Activity-related pain and sensitization predict within- and between-person pain experience in people with knee osteoarthritis: An ecological momentary assessment study

Background and objectives

Knee Osteoarthritis (OA) is a prevalent musculoskeletal condition that often results in pain and disability. Determining factors predicting variability in pain experience is critical to improving clinical outcomes. Underlying pain sensitization and its clinical manifestations, such as activity-related pain, may better predict the knee OA pain experience. This study aimed to determine whether Quantitative Sensory Testing (QST) derived sensitization measures and activity-related pain predict knee OA pain experiences collected via smartphone ecological momentary assessment (EMA).

Design

Individuals with knee OA were recruited from an urban community in New Zealand. Those eligible to participate underwent baseline QST with clinical measures of activity-related pain also being collected. The knee OA pain experience was collected via smartphone EMA three times daily for two weeks. Mixed effects location scale models were developed using a multilevel modelling approach.

Results

Eighty-six participants with knee OA participated in the study. Mean age was 67.3 years, with most of the participants being female (64%) and New Zealand European (90.6%). Activity-related pain predicted worse and more variable pain intensity, pain interference, and bothersomeness outcomes within and between individuals with knee OA. Widespread cold hyperalgesia and local mechanical hyperalgesia were shown to predict higher within-person variability in pain intensity and pain interference respectively, while mechanical temporal summation predicted less within-person variability in pain intensity and interference.

Discussion

Those demonstrating activity-related pain and sensitization could be at risk of experiencing worse and more variable knee OA pain in the subsequent weeks. Testing for sensitization in clinical practice could therefore identify those at greatest risk of higher and more variable knee OA pain experiences and in greatest need of treatment. Larger validation studies are required, which include individuals with more severe knee OA.

Exploring challenges affecting resilience in carers of stroke survivors: a qualitative descriptive study

PURPOSE

To develop an intervention to build resilience in carers of stroke survivors this study aimed to understand these carers' (1) Challenges that adversely affect their resilience, and (2) suggestions for a relevant intervention to build resilience.

METHODS

Individual semi-structured interviews were used. Participants included carers of stroke survivors (stroke duration > six months). Transcripts were analysed using the General Inductive Approach. This study followed guidelines of Consolidated criteria for Reporting Qualitative research (COREQ).

RESULTS

Four themes were identified that affected resilience: (1) carer psychosocial outcomes, (2) stroke's sudden and unexpected impact, (3) financial stressors, and (4) carer exclusion in care planning. Carers suggested an intervention comprising information sharing and training in coping skills, positive communication, problem-solving, and connection with "people who have gone through this" to improve resilience. Most supported a group, monthly delivery of the intervention.

CONCLUSION

These findings provide direction for a suitable intervention. Further, they suggest that stroke rehabilitation could be improved by adopting a family-centered model of care so that carers can be included as active partners in care process. Protecting carers from the negative impact of caring role on their resilience may sustain their ability to provide long-term care for the stroke survivor.IMPLICATIONS FOR REHABILITATIONThe provision of informal care to stroke survivors can be associated with significant emotional consequences, withdrawal from social activities, and poor quality of life for the carers.The abruptness of stroke presentation along with its long-term nature can negatively affect the resilience of informal carers.Exploration of challenges affecting carer resilience is important to develop interventions to build resilience in carers of stroke survivors.Integrating interventions focusing on carers' resilience as part of the stroke rehabilitation process is imperative to ensure well-being of carers and sustainability of the care provided to the stroke survivor.

Experiences and Perceptions of Using Smartphone Ecological Momentary Assessment for Reporting Knee Osteoarthritis Pain and Symptoms

BACKGROUND

Knee osteoarthritis (OA) is a prevalent, painful, and disabling musculoskeletal condition. One method that could more accurately monitor the pain associated with knee OA is ecological momentary assessment (EMA) using a smartphone.

OBJECTIVES

The aim of this study was to explore participant experiences and perceptions of using smartphone EMA as a way of communicating knee OA pain and symptoms following participating in a 2-week smartphone EMA study.

MATERIALS AND METHODS

Using a maximum variation sampling method, participants were invited to share their thoughts and opinions in semistructured focus group interviews. Interviews were recorded and transcribed verbatim before thematic analysis using the general inductive approach.

RESULTS

A total of 20 participants participated in 6 focus groups. Three themes and 7 subthemes were identified from the data. Identified themes included: user experience of smartphone EMA, data quality of smartphone EMA, and practical aspects of smartphone EMA.

