Noise-driven neuroplasticity in self-organizing feature maps: a neurocomputational model of phantom limbs

The term "phantom limb" denotes the sensation that an extremity is present although it has been lost. A number of clinical features and recent findings of cortical map plasticity after destruction of afferent pathways (deafferentation) suggest that phantom limbs are caused by large-scale cortical reorganization processes. However, in paraplegics, who also suffer from cortical deafferentation, phantom sensations rarely develop, and if they do, they are weak, lacking in detail, and delayed, occurring after months. This has been taken to suggest a non-cortical genesis of phantom limbs. This article proposes a biologically plausible minimal neural network model to solve this apparent puzzle. Deafferentation was simulated in trained self-organizing feature maps. Reorganization was found to be directed by input noise. According to the model, the production of input noise by the deafferented primary sensory neuron promotes cortical reorganization in amputees. No such noise is generated or conducted to the cortex in paraplegics.     

The relation between limb dominance, acceptance of disability, and the phantom limb phenomenon.

Examined 2 hypotheses regarding the phantom limb sensation (PLS). One predicted that the frequency of PLS would be greater for the dominant than the nondominant limb. The 2nd hypothesized that there is an inverse relation between acceptance of the disability and frequency of PLS. 18 double-amputees who had lost 2 homologous limbs while in military service were administered questionnaires examining limb dominance, frequency of the PLS, and acceptance of disability. Results confirm only the 1st hypothesis. The PLS is discussed in light of the present findings, and it is concluded that the role of physiological factors seems to be clearer than that of psychological ones. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Healthy youth development as a model for youth health promotion. A review

To explore the possible mechanisms of phantom limb discomfort after amputation, three amputees with phantom limb pain were studied. This study examined the change of regional cerebral blood flow using technetium-99m hexamethylpropyleneamine oxime-single photon emission computerized tomography, which was arranged at the time of severe phantom limb discomfort and after the discomfort subsided or was completely relieved. Nine representative transverse slices parallel to the orbitomeatal line were selected for quantification. The cortical ribbon (2-cm thickness) was equally subdivided into 12 symmetrical pairs of sector regions of interest in each slice. The irregularly shaped regions of interest were drawn manually around the right thalamus and basal ganglion and then mirrored to the left thalamus and basal ganglion. The contralateral to ipsilateral ratio of regional cerebral blood flow for each area was calculated. The intensity of phantom limb pain was evaluated on a 0 to 10 visual analog scale. In Cases 1 and 2, the contralateral to ipsilateral regional cerebral blood flow ratios of multiple areas of the frontal, temporal, or parietal lobes were increased at the time of more severe phantom limb pain, and the ratios were normalized or even decreased when the phantom limb pain subsided. In Case 3, increased contralateral to ipsilateral regional cerebral blood flow ratios were also found over the frontal, temporal, and parietal lobe. However, most of the increased regional cerebral blood flow ratios of regions of interest in the first study persisted in the follow-up study. Also, the regional cerebral blood flow ratios of greater number of regions of interest of the same gyrus and new gyrus were increased. There was no significant right-left difference of regional cerebral blood flow over bilateral thalami and basal ganglia in all three cases. The results suggested that phantom limb pain might be associated with cortical activation involving the frontal, temporal, or parietal cortex, and it may imply the possibility of the existence of an ascending polysynaptic pathway that conveys the uncomfortable phantom limb sensation to the cerebral cortex. These findings may also indicate that reorganization of the cortical blood flow occurs in amputees. However, it is still difficult to conclude that the changes in regional cerebral blood flow were attributable directly to pain. With no comparison group of amputees and because of the small number of cases, it is hard to generalize about cerebrocortical involvement in phantom pain, and it is possible that the findings represent a normal phenomenon seen after 'amputation. Another possibility is that the findings represent increased arousal caused by pain rather than an intrinsic pain pathway. Further study is worthwhile.     

