Hypnotisability-related interoceptive awareness and inhibitory/activating emotional traits.

Emotions are influenced by several individual factors. Hypnotizability - a psychophysiological trait associated with morpho-functional cerebral and cerebellar variations able to sustain differences in interoception and emotion - could be one of them. The aims of the study were to find out possible differences in Interoceptive Awareness (IA) and in the emotional traits sustained by the Behavioral Inhibition/Activation System (BIS/BAS) in participants with high (highs), medium (mediums) and low (lows) hypnotizability and to investigate the association of interoceptive awareness and BIS/BAS related emotional traits as a function of hypnotizability. Thus, IA and BIS/BAS were studied in 284 subjects of both genders by the Multidimensional Assessment of Interoceptive Awareness (MAIA) and by BIS/BAS scales, respectively. Significantly lower BIS scores (lower inhibitory control/conflict monitoring) in highs and lows with respect to mediums and significantly higher IA (proneness to notice and interpret interoceptive information) in highs with respect to mediums and lows were found. In addition, different correlations between MAIA and BIS/BAS scales were observed in the three groups, indicating different hypnotizability-related associations.The hypnotizability-related relation between interoceptive awareness and emotional traits could be accounted for by different models and their knowledge may be relevant to the science of emotion and to clinical applications.

Minimal changes of thyroid axis activity influence brain functions in young females affected by subclinical hypothyroidism.

There is evidence of an association between thyroid hormones (TH) alterations and mental dysfunctions related to procedural and working memory functions, but the physiological link between these domains is still under debate, also for the presence of age as a confounding factor. Thus, we investigated the TH tuning of cerebral functions in young females affected by the borderline condition of subclinical hypothyroidism (SH) and in euthyroid females of the same age. The experiment consisted in the characterization of the affective state and cognitive abilities of the subjects by means of specific neuropsychological questionnaires, and of brain activity (EEG) in resting state and during the passive viewing of emotional video-clips. We found that SH had i) increased anxiety for Physical Danger; ii) better scores for both Mental Control and no-working-memory-related functions; iii) association between anxiety for Physical Danger and fT4 levels. Thus, in young adults, SH increases inward attention and paradoxically improves some cognitive functions. In addition, self-assessed questionnaires showed that SH had a greater susceptibility to unpleasant emotional stimulation. As for EEG data, SH compared to controls showed: i) reduction of alpha activity and of gamma left lateralization in resting state; ii) increased, and lateralized to the right, beta2 activity during stimulations. Both results indicated that SH have higher levels of arousal and greater susceptibility to negative emotion than controls. In conclusion, our study indicates that minimal changes in TH levels produce subtle but well-defined mental changes, thus encouraging further studies for the prediction of pathology evolution.

Manipulation of attention in highly and low hypnotizable individuals: a study on verbal priming.

This study investigated the effects of manipulation of attention on verbal priming in highly (Highs) and low (Lows) hypnotizable individuals. Priming was evaluated via the word-stem completion task (WSCT). The experimental paradigm consisted of one condition in full-attention and in two conditions with colored words in which attention was directed, respectively, only to the color and to both color and word. No significant differences between Highs and Lows were found in none of the three attentional conditions. However, during encoding in full-attention, Highs showed shorter reaction times (RTs) than Lows. This is in accord with previous evidence of faster simple and choice RTs in Highs than in Lows, and suggests hypnotizability-related differences in arousal, likely driven by a different cognitive control activity. Also, Highs' self-report of interference of color-naming on word-reading suggests possible differences between Highs and Lows in cognitive activity related to mental effort.

Hypnotizability and spatial attentional functions.

Many theories of hypnotic responding have proposed that differences in hypnotic trait rely on differences in frontal attentional functions. Evidence of hypnotizability-related attentional abilities are, however, very scant. This study was designed to investigate the relationship between hypnotizability and executive control components of attention in the spatial domain. We chose the Attention Network Test that enables to analyze alerting, orienting and executive control functions by measuring reaction times (RTs) to targets cued for different locations in space. According to Posner theory, alerting, orienting and executive control effects were found in both groups. No differences between highly susceptible (Highs) and low susceptible individuals (Lows) on executive control functions were found. However, in Highs alerting was significantly smaller than in Lows and Highs were significantly faster than Lows in the no and central cue conditions. These findings suggest that Highs would be endowed with a basal higher efficiency in achieving and maintaining their readiness to respond to incoming stimuli. This relation between hypnotizability and alerting, is discussed in terms of a possible more efficient noradrenergic activity driven by frontal attentional systems.

