is specialised in speech production

Question 23

what did Duncan mean by ‘multiple demand’ brain areas?

Answer 23

certain brain areas which were always activated over different cognitive tasks

Question 24

what is meant by reverse inference in relation to localisation of function?

Answer 24

using activation in certain brain areas and the knowledge of which functions these brain areas serve to infer what is going on

e.g seeing which parts of brain are active in PTSD flashbacks to determine whether auditory, visual etc.