Outpatient group treatment of chronic pain: Effects of spouse involvement.

Evaluated the efficacy of outpatient group treatment of chronic pain and the effect of spouse involvement in treatment in chronic pain patients ranging in age from 23 to 69 yrs who were randomly assigned to couples group treatment (n?=?17), patient-only group treatment (n?=?14), or waiting-list controls (n?=?12). 29 Ss had low back pain; the remaining Ss reported pain in the knee, arm, leg, hip, head, and phantom limb. The Ss completed the MMPI—168 and measures of health-related psychosocial and physical dysfunction and marital satisfaction. Results indicate that the 16-hr cognitive-behavioral program produced reductions in pain, somatization, spouse-observed pain behavior, physical and psychosocial dysfunction, spouse-rated dysfunction, and utilization of health care resources. Depression was not affected by treatment. Spouse involvement did not facilitate response to treatment on any variables. Also, Ss in the individual condition only showed improved marital satisfaction. All treatment gains were maintained at 3-mo to 7-mo follow-ups. Results indicate that brief outpatient treatment can significantly ameliorate chronic pain problems, and spouse involvement is not essential for a positive response to treatment. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of preparatory information about sensations, threat of pain, and attention on cold pressor distress.

Three experiments with 170 male undergraduates investigated pain experience conceptualized as a combination of stimulus sensations (e.g., aching) and emotional distress. In Exp I, less distress was reported to cold pressor stimulation by Ss first told about stimulus sensations than by Ss who were uninformed or were told about symptoms of bodily arousal (e.g., tension). Adding a pain warning to sensation information blocked distress reduction, presumably by eliciting an emotional interpretation of the stimulus. In Exp II, Ss attending only to hand sensations reported less distress than Ss attending to their bodies. This decrease in the power of the stimulus to provoke emotion is presumably mediated by a schema of hand sensations formed by attention. In Exp III, Ss attending to hand sensations early in the immersion and distracting themselves later reported the same low levels of distress as did Ss who attended to hand sensations throughout. Ss distracted throughout and Ss attending to hand sensations later showed no distress reduction. Therefore, stimulus schematization must precede distress reduction. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prevalence and correlates of dating violence in a Canadian university sample.

Assessed the prevalence and correlates of dating violence among 116 female and 50 male undergraduates. Ss responded to the Conflict Tactics Scale, a self-esteem inventory, and questions regarding their course major, demographic characteristics, and current or most recent dating relationship. 52 women and 24 men reported having experienced physical violence in their current or most recent dating relationship. Ss who reported dating violence also reported greater relationship commitment, longer relationship durations, and higher levels of reasoning and verbal aggression strategies than did Ss who did not report dating violence. Women reported more frequent expressions of physically and verbally aggressive conflict resolution tactics than did men. Men were more likely than women to report being the targets of verbal and physical aggression by their partners. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The cortical somatotopic map and phantom phenomena in subjects with congenital limb atrophy and traumatic amputees with phantom limb pain

The extent of the cortical somatotopic map and its relationship to phantom phenomena was tested in five subjects with congenital absence of an upper limb, four traumatic amputees with phantom limb pain and five healthy controls. Cortical maps of the first and fifth digit of the intact hand, the lower lip and the first toe (bilaterally) were obtained using neuroelectric source imaging. The subjects with congenital upper limb atrophy showed symmetric positions of the left and right side of the lower lip and the first toe, whereas the traumatic amputees with pain showed a significant shift (about 2.4 cm) of the cortical representation of the lower lip towards the hand region contralateral to the amputation side but no shift for the toe representation. In healthy controls, no significant hemispheric differences between the cortical representation of the digits, lower lip or first toe were found. Phantom phenomena were absent in the congenital but extensive in the traumatic amputees. These data confirm the assumption that congenital absence of a limb does not lead to cortical reorganization or phantom limbs whereas traumatic amputations that are accompanied by phantom limb pain show shifts of the cortical areas adjacent to the amputation zone towards the representation of the deafferented body part.     

