Richard D. Walter

The auditory evoked response in normal and autistic children during sleep

Abstract 1. 1. The auditory averaged evoked response (AER) was measured at the vertex in age-matched groups of normal and autistic children during Stage 2 and REM sleep and during the ocular quiescent and eye movement burst phases of REM sleep. Amplitudes and latencies of wave N2 of the auditory AER were compared during these different sleep stages. 2. 2. In a group of sixteen autistic children under 5 years 1 month old, the relative amplitude of wave N2 during REM sleep (relative to Stage 2 sleep) was significantly greater than in a group of sixteen normal children. 3. 3. In a group of seventeen autistic children under 61 months old, the relative amplitude of wave N2 during the eye movement bursts (relative to ocular quiescence) was greater than that measured in a group of eighteen normal children. 4. 4. In a group of ten normal children under 61 months old, there was no appreciable difference between amplitudes of wave N2 obtained during the ocular quiescent phase of REM sleep and Stage 2 sleep. In contrast, amplitudes of wave N2 obtained during the eye movement burst phase of REM sleep were significantly smaller than during Stage 2. 5. 5. A group of eleven autistic children showed significantly larger relative amplitudes of wave N2 during both the ocular quiescent and the eye movement burst phases of REM sleep (relative to Stage 2 sleep) than did the group of ten normal children. The relative reduction of response amplitude during the eye movement bursts in normals was markedly overridden in these autistic subjects. 6. 6. The finding that relative reduction of response amplitude during REM sleep in normals is confined to the eye movement burst phase was related to the concept of phasic inhibition distinct from tonic inhibition during REM sleep. The phasic inhibition has been shown to be mediated by vestibular nuclei. The overriding of phasic inhibition in the autistic children was related to clinical observations suggesting vestibular dysfunction and faulty registration of the significance of sensory input.

The variability of the auditory averaged evoked response during sleep and dreaming in children and adults

Abstract 1. 1. The auditory averaged evoked response (AER) was measured at the vertex in normal children and adults during Stage 2 and REM sleep. 2. 2. When time related effects were compensated, marked inter-individual variability in the amplitude of wave N 2 of the AER during REM in respect to Stage 2 sleep occurred. It was not possible to confirm earlier reports of consistent reduction of amplitude during REM sleep. 3. 3. In both children and adults, latencies were shorter during REM than during Stage 2, confirming earlier studies on adults. 4. 4. The latency of wave N 2 in the children was significantly shorter than in the adult group during Stage 2 while there was no corresponding difference during REM sleep. 5. 5. Another maturational difference in the auditory AER was the replacement of the adult positive-negative-positive wave complex preceding wave N 2 with a single positive deflection in the younger children. 6. 6. Within REMs, in all subjects over 19 months of age, the auditory AER was consistently smaller during the bursts of ocular activity than during ocular quiescence. This finding was related to the concept of a phasic inhibition distinct from tonic inhibitory effects and associated with the phasic excitation manifested by ocular activity during REMs. Inter-individual variability in relative amplitude of the auditory evoked response averaged over the entire REM stage may be due to the individual subjects balance between the phasic-excitatory, phasic-inhibitory and tonic-inhibitory components of the REM state.

Tactical Considerations Leading to Surgical Treatment of Limbic Epilepsy

Publisher Summary This chapter discusses tactical considerations leading to surgical treatment of limbic epilepsy. The clinician or clinical neurophysiologist involved in the evaluation of patients with limbic epilepsy for appropriate surgical treatment is confronted with a variety of decisions that relate to a successful outcome. These decisions can be looked upon as a tactical problem leading to the solution of the individual patients seizure disorder. The chapter describes the decisions involved in the evaluation of patients for possible surgical treatment. Olfactory or gustatory phenomena in the seizure history are particularly associated with structural lesions other than hippocampal sclerosis. Change in seizure patterns, the development of neurological signs, and the appearance of the traditional sign of increased intracranial pressure force the decision in the direction of surgical consideration. The most reliable and useful information is derived from the ictal recordings that can be technically facilitated using telemetry techniques. Information is obtained based on the interictal recordings, during clinical seizures, and in response to electrical stimulation of the depth sites.

The effect of sleep onset on the auditory averaged evoked response

1. 1. The auditory averaged evoked response (AER) was measured at the vertex in normal children and adults during the transition from wakefulness to sleep and throughout the night. 2. 2. The amplitude of wave N2 at sleep onset was compared to values obtained during subsequent non-REM sleep. 3. 3. The largest amplitude of wave N2 of the auditory AER occurred within 10 min of sleep onset regardless of state of consciousness. 4. 4. The influence of sleep onset per se on wave N2 amplitude was greater than the effect of stage of sleep.

The EEG and rapid eye movements during REM sleep in normal and autistic children

Abstract 1. 1. 10.5–15 c/sec EEG activity, synchronous slow wave EEG activity and eye movement activity during REM sleep were quantified in eight young autistic and six age-matched normal children. 2. 2. A significantly greater amount of 10.5–15 c/sec activity was found in the autistic children than in the normals. 3. 3. A significantly reduced number of single eye movements and percent time of eye movement burst activity was found in the autistic children as compared with the normals. 4. 4. Considerable synchronous slow wave activity was found in both groups of children. However, there was a strong quantitative association the eye movement bursts in the normals, while this association was reduced in the autistic children. 5. 5. It is postulated that the depressed eye movement burst activity in the autistic children is a manifestation of deficient or inhibited central vestibular function. The reduced quantitative association between the synchronous slow waves and the eye movement bursts further suggests impairment of an organizing influence underlying integration of cortical and oculomotor activity. 6. 6. These neurophysiologic abnormalities in the autistic children may be related to maturational factors as suggested by the persistence of 10.5–15 c/sec frequencies in the REM sleep EEG and the tendency to approach more normal values with increasing age.

Effects of imipramine on the sleep-dream cycle: an EEG study in boys.

Abstract The effect of imipramine on the sleep cycle in seven boys, aged 9–11, was studied by a single blind technique recording EEG and EOM. It was demonstrated that imipramine influences the sleep-dream cycle in the following manner: (1) the percentage of time spent in REM state sleep was decreased; (2) the percentage of time spent in Stage 2 sleep was increased; (3) a longer latency from the onset of sleep to the first REM epoch was produced. No difference was observed between the amounts of time spent in combined Stages 3–4 sleep or in the over-all length of time spent asleep in the laboratory.

Electrical activity of human limbic system during sleep

Abstract Visual analysis of 12 all-night depth recordings from two schizophrenic and six epileptic patients was compared to a previous study of chimpanzee sleep. Findings present in both human disease conditions and in normal chimpanzee include amygdaloid independence from cortical sleep staging, presence of a characteristic nonREM hippocampal waveform, and hippocampal preceding cortical flattening during arousal from stage 4 sleep. Some limbic sites in the human patients showed slow activity during REM and low voltage fast activity during stage 4. This last observation supports a sleep model which suggests that the differences in mental activity and in brain electrical activity during different sleep stages represent environmental surveillance by one portion of the brain during REM periods and by another during nonREM periods.

The auditory evoked response in babies during REM sleep.

Abstract 1. 1. The auditory averaged evoked response (AER) was measured at the vertex in twelve 6–12-month-old normal babies during Stage 2 and rapid eye movement (REM) sleep and during the ocular quiescent and eye movement burst phases of REM sleep. Amplitudes and latencies of wave N 2 of the auditory AER were compared during the different sleep stages and to previously reported values for normal and autistic children. 2. 2. The latencies of wave N 2 in the babies were similar to those of the normal children during Stage 2. However, latencies during REM sleep and during both the eye movement burst and ocular quiescent epochs of REM sleep were significantly longer in the babies. 3. 3. The babies showed a tendency toward greater amplitudes of wave N 2 during both the eye movement burst and ocular quiescent phases of REM sleep than during Stage 2 sleep. In the group of babies, the relative amplitudes of wave N 2 during both REM sleep and the eye movement bursts of REM sleep (relative to Stage 2 sleep) were significantly greater than in a group of normal children, but were similar to those of a group of young autistic children. 4. 4. These findings suggest that the normal phasic inhibition of evoked responses accompanying the ocular activity of REM sleep may not be present in the very young organism and that the development of phasic inhibition may be related to maturational factors underlying the post-natal reduction of REM sleep time.

The EEG and rapid eye movements during REM sleep in babies

Abstract EEG activity of 10.5 to 15.0 c/sec and eye movement activity during rapid eye movement (REM) sleep were quantified in six normal 6 to 8-month-old babies. The values in the babies were compared to perviously reported values for normal and autistic children. The amount of 10.5 to 15.0 c/sec activity was significantly greater in the babies than in the normal children but was similar to that of the autistic children. The mean duration of eye movement bursts was significantly shorter in the babies than in the normal children but was similar to that in the autistic children. The mean duration of eye movement bursts in the babies increased linearly with successive REM sleep periods.

Amnestic Confusional Phenomena, Hippocampal Stimulation, and Laterality Factors

The association between hippocampal function and phenomena of consciousness is usually indirectly inferred, i.e., through clinicopathological observations, in contrast to direct laboratory observations, of the involvement of limbic structures in seizures and seizure related disorders of consciousness in man. Equally, the association between hippocampal functions and memory is usually inferred through observations of memory impairment in man with hippocampal damage (Grunthal, 1947; Glees and Griffith, 1952). However, direct or experimental evidence of these associations is, understandably, rare in man. Only through the utilization of opportunities provided by legitimate diagnostic or therapeutic procedures, such as depth implantation for electrical recording and stimulation of epileptic patients with uncontrollable seizures considered for neurosurgery, can such evidence be obtained (Penfield and Jasper, 1954; Bickford et al., 1958). The following chapter deals first with background data relevant to the quest, then presents direct evidence of the experimental type mentioned above and finally discusses the implications of the evidence for cerebral lateralization and clinical syndromes of the literature.