Brain Anatomy

Question 1

What is the development that occurs in the womb?

Answer 1

• nervous system begins to develop at about 2 weeks
• starts as little group of cells that slowly thickens
• then differentiates into a forebrain, midbrain and hindbrain, then folds over itself
• during so, the forebrain dedvelops into cortex and covers the midbrain while the develops into structures like the thalamus, hindbrain develops into cerebellum

Question 2

What is the basic structure of the central nervous system (CNS)?

Answer 2

• brain and spinal cord
• brain contains the brain stem and cerebral hemispheres
• the cerebral hemispheres contain: cortex,, sub-cortical structures, white-matter tracts

Question 3

What is the basic structure of the peripheral nervous system (PNS)?

Answer 3

• somatic nervous system (willful movement) and autonomic nervous system (non-conscious regulation of various functions)
• the ANS contains the sympathetic nervous system and the parasympathetic nervous system

Question 4

What is the corpus callosum?

Answer 4

• white matter tracts (numerous axons) connecting the 2 hemispheres
• electrical impulses travel from neurons in one hemipshere and reach neurons in the hemisphere via corpus callosum are referred to as intercallosal transfer
• contains 99% of all connexions
• primary function is to communicate information from 1 side to the other

Question 5

What are the basic features of the brain (cerebral cortex, grey and white matter, gyrus, sulcus)?

Answer 5

• cerebral cortex is sheet of neural tissue (grey matter) on the outer part of the brain, made of bodies of nerve cells (neurons)
• white matter situated under the grey matter, it’s made of long elongated part of the nerve cells (axon)
• gyrus: plateau on cortical surface
• sulcus: fold/ditch in cortical surface, major sulci are referred to as fissures

Question 6

What are the features of a neuron?

Answer 6

• body/soma of a neuron are part of the grey matter
• protrusions are called dendrites
• axon of a neuron are part of the white matter, they’re covered in protective layer of myelin (white appearance of white matter comes from the light colour of myelin)

Question 7

What is cytoarchitecture?

Answer 7

• Brodmann found that cortical regions vary in the detailed cellular structure (types of neurons) and cellular arrangements (numbers of layers, density)
• Brodmann divided the cortex into a number of areas, many serve specific functions

Question 8

What are the different lobes?

Answer 8

• cerebral hemisphere is divided into 4 lobes: frontal, parietal, occipital, temporal
• divided by 3 major sulci: central, lateral and parietal-occipital sulci

Question 9

What are the different coordinates and orientations?

Answer 9

• superior (dorsal): top of brain
• anterior (rostral): front of brain
• posterior (caudal): back of brain
• inferior (ventral): bottom of brain
• lateral means outside of brain, medial means inside of brain

Question 10

What are the distribution of functions?

Answer 10

• basic physiological and metabolic processes are controlled by groups of neurons in the brainstem including thalamus and hypothalamus
• functions such as: respiration, digestion, arousal, swallowing, vomiting, circadian rhythms, blood pressure

Question 11

What is the control of basic physiology?

Answer 11

• specific groups of neurons include: reticular formation, suprachiasmatic nucleus, ventromedial nucleus
• reticular formation: complex network of cells in the core of the brainstem involved in the control of arousal and sleep
• suprachiasmatic nucleus: controls circadian 24hr biological rhythms (hypothalamus, but stimulants can block it)

Question 12

What areas are related to perception?

Answer 12

• cortical areas where sensory information arrives are referred to as primary visual/auditory/sensory-motor areas
• it arrives via nuclei in brainstem (particularly via thalamus)
• perceptual information gets passed to secondary sensory areas where sophisticated processing takes place
• from there, processing moves to the association areas where information from different modalities/ different types is integrated

Question 13

What is the hierarchical organisation of visual perception?

Answer 13

• what and where pathways
• visual processing is segregated into pathway specialised in analysis of stimulus features and a pathway specialised in rapid detection of stimulus location and motion

Question 14

How is the Fusiform gyrus related to visual processing?

Answer 14

• cells in the inferior temporal lobe (fusiform gyrus) seem to respond to highly complex visual stimuli
• area that specialises in face recognition (Fusiform Face Area)
• damage/cell loss due to degeneration in FFA often results in impaired face recognition (prosopagnosia)

Question 15

What is the hierarchical organisation of motor control?

Answer 15

• primary motor cortex exerts direct control over movement
• other areas (premotor and supplementary motor) are involved in planning of movement and integration of motor behaviour with other behaviours
• some sub-cortical structures (basal ganglia) and brainstem structures and groups of cells (cerebellum, substantia nigra) are also involved in the fine-grained co-ordination/ timing of movements
• Brodmann areas 4, 6, 8

Question 16

What are the challenges in functional localisation?

Answer 16

• dorso-lateral prefrontal cortex is the region of the brain which expanded more than any other in course evolution of primates
• some processes show clear and specific localisation and some regions are clearly specialised
• some regions are more essential for certain processes than others
• higher cognition may be localised to a degree but it’s likely distributed and more variables
• challenge is to identify more elementary constituent processes, the issue is that it’s difficult to isolate the behaviour, as well as that there seems to be a large multiple demand brain regions