Limb swelling in patients who have fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva is a rare heritable disorder of connective tissue characterized by progressive heterotopic ossification of soft tissues and by congenital malformation of the great toes. Limb swelling has also been noted, yet little is known about this complication of fibrodysplasia ossificans progressiva. To determine the prevalence of limb swelling in this condition, the authors reviewed detailed medical records on 74 patients (25 males, 49 females; age range, 1-49 years) who had a documented history of fibrodysplasia ossificans progressiva. The study population included more than 90% of all patients known to have fibrodysplasia ossificans progressiva in the United States. Acute swelling of the limbs occurred in association with flareups of the condition in nearly all cases. Acute swelling in the upper limbs was focal and nodular in contrast to acute swelling in the lower limbs, which was more diffuse. Acute swelling in the upper limbs occurred in all 74 patients whereas acute swelling in the lower limbs occurred in 47 of the 74 patients (64%). Two of the 74 patients who had acute swelling in the lower limbs (4%) had a documented episode of deep vein thrombophlebitis. Chronic swelling in the upper limbs occurred in 9 of the 74 patients (12%) and was not seen before the age of 12 years. Chronic swelling in the lower limbs occurred in 36 of the 74 patients (49%) and was not seen before the age of 9 years. The intense angiogenesis and edema seen on histopathologic evaluation of preosseous fibrodysplasia ossificans progressiva lesions may play a role in the pathogenesis of the limb swelling. The data show an age related prevalence of limb swelling in fibrodysplasia ossificans progressiva and suggest a model for understanding the complex pathways leading to limb swelling in this disorder.     

Biased reporting of therapist–patient sexual intimacy.

To investigate bias in reports of therapist–patient sexual intimacy, information about 559 patients who were sexually intimate with their previous therapists was collected via questionnaire from 318 psychologists who subsequently saw these patients in therapy. Psychologists, the experimental Ss in the present study, were predominantly aged 40–49 yrs, and 64% were male. It was found that Ss who reported that no harm occurred to patients as a result of therapist–patient sexual intimacy (SI) admitted twice the prevalence of SI between patients and themselves than did Ss in general. Those Ss who had experienced SI with patients were less likely to report adverse effects of SI either for patients or for therapy. Fewer Ss with a history of SI than those without reported anger toward offending therapists, and fewer recommended punishment. A higher percentage of female than male Ss reported anger toward offenders and recommended punishment, yet women did not rate the effects of SI as more harmful than did men. In general, anger toward offending therapists and recommendations for punishment were associated with the degree to which patients were thought to have been harmed. Ss who had been consultants to a greater number of other therapists about sexual contact with patients reported relatively more cases in which therapy ended soon after SI began than did Ss who were consulted by fewer therapists. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

From rarity to evaluative extremity: Effects of prevalence information on evaluations of positive and negative characteristics.

Experiments showed a scarcity principle in evaluative judgments such that the identical characteristic is evaluated more extremely the lower its perceived prevalence. In Study 1, Ss evaluated a fictitious medical condition that was described as either beneficial or detrimental to health and as occurring in either 30% or in one half of 1% of a test population. The condition was evaluated more extremely—as a more positive health asset or a more negative health liability—in the low-prevalence than in the high-prevalence conditions. Study 2 demonstrated the same effect in self-evaluations and with a different manipulation of perceived prevalence. Ss were told that they actually had the fictitious medical condition, that it was either beneficial or detrimental to their health, and either that they were the only 1 of 5 Ss who had it or that 4 of the 5 did. Low-prevalence Ss exhibited more extreme evaluative, affective, and behavioral reactions to the medical condition than did high-prevalence Ss. The origins and validity of the scarcity principle are discussed, as are its implications for uniqueness theory, reactance theory, and social evaluation theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in self-control behaviors and tolerance of painful stimulation.

