What is the white matter in the brain and where does the name come from?
‘white substance around axons’ —> fat
few cell bodies
mainly myelinated axon tracts (= network of long fibers of nerve cells that allow exchange of in formation and communication between different areas of grey matter)
axons surrounded by fatty substance (myelin) —> white color
What is the grey matter and where does the name come from?
outermost layer of brain
composed of :
neuronal cell bodies
dendrites
(un)myelinated axons
glial cells
capillaries, …
cell bodies and capillaries —> grey color
Dimensions of cortex
52 Brodmann areas
Four lobes
Six layers
grey matter: 16 billion nerve cells
Neurons either excitatory (84%) or inhibitory (16%)
What increases inhibition of neurons?
sleep
Why is the cortex folded?
big cortex fits in smaller surface
What are Gyrus, Sulcus and Fissure?
Gyrus = ridge / mountains of the brain
Sulcus = shallow groove surrounding the gyrus
Fissure = deep furrow/groove dividing brain into lobes and hemispheres
What are the most important fissure?
longitudional fissure —> divides brain in left and right hemisphere
every species has it
lateral / Sylvian fissure —> separates frontal, parietal lobes from temporal lobe
central / Rolando —> seperates frontal and Parietal lobe
What are in general the four main lobes
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
What are functions of frontal lobe?
motor and non-motor functions
motor:
conscious (bewusst) movement
non-motor:
emotional expression
problem solving
memory
language
judgement
sexual behaviours
What are functions of Parietal lobe?
sensory information integration
spatial orientation
cognition
computation
What are functions of Occipital lobe?
visual perception
color recognition
reading (comprehension)
depth perception
recognitio of object movement
What are functions of Temporal lobe?
auditory perception
speech
language comprehension
emotional responses
visual / facial recognition
What are the functions of Broca and Wernicke area and where are they located?
Broca: learning of speech / language processing
Wernicke: comprehending of written and spoken language
What did Brodman discover about the anatomy of the brain?
defined areas in brain that look anatomical different —> 52 areas
—> different anatomical areas have different functions
Human Connectome Project found 180 different areas
What is Cytoarchitecture and Myeloarchitecture?
Cytoarchitecture = cells in cortical layers and sublayers
shows density and morphology
Myeloarchitecture = axons with myelin sheaths
What are the six layeres of the cortex
Layer I: Integrates intracortical inputs
Layer II/III: Local cortical processing —> Intercortical communication
Layer IV: Thalamic sensory input —> Sensory processing
Layer V: Subcortical outputs —> motor control
Layer VI: Sends feedback outputs to thalamus
Are the layers in sensory, associtaion and motor the same?
thickness of different layers very different
sensory big layer IV, motor fast gar nicht
What is the job of the Thalamus?
most cortical areas input comes from thalamus (—> filters input)
What happens when you stick an electrode vertically and horizontally in cortical layers?
stimulus = small bars of light
vertically —> one column completely reacts to one stimulus
horizontally —> each column reacts differently
Briefly describe a simple cell circuit that reacts to light.
LGN: (Lateral Geniculate Nucleus)
process visual information, e.g. light
have receptive fields with center-surround structure
center and surrounding region react opposite (e.g. excitatory/inhibitory)
Simple Cell
Neuron that responds to oriented edges/ bars of light
Integrate input from multiple LGN cells to detect orientations and positions of visual stimuli
Stimulus
if the stimulus is aligned with receptive fields —> strong signal
Describe how one can construct a complex cell circuit from simple cells.
Complex cell: neuron in the visual cortex that builds on the information from simple cells
also orientation-selective
can detect light over wider area (higher degree of spatial invariance)
Which areas react when you want to repeat a word?
1. Auditory area
2. Processing of language in Wernicke
3. Execution in Broca (give command to motor cortex)
4. Motor cortex (talking)
Which areas react when you want to read a word?
1. Visual Area
2. Translate visual image to make sense of it (Angular Gyrus)
3. Wernicke (Processing language)
4. Broca (execution, give command to motor cortex)
5. Motor cortex (talking)
What are split-brain patients?
see words on the right —> can read out loud
see words on left —> can draw with eyes closed
What happens when you have a damaged Broca’s area?
having trouble speaking, forming sentences —> non-fluent Aphasia
understanding good, finding word difficult
intelligence remains intact
What happens when you have a damaged Wernicke’s area?
fluent Aphasia
sentences make no sense
How do we lose consciousness according to the Integrated Information Theory? e.g. due to anesthesia?
Integrated Information Theory (IIT)
loss of integration —> parts cannot communicate anymore
loss of capacity —> less communication
—> both lead to loss of consciousness due to loss of information integration
Last changed4 months ago
