Basic brain anatomy

Question 1

Structure of the nervous system

Answer 1

1. central nervous system - brain and spinal cord
2. brain - brainstem and cerebral hemispheres - cortex, subcortical structures and white matter tracts
3. peripheral nervous system - somatic nervous system (deliberate movements), autonomic nervous system (unconscious)

Question 2

Brain stem

Answer 2

1. at the base of the brain
2. cerebellum may be included
3. basic physiological and metabolic processes are controlled by groups of neurons in the brain stem (plus thalamus and hypothalamus)
4. functions such as respiration, digestion, glucose metabolism, blood pressure, swallowing, coughing
5. reticular formation - a complex network of cells in the core of the brainstem is involved in the control of arousal and sleep
6. thalamus and hypothalamus - thalamus acts as a relay station in the brain, transmitting sensory and motor signals, suprachiasmatic nucleus (in hypothalamus) controls circadian biological rhythms

Question 3

Cortex of the brain

Answer 3

1. left and right hemisphere
2. corpus callosum - white matter tracts connecting the two hemispheres
3. electrical impulses that travel from neurons in one hemisphere and reach neurons in the other hemisphere via the corpus callosum (intercallosal transfer)
4. grey matter - on the outer part of the brain, cerebral cortex, at the level of microstructure, the cortex is made of bodies of nerve cells
5. white matter - situated under the grey matter, white matter is made of the elongated part of the nerve cells - axon
6. gyrus - plateau on cortical surface
7. sulcus - fold/dotch in cortical surface, major sulci are often referred to as fissures
8. fissures - parieto-occipital sulcus, central sulcus (between frontal and parietal), sylvian
9. lobes - each hemisphere is divided into frontal lobe, parietal lobe, occipital and temporal, lateral sulcus separates temporal and parietal

Question 4

coordinates and orientations

Answer 4

1. anterior/rostral - front
2. superior/dorsal - up
3. posterioir/caudal - back
4. inferioir ventral - down
5. medial superioir - inside up
6. medial inferior - inside down
7. axial slice - across the top
8. coronal slice - vertical
9. saggital slice - side

Question 5

Cytoarchitecture

Answer 5

1. Brodmann found that cortical regions vary in the detailed cellular structure
2. brodmann divided the cortex into 52 areas
3. many of these areas turned out to have distinct functions

Question 6

Localisation of function

Answer 6

1. phrenology - school of thought that attempted to localise mental processes anatomically
2. equipotentiality - flourens was one of the earliest proponents of the idea that cognitive functions are not localised by diffusely distributed
3. concluded following animal experiments, that basic physiological regulation and motor functions are localised, but cognitive functions are not, and different parts of the brain are equally involved in these functions
4. primary motor cortex - controls body and limb movements
5. somatosensory cortex - sensation of touch, skin and muscles and some internal organs
6. primary visual cortex - basic vision
7. primary auditory cortex - basic hearing
8. olfactory and gustatory cortices - smell and taste
9. primary and association areas - most have something that executes the function and other areas that support and are associated

Question 7

hierarchical organisation in vision

Answer 7

1. cortical areas where the sensory information arrives are referred to as primary visual (V1)
2. this perceptual information then gets passed to the secondary sensory areas where more sophisticated processing takes place
3. from the secondary sensory areas, the processing moves to the associated areas, where information from different modalities is integrated

Question 8

Thalamic nuclei

Answer 8

acts as ‘relays’ for sensory information

Question 10

fusiform gyrus

Answer 10

1. at the bottom of the temporal lobe
2. cells in the inferioir temporal lobe seem to respond to highly complex visual stimuli
3. there is an area in the fusiform that seems to specialise in face recognition (FFA)
4. neuroimaging studies of face processing consistently find FFA activation
5. damage to FFA or cell loss in FFA often results in impaired face recognition

Question 11

hierarchical organisation in motor control

Answer 11

1. control of movement has a similar hierarchical structure
2. the primary motor cortex exerts direct control over movement, however other areas are involved in planning of movement and integration of motor behaviour with other behaviour

Question 12

basal ganglia and cerebellum

Answer 12

1. some subcortical structures (basal ganglia) and brainstem structures (cerebellum) are also involved in the fine-grained coordination and timing movements
2. more motor cortex dedicated to hands, lips and face

Question 13

challenges in localisation

Answer 13

1. dorso-lateral prefrontal cortex is the region of the brain which expanded more than any other in evolution, yet patients with lesions to this region rarely show specific deficits, shows PFC is important
2. Broca’s area may only be one part specialised
3. Fedorenco - found using fMRI that Broca’s area contains two distinct types of subregions, one specialised for language processing and another more general purpose region engaged in a wide range of cognitive tasks

Question 14

Is there localisation of function?

Answer 14

1. some processes show very clear and specific localisation and some brain regions are clearly specialised
2. higher cognition may be localised to a degree, but this localisation is more distributed and more variable over individuals
3. current imaging techniques analysis may be coarse
4. some large multiple demand brain regions