Studied the relation between Ss' general repertoire of self-control behaviors and their ability to tolerate a cold pressor. In Exp I, with 40 undergraduate Ss, it was found that Ss who were instructed to think of a pleasant event while exposed to a cold pain tolerated that pain longer than a control group, thus replicating previous findings. In Exp II, with 54 undergraduate Ss, one experimental group was required to spend 5 min in self-planning of strategies to cope with the upcoming pain, and a 2nd group was merely informed on the effectiveness of self-control methods in coping with pain. Both groups did not show longer durations than Ss in a control group who were not encouraged to employ their own self-control methods. High self-control (HSC) Ss across the various treatment conditions consistently tolerated the cold pressor longer than low self-control Ss. HSC Ss also reported using self-control methods more often and more effectively while exposed to the cold pressor. The 2 self-control groups did not differ in their ratings of pain intensity. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of hypnotic susceptibility, suggestions for analgesia, and the utilization of cognitive strategies on the reduction of pain.

96 undergraduates were stratified in terms of hypnotic susceptibility (high, medium, and low) on the Harvard Group Scale of Hypnotic Susceptibility, Form A. Ss next had 1 arm immersed in ice water for a 60-sec pretest and, afterward, were assigned to 1 of 4 treatments: (a) hypnosis plus analgesia suggestion, (b) hypnosis alone, (c) suggestion alone, or (d) no hypnosis—no suggestion. Ss were retested in ice water and then interviewed about their experiences during the retest. High susceptibles reported the use of more cognitive strategies during the retest and showed greater pretest-to retest pain magnitude reductions than did low susceptibles. Similar effects occurred for Ss given, as opposed to not given, a suggestion. The hypnosis variable, however, failed to affect either strategy use or pain magnitude. Strategy use facilitated pain reduction only for Ss who did not worry about and did not exaggerate the unpleasantness of the situation (i.e., noncatastrophizers). The few Ss who showed dramatic pretest-to-retest reductions in pain magnitude (50% reduction or more) were all high-susceptible noncatastrophizers who used one or more cognitive strategies. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychotherapists' attitudes toward suicide.

Assessed psychotherapists' attitudes toward a number of potential suicides and their attitudes toward the concept of rational suicide in general. 186 Ss received a case scenario in which a current client of a member or the general public was considering suicide because of a terminal illness, physical pain, psychological pain, or bankruptcy. Ss also completed the Suicide Semantic Differential Scale. Ss were differentially accepting of suicidal ideation, based on precipitating circumstances, and Ss would take different amounts of action to prevent a suicide depending on why the person had decided to commit suicide. Ss who had been in practice for 30+ yrs were more accepting of suicide and would take less action to prevent a suicide than less experienced Ss. 81% of the Ss believed in the idea of rational suicide. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phantom limb pain and pain interference in adults with lower extremity amputation: The moderating effects of age.

Purpose/Objective: To determine whether the relationship between phantom limb pain severity and pain-related interference was moderated by age and to compare 2 theoretical perspectives used in the literature to account for age-related differences in the experience of chronic pain. Research Method/Design: Analysis of survey data provided by 375 adults with lower extremity amputations who reported phantom limb pain. Results: The relationship between phantom limb pain severity and pain-related interference was shown to be moderated by age (β = -.10, p     

Change in obsessive-compulsive and avoidant personality disorders following time-limited supportive-expressive therapy.

24 patients with avoidant personality disorder (AVPD) and 14 patients with obsessive-compulsive personality disorder (OCPD; all Ss 20–65 yrs old) were assigned to 52 sessions of time-limited Supportive-Expressive dynamic psychotherapy. At intake, most Ss had least 1 concurrent depressive and/or anxiety disorder. OCPD Ss lost their personality disorder diagnoses significantly faster than did AVPD Ss. By the end of treatment, 39% of AVPD Ss still retained their diagnosis while only 15% of OCPD did so. Using hierarchical linear modeling, both patient groups improved significantly across time on measures of personality disorders, depression, anxiety, general functioning, and interpersonal problems. OCPD Ss remained in treatment significantly longer and tended to improve more than did AVPD Ss. Alliance ratings from both Ss and therapists increased significantly over time, expect for those OCPD Ss who remained constant. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The menstrual cycle and response to erotic literature

