Temporal Dysfunction Research Articles

Variant Creutzfeldt–Jacob disease: the second case in Portugal and in the same geographical region

We present the second variant Creutzfeldt–Jacob patient in the same district of northwest Portugal as was previously reported. A 14-year-old previously healthy girl had unexplained pain in the left leg,...

Eye movement and visual motion perception in schizophrenia I: Apparent motion evoked smooth pursuit eye movement reveals a hidden dysfunction in smooth pursuit eye movement in schizophrenia

To date, smooth pursuit eye movement in schizophrenia has only been investigated using a target stimulus in continuous motion. However, smooth pursuit can also be evoked by an oscillating jumping dot that appears to be in apparent motion and although there is no continuous motion on the retinal surface this apparently moving stimulus can effortlessly elicit smooth-pursuit eye movement. In the first of two experiments smooth pursuit eye movement was evoked by target stimuli in continuous (real) motion at seven target velocities from 5.0 to 35.0 deg/s, and in a second experiment it was measured in response to an oscillating jumping dot in apparent motion at eight target velocities from 5.0 to 25.0 deg/s in a group with mixed-symptoms in schizophrenia and in a control group. The results of Experiment 1 provided no evidence for a dysfunction in continuous motion evoked smooth pursuit eye movement in the group with schizophrenia. However, following the removal of saccadic eye movements in smooth pursuit, the group with schizophrenia showed significantly lower smooth pursuit eye velocity at target velocities from 20.0 to 35.0 deg/s. The results of Experiment 2 revealed that apparent motion evoked smooth pursuit eye velocity in the group with schizophrenia was significantly lower in comparison with normal observers at all target velocities up to 25.0 deg/s with the inclusion or exclusion of saccadic eye movements. The findings demonstrate that overall smooth pursuit eye movement evoked in response to a continuous (real) motion target in the group with schizophrenia may nevertheless contain a hidden temporal resolution and integration dysfunction that is revealed when smooth pursuit eye movement is evoked in response to an oscillating jumping dot in apparent motion. The findings also demonstrate that normal smooth pursuit eye movement in normal observers can be made to resemble the dysfunctional smooth pursuit eye movement that is naturally found in some people with schizophrenia by using a target stimulus in apparent motion.

Poor Penmanship in Children Correlates With Abnormal Rhythmic Tapping: A Broad Functional Temporal Impairment

Timing is crucial for proficient motor tasks; temporal impairments may lead to dysfunctional motor activities. Although much research has been dedicated to the study of movement timing, clinical examination often overlooks temporal impairment of motor activity. The authors hypothesize that some children have a global temporal impairment leading to dysfunctional motor skills. This article checks whether temporal abnormalities detected on a simple tapping task correlate with temporal dysfunction during complex motor skills such as handwriting. Twenty-three school-aged children, 8-14 years (11.1 +/- 1.3 years), underwent tests to assess finger tapping and cursive handwriting. Handwriting samples were rated by experienced teachers. Children with abnormal tapping had lower handwriting rating scores. Temporal features were similar in both tasks; variability on the tapping test correlated with handwriting variability. Temporal variability was not significantly higher for children with poor penmanship as a whole but rather specific to the subgroup of children with a tapping abnormality. Poor penmanship could be attributed in certain children to global temporal impairment reflected as variable finger tapping and handwriting. Evaluation of dysfunctional motor performance should include temporal aspects, and further studies are needed to better delineate and address treatment of "dysrhythmia."

Right temporal cerebral dysfunction heralds symptoms of acute mountain sickness

Acute mountain sickness (AMS) can occur during climbs to high altitudes and may seriously disturb the behavioral and intellectual capacities of susceptible subjects. During a Himalayan expedition 32 mountaineers were examined with electroencephalography (EEG) and transcranial doppler sonography (TCD) to assess relative changes of middle cerebral artery velocity in relation to end-expiratory CO2 (EtCO2), peripheral saturation (SaO2), and symptoms of AMS. We tested the hypothesis that O2 desaturation and EtCO2 changes precede the development of AMS and result in brain dysfunction and compensatory mechanisms which can be measured by EEG and TCD, respectively. Contrary to our hypothesis, we found that subjects who later developed symptoms of AMS between 3,440 m and 5,050 m altitude exhibited an increase of slow cerebral activity in the right temporal region already at 3,440 m. Cerebral blood flow increased in these mountaineers in the right middle cerebral artery at 5,050 m. These findings indicate that regional brain dysfunction, which can be documented by EEG, heralds the appearance of clinical symptoms of AMS.