Relaxation as a cognitive task.

In the present experiment the instruction to relax was given to awake highly (Highs) and non hypnotizable subjects (Lows), while their heart rate, respirogram and skin resistance were recorded together with electroencephalogram, electroculogram and corrugator electromiogram. At the beginning of the experiment, Highs exhibited no significant difference in heart rate (HR), respiratory frequency (RF) and heart rate variability (HRV) with respect to Lows, but showed a higher EEG alpha and theta1 power. During the session, both groups decreased their heart rate, but changes were significant only in Lows, which increased significantly also the parasympathetic component of their HRV (high frequency, HF). In both groups, EEG showed alpha, beta2 and theta2 power decrements; theta1 activity decreased only in Lows, while gamma power increased in Highs and decreased in Lows. Results suggest that Highs and Lows used different cognitive strategies in the elaboration of the relaxation request and that Highs performed the task through a higher integrative activity.

Kinematic strategies for lowering of upper limbs during suggestions of heaviness: a real-simulator design.

The aim of the experiment was to study possible differences between the kinematic strategies for the "involuntary" arm lowering of hypnotized highly susceptible subjects (H-Highs) and for the voluntary movement of non-hypnotizable simulators (Sims) during suggestions of arm heaviness (Part I). In addition, a comparison between awake susceptible subjects (W-Highs) and H-Highs was carried out to clarify the specific role of the hypnotic state and hypnotizability (Part II). Subjects' absorption and attentional/imagery capabilities were evaluated through neuropsychological tests. Their arm movements were monitored three-dimensionally at hand, wrist and elbow level through a Polhemus Fastrack system. A final interview collected self-reports concerning the perception of movement involuntariness. Neuropsychological tests showed better "absorption" and imagery capabilities in Highs. In the interview, H-Highs perceived a higher involvement in the task and greater involuntariness and difficulties in contrasting the arm lowering than the Sims. Kinematic analysis showed significant differences between H-Highs and Sims for arm displacements along the vertical axis and on the horizontal plane. In fact, the former lowered the left arm earlier and to a greater degree than the right arm; on the horizontal plane, a forearm flexion was observed for H-Highs on the right side. On comparing W-Highs and H-Highs, hypnosis appeared to magnify the waking motor strategies, but also to induce specific changes, mainly concerning the horizontal plane. These results cannot be interpreted on the basis of "role playing" and socio-cognitive factors. They are believed to be due to a balance between the effectiveness of the frontal executive control towards the selection of behaviors and movement automaticity, which is in line with the neo-dissociation theory of hypnosis.

Influence of mental motor imagery on the execution of a finger-to-thumb opposition task.

The present fMRI study compares regional distribution of the cortical activity during the execution of unilateral hand movements (finger-to-thumb opposition) preceded or not by their motor simulation (S + E and E condition, respectively). The results show that, overall, the number and the spatial distribution of activated voxels are both increased in the S + E with respect to the E condition. The motor performance preceded by mental rehearsal is related to selective increase of the cortical activity. Among the motor areas that are found active during the simple motor execution a significant enhancement of functional activation during the S + E condition ipsilateral primary motor regions (M1). The activity increase may be accounted by a sort of neural recruiting that is made possible by the overlapping of cortical networks involved in both motor output and motor imagery. The beneficial effects of "mental practice" on the physical performance may rely to the close temporal association between motor rehearsal and actual performance.

Autonomic and EEG correlates of emotional imagery in subjects with different hypnotic susceptibility.