DISCUSSION

Overall, smartphone EMA was deemed as being an acceptable method for monitoring pain and symptoms associated with knee OA. These findings will assist researchers in designing future EMA studies alongside clinicians implementing smartphone EMA into practice.

PERSPECTIVE

This study highlights that smartphone EMA is an acceptable method for capturing pain-related symptoms and experiences of those expereiencing knee OA. Future EMA studies should ensure design features are considered that reduce missing data and limit the responder burden to improve data quality.

Activity-related pain predicts pain and functional outcomes in people with knee osteoarthritis: A longitudinal study

Knee Osteoarthritis (OA) is a prevalent musculoskeletal condition, commonly resulting in pain and disability. However, pain and disability in this population are poorly related with the degree of structural joint damage. Underlying pain mechanisms, including activity-related pain and sensitization assessed via Quantitative Sensory Testing (QST), may better predict pain and functional outcomes of those with knee OA. Therefore, the aim of this study was to explore whether activity-related pain and sensitization assessed via QST predict future pain, function, fatigue, physical performance and quality of life outcomes in those living in the community with knee OA. Eighty-six participants with knee OA were recruited in Dunedin, New Zealand. Those eligible to participate underwent baseline testing including QST as well as measures of activity-related pain including Movement-evoked Pain (MEP) and Sensitivity to Physical Activity (SPA). Outcome measures exploring pain, function, fatigue and quality of life outcomes were collected at baseline, and two follow-up periods (two and nine weeks). Univariable linear regression models were developed followed by multivariable linear regression models for each prognostic marker adjusting for age, gender, BMI, OA duration, baseline pain intensity and socioeconomic status. Activity-related measures of pain, including MEP and SPA, demonstrated predictive associations with pain and functional outcomes prospectively in those with knee OA. Therefore, those demonstrating activity-related pain are at future risk of greater pain, disability and reduced quality of life. Larger, externally validated longitudinal studies are required which include individuals with more severe knee OA.

Sensitivity to movement-evoked pain, central sensitivity symptoms, and pro-nociceptive profiles in people with chronic shoulder pain: A parallel-group cross-sectional investigation

OBJECTIVE

To investigate whether sensitivity to movement-evoked pain (SMEP), central sensitivity symptom burden, and quantitative sensory testing (QST) outcomes differ between healthy controls and people with chronic shoulder pain.

METHODS

People with chronic shoulder pain (n = 39) and healthy controls (n = 26) completed validated questionnaires measuring demographic, pain characteristics, psychological factors, social support, sleep quality, central sensitivity inventory (CSI), and physical activity levels. A blinded assessor administered QST measuring pressure pain threshold, temporal summation, conditioned pain modulation, and cold hyperalgesia. All participants performed repeated lifting of weighted canisters and reported severity of pain over successive lifts of the weighted canisters. Between-group differences in the QST, SMEP and CSI scores were investigated. Demographic and psychosocial variables were adjusted in the analyses.

RESULTS

Dynamic mechanical allodynia, mechanical temporal summation, movement-evoked pain scores, SMEP index, and CSI scores were significantly (p ≤ 0.05) higher in the chronic shoulder pain group than in healthy controls. A significant proportion of people with chronic shoulder pain presented with pro-nociceptive profiles and experienced higher pain severity, interference, and disability.

CONCLUSIONS

People with chronic shoulder pain displayed symptoms and signs of central sensitization. Future research should investigate the predictive role of central sensitization on clinical outcomes in shoulder pain.

Spin-hedgehog-derived electromagnetic effects in itinerant magnets

In itinerant magnets, the indirect exchange coupling of Ruderman-Kittel-Kasuya-Yosida type is known to stabilize incommensurate spin spirals, whereas an account of higher order spin interactions favors the formation of a noncoplanar magnetic texture. This is manifested by the finite Berry phase the conduction electrons accumulate when their spins follow this texture, leading thus to the topological Hall effect. We herein utilize the effective spin model with bilinear-biquadratic exchange interactions for studying the formation of the magnetic hedgehog lattice, that represents a periodic array of magnetic anti- and monopoles and has been recently observed in the B20-type compounds, in a three-dimensional itinerant magnet. As opposed to widely used Monte Carlo simulations, we employ a neural-network-based approach for exploring the ground state spin configuration in a noncentrosymmetric crystal structure. Further, we address the topological Hall conductivity, associated with nonzero scalar spin chirality, in the itinerant magnet due to the coupling to the spin hedgehog lattice, and provide the evidence of a magneto-optic Kerr effect.

