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Neuroimaging - Coggle Diagram

- - - - Homodynamic Response Function: 0.5%-3% change in signal. Focal and not everyone can find it. (pericytes control blood flow)The signal rises after the stimulus begins. Peak between4 5 sec. Signal suppressed. It also variants between subjects(latency and amplitude).
        
        linearity of bold response(superposition and scaling), neuromuscular coupling and bold reaction summation
        
        Nonlinearity of BOLD at < 6s
        
        BOLD best correlates with LFP and thus represent
        postsynaptic inhibitory and excitatory potentials
    - - what is difusion tensor: mathemathical estimation that can be Isotropic or anisotropic. By doing this with each voxel you can track fibers -called stream as stream lines
      - Only 7% of all participants has the same connection repeated.
      - Connection weight by a number of streamlines, streamline volume density, how long is the streamline, fractional anisotropy.
- - - - Preprocessing: due to lack of golden stnd yet this step is very. A broad frequency range results in more stable networks. Global signal regression shifts the distribution of correlation values of a seed region in the negative direction. Negative correlation needs to be discarded before computing the measures. Will affect the topology. Correlated with respiration induced FMRI signal fluctuations. Order affect impact as well as motion correction pipelines.
      - Defining nodes:a)intrinsic consistency b) Extrinsic differentiation d) Spatially constrained (you don't always need to add more nodes- over a cost of 20%).
      - Defining Edges: to which node the closest road exists, we need to avoid indirect correlations. Sometimes we use partial correlation or some other system. sparsity methods to get rid of inderect links. normalization by wiring cost'.
      - Building the graph. altering threshold alter the conectivity. There are between subjects differences. Control each individual network over a distribution of threshilds.
    - - Functional segregation: clustering coefficient (how many nearest neightboars are also conected btween each other. Modular structure
      - Functional integration: the ability to combine specialised information from distributed brain regions. Used in intelligent literature. e.g. small world network - high clustering, low edge length. Parallel information processing facilitates neuronal assemblies to support changing cognitive states.
      - Centrality: Important brain regions (hubs) often interact with many other regions and facilitate functional integration. Ways of measuring. 6% accounts for 90% of the connections. measurements: connections between modules.
        Rich Club-brain
      - ResilienceAnatomical brain connectivity influences the capacity of neuropathological
        lesions to affect functional brain activity. Degeneracy> the ability to take a function from another brian region.
  - - - Resampling: Interpolation, using realignment in SPM.
      - Registration: get the difference between original position and (i) position. with interpolation