The autonomic and EEG correlates of the response to a cognitive unpleasant stimulation (US) verbally administered to awake hypnotizable and non hypnotizable subjects were studied. They were compared with the values obtained during a resting condition immediately preceding the stimulus and with those produced by a cognitive neutral stimulation (NS), also administered after a basal resting period. Results showed hypnotic trait effects on skin resistance, heart and respiratory rate as well as on EEG theta, alpha, beta and gamma relative power changes. The autonomic and EEG patterns observed indicated different strategies in the task execution for hypnotizable and non hypnotizable subjects and a discrepancy between the autonomic and EEG changes associated to the US in susceptible subjects. Results support dissociation theories of hypnosis and suggest for hypnotizable persons an active mechanism of protection against cardiac hazard.

Human hypnosis: autonomic and electroencephalographic correlates of a guided multimodal cognitive-emotional imagery.

The effects of a guided neutral and unpleasant imagery involving several sensory modalities were studied in hypnotized subjects. Heart rate (HR), respiratory frequency (RF), tonic skin resistance and different electroencephalographic rhythms were evaluated during a long-lasting hypnotic session including the guided suggestion of a neutral (NS) and an unpleasant (US) imagery, each preceded by a hypnotic relaxation rest period. During NS, the absence of autonomic changes, associated with electroencephalographic gamma power decrement and theta1 power increment, indicated the prevalence of relaxation on the expected task-related modifications. In contrast, US elicited HR and RF increments together with higher electroencephalographic gamma, beta3 and beta2 activities. Thus, hypnotic state appears to prevent the autonomic responses expected during the neutral stimulation, while the emotional valence of the unpleasant imagery overwhelms the hypnosis-related relaxation.

Changes in autonomic and EEG patterns induced by hypnotic imagination of aversive stimuli in man.

Autonomic and electroencephalographic (EEG) responses to aversive stimuli presented by means of hypnotic suggestion have been studied in man.Healthy volunteers with simple phobia were screened for susceptibility to hypnosis. The experimental paradigm included periods of rest during which the hypnotized subjects were asked to produce an emotionally neutral mental image and periods of emotional activation in which they were asked to image a phobic object. Heart rate (HR), respiratory frequency (RF) and EEG were processed to obtain the HR-related indexes of sympatho-vagal balance and the EEG spectral components. The results showed a significant increase in HR and RF with a shift of the sympatho-vagal indexes towards a sympathetic predominance during the hypnotic emotional activation. EEG activity showed a significant increase in the gamma band with a left fronto-central prevalence. There was also a less pronounced increase in the beta band. In conclusion, by means of hypnosis, autonomic and behavioral responses to fear-like stimuli can be induced in man in a reproducible and controlled manner. Such a paradigm could be applied in human neuroimaging studies to identify central nervous structures that modulate stress and fear-related reactions.

Effects of early cerebellar removal on the classically conditioned bradycardia of adult rabbits.

The magnitude of classically conditioned bradycardia was studied in 18-day-old and adult rabbits in which the cerebellar vermis had been surgically removed on either the 5th or 18th postnatal day. In the conditioning procedure, an auditory stimulus (5 s, 1000 Hz) served as conditioned stimulus (CS) and a train of electric impulses applied to the ear (100 Hz, 500 ms, 1.5 mA) was employed as the unconditioned stimulus (US). Heart rate (HR) responses developed in the operated animals during the CS-alone (orientation), and CS-US paired presentations (conditioning) were analyzed and compared with those developed in control animals. In all the experimental groups, lesions were localized to the cortex of lobules IV-VII and the underlying white matter, sparing the deep cerebellar nuclei. None of the lesioned animals showed any behavioral or somatomotor deficit. All the operated animals exhibited a normal baseline HR and a marked orienting response, both comparable with those of controls. In contrast, while the animals tested at 18 days showed a normal pattern of conditioned bradycardia, at the age of 3 months the HR conditioned response differed significantly from that observed in control rabbits: the animals that received the earliest cerebellar lesion showed a conditioned bradycardia greater than that of controls, the rabbits lesioned on the 18th postnatal day exhibited a reduced bradycardic response. These results suggest that the timing of cerebellar vermis removal, at early stages of development, represents a crucial factor in the organization of the bradycardic response in the adult.

Development of fear-related heart rate responses in neonatal rabbits.