Psychosocial interventions for building resilience of informal carers of people living with stroke: a systematic review

PURPOSE

To identify and synthesise the evidence of interventions purported to build resilience among informal carers of stroke survivors.

METHODS

A systematic review of randomised controlled trials of psychosocial interventions to build resilience for carers of people post-stroke was planned. A systematic search was conducted in seven online databases from inception to March 2021. Outcomes measured were resilience and its proxy constructs including copying, adaptation, adjustment, problem-solving, self-efficacy, locus of control, competence and strength.

RESULTS

Twelve studies were included in the review and were grouped into four intervention categories (i) Education and social support, (ii) problem-solving skills, (iii) problem-solving skills, and psychoeducation and (iv) information provision, problem-solving skills and psychoeducation. Level of evidence A exists for interventions that combine information provision, problem-solving skills and psychoeducation over the interventions that only use problem-solving skills intervention or problem-solving skills with psychoeducation strategies. All interventions apart from one reported significant within and/or between group changes in outcomes.

CONCLUSION

Interventions comprising of information provision, problem-solving skills and psychoeducation appear to be beneficial to improve resilience of carers. However, because of the heterogeneity of the interventions and outcome measures reported across the twelve studies no particular intervention could be definitively supported.

CLINICAL TRIAL REGISTRATION

Systematic review registration: CRD 42020172824 https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020172824 IMPLICATIONS FOR REHABILITATIONProviding care for stroke survivors is particularly demanding due to the lack of preparation for managing the unexpected and complex nature of stroke, resulting in negative physical, social, behavioral, emotional, and financial outcomes.The long-term nature of stroke and its many residual problems can negatively affect the physical and psychological well-being of the individual and their carers, which may subsequently affect the recovery of the stroke survivor.Evidence suggests that resilience is the protective shield for carers' stress and burnout.Integrating interventions focusing on carers' resilience as part of the stroke rehabilitation process is imperative to ensure the well-being of carers and the sustainability of the care provided to the stroke survivor.

Reliability and clinical utility of the chronic pain classification in the 11th Revision of the International Classification of Diseases from a global perspective: results from India, Cuba, and New Zealand

ABSTRACT

Chronic pain affects 1 in 5 persons and contributes substantially to the global burden of disease. The 11th Revision of the International Classification of Diseases (ICD-11) includes a comprehensive classification of chronic pain. The aim of this ecological implementation field study was to evaluate the classification's interrater reliability and clinical utility in countries with different income levels. The study was conducted in 4 pain clinics in Cuba, India, and New Zealand. Twenty-one clinicians used the ICD-11 to diagnose and code n = 353 patients with chronic pain. Of these, 111 were assessed by 2 clinicians, and Fleiss' kappa was calculated to establish interrater reliability for any diagnosis assigned to ≥15 patients. The clinicians rated the clinical utility of all diagnoses. The interrater reliability could be calculated for 11 diagnoses. It was substantial for 10 diagnoses and moderate for 1 (kappa: 0.596-0.783). The mean clinical utility of the ICD-11 chronic pain diagnoses was rated as 8.45 ± 1.69/10. Clinical utility was rated higher for ICD-11 than for the commonly used classification systems (P < 0.001, η2 = 0.25) and differed between all centers (P < 0.001, η2 = 0.60). The utility of the ICD-11 diagnoses was rated higher than the commonly used diagnoses in Dunedin and Havana, and no difference was found in Kolkata and Hyderabad. The study showed the high interrater reliability of the new chronic pain diagnoses. The perceived clinical utility of the diagnoses indicates their superiority or equality compared with the classification systems currently used in pain clinics. These results suggest the global applicability of the classification in specialized pain treatment settings.

Group singing improves both physical and psychological wellbeing in people with and without chronic health conditions: A narrative review

The aim of this narrative review was to establish a link between psychological and physical wellbeing in people with and without chronic health conditions who participated in group singing. Four databases were searched (PubMed, WoS, MEDLINE, and Scopus) using a systematic search method. Articles were screened, yielding 19 suitable articles. In most studies that were included group singing led to an increase in both psychological and physiological wellbeing. The major impacts were on affect and depression and anxiety.Group singing positively affects both physical and psychological wellbeing in people with and without chronic health conditions. No direction of causality could be established.

Morphological analysis of palatal rugae patterns in a population of Maharashtrian ancestry: a cross-sectional study

AIM

To analyze the morphological parameters of palatal rugae in a population of Maharashtrian ancestry.