Right temporal cerebral dysfunction heralds symptoms of acute mountain sickness

Right temporal cerebral dysfunction heralds symptoms of acute mountain sickness

Working memory dysfunction in schizophrenia compared to healthy controls and patients with depression: Evidence from event-related fMRI

Studies on working memory (WM) dysfunction in schizophrenia have reported several functionally aberrant brain areas including the lateral prefrontal cortex, superior temporal areas and the striatum. However, less is known about the relationship of WM-dysfunction, cerebral activation, task-accuracy and diagnostic specificity. Using a novel WM-task and event-related functional magnetic resonance imaging (fMRI), we studied healthy control subjects ( n = 17) and partially remitted, medicated inpatients meeting DSM-IV criteria for schizophrenia ( n = 19) and major depressive disorder ( n = 12). Due to the event-related technique, we excluded incorrectly performed trials, thus controlling for accuracy-related activation confounds. Compared with controls, patients with schizophrenia showed less activation in frontoparietal and subcortical regions at high cognitive load levels. Compared with patients with depression, schizophrenic patients showed less prefrontal activation in left inferior frontal cortex and right cerebellum. In patients with schizophrenia, a lack of deactivation of the superior temporal cortex was found compared to both healthy controls and patients with depression. Thus, we could not confirm previous findings of impaired lateral prefrontal activation during WM performance in schizophrenic patients after the exclusion of incorrectly performed or omitted trials in our functional analysis. However, superior temporal cortex dysfunction in patients with schizophrenia may be regarded as schizophrenia-specific finding in terms of psychiatric diagnosis specificity.

0063 CRIMINAL BEHAVIOUR IN FIRST ONSET PSYCHOSIS

Some patients with left temporal degeneration develop visual artistic abilities. These new artistic abilities may be due to disinhibition of the visuo-spatially dominant right hemisphere. Many famous artists have had epilepsy and it is possible that some may have had left temporal seizures (LTS) and this left temporal dysfunction disinhibited their right hemisphere. Alternatively, unilateral epilepsy may alter intrahemispheric connectivity and right anterior temporal lobe seizures (RTS) may have increased these artists' right hemisphere mediated visual artistic creativity.To test the disinhibition versus enhanced connectivity hypotheses we studied 9 participants with RTS and 9 with left anterior temporal seizures (LTS) who underwent unilateral lobectomy for the treatment of medically refractory epilepsy. Creativity was tested using the Torrance Test of Creative Thinking (TTCT).There were no between group differences in either the verbal or figural scores of the TTCT, suggesting that unilateral anterior temporal ablation did not enhance visual artistic ability; however, for the RTS participants' figural creativity scores were significantly higher than verbal scores. Whereas these results fail to support the left temporal lobe disinhibition postulate of enhanced figural creativity, the finding that the patients with RTS had better figural than verbal creativity suggests that their recurrent right hemispheric seizures lead to changes in their right hemispheric networks that facilitated visual creativity. To obtain converging evidence, studies on RTS participants who have not undergone lobectomy will need to be performed.

