Somatic responses in behavioral inhibition

In the present study, skin conductance responses (SCRs) were measured postdecision and prefeedback in a go/no-go (GNG) task in which participants used response feedback to learn when to respond or not to respond to numeric stimuli. Like somatic markers in gambling tasks and somatic reactions to error monitoring in choice reaction time tasks, SCR patterns distinguished between correct and incorrect trials over time. These somatic reactions were disrupted by a reversal of GNG contingencies, and they were facilitated by pretraining of the stimulus—response mappings. In all cases, however, the somatic reactions appeared to be a product of competent decision making rather than a contributor to performance. Differential somatic responses to good and bad choices appear to be a robust and fairly general phenomenon, but researchers should be cautious in assuming that the somatic responses contribute to performance.     

Effect of behavioral inhibition on interactions in mixed-sex dyads

The present studies assessed the effect of behavioral inhibition on interactions of college students in mixed-sex groups. In Study 1, 20 participants were arranged into two dyadic groups based on self-rated measures of approach/withdrawal behavior. These dyads (inhibited men/uninhibited women; inhibited women/uninhibited men) were videotaped during an unstructured 5-min. interaction in a laboratory. Time series analysis indicated greater behavioral covariation in the inhibited men/uninhibited women dyads and less behavioral covariation in the inhibited women/uninhibited men dyads. Additional analyses indicated a relationship between inhibition and comfort experienced during the interaction. Inhibited participants, particularly women, reported feeling uncomfortable while interacting with an uninhibited male partner. A second study corroborated the findings reported in Study 1 and also noted elevated heart rate in the inhibited women. This increased discomfort in women appeared to be related to heightened self-consciousness during the interaction.     

Age-dependent changes in olfactory-mediated behavioral investigations in the male rat.

In the present experiment male Sprague-Dawley rats at three different ages (young, middle-aged, and old) were tested in a series of olfactory-mediated behavioral tests. The amount of ano-genital investigation directed to receptive females by old rats was significantly reduced compared to that of young and middle-aged animals. In contrast, general body investigation of receptive females was similar among the three age groups. The amount of anogenital investigation directed to nonreceptive females or immature male rats indicated significant differences only between young and old rats, with values from middle-aged rats being intermediate and not significantly different from either of the two extreme groups. General body investigation of nonreceptive females and immature males did not differ among the three age groups. Old rats showed the best performance in a location of buried food test with latencies to locate food approximately one-half that obtained from young and middle-aged rats. Measures of general locomotor activity indicated significantly greater values from young compared to middle-aged and old rats, with the latter two showing very similar levels. These results demonstrate clear discriminatory differences in olfactory-mediated behavioral performance of the male rat as a function of the specific test and age of the animal. Overall, the results suggest that olfactory-mediated behaviors related to reproduction appear more sensitive to age-related declines, while behavior related to food procurement is more minimally affected.     

Stress or no stress: mineralocorticoid receptors in the forebrain regulate behavioral adaptation

Corticosteroid effects on cognitive abilities during behavioral adaptation to stress are mediated by two types of receptors. While the glucocorticoid receptor (GR) is mainly involved in the consolidation of memory, the mineralocorticoid receptor (MR) mediates appraisal and initial responses to novelty. Recent findings in humans and mice suggest that under stress, the MR might be involved in the use of different learning strategies. Here, we used male mice lacking the MR in the forebrain (MR(CaMKCre)), which were subjected to 5-10 min acute restraint stress, followed 30 min later by training trials on the circular hole board. Mice had to locate an exit hole using extra- and intra-maze cues. We assessed performance and the use of spatial and stimulus-response strategies. Non-stressed MR(CaMKCre) mice showed delayed learning as compared to control littermates. Prior stress impaired performance in controls, but did not further deteriorate learning in MR(CaMKCre) mice. When stressed, 20-30% of both MR(CaMKCre) and control mice switched from a spatial to a stimulus-response strategy, which rescued performance in MR(CaMKCre) mice. Furthermore, MR(CaMKCre) mice showed increased GR mRNA expression in all CA areas of the hippocampus and an altered basal and stress-induced corticosterone secretion, which supports their role in the modulation of neuroendocrine activity. In conclusion, our data provide evidence for the critical role of MR in the fast formation of spatial memory. In the absence of forebrain MR spatial learning performance was under basal circumstances impaired, while after stress further deterioration of performance was rescued by switching behavior increasingly to a stimulus-response strategy.     

