Shelley Channon

Classical conditioning after temporal lobe lesions in man : impairment in conditional discrimination

Left and right temporal lobectomy patients, patients with frontal lobe lesions, and healthy control subjects participated in an eyelid conditioning study based on conditional discrimination learning. All groups acquired the first conditioned response at a similar time during learning, but both temporal lobectomy groups showed poorer discrimination than control subjects. The results support models that relate hippocampal function to operation of if-then rules.

Working memory in clinical depression : an experimental study

This study compared clinically depressed subjects with normal controls on a range of working memory tasks. The findings suggested the articulatory loop and visuospatial sketch pad components of working memory to be unimpaired in depression. On a range of clinical tasks likely to involve central executive function, depressed subjects showed impairment only on some tasks.

Depressive symptomatology in a general hospital sample of outpatients with temporal lobe epilepsy: a controlled study.

Summary: We compared temporal lobe epilepsy (TLE) outpatients attending a general hospital with depressed psychiatric patients and normal control subjects to investigate depressive symptomatology. Both clinicianrated measures and self‐report questionnaires were used. Rates of depressive and anxious symptomatology in TLE subjects were higher than those in a normal control sample, but TLE subjects did not differ significantly from controls on anxiety measures. The depressed psychiatric group scored higher than the TLE and control groups on both depression and anxiety measures. Rates of depressive symptomatology in the TLE group were lower than those reported in previous studies for persons attending specialist epilepsy clinics, but similar to the findings of one community study.

Classical conditioning after temporal lobe lesions in man: sparing of simple discrimination and extinction

Recent reports of impaired conditional discrimination learning in temporal lobectomy subjects have raised the question of response inhibition deficits in these patients. In the present study, left and right temporal lobectomy subjects and healthy controls completed an eyelid conditioning task, which required simple two-tone discrimination learning, followed by extinction. There were no group differences with regard to discrimination learning or extinction. General deficits in response inhibition are therefore not likely to account for the impairment in conditional discrimination observed in temporal lobectomy patients.

T-Maze Discrimination and Reversal Learning After Unilateral Temporal or Frontal Lobe Lesions in Man

The interpretation of conditional discrimination and reversal learning as acquisition of declarative knowledge suggests that subjects with temporal lobe/hippocampal lesions are likely to be impaired on such tasks. Patients with unilateral left or right temporal lobectomy (and small hippocampal excisions) and patients with unilateral frontal lobe resections were compared with healthy controls on a discrimination reversal task, embedded in a computer game modelled on T-maze tasks traditionally used in animal experiments. The right temporal group showed a deficit in acquiring an initial conditional discrimination, and the frontal group tended to display a marginal impairment in discrimination reversal. These findings are compared with results from animal studies in terms of the mechanisms underlying reversal learning.

Real-life-type problem solving in Tourette syndrome.

ObjectiveThe main objective of the study was to examine social problem solving in real-life–type situations in Tourette syndrome (TS). BackgroundStudies of cognitive functioning in TS have usually focused on nonsocial, abstract tasks, with mixed findings as to whether there is evidence of impairment in executive functions in those without comorbid disorders. The current study focuses primarily on social functioning, using a problem-solving task known to be sensitive to frontal lobe lesions. MethodsTS participants without comorbid diagnoses were compared with matched healthy control participants on a problem-solving task, using a range of interpersonal problem scenarios presented on video. A set of more abstract executive tests was also included. ResultsParticipants with TS were found to perform below a matched control group on the problem-solving task both in generating a range of potential problem solutions, and in selecting appropriate final solutions. They also performed more poorly on aspects of executive function. ConclusionsThis study provides evidence of difficulties in both social and nonsocial aspects of functioning in TS. The implications of the findings for our understanding of TS and problem solving are discussed.

Effects of structure and clustering on recall and recognition memory in clinical depression.

The present study compared retrieval of high, medium, and low structured material, using word lists consisting of uncategorized words and categorized words presented in randomized and clustered order. Clinically depressed subjects were found to be significantly impaired relative to controls only on the medium level of structure and the randomized categories list when measured by free recall. There were no effects of group nor any interactions for recognition memory, although there was a main effect for group on d when signal detection analysis was applied. The implications of the findings for models of memory deficits in depression are discussed.

The effect of categorization on verbal memory after temporal lobectomy

Epileptic patients with left or right temporal lobectomies were compared with normal subjects on a verbal memory task involving recall and recognition of categorized and uncategorized word lists. The left temporal group recalled significantly fewer words than the normal control subjects, and recognition performance was also poorer. The right temporal group did not differ significantly from the normal controls on recognition, although differences neared significance on recall. Categorization improved performance in all the groups. The left temporal patients improved if words were presented in order of category membership, but recalled less if category membership was randomized over order of presentation.

Operant conditioning after temporal lobe lesions in man: Conditional and simple discrimination learning

Temporal lobe lesions have been found to impair the acquisition of classical conditional discrimination learning in an eyelid conditioning paradigm, with sparing of simple eyelid conditioning. In the present study, subjects with left or right temporal resections were compared with normal controls on two operant conditioning tasks using a conditional and a simple discrimination paradigm analogous to the previously reported classical conditioning tasks. Subjects with right temporal lesions, and to a lesser extent those with left temporal lesions, were impaired relative to frontal lobe and control subjects in the acquisition of a conditional discrimination within an operant conditioning setting. A subsequent experiment showed that both left and right temporal lobe subjects were unimpaired on a simple operant discrimination task. These findings are compatible with theory relating hippocampal function to the learning of if-then rules.

Cognitive strategies and hypothesis testing during discrimination learning in Parkinson's disease

This study investigated the nature and extent of impairments in the use of hypotheses and cognitive strategies in medicated subjects with idiopathic Parkinsons disease (PD) and matched control subjects. PD subjects did not differ from controls in solving one- or two-dimensional discrimination learning problems, but showed impairment on four-dimensional problems which did not appear to be attributable to memory deficits. They achieved fewer correct solutions, used fewer hypotheses, and were less likely to use appropriate lose-shift strategies following negative feedback. The pattern of findings was similar to those previously reported for subjects with frontal lobe lesions.