Classical simple conditioning of heart rate (HR) was studied in rabbits between the 1st and 18th neonatal day. An auditory stimulus (1000 Hz, 5 s) served as the conditioned stimulus (CS), and a train of electric impulses (100 Hz, 500 ms, 1-1.5 mA) was used as the unconditioned stimulus (US). HR responses developed during orientation session (CS-alone) as well during acquisition (CS-US paired) were analyzed and compared to those developed by young adult rabbits (3-month-old). In all neonatal animals tested, baseline HR measured during an adaptation session preceding conditioning, was similar though significantly higher than that measured in adult rabbits (Newman-Keuls P < 0.05). Before the 10th neonatal day, the animals did not show either somatomotor or HR orienting responses to the CS-alone presentations. Consequently, since orienting reactions play a necessary role in the formation and manifestation of conditioned reflexes, 1 to 10-day-old infant rabbits were not submitted to the acquisition session. All the other neonatal groups, while showing orienting behaviours similar to those exhibited by adults (head and pinna movement), presented different patterns of HR orienting responses (no response, bradycardia, tachycardia, bradycardia/tachycardia etc.). As for the acquisition session, the first bradycardic response, similar to that developed by adult rabbits, was found in 18-day-old rabbits. However, also in this neonatal group the amplitude of the conditioned response was significantly smaller when compared to that exhibited by young adults (Newman-Keuls P < 0.01). In addition, in some of the 10-day-old neonates, HR appeared very unstable and dropped to very low values (as low as 146 beats/min) early during conditioning, apparently as a consequence of CS-US association. As for the unconditioned response, no differences were found between adult rabbits and the neonatal animals older than 12 days. In contrast, most of the 10-day-old rabbits showed either bradycardia or no response to the unconditioned stimulus. Considering the ability of mammalian infants to learn somatomotor conditioned responses at early stages of maturation, conditioning of HR responses occurs late during ontogeny. Since this incapacity to show HR conditioned responses before the 18th postnatal day cannot be ascribed to their inability to show phasic HR changes nor to a failure in detecting the auditory stimulus, these results suggest the possibility that HR conditioned responses may be mediated by neural structures developing later during maturation.

Purkinje cell responses in the anterior cerebellar vermis during Pavlovian fear conditioning in the rabbit.

Extracellular single-unit recordings of Purkinje cells in the anterior cerebellar vermis (ACV) of the rabbit found evidence of short-latency (20-30 ms) differential responses to discriminatively-conditioned auditory stimuli during Pavlovian fear conditioning procedures. These differential unit responses appeared to be a function of learning as differential ACV Purkinje cell responses were not observed in naive (untrained) animals. Some of these evoked neurophysiological responses were also correlated with the behavioral conditioned autonomic response. (CAR); a conditioned bradycardiac response. These electrophysiological data, coupled with previous lesion results, suggest that the ACV is part of an important neural circuit for Pavlovian conditioned bradycardia.

Reorganization of visual pathways following posthatching removal of one retina in pigeons.

Organization of visual pathways was studied in 2-month-old pigeons that underwent unilateral retinal removal on either the day of hatching (ERA, i.e., early retinal ablated) or the 9th day after hatching (LRA, i.e., late retinal ablated). A general size reduction of visual areas contralateral to the removed retina was found in ERA pigeons, which additionally showed an altered differentiation of thalamic visual targets as well as a different cytoarchitectonic arrangement of the superficial layers of the optic tectum. No comparable modifications were found in LRA pigeons. The retinal projections of the remaining eye were studied following intraocular injections of 3H-proline. Both in ERA and LRA pigeons, the distribution of retinofugal afferents to primary visual regions contralateral to the injected eye was similar to that of control pigeons. Anomalous ipsilateral projections from the remaining retina to primary retinorecipient regions were found in ERA pigeons only. Effects of early ablation of one retina on second-order visual connections were also studied. Following injections of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) into the visual Wulst contralateral to the operated eye, a smaller number of ipsilateral projecting thalamo-Wulst neurons was found as compared with control pigeons. In contrast, the contralateral thalamo-Wulst projections were increased. No changes in thalamo-Wulst projections were found following tracer injections into the opposite Wulst, i.e., ipsilateral to the operated eye. The present study demonstrates a substantial anatomical reorganization of both primary and secondary visual pathways following unilateral retinal removal immediately after hatching, when maturation of the visual system is not yet completed.