Post by dantam on Feb 9, 2011 19:52:13 GMT -5
Good evening,
There are certain notions on which I'm still unsure. I'd very much appreciate some clarifications.
1. First of all, in chemical messengers, I understand that Ca++ is involved in the release of neurotransmitters into the synapse.
But then, later on, it is said that "if the ion channel allows positive ions (Na+ or Ca++) to enter, the inflow of positive current leads to excitation." But Ca++ was never mentioned in the chapter about action potentials.
Is it right to say that Ca++ also plays a role in action potentials?
2. Secondly, brain imaging.
a) Electrophysiological techniques are briefly mentioned, but not greatly explained. Does it have anything to do with EEG? Or is it a type of brain scanning?
b) During a fMRI scan, why is the subject presented with two stimuli, if the researcher is only interested in the first one? Is the second stimuli or task used as a reference point? Or is the whole expirement to see the interaction between regions of the brain...? Why subtract?
c) What is a diffusion tensor imaging (DTI)? How does it work to obtain such detailed images? Since it was not explained in the document, I suppose I don't need to know more. But I'm just curious.
3. In the Artificial neural networks chapter, I sort of understand how a feedforward associator works, but then it is said "See Mathematical Puzzle Box". That's where they lose me. I don't understand how it works, and that is supposed to explain how a feedforward associator functions. But if so, then I probably misunderstood the feedforward associator.
4. And finally, is it possible to have some sample questions to practise with? It would help see the degree of precision that is asked of us.
Thank you in advance,
D-T
There are certain notions on which I'm still unsure. I'd very much appreciate some clarifications.
1. First of all, in chemical messengers, I understand that Ca++ is involved in the release of neurotransmitters into the synapse.
But then, later on, it is said that "if the ion channel allows positive ions (Na+ or Ca++) to enter, the inflow of positive current leads to excitation." But Ca++ was never mentioned in the chapter about action potentials.
Is it right to say that Ca++ also plays a role in action potentials?
2. Secondly, brain imaging.
a) Electrophysiological techniques are briefly mentioned, but not greatly explained. Does it have anything to do with EEG? Or is it a type of brain scanning?
b) During a fMRI scan, why is the subject presented with two stimuli, if the researcher is only interested in the first one? Is the second stimuli or task used as a reference point? Or is the whole expirement to see the interaction between regions of the brain...? Why subtract?
c) What is a diffusion tensor imaging (DTI)? How does it work to obtain such detailed images? Since it was not explained in the document, I suppose I don't need to know more. But I'm just curious.
3. In the Artificial neural networks chapter, I sort of understand how a feedforward associator works, but then it is said "See Mathematical Puzzle Box". That's where they lose me. I don't understand how it works, and that is supposed to explain how a feedforward associator functions. But if so, then I probably misunderstood the feedforward associator.
4. And finally, is it possible to have some sample questions to practise with? It would help see the degree of precision that is asked of us.
Thank you in advance,
D-T