MATERIAL AND METHODS

This study was conducted on 1000 subjects of Maharashtrian ancestry with at least 3 generations on the mother's and father's side. Their palatal impressions were obtained with alginate and the casts were analyzed for length, shape and direction of palatal rugae.

RESULTS

Our results showed that the most predominant rugae were primary followed by secondary and fragmentary with significant differences between them. The most prevalent rugae shapes found were straight followed by wavy followed by curved with significant differences between them. According to direction, forward rugae were significantly higher than perpendicular rugae and backward rugae.

CONCLUSION

The rugae are considered to have population specific configurations. This baseline data of patterns of palatal rugae in a sample of Maharashtrian ancestry may serve `as an accessory tool' for population identification in Forensic Dentistry.

Relationships Between Psychological, Sleep, and Physical Activity Measures and Somatosensory Function in People With Peripheral Joint Pain: A Systematic Review and Meta-Analysis

OBJECTIVE

Alteration in somatosensory function has been linked to pain experience in individuals with joint pain. In this systematic review we aimed to establish the level of evidence of associations between psychological, social, physical activity, and sleep measures and somatosensory function that were assessed via quantitative sensory testing (QST) among individuals with joint pain.

METHODS

A comprehensive literature search was conducted in 6 electronic databases from their inception to July 2019. Two reviewers independently assessed the methodological quality using a modified Quality in Prognostic Studies (QUIPS) tool and supplemented with recommendations from the Critical Appraisal and Data Extraction for Systematic Review of Prediction Modelling Studies (CHARMS) checklist and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The level of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system. Data were pooled to evaluate the strength of the relationships of interest.

RESULTS

Seventeen studies related to joint pain were included. Pain catastrophizing, depression, anxiety, and physical activity level have been shown to have a significant (small to fair) association with several QST measures. Pressure pain threshold (PPT) is the only measure that was found to be consistently correlated with all the domains. The overall quality of evidence for all factors ranged from very low to moderate. Subgroup analysis revealed a stronger association for depression and pain catastrophizing and PPT and temporal pain summation in individuals with shoulder pain.

CONCLUSION

Psychological factors and physical activity levels are associated with somatosensory function in people with joint pain. These factors need to be adjusted when establishing predictive relationships between somatosensory function and pain outcomes in individuals with joint pain.

Prognostic evaluation of metastasizing ameloblastoma: A systematic review of reported cases in literature

Ameloblastoma is a benign odontogenic tumor which undergoes malignant transformation to ameloblastic carcinoma. However, rarely it metastasizes without undergoing cytological malignant changes, an entity referred to as Metastasizing Ameloblastoma (MA). Through this study, we aimed to review cases of MA reported since 2000 to explore the impact of clinico-demographic variables on its prognosis. Based on PRISMA guidelines, a review of relevant literature from PubMed/Medline, Science Direct and Cochrane database was performed from January 2000 to March 2019. A total of 65 cases were considered for further evaluation as per predefined inclusion and exclusion criteria. Results showed that lungs followed by lymph nodes were the most common sites for benign metastatic deposits. Multiple recurrences and inadequate surgical removal increase the probability of distant metastatic spread. Despite having benign cytological features, tumor recurrence and metastasis were associated with an unfavorable clinical outcome in MA.

A communication skills intervention to minimise patient perpetrated aggression for healthcare support workers in New Zealand: A cluster randomised controlled trial

Healthcare support workers face challenging situations in their day-to-day work but may have minimal training on how to deal with such incidents. Although staff training is often recommended as an essential part of any comprehensive approach for preventing and managing workplace violence, there is paucity of evidence on the content and effectiveness of such training. This study aimed to evaluate the effect of an intervention (communication skills training) to reduce the experience of aggression for healthcare support workers. A two arm, cluster randomised, single-blinded, controlled trial among healthcare support workers in nongovernmental organisations (NGOs) and District Health Boards (DHBs) in New Zealand was conducted. The trial was conducted across 14 NGOs and DHB in Otago, Southland, and Auckland regions of New Zealand. One hundred and twenty-seven participants were randomised to one of two groups. Both the intervention (communication skills) and control condition (mindfulness) were group-based, fully scripted, and structured training interventions that consisted of four once weekly workshops that were facilitated by one of two nonclinical facilitators. Measurements of perceived aggression, psychological well-being, and distress and communication competence were taken pre-, post-, 3 months' post-, and 6 months' postintervention. There was a significant drop in the rate of aggression over time with a mean score and standard deviation of 10.37 (9.169) at baseline dropping to 6.07 (6.923) for the Perception of Patient Aggression Scale-New Zealand across both intervention and control. Equivalent results were noted with increased psychological well-being and communication competence and decreased distress with both interventions. This was sustained at 6 months' follow-up. However, the between groups effect did not demonstrate a statistically significant difference between the intervention and control groups. Both mindfulness and communication skills training can reduce the experience of aggression reported by healthcare support workers.

