Plasticity in the brain

Different types of plasticity that exist in the brain

• Hebbian/correlation based: STDP: temporal correlation
  
• Homeostatic:
  Synaptic scaling:scale all weights per synapse according to target firing rate
  Intrinsic plasticity: change the excitability of a synapse depending on postsynaptic firing (change the transfer function)
• Short term plasticity:
  The release of neurotrasmitter is influenced by the recent firing history of the presynaptic neuron, on timescale of ms to minutes. In this way the synaptic transmission of dynamic synapses encodes not only the spike but also the history of previous spikes. In computational terms short term plasticity has been shown to implement a temporal filter (high or low-pass / increase or decrease of neurotransmitter release as response to a spike)
• Structural plasticity:
  controversial, creation of new connections based on correlated firing patterns
• Metaplasticity:
  Experience can change the plasticity rules themselves (!), e.g. regulating the balance of excitation and inhibition by altering the threshold for LTD/LTP. However, confusion in the literature on categorization though, needs still research to clarify

Finally: Amazing experiment made famous by Erismann and Kohler in the 1950's demonstrating the adaptability of our brain: http://whatisupright.livejournal.com/

Matlab logfiles

function WriteLog(Data,cmd)
persistent FID

% Open the file
if nargin > 1
if strcmp(cmd, 'open')
date_now = clock;
date_now = strcat(num2str(date_now(1)),'_',num2str(date_now(2)),'_', num2str(date_now(3)));
FID = fopen(strcat('NCR_', date_now,'.log'), 'a');
if FID < 0
error('Cannot open file');
else
fprintf(FID, '%s\n', strcat(timestring,' openfile ---------------------------------------'));
end
return;
elseif strcmp(cmd, 'close') && FID ~= -1
fprintf(FID, '%s\n', strcat(timestring,' closefile---------------------------------------'));
fclose(FID);
FID = -1;
end
else
fprintf(FID, '%s\n', Data);
% also write to console
fprintf('%s\n', Data);
end



function s = timestring ( )
t = now;
c = datevec ( t );
s = datestr ( c, 0 );
end

Matlab axis at origin

Matlab cannot plot axis at origins apparently. There are 2 contributions at FEX, axescenter and centeraxes to consider. The first has the issue that its not possible to delete properly (without clearing the figure) the second is basically not working as documented.

Best workaround i found is plotting them manually (without ticks though)

plot(-pSTDP.delta:-1, postpre(end:-1:1),'-');
hold on
plot(1:pSTDP.delta, prepost,'-');
plot([-pSTDP.delta pSTDP.delta],[0 0], 'k:');
plot([0 0],[pSTDP.Aplus pSTDP.Aminus],'k:');
hold off
ylabel('synaptic change')
xlabel('dt')

Application 32 or 64 bit?

Under Windows 7 32 bit applications should be installed under 'Program Files (x86)' and 64 bit under 'Program Files'

How to determine if 64 or 32 bit, for a specific dll or exe file:
Use cygwin and file:

bwalth@gonzales4G /cygdrive/c/Program Files/MATLAB/R2010b/bin/win64
$ file MATLAB.exe
MATLAB.exe: PE32+ executable (GUI) x86-64, for MS Windows

alternativley look at processes in Task Manager 32 bit processes are marked *32

We learn ..

A popular quote that is easy to find online says “We learn… 10 percent of what we read, 20 percent of what we hear, 30 percent of what we see, 50 percent of what we see and hear, 70 percent of what we discuss with others, 80 percent of what we experience, and 95 percent of what we teach to someone.

Our minds have developed so that we remember the items that really make an imprint. Also, emotional events are very well remembered by us. You learn so much of what you teach to others because big pressure is on you at that time to not seem clueless while explaining the content. There is pressure on you here, since you would appear foolish if you offered to teach something and didn’t have the concept understood. You also learn a lot from what you experience because you do it on the spot, and have to correct errors during the process or it won’t work out. The pressure is on you there to continue through until you complete the procedure. You remember much of what you discuss with others because you have to have solid comprehension to be able to respond to others and their possible arguments or comments. This goes on for the other points. The more pressure there is on you to know the material, the higher the probability that it will be encoded into your cognition.