P1-131: Acute phase and following phase in transient global amnesia

Transient global amnesia is a reversible memory disorder characterized by episodic dysfunction of declarative memory. The purpose of this study is to investigate the change on clinical aspect and functional imaging during and after attack of TGA. Six patients were included in this study with amnestic episodes which fulfilled the criteria for TGA, as published by Hodges and Warlow. The patients were divided into two subgroups according to encoding failure on episodic memory. Acute phase group was defined as patients having encoding failure on episodic memory. Following phase group was defined as patients recovering from amnestic period. Two patients belonged to the acute phase group and the remaining four patients to following phase group. All the subjects underwent brain perfusion SPECT. Clinical aspect in memory disturbance was rated with full neuropsychological test. It consists of many tests in five domains (attention, language and related functions, visuospatial function, memory and frontal executive function). Two patients, who were evaluated during the attack of TGA, showed encoding failure on verbal and visuospatial memory. Brain perfusion SPECT ,however, revealed no perfusion defect. In following phase group (n=4), neuropsychological test demonstrated frontal lobe dysfunction involving retrieval difficulty in verbal and visuospatial memory, decreased semantic word fluency and decreased inhibition ability on stroop test in three patients. The remaining one patient showed encoding failure in visuospatial memory. Brain perfusion SPECT demonstrated variable abnormality on cortical areas; hypoperfusion on right medial temporal and basal ganglia (n=1), bilateral temporal lobe (n=1), left post. sup. parietal lobe (n=1) and normal perfusion with decreased vascular reserve on right basal ganglia (n=1). No perfusion defect in SPECT was exhibited in the two patients evaluated during the attack of TGA, who showed bilateral temporal dysfunction in neuropsychological studies at the same time. Hypoperfusion in the variable cortical area was revealed in the following phase group, but perfusion defect was not found in the frontal lobe. Three patients showed frontal lobe dysfunction in neuropsychological test at that time. These findings suggested that hypoperfusion is not a primary event in TGA. It probably represents the secondary response to decreased metabolism.

Patterns of memory impairment in bipolar disorder and unipolar major depression

Unipolar and bipolar depression are known to exert detrimental effects on learning and memory processes. However, few comparisons have been undertaken between bipolar and unipolar patients with comparable illness histories, and predictors of impairment are not well understood. Adult outpatients with unipolar major depressive illness (UP, n = 30) and bipolar disorder (BP, n = 30), group-matched for illness duration and severity of depressive symptomatology (16% clinically remitted, 42% partially remitted, 42% depressed), and 30 demographically matched controls completed measures of general cognitive functioning and declarative memory. Despite comparable general intellectual abilities, BP and UP patients exhibited significant memory deficits relative to healthy controls. A similar deficit profile was observed in both patient groups, involving poorer verbal recall and recognition. Impairments were not secondary to strategic processing deficits or rapid forgetting. Although depression severity was not associated with neurocognitive performance, number of hospitalizations and family history of mood disorder significantly affected memory function in BP, but not UP, patients. Results suggest qualitatively similar patterns of memory impairment in BP and UP patients, consistent with a primary encoding deficit. These impairments do not appear to be secondary to clinical state, but rather suggest a similar underlying pathophysiology involving medial temporal dysfunction.

Word Reading and Posterior Temporal Dysfunction in Amnestic Mild Cognitive Impairment

Patient studies that combine functional magnetic resonance imaging with chronometric analysis of language dysfunction may reveal the critical contribution of brain areas to language processes as well as shed light on disease pathogenesis. In amnestic mild cognitive impairment (MCI), a prodromal stage of Alzheimer's disease, we examined whether the brain system for associative-semantic judgments with words or with pictures is affected and how this relates to off-line chronometric analysis of word reading and picture naming. A consecutive memory clinic-based series of 13 amnestic MCI patients as well as 13 matched controls participated. One area, the lower bank of the posterior third of the left superior temporal sulcus (STS), showed a significant group-by-task interaction: In controls, it was activated during the associative-semantic condition with words compared with the visuoperceptual control condition but not when the same tasks were compared with pictures as input. In MCI, this word-specific activation was significantly reduced. Response amplitude correlated (r = 0.90) with the steepness of the slope of the time-accuracy curve for word reading. Our data provide converging evidence for a critical contribution of the lower bank of the left posterior STS to mapping word form onto word meaning (lexical-semantic retrieval).