Distress in informal carers of the elderly in New Zealand

AIMS

Informal care, which is unpaid and often provided by family and friends, is the primary source of aged care in New Zealand. In addition to financial costs there are known psychological costs of being a carer, including poor mental health.

METHODS

This research aimed to interview a group of New Zealand carers and describe their rates of depression and anxiety, their motivations for providing care, costs of care and their experience of aggression. Interviews used standardised questions and were conducted over the phone.

RESULTS

Results are reported from interviews of 48 carers and suggest this group have elevated symptoms of depression and anxiety. Most of the carers are partners or children of the carees and likely do the caring out of love. Unpaid family carers experience low levels of aggression. Carers reported personal and social restriction, and physical and emotional health the most burdensome aspect of being a carer.

CONCLUSIONS

Carers of the elderly in New Zealand show elevated levels of distress. Higher levels of emotional support are needed for New Zealand carers. If the health system continues to rely on unpaid carers more should be done to support them.

A qualitative study of pain experiences in patients requiring hip and knee arthroplasty

The aim of this study was to conduct an in-depth investigation of experiences with pain before knee and hip replacement surgery. A total of 20 patients were interviewed, and interpretative phenomenological analysis was used to identify themes. These were as follows: living with pain, pain conceptualised, pain treatments and healthcare system. Pre-surgical pain is very disabling and is viewed as biological. There was an associated loss of independence. Pharmaceutical management is used by all but not entirely effective, psychological therapies are underutilised. Patients were frustrated, angry, and confused about qualifying for surgery. Many areas of care could be improved to help these pre-surgical patients.

Healthcare Managers' Perceptions of Patient Perpetrated Aggression and Prevention Strategies: A Cross Sectional Survey

Patient or client aggression towards staff is a risk in healthcare. Healthcare takes place in a variety of settings, including hospitals, community, and Aged Care facilities. A minimal amount is known regarding the existence of safety and training measures available throughout the broad range of hospital and community healthcare services. A web-based survey of the type and frequency of violence experienced by healthcare staff was sent to unit managers working in mental health and older peoples' services of District Health Boards, Non-Governmental Organisations, and Aged Care facilities across New Zealand. One hundred and forty-one managers responded to the survey with a response rate of 79.21%. Managers reported high rates of verbal aggression and assaults against staff within their services. A total of 60% of respondents stated that an increase in assaults against staff was due to an increase in violent events and 43.1% related this to increased staff awareness and reporting of violent events to management. Communication skills and de-escalation training were provided across approximately 95% of organisations. The availability of safety measures including panic buttons, personal alarms, use of security personnel, and police assistance were more widely available and accessible within hospital settings and the community sector was found to mostly rely on police for assistance when violence occurs. The perception of violence is high in healthcare. Prevention and management training is provided in public hospital and aged care setting but not so much in NGOs. All areas of healthcare provision could benefit from increased evidence based aggression prevention programmes.

Patient aggression experienced by staff in a New Zealand public hospital setting

AIMS

Working in a healthcare environment is a known risk factor for violence. Patient aggression towards staff is often present in a hospital setting but the extent, type and variation among various occupations and roles are not known.

METHOD

This research examines the type and frequency of aggression experienced by healthcare staff, using a previously used measure the POPAS-NZ, which is a short pen and paper survey. Responses were gathered from 227 people working in a single district health board.

RESULTS

Responses showed verbal anger was experienced by 93% of healthcare workers in the previous year and physical aggression was experienced by 65% of respondents. Also, 38% of staff reported experiencing a physical assault in the previous year. When analysed by role it was found that nurses and support staff experienced the greatest number of aggressive incidents compared to doctors and allied health staff. No effects of gender of the healthcare worker were found. Psychiatric units showed greater levels of destructive behaviour and attempted assaults but were similar to other areas of the hospital on all other measures.

CONCLUSION

These results demonstrate many hospital staff, of all roles and workplaces experience aggression on a frequent basis. Implications for staff training are discussed.

Chronic pain in New Zealand: a community sample

AIM

The 2010 New Zealand Chronic Pain Survey aimed to gather information from people who experience chronic pain about their pain, mental health, disabilities, and acceptance of pain.

