Experience-dependent changes in human brain activation during contingency learning.

Successful adaption requires learning to respond appropriately to cues associated with response-reinforcer contingencies. In this investigation, we used functional magnetic resonance imaging to characterize changes in frontal and limbic activation associated with learning under a positive reinforcement contingency. Imaging analyses identified linear and nonlinear changes in brain activation across nine reinforcement trials when response accuracy and reaction times were stable. The development of contingency control was generally associated with linear increases or inverted-U shaped changes in activation in superior, medial and orbitofrontal (OFC) regions, amygdala, insula and the medial temporal lobe. Linear decreases and U-shaped changes in activation were generally observed in parietal, occipital and cerebellar regions. Results highlighting linear increases in activation in superior, medial and OFC regions suggest involvement in the development of contingency control, even when behavior is stable. Results also highlighted a positive correlation between changes in OFC activation and amygdala activation. However, inspection of the correspondence between group changes and individual subject changes in OFC, amygdala and insula activation revealed that approximately half of subjects exhibited changes resembling group changes and the strength of the OFC-amygdala relationship varied markedly between subjects. Such disparities highlight a unique opportunity for exploring individual differences in regional sensitivity to contingency as well as improving experimental preparations to better highlight and control the effects of extraneous variables.

Experience-dependent plasticity: differential changes in activation associated with repeated reinforcement.

Experience-dependent change in blood-oxygen-level-dependent (BOLD) signal is increasingly being employed in neuroimaging research to examine questions about function and plasticity. In this investigation, plasticity was examined during consecutive visual cue presentations that preceded correct button presses and subsequent reinforcer deliveries. Using functional neuroimaging and a modified repeated acquisition methodology, 10 adult subjects learned, through trial and error, a series of novel cue-response-reinforcer relations. Separate BOLD responses were obtained to consecutive cues and reinforcers. Repeated measures analysis of variance highlighted differential BOLD response changes. Consecutive visual cue presentations elicited rapid bilateral increases in activation in the anterior cingulate and medial frontal gyrus and moderate increases in medial temporal lobe structures and the striatum. Consecutive reinforcer presentations elicited rapid increases in activation in the left precuneus, lingual and fusiform gyri and moderate increases in medial temporal lobe structures and striatum. Within the medial temporal lobe, cues elicited a gradual increase then an abrupt decrease in activation and rewards elicited abrupt and then sustained activation. Consideration of experience-dependent BOLD response change and variability provides basic research a new perspective from which to examine regional plasticity and further explore dynamic experience-dependent shifts among cognitive processes. Furthermore, BOLD change and variability offer many clinical research areas novel supplemental indices of neuropathology.

Relations between decision-making deficits and discriminating contingencies following brain injury.

Deficits in decision-making characterized by failures to respond adaptively to consequences that follow responding are common following brain injury. To examine decision-making about consequences, individuals with and without acquired brain injury responded under different response-reinforcer contingencies. In two control conditions, reinforcement was contingent on responding and response repetition. Results showed responding (pressing four computer keys) by both groups produced similar amounts of reinforcement (money) and highlight equal sensitivity to money as a reinforcer. In subsequent experimental conditions, reinforcement was contingent upon varying responses. Results showed both groups produced variable response patterns, but injured subjects earned less reinforcement than controls. With instructions to vary responding across trials, injured subjects earned similar amounts of reinforcement as controls. Collectively, the results suggest reductions in sensitivity to contingencies may be present following injury and function as one behavioural mechanism of maladaptive decision-making.

When instructions fail. The effects of stimulus control training on brain injury survivors' attending and reporting during hearing screenings.

Bedside hearing screenings are routinely conducted by speech and language pathologists for brain injury survivors during rehabilitation. Cognitive deficits resulting from brain injury, however, may interfere with obtaining estimates of auditory thresholds. Poor comprehension or attention deficits often compromise patient abilities to follow procedural instructions. This article describes the effects of jointly applying behavioral methods and psychophysical methods to improve two severely brain-injured survivors' attending and reporting on auditory test stimuli presentation. Treatment consisted of stimulus control training that involved differentially reinforcing responding in the presence and absence of an auditory test tone. Subsequent hearing screenings were conducted with novel auditory test tones and a common titration procedure. Results showed that prior stimulus control training improved attending and reporting such that hearing screenings were conducted and estimates of auditory thresholds were obtained.

The effects of traumatic brain injury on reporting and responding to causal relations: an investigation of sensitivity to reinforcement contingencies.

Impairments in judging and responding to consequences that follow behaviour are often attributed to changes in various cognitive processes. An alternative conceptualization is that impairments may produce a reduction in sensitivity to reinforcement contingencies. The present investigation employed a methodology commonly used in research on judgements of causality to examine the effects of TBI on sensitivity to reinforcement contingencies. Participants were non-injured control subjects and adults with TBI. The experimental task required subjects to press a response key under a series of concurrent response-reinforcer contingencies that periodically delivered money for responding and not responding. Afterwards, subjects provided a judgement about each response-reinforcer contingency by reporting the amount of money earned for responding and for not responding. Results suggest that TBI reduced the sensitivity of judgements and responding under select contingencies. These results lend some support to the view that TBI may reduce sensitivity to reinforcement contingencies. Furthermore, the investigation highlights the potential benefits of employing methods commonly used in human and animal operant research for the study of TBI.

Relations between traumatic brain injury and the environment: feedback reduces maladaptive behaviour exhibited by three persons with traumatic brain injury.

Feedback is a commonly used technique in neurorehabilitation. It functions to strengthen or weaken select relations between individuals' behaviour and their environment. The study of behaviour-environment relations is a focus of operant psychology, commonly referred to as behaviour analysis. Central to behaviour analysis is the analysis of interrelations among stimuli, behaviour, and consequences. The focus on behaviour-environment relations may have considerable benefits for designing clinical treatments and accounting for successful and unsuccessful treatments, especially psychological interventions for maladaptive behaviour. In the present investigation, three persons with traumatic brain injuries, diagnosed with depression and presenting mild cognitive impairments, received feedback about their maladaptive behaviour. Weekly feedback resulted in general reductions in the variability and frequency of maladaptive behaviour. The results support the utility of giving equal consideration to relations between persons with traumatic brain injury and their environment, despite existing psychological or cognitive impairments. Future research on variables that influence the development and maintenance of behaviour-environment relations, and more generally operant behaviour, may provide a unique perspective on the effects of traumatic brain injury.

Characteristics and outcomes of a home and community-based neurorehabilitation programme.

The potential clinical and financial advantages of providing neurorehabilitation directly in patients' homes and communities have recently been discussed. However, the specific characteristics and outcomes of a coordinated, interdisciplinary, home-based programme does not currently exist in the rehabilitation literature. The present paper presents patient demographics, type and intensity of services provided, satisfaction measures, and clinical outcomes for 77 brain injured individuals in an attempt to begin to define and evaluate this new level of care. Additionally, the challenges of conducting home-based rehabilitation, and needs for further research are discussed.

Self awareness: effects of feedback and review on verbal self reports and remembering following brain injury.

Brain injury may produce impairments in self awareness. The magnitude of impairment is often determined by comparing patient self reports with self reports of others (report-report) or with patient performance (report-performance). This paper presents data on the pattern of a self-awareness deficit in memory functioning exhibited by a brain injury survivor 5 years post-injury. The effects of practice and feedback on reporting-recall differences was examined using single case methodology. Several prospective and retrospective self reports were obtained, to allow an examination of reporting about past or future recall. Results showed that recall improved and the magnitude of report-recall differences were reduced with practice and feedback.