Right Temporal Cerebral Dysfunction Heralds Symptoms of Acute Mountain Sickness

Right Temporal Cerebral Dysfunction Heralds Symptoms of Acute Mountain Sickness

Behavioral and Electrophysiological Indices of Temporal Processing Dysfunction in Schizophrenia

Timing deficits in schizophrenia have been noted in several behavioral studies. However, the involvement of mediating factors, such as inattention, has not been ruled out as contributing to these effects. Mismatch negativity (MMN), an electrophysiological measure, may provide a more direct index of stimulus processing ability in individuals with schizophrenia. The current study explored the relationship between behavioral time judgments and a time-based MMN paradigm. Participants were administered two MMN paradigms consisting of an "easy" or "difficult" deviant and an analogous behavioral measure of time processing. Matched against a healthy comparison group, patients exhibited decreased MMN amplitude on the "difficult" deviant interval only. However, on the behavioral paradigm, the patients made significantly more errors across all conditions. These results suggest that behavioral measures of time processing may reflect different processes than those captured by preattentive physiological measures in this population.

Behavioral and Electrophysiological Indices of Temporal Processing Dysfunction in Schizophrenia

Timing deficits in schizophrenia have been noted in several behavioral studies. However, the involvement of mediating factors, such as inattention, has not been ruled out as contributing to these effects. Mismatch negativity (MMN), an electrophysiological measure, may provide a more direct index of stimulus processing ability in individuals with schizophrenia. The current study explored the relationship between behavioral time judgments and a time-based MMN paradigm. Participants were administered two MMN paradigms consisting of an “easy” or “difficult” deviant and an analogous behavioral measure of time processing. Matched against a healthy comparison group, patients exhibited decreased MMN amplitude on the “difficult” deviant interval only. However, on the behavioral paradigm, the patients made significantly more errors across all conditions. These results suggest that behavioral measures of time processing may reflect different processes than those captured by preattentive physiological measures in this population.

Utility of the Boston Naming Test in Predicting Ultimate Side of Surgery in Patients with Medically Intractable Temporal Lobe Epilepsy

Confrontation naming tasks have long been presumed to be sensitive to left temporal dysfunction and, consequently, are frequently used in the evaluation of surgical epilepsy patients. Despite wide and frequent use, few studies have examined the utility of confrontation naming tasks in individuals with temporal lobe epilepsy (TLE). The current study examined the presurgical Boston Naming Test (BNT) performance of 217 right-handed adult patients with intractable TLE (left, 108; right, 109) to determine the utility of this measure in predicting ultimate side of surgery. The results support the clinical utility of the BNT in determining ultimate side of surgery and suggest that the BNT has incremental validity over and above presurgical delayed memory and intelligence scores. This relation was found to be moderated by Full Scale IQ (FSIQ), age at seizure onset, and duration of epilepsy. The use of a logistic regression equation to predict side of surgery revealed that prediction of left temporal surgery was best among patients with low BNT scores, high FSIQs, and late age at seizure onset. In contrast, right temporal surgery was best predicted among patients with high BNT scores, low FSIQs, and short duration of epilepsy. This study supports the clinical utility of the BNT in the preoperative evaluation of candidates for TLE surgery and highlights the importance of examining potential moderating variables when making predictions about side of surgery. This study further provides clinicians with a regression equation that can be used to predict side of surgery in patients with temporal lobe epilepsy.

Neural correlates of anosognosia for cognitive impairment in Alzheimer's disease

We explored the neural substrate of anosognosia for cognitive impairment in Alzheimer's disease (AD). Two hundred nine patients with mild to moderate dementia and their caregivers assessed patients' cognitive impairment by answering a structured questionnaire. Subjects rated 13 cognitive domains as not impaired or associated with mild, moderate, severe, or very severe difficulties, and a sum score was calculated. Two measures of anosognosia were derived. A patient's self assessment, unconfounded by objective measurements of cognitive deficits such as dementia severity and episodic memory impairment, provided an estimate of impaired self-evaluative judgment about cognition in AD. Impaired self-evaluation was related to a decrease in brain metabolism measured with 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in orbital prefrontal cortex and in medial temporal structures. In a cognitive model of anosognosia, medial temporal dysfunction might impair a comparison mechanism between current information on cognition and personal knowledge. Hypoactivity in orbitofrontal cortex may not allow AD patients to update the qualitative judgment associated with their impaired cognitive abilities. Caregivers perceived greater cognitive impairments than patients did. The discrepancy score between caregiver's and patient's evaluations, an other measure of anosognosia, was negatively related to metabolic activity located in the temporoparietal junction, consistent with an impairment of self-referential processes and perspective taking in AD.

