Hemispheric Asymmetry and Regional Differences in Electroencephalographic Alpha Activity at the Wake-Sleep Transition

Electroencephalographic (EEG) alpha activity at the wake-sleep transition was studied in six right-handed adults in terms of hemispheric asymmetry and regional differences. Twelve-channel EEGs with linked mastoid references were recorded together with horizontal and vertical electro-oculograms (EOGs). Two types of alpha coefficient were obtained every 5.12 s by computing the relative proportion of right vs. left alpha band power and of anterior vs. posterior alpha band power. Four stages were scored using EEG sleep patterns (theta waves, vertex sharp waves, spindles, and K complex) and slow eye movement (SEM): stage W had neither EEG sleep patterns nor SEM; stage D1 had SEM and no EEG sleep patterns; stage D2 had theta waves or vertex sharp waves and SEM; stage S had spindles or K complex without SEM. It was found that the two types of alpha coefficient changed as a function of EEG-EOG stage and were correlated. Right-decreased and anterior-shifted alpha activities were manifest at stages D2 and S. Drowsiness was considered to be a heterogeneous state, exhibiting different spatial changes in alpha activity between stages D1 and D2.     

Some types of clustering with relational constraints

For the clustering problem with general (not necessarily symmetric) relational constraints, different sets of feasible clusterings, also called clustering types, determined by the same relation, can be defined. In this paper some clustering types are discussed and adaptations of the hierarchical clustering method compatible with these clustering types are proposed.     

Note on ultrametric hierarchical clustering algorithms

Milligan presented the conditions that are required for a hierarchical clustering strategy to be monotonic, based on a formula by Lance and Williams. In the present paper, the statement of the conditions is improved and shown to provide necessary and sufficient conditions.This work was supported in part by the Boris Kidri Fund, Yugoslavia.     

Attention and memory cues in concept learning as a function of task complexity and age

The effects of attention and memory cues on concept learning performance were investigated as a function of task complexity and grade level of Ss. It was found that: (1) the attention and memory cues were closely interrelated in their effects upon performance with both significantly improving performance at all but the lowest levels of complexity; (2) both types of cues considerably lessened the effect of stimulus complexity upon performance; and (3) the attention cue elicited the best performance from Ss in the first through ninth grades, while the memory cue elicited the best performance from 4-year-old and kindergarten Ss.     

Spatial ecology: Its effects on the choice of friends and enemies

The present research examined relationships between physical distance, frequency of face-to-face contacts, and the probability that individuals would be chosen as friends or enemies. Consistent with previous research, the probability of being chosen as a friend increased as the distance between people decreased. There was also a positive linear relationship between the frequency of contact and the strength of linking. In contrast, the probability of being chosen as a disliked individual was even more dependent upon physical distance (more disliked than liked individuals lived close to the subjects), but the strength of disliking was unrelated to the frequency of face-to-face contact. Friends also tended to live farther away from the subjects the longer the latter had lived in their residences, but the distance that disliked individuals lived from the subjects did not depend upon time. The overall pattern of results was consistent with an “environment-spoiling” hypothesis which proposed that many negative interpersonal relationships primarily occur because the actions of specific others spoil one's living environment, whereas most positive interpersonal relationships result from frequent face-to-face contacts.     

Arousal,positive and negative affect,and preference for Renaissance and 20th-century paintings

Treatments expected to raise the level of arousal and induce different degrees of positive and negative affect were paired on some trials with Renaissance or 20th-century paintings, whereas no paintings were shown on other trials. The design was within-subjects (24 females); the dependent measures were skin conductance (SC) and the preference for paintings. All treatments, including the paintings/no paintings factor, raised SC over the base-line, and the pattern was essentially additive. The perceived failure to attain control over aversive auditory stimulation (resulting in negative affect) raised SC to a higher level than did the unavoidable aversive stimulation (minimal affect) or monetary gains (positive affect). Paintings paired with affect (positiveor negative) were rated as more pleasing than were those paired with no affect. The Renaissance works were preferred to the 20th-century works when negative affect was induced, whereas the opposite was true in the case of positive affect. The collative-motivation model could not account for the fact that pleasingness of paintings was not related to SC by an inverted-U function. The contiguity model could not explain the considerable rated pleasingness of paintings paired with negative affect. In contrast, there was considerable support for a more comprehensive hypothesis (distraction/soothingness) based on attentional and affective considerations, and the differential cognitive labeling of fluctuations of arousal.This research was supported by Grant GS-42802 from the National Science Foundation to VJK. Some of the findings were presented at the 6th International Colloquium of Empirical Aesthetics, and the 21st International Congress of Psychology, both held during July 1976 in Paris, France.     

Evaluative and skin-conductance responses to Renaissance and 20th-century paintings

Normative data on paintings from two periods are reported. Subjects rated the pleasingness and interestingness of 60 Renaissance and 60 20th-century (abstract) works, and indicated how much they wished to own a reproduction of each painting. Skin-conductance changes elicited by the paintings were also assessed. The data may facilitate the inclusion of real works of art in future experiments involving visual aesthetic materials (on either the independent- or the dependent-variable side) and are relevant for the research on some motivational and cognitive issues of current interest in the psychology of art.     

ERPs and contextual semantic discrimination: degrees of congruence in wakefulness and sleep

This study explores whether the brain can discriminate degrees of semantic congruency during wakefulness and sleep. Experiment 1 was conducted during wakefulness to test degrees of congruency by means of N400 amplitude. In Experiment 2, the same paradigm was applied to a different group of participants during natural night sleep. Stimuli were 108 sentences (definitions with two attributes) with four possible degrees of congruence as ending targets. In both studies, the amplitude of N400-like effect showed modulation according to the degree of congruency. The results indicate that the brain can accomplish sentential semantic discriminations not only in wakefulness but also in sleep.     

Chemical plasticity of visual cortical neurons in integrative organization of feeding behavior in cats

The P.K. Anokhin conception of organization of systemic behavior was used to study the discharge activity and chemical plasticity of cortical neurons in a goal-directed behavior. Chemical sensitivity of neurons in the visual cortex of instrumentally conditioned cats was studied during successive stages of food procuring and consuming. The results showed that definite stages of this integrated behavioral act are characterized by differences in the chemical sensitivity of visual neurons to neurotransmitters. The largest number of neurons resistant to neurotransmitters was found among cells that did not respond at successive stages of goal-directed behavior. The iontophoretic delivery of cycloheximide and lyzilvasopressine altered the discharge activity of individual cortical neurons at different stages of stereotyped instrumental conditioned acts. This suggests that the integrative organization of the feeding behavior is determined by chemical plasticity of the brain’s visual cortical neurons and is dependent upon the processes of protein synthesis. According to the functional system theory (Anokhin, 1974) each brain neuron is included, by various degrees of freedom, in the stages of systemic organization that underlie the goal-directed behavior. Thanks to the plastic reorganization of brain units, each stage is directed toward the achievement of useful adaptive results for the organism during interaction with different environmental factors (Adrianov, 1993; Fadeev, 1988). It may be proposed that the reorganization of discharges of brain neurons that occurs at different stages of activity is due to changes in their chemical capacities. In concordance with such a hypothesis, the purpose of the present investigation was to study the chemical sensitivity of single visual cortical neurons to neurotransmitters at different stages of systemic organization of feeding behavior. The influence of protein synthesis inhibitors on the sensitivity of cortical neurons was also investigated.