133 undergraduate females responded to a pre-experimental questionnaire assessing their contraceptive use (28% on contraceptive pills), sexual experience (71% had had sexual intercourse), and present phase of menstrual cycle. Ss then read an erotic story intended to induce sexual arousal. Results of a self-report postexperimental questionnaire assessing sexual arousal and genital stimulation show no significant response differences based on menstrual cycle phases for Ss not using contraceptive pills. Greatest degree of arousal and sensation was experienced by Ss on contraceptive pills who were in the menstrual phase of the cycle; least arousal and sensation was experienced by Ss on contraceptive pills who were in the premenstrual phase of the cycle. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceived threat as a major factor in tolerance for experimentally induced cold-water pain.

In Study 1, 12 undergraduates informed only of the normal physiological reactions to hand immersion in cold water and 12 Ss informed that they were participating in a "study of the perception of novel stimuli" showed much greater tolerance and reported significantly less pain than did 12 controls given no pretesting message. Therefore, giving Ss the chance to ascribe uncomfortable sensations to a nondamaging process increased tolerance. Study 2, with 5 graduate students, showed that repeated exposure to cold-water immersion (employed to demonstrate safety of the procedure) did not reduce the reported sensation of pain, indicating that the increased tolerance following assurances of safety was directly due to decreased threat and not to decreased sensation. Findings support the distinction between pain sensation and emotional-motivational reaction leading to escape or avoidance. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychological distress in workers with traumatic upper or lower limb amputations following industrial injuries.

Objective: To determine whether individuals with traumatic upper limb amputations would report more symptoms of posttraumatic stress disorder (PTSD) and depression than individuals with traumatic lower limb amputations. Study Design: Retrospective file review. Setting: CARF-accredited outpatient rehabilitation center. Participants: Thirty workers with unilateral upper limb amputations and 25 workers with unilateral lower limb amputations. Main Outcome Measures: Presence or absence of depression, symptoms of PTSD, and pain. Results: The upper limb group had a higher frequency of depression and symptoms of PTSD than the lower limb group. The 2 groups did not differ with respect to pain complaints. Conclusion: More so than injuries to the lower limbs, upper limb injuries may render individuals vulnerable to PTSD and depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of two cognitive strategies on pain threshold.

While 1 arm was immersed in ice water, each of 48 female student nurses were asked either to imagine a situation that, if real, would be inconsistent with pain (relevant strategy) or imagine a situation unrelated to pain (irrelevant strategy), or they were not given special instructions (control group). Ss were further divided into those with high and low pain thresholds based on a pretest. The use of strategies (relevant or irrelevant) did not alter the pain thresholds for Ss with low thresholds. Among those Ss with high thresholds, use of a relevant strategy led to a greater increase in threshold than an irrelevant strategy, which, in turn, led to a greater increase than the control condition. Ss who were highly involved in their imaginings showed greater increases in pain threshold than those who were not. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social support and recovery from surgery.

Examined the relationship of naturally occurring social support from the spouse with the preoperative anxiety and postoperative recovery of 56 male coronary-bypass patients (aged 38–69 yrs). Ss were divided into groups based on whether the overall perceived quality of their marital relationship was relatively good or bad at the time of surgery and on whether they received relatively high or low spouse support in the hospital (defined in terms of frequency of visits). Ss were also compared with 16 unmarried male coronary-bypass patients. Married Ss who received more hospital support took less pain medication and recovered more quickly than low-support Ss. In contrast, perceived quality of the marital relationship was relatively insignificant. Speed of recovery for unmarried Ss was generally slower than for married, high-support Ss and faster than for married, low-support Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)