METHODS

In December 2010, surveys were distributed in paper or online to GPs, hospitals, pain clinics asking for people with chronic pain to respond. The survey was open for 6 weeks.

RESULTS

There were 142 responses to the survey. Most people reported more than one cause of their pain, and pain in more than one site. Although respondents reported a wide range of causes of their pain, most people were unsure of the cause, or endorsed injury or arthritis as the cause. The most common site of pain was the lower back, followed by the pelvis and joints. Levels of disability were high. Pain was significantly correlated with depression and anxiety, and negatively correlated with acceptance.

CONCLUSION

New Zealanders experience chronic pain stemming from multiple origins, with multiple causes. Consistent with international data, the experience of pain causes high levels of mental health issues and disability, but can be modulated by acceptance. Future studies should examine treatment availability and effectiveness.

Oral submucous fibrosis: a report of two pediatric cases and a brief review

Oral submucous fibrosis is a chronic debilitating disorder which is usually seen in adults with areca nut chewing habit. A rapid upsurge in the popularity of commercial areca nut products, especially among the younger generation, is a cause of grave concern, as satisfactory management is still lacking. Hereby, two pediatric cases of oral submucous fibrosis are reported.

Taking personal responsibility for well-being increases birth satisfaction of first time mothers

Birth satisfaction has been found to enhance a mother’s capacity to develop a sense of maternal identity. This study used a phenomenological form of thematic analysis to gain in-depth insights into the birth experiences of first-time New Zealand mothers. Taking personal responsibility (the choices participants made in relation to being in control of and accountable for their own birth processes) was a core theme. Those participants who described the neoliberalist ideal of taking personal responsibility to be well informed and well prepared for any birth experience felt more confident that they would be able to work with whatever labour and birth event eventuated.

Patient aggression perceived by community support workers

Objective: Aggression by patients is a known risk factor for hospital workers. Within New Zealand, the bulk of ongoing care for physical and mental disabilities and health issues is not hospital based, but contracted to various non-governmental agencies. The rate of client aggression towards care workers from these organizations, to our knowledge, has not been assessed. Method: Two hundred and forty-two support workers in non-governmental agencies caring for people with disabilities responded to an anonymous mailed survey on client aggression, personal distress, and communication style. Results: Most support workers did experience verbal forms of aggression or destructive behaviour, fewer experienced physical aggression, and a minority were injured, sexually harassed, stalked or harassed by means of formal complaint. The median total violence score was five (interquartile range 12.25). A higher total violence score (using the POPAS-NZ) was associated with age and gender, the primary disability of clients, and the numbers of hours worked. The length of time worked was not associated with total violence risk. Communication style, after correcting for other factors, was a predictor of aggression. Almost 6% of care workers reported distress symptoms at a level associated with clinically significant stress reactions. Conclusions: Patient aggression is common among care workers, and can cause distress in the minority. We suggest that further research to clarify risk factors and develop interventions for care workers is needed.

The effects of hippocampal and area parahippocampalis lesions in pigeons: I. Delayed matching to sample

Four experiments were conducted to determine the effects of bilateral damage to the hippocampus and area parahippocampalis (Hp-APH) on visual memory in pigeons using the delayed matching-to-sample (DMS) procedure. In Experiment 1, we generated visual retention gradients with delays of 0, 1.5, 3, 6, and 12 sec both preoperatively and postoperatively in three pigeons with considerable preoperative visual DMS experience. Bilateral Hp-APH lesions had no effect whatsoever on visual retention. In Experiment 2, we examined the effects of Hp-APH lesions on both the acquisition of a visual DMS task with a 0-sec delay, and the subsequent retention performance with delays of 0, 3, 6, 12, and 24 sec. There was no difference between unoperated control pigeons and Hp-APH pigeons either in terms of the number of sessions required to learn the visual DMS task or in terms of their subsequent visual retention performance levels. In Experiments 3 and 4, we examined whether Hp-APH pigeons might be more sensitive than control pigeons to the effects of proactive interference (by reducing the duration of the intertrial interval) and retroactive interference (by introducing delay-interval illumination). Although reducing the duration of the intertrial interval and increasing the level of delay-interval illumination both resulted in lower performance levels on the visual DMS task, there was no indication that the Hp-APH pigeons were any more affected by the changes in interference levels than were unoperated control pigeons. These findings support the view that the Hp-APH in pigeons plays little role in the processing and retention of purely visual information.