Neuropsychology/Language/Behavior: Adult

Neuropsychology/Language/Behavior: Adult

Memory deficits in abstinent MDMA (ecstasy) users: neuropsychological evidence of frontal dysfunction

Chronic administration of the common club drug 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is associated with long-term depletion of serotonin (5-HT) and loss of 5-HT axons in the brains of rodents and non-human primates, and evidence suggests that recreational MDMA consumption may also affect the human serotonergic system. Moreover, it was consistently shown that abstinent MDMA users have memory deficits. Recently, it was supposed that these deficits are an expression of a temporal or rather hippocampal dysfunction caused by the serotonergic neurotoxicity of MDMA. The aim of this study is to examine the memory deficits of MDMA users neuropsychologically in order to evaluate the role of different brain regions. Nineteen male abstinent MDMA users, 19 male abstinent cannabis users and 19 male drug-naive control subjects were examined with a German version of the Rey Auditory Verbal Learning Test (RAVLT). MDMA users showed widespread and marked verbal memory deficits, compared to drug-naive controls as well as compared to cannabis users, whereas cannabis users did not differ from control subjects in their memory performance. MDMA users revealed impairments in learning, consolidation, recall and recognition. In addition, they also showed a worse recall consistency and strong retroactive interference whereby both measures were previously associated with frontal lobe function. There was a significant correlation between memory performance and the amount of MDMA taken. These results suggest that the memory deficits of MDMA users are not only the result of a temporal or hippocampal dysfunction, but also of a dysfunction of regions within the frontal cortex.

What is the Role of Audition in Literacy?

What is the Role of Audition in Literacy?

Interaction Between Emotion and Memory: Importance of Mammillary Bodies Damage in a Mouse Model of the Alcoholic Korsakoff Syndrome

Chronic alcohol consumption (CAC) can lead to the Korsakoff syndrome (KS), a memory deficiency attributed to diencephalie damage and/or to medial temporal or cortical related dysfunction. The etiology of KS remains unclear. Most animal models of KS involve thiaminedeficient diets associated with pyrithiamine treatment. Here we present a mouse model of CAC-induced KS. We demonstrate that CAC-generated retrieval memory deficits in working/ episodic memory tasks, together with a reduction of fear reactivity, result from damage to the mammillary bodies (MB). Experimental lesions of MB in non-alcoholic mice produced the same memory and emotional impairments. Drugs having anxiogenic-like properties counteract such impairments produced by CAC or by MB lesions. We suggest (a) that MB are the essential components of a brain network underlying emotional processes, which would be critically important in the retrieval processes involved in working/ episodic memory tasks, and (b) that failure to maintain emotional arousal due to MB damage can be a main factor of CAC-induced memory deficits. Overall, our animal model fits well with general neuropsychological and anatomic impairments observed in KS.

Somatoform disorders after temporal lobectomy.

Depression, anxiety, and psychosis are the most frequent psychiatric disorders after epilepsy surgery. The only new-onset somatoform disorder reported postoperatively is conversion disorder. We identified 10 patients who developed somatoform disorder other than nonconversion epileptic seizures after anterior temporal lobectomy. We retrospectively reviewed the charts of 325 anterior temporal lobectomy and 125 extratemporal surgeries between 1991 and 2000. Seven of the patients developed undifferentiated somatoform disorder after anterior temporal lobectomy, 1 had pain and body dysmorphia, another had pain disorder, and another had body dysmorphia alone, but none were found after extratