Central slowing of auditory brainstem responses (ABRs) and excessive breathing irregularity on pneumogram recordings indicate dysfunction in central auditory pathways and brainstem respiratory control mechanisms, respectively. These centers are anatomically proximate within the brainstem so that ABR slowing and respiratory instability might be expected to occur concomitantly, reflecting overall dysfunction of this part of the central nervous system. To examine the relationship between these two assessments, testing results were compared for 15 infants in the intensive care nursery who had ABRs and 12-hour pneumograms performed at about the same age for separate clinical indications. Wave V latency at 70 dB was found to correlate significantly with three pneumogram measurements of breathing irregularity: the density of short apneas during sleep (p less than 0.01), the number of episodes of periodic breathing per 100 minutes of sleep (p less than 0.05), and the percentage of sleep time spent in periodic breathing (p less than 0.05). Interwave interval I-V correlated significantly with the density of short apneas during sleep (p less than 0.01). The auditory brainstem response and the pneumogram appeared to serve as related indicators of brainstem function in these infants.
The identification of evoked scalp potentials in man to a single acoustic stimulus such as a word becomes possible by combining several techniques. Either multiple EEG derivations from one subject or single derivations from several subjects, can be summed algebraically to yield a tracing with a significant increase (by a factor of 2 or more) in the size of the response relative to the background. A specific template has been found which, when cross correlated with the EEG, yields 2 dimensional (correlation and time) description of when the response occurs.
TO i n v e s t i g a t e e l e c t r o l y t e s and glucose homeostasis i n asphyxia and PV-IVH, Na, K , C1 and glucose were measured i n CSF and blood of 1 4 newborns who had simultaneous lumbar and venipunctures a t a mean age of 26 hours. Glucose was determined by glucose-oxldase method, Na and K by ion s e l e c t i v e e l e c t r o d e and CL by coulometric-amperometric method. Cranlal ultrasounds were done within 48-72 hours a f t e r b i r t h .Babies w~t h PV-IVH had s i g n i f i c a n t l y lower CSF Na and C 1 than those with no PV-IVH ( s e e t a b l e ) . There were no s i g n i f icant d i f f e r e n c e s i n CSF glucose and serum Na, C1, and glucose between babies with and without PV-IVH. W e conclude t h a t PV-IVH s i g n i f i c a n t l y lowers Na and CI i n CSF while asphyxia does not.
OhioCerebral blood flow (CBF) and cerebral metabolic r a t e of oxygen (CMRO ) were measured during normocarbia and both moderate and severe hjpocarbia i n 8 newborn mongrel dogs 1 t o 7 days of age. The animals were paralyzed with pancuronium and v e n t i l a t e d wlth 70% N 0 and 30% 0 The r e s p i r a t o r was adjusted t o achieve a paCO of215 t o r r , al?'subsequent changes t o 25 and 40 t o r r were made b j bleeding CO i n t o t h e system. The sequence of paC02 l e v e l s were randmiged. CBF was measured by microsphere technique and CMRO c a l c u l a t e d a s a r t e r i a l -s a g i t t a l s i n u s O2 content di fference2times hemispheric blood flow. A1 1 measurements were made a f t e r 30 minutes a t each paC02. 40 t o r r 25 t o r r 15 t o r r
The purpose is to study diffuse EEG responses relative to both the acoustic and informational content of verbal stimuli. Averaging of the EEG is not desirable because the information within a word varies with each individual setting. Two methods are used to replace averaging and enhance the detection of the signal in noise. One is to algebraically sum the EEG patterns simultaneously derived from four or more subjects. This, incidentally, improves the control of the interexperimental variation between subjects. The other is to detect the response by cross correlation of the EEG pattern with a template. The template is described by 6 parameters and represents an analog of the expected diffuse cerebral response. The cross-correlation calculations for a response to a single word result in a correlogram displaying both a maximal value and its time of occurrence. Under our experimental conditions, the characteristics of the sound stimulus are reflected in the time of occurrence of the maximal cross correlation and not in its amplitude.
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