Cortical neuroanatomical correlates of behavioral deficits produced by lesion of the basal forebrain in rats

Morphological changes in the frontoparietal cortex were assessed in rats that exhibited deficits in a go/no go alternation task due to electrolytic lesion of the basal forebrain. Cortical area, laminar thickness, neuronal density, and soma area were examined in frontal, hindlimb, forelimb, and parietal areas of the cortex. Quantitative morphological analysis of the frontoparietal cortex in lesioned rats revealed a decrease in laminar thickness due to reduced soma size in particular cortical laminae. Neuronal density was not affected. These effects were present in all cortical areas examined and most pronounced in laminae II-III. Similar morphological changes were observed in the same cortical areas following lesions of the basal forebrain made with ibotenic acid, allowing a discrimination of lesion effects from those induced by damage to fibers of passage or differential behavioral testing. Lesions of the basal forebrain have previously been shown to produce both behavioral deficits and changes in cortical cholinergic activity. The cortical morphological changes observed in the present study following basal forebrain lesion provide further evidence for the importance of ascending cholinergic inputs to the cortex and their role in learning and memory.     

Effects of desalivation on schedule-induced polydipsia in the rat.

The development and magnitude of schedule-induced polydipisa (SIP) were examined in desalivate and control rats in two experiments. In Experiment 1 animals were placed on a noncontingent fixed time (FT) 60-sec schedule for 24 days. Results indicate speeded development but asymptotically lower levels of SIP in desalivate rats compared to controls. Home cage consumption, however, was elevated in desalivate rats. In Experiment 2 schedule length, pellet size, and the percentage of body weight were manipulated. Desalivate rats consumed less fluid during each schedule condition relative to controls, but the pattern of results across schedules was similar to controls. It was concluded that (a) desalivation attenuates SIP; (b) SIP is a learned phenomenon; (c) dry mouth theories of SIP appear inadequate; and (d) the developmental aspect of the SIP phenomenon deserves additional research attention.     

Motivational processes and behavioral inhibition in breath holding

Large individual differences in breathing performance have made it difficult to investigate the effects of psychological variables on respiratory parameters. This study uses an experimental approach to investigating the effects of attentional and motivational factors on breath-holding span in humans. The effects of shock threat (negative incentive), monetary reward (positive incentive), and mantra meditation (attentional control) on breath-holding span at functional residual capacity (FRC) were compared. Based on Jeffrey Gray's (1975, 1987) theory of behavioral inhibition, it was predicted that shock threat would extend FRC breath holding. Breath holding was increased under the shock threat condition but not under the monetary reward or mantra meditation conditions.     

Biological and caregiver correlates of behavioral inhibition

The aim of this study was to explore the relationships among measures of behavioral inhibition, physiological reactivity, and caregiver attitudes. Measures comprised of heart rate; survey assessments of caregiver empathy with the child, appropriateness of caregiver developmental expectations of the child, and use of positive discipline techniques; and observational measures of behavioral inhibition were gathered in a laboratory setting on 72, 5–6‐year old children. It was found that heart rate and behavioral inhibition were positively correlated (0.595), whereas behavioral inhibition was negatively correlated with caregiver attitudes of empathy (?0.356), appropriate expectations (?0.366), and use of positive discipline techniques (?0.275). However, there was no correlation between heart rate and caregiver attitudes. These data suggest that physiological reactivity to novel stimuli and caregiver attitudes of empathy, appropriate expectations, and use of positive discipline techniques conjointly influence behavioral inhibition in early childhood. Further, these three caregiver variables accounted for significant variance in children who had high reactive physiological profiles associated with inhibited behavior patterns, but did not display such patterns. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of total sleep loss on sleep tendency.

