?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Dynamics+of+event-related+potentials+to+trains+of+light+and+dark+flashes%3A+responses+to+missing+and+extra+stimuli+in+elasmobranch+fish.&rft.creator=Karam%C3%BCrsel%2C+Sacit&rft.creator=Bullock%2C+T.H.&rft.subject=Neurochemistry&rft.subject=Neurophysiology&rft.subject=Neurophysiology&rft.subject=Neuropsychology&rft.subject=Neuropsychiatry&rft.description=To+characterize+the+dependencies+of+ERPs+in+lower+vertebrates+and+brain+levels+upon+recent+history+and+sequences+of+stimuli%2C+trains+of+flashes+were+delivered+at+various+frequencies+to+unanesthetized+rays+while+recording+in+optic+tectum+and+telencephalon.+ERPs+to+repetitive+stimuli+cannot+be+understood+in+terms+of+simple+refractoriness+and+recovery.+Processes+must+be+invoked+such+as+simultaneous+excitation+and+suppression%2C+facilitation+and+its+opposite%2C+rebound+and+induced+rhythms%2C+each+with+development+and+decay+times+and+nonlinearities.+Some+of+these+processes+are+uncovered+by+omitting+a+stimulus+from+a+train.+Omitted+stimulus+potentials+(OSPs)+act+as+though+the+brain+expects+a+stimulus+within+5-7+ms+of+the+interstimulus+interval+(ISI)+of+the+train.+Very+few+ISIs+suffice.+The+effect+upon+VEP+form+and+duration+of+the+number+of+stimuli+in+short+trains%2C+before+the+steady+state+response+(SSR)+is+established%2C+is+complex.+Alternation+of+the+amplitude+of+successive+VEPs+(1+large+every+2+VEPs%2C+1+in+3%2C+1+in+4)+is+one+indication+of+complexities+in+the+SSR.+OSPs+also+alternate.+A+single+extra+stimulus+interpolated+into+a+regular+train+causes+distinct+effects+according+to+its+position.+Sharp+discontinuities+in+these+effects+appear+with+%3C5+ms+shifts.+Total+power+of+the+SSR+decreases+with+stimulation+frequency+but+there+is+a+large+peak+of+increased+power+at+7+Hz+and+another+at+12+Hz.+Induced+rhythms+are+a+labile%2C+late+phase+of+OSPs+as+well+as+of+rested+VEPs+and+of+the+OFF+response+to+a+long+light+pulse.+Jittered+ISI+experiments+show+that+the+apparent+expectation+of+the+OSP+is+little+affected+and+that+the+intervals+in+the+last+few+hundred+milliseconds+are+most+influential.+The+OSP+studied+here+(ISI+%3C0.5+s)is+quite+different+from+that+so+far+studied+in+human+subjects+(ISI+%3E1s).+We+predict+further+similarities+when+each+taxon+is+tested+in+the+other+ISI+range.+A+major+category+of+response+characteristics%2C+besides+sensitivity%2C+receptive+fields+and+recovery+times%2C+is+dependence+upon+recent+history+of+iterative+events%2C+including+intervals%2C+delays%2C+omissions+and+perhaps+multiple+facilitating+and+forgetting+time+constants.+The+variables+examined+parametrically+in+this+study+are+only+some+of+those+available.+Such+dynamical+characteristics+are+important+neglected+properties+of+afferent+systems+at+each+level.&rft.date=1994&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=text%2Fhtml&rft.identifier=http%3A%2F%2Fcogprints.org%2F124%2F1%2Fdynamic_elasfish.htm&rft.identifier=++Karam%C3%BCrsel%2C+Sacit+and+Bullock%2C+T.H.++(1994)+Dynamics+of+event-related+potentials+to+trains+of+light+and+dark+flashes%3A+responses+to+missing+and+extra+stimuli+in+elasmobranch+fish.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F124%2F