ATTENTION, CONSCIOUSNESS, SLEEP AND WAKEFULNESS 



the point of view that there is a vertical stratification 

 of consciousness ranging from near zero in the new- 

 born baby asleep (or an adult in deep dreamless 

 sleep) to an alert attentive adult after two cups of 

 coffee. Lindsley in the 1950 volume and Monnier in 

 the 1952 volume also stress the fact that consciousness 

 is a matter of degree and level of complexity of 

 perceptual discrimination. The newborn infant with 

 a relatively nonfunctional cortex or the anencephalic 

 monster without the cortex are rather alike in being 

 essentially brain-stem creatures in whom reflexes and 

 arousal responses exist, but very little differentiation 

 of discrimination and response. Discrimination if 

 present is at its lowest ebb, and attention, except for 

 the crudest form of orienting reflex, is literally absent. 

 As Lindsley (160) has indicated: "Although a new- 

 born or young infant may show reaction to stimula- 

 tion it is undifferentiated and not at all selective. 

 Sensory discrimination, if present at all, is most 

 elemental), and in this sense one must conceive of 

 consciousness as being very restricted." The onset of 

 the occipital alpha rhythm in the young human infant 

 (see fig. 9) at 3 or 4 months of age appears to be 

 correlated with the first consistent behavioral mani- 

 festations of integrated attention. Docs the absence of 

 persistent alpha rhythms in sensory /ones prior to 

 that indicate a lack of awareness and consciousness 

 in the field of these sense modalities? It probably docs 

 so far as perceptual discrimination and integration 

 are concerned. As we observed earlier, the return of 

 alpha waves signifies the emergence from sleep and 

 also the onset of awareness or consciousness of the 

 environment which can only be discriminated as this 

 stage of the EEG develops. There is a correspondence 

 in the development and maturation of the structure 

 and function (EEG) of the brain and the perceptually 

 oriented behavior it manifests. 



Consciousness and EEG Characteristics 



Let us turn now to the EEG in relation to some 

 reversible changes of consciousness. Gibbs et al. (90) 

 were among the early workers to study the EEG 

 changes in epilepsy and conditions of impaired 

 consciousness. Davis & Davis (52) surveyed this 

 topic in a very thorough fashion in 1939, and very 

 little can be added except in respect to interpretation 

 in terms of recent neurophysiological concepts. With 

 regard to determining the state of consciousness and 

 its electrical correlates in the early stages of sleep, 

 they draw upon the description of experiments con- 

 ducted by Davis et al. (53). "The subject lies down to 



sleep with a rubber bulb in one hand, and is instructed 

 to squeeze it once whenever he feels that he has 

 just 'drifted or floated off for a moment and twice if 

 he feels that he has awakened from 'real sleep.'. . . 

 The accuracy of the signalling is remarkable, con- 

 sidering how unfavorable drowsiness is for intro- 

 spection and signalling. . . . The common denomina- 

 tor in the subjective reports of the experience of 

 'floating" is a depression of sensory perception. Some 

 identify the state by suddenly realizing that they 

 have ceased to hear noises or that they have lost 

 their awareness of the bed clothes or the position of 

 their body. Others stress the appearance of visual 

 phantasies or interruptions in the train of logical 

 thought, but in all cases there is loss of awareness, 

 particularly of immediate external stimuli. This 

 transient clouding of consciousness appears to be correlated 

 with definiU objectivt <i/tti:iiit>n> m i ; it activity 



at the brain." The 'floating or drifting off experiences 

 occur in the B stage when alpha waves are greatly 

 diminished or absent lor 5 see. or more. As these 

 experiences become more persistent and longer last- 

 ing, low-voltage delta waves appear and merge into 

 the C Stage ol real sleep with spindle bursts of 14- 

 pei -sec. w .iv es. 



induced physiologii vi. changes. I he breathing of 

 an 8 per cent oxygen mixture was carried out in 



three subjects to the point of unconsciousness by 

 Davis et at. i",4>, with EEG and handwriting as 

 indicators of change of state of consciousness. After 



4 iniii. of low oxygen a subject reported "'fullness in 

 the head, ringing in the ears and a desir [sic] to breathe 

 more deeply." Alter 17 min. he felt "fuzzy," dizzy 

 and experienced a spell of remoteness. His writing 

 deteriorated in quality and composition and finallv 

 stopped entirely (hand "froze"'). In each of the three 

 subjects with the onset of unconsciousness large slow 

 waves became persistent in a 'locked' pattern. 

 Although none realized they had lost consciousness, 

 they were unaware when the mouthpiece of the 

 breathing apparatus had been removed. The slow 

 waves became 'unlocked' after breathing room air for 



5 sec. and after 5 sec. more the subject was able to 

 write in a distorted fashion. At this point slow waves 

 were receding. After 2 min. on room air all slow waves 

 had disappeared and the record showed low-voltage 

 fast activity, and not until 4 min. or more did alpha 

 waves and control picture return. Thus we see that 

 the deterioration of consciousness and writing be- 

 havior began with the loss of alpha waves, but uncon- 

 sciousness did not become complete, nor behavior 