Effects of two nights of sleep loss were assessed in six young adult (18--21 yr.) volunteers (2 women, 4 men). Performance on the Wilkinson Addition Test fell significantly below baseline values during the sleep-loss procedure and recovered after one or two full nights of sleep. Performance on a Serial Alternation Task also declined during sleep loss. Mood and sleepiness, assessed by subjective self-rating scales, showed a significantly less positive mood and a greater degree of sleepiness during sleep loss, with a recovery to baseline levels after one full night of sleep. Sleep tendency, measured at 2-hr. intervals during all waking periods, was assessed using an objective measure of latency to sleep onset, the Sleep Latency Test. The scores fell to about 1 min. at 0600 on the first night of sleep loss and remained at similarly low values throughout the sleep loss period. After one night of recovery sleep the scores remained significantly below baseline levels, which were not achieved until after the second recovery night. The multiple sleep latency test appears to be a valuable operationally defined tool for measuring daytime sleepiness.     

Positive and negative behavioral contrast in the rat

Three groups of rats received either 8, 23, or 53 sessions of multiple variable-interval variable-interval baseline training before being shifted to a multiple extinction variable-interval schedule. The rate of responding during the unaltered component was higher for the groups shifted to multiple extinction variable-interval than for control groups remaining on multiple variable-interval variable-interval (positive contrast). Furthermore, when the multiple variable-interval variable-interval schedule was re-instated, stable negative contrast was found in the groups that had received 23 or 53 baseline sessions, but not for the group that had received only eight sessions. Positive and negative contrast were also demonstrated in the eight and 23-session groups when the multiple extinction variable-interval and multiple variable-interval variable-interval schedules were re-administered in further phases of the experiment. These results suggest that both positive and negative behavioral contrast can be obtained reliably in a species other than the pigeon.     

Acetylcholine activity in selective striatal regions supports behavioral flexibility

Daily living often requires individuals to flexibly respond to new circumstances. There is considerable evidence that the striatum is part of a larger neural network that supports flexible adaptations. Cholinergic interneurons are situated to strongly influence striatal output patterns which may enable flexible adaptations. The present experiments investigated whether acetylcholine actions in different striatal regions support behavioral flexibility by measuring acetylcholine efflux during place reversal learning. Acetylcholine efflux selectively increased in the dorsomedial striatum, but not dorsolateral or ventromedial striatum during place reversal learning. In order to modulate the M2-class of autoreceptors, administration of oxotremorine sesquifumurate (100 nM) into the dorsomedial striatum, concomitantly impaired reversal learning and an increase in acetylcholine output. These effects were reversed by the m(2) muscarinic receptor antagonist, AF-DX-116 (20 nM). The effects of oxotremorine sesquifumurate and AF-DX-116 on acetylcholine efflux were selective to behaviorally-induced changes as neither treatment affected acetylcholine output in a resting condition. In contrast to reversal learning, acetylcholine efflux in the dorsomedial striatum did not change during place acquisition. The results reveal an essential role for cholinergic activity and define its locus of control to the dorsomedial striatum in cognitive flexibility.     

Effects of COMT genotype on behavioral symptomatology in the 22q11.2 Deletion Syndrome.

The 22q11.2 Deletion Syndrome (DiGeorge/velocardiofacial syndrome) is associated with elevated rates of psychosis, and is also characterized by severe attentional difficulties and executive dysfunction. Behavioral manifestations of this syndrome could result from haploinsufficiency of the catechol-O-methyltransferase (COMT) gene, located within the 22q11 region. The goal of the present study was to examine COMT genotype in relation to behavioral symptomatology in this syndrome. Val158/108Met was genotyped in 38 patients (16 Met/-, 22 Val/-) with confirmed 22q11.2 deletions who had received the Child Behavior Checklist (CBCL) as part of a comprehensive evaluation. Results indicated that the Val genotype was associated with significantly greater internalizing and externalizing behavioral symptomatology in children with 22q11.2 deletions. Val allele status was associated with a greater-than-four-fold increase in risk for clinically significant behavior problems in children with this syndrome. These data are consistent with previous findings of increased psychopathology associated with the Val genotype in normal individuals and suggest that a functional genetic polymorphism in the 22q11 region may influence behavior in individuals with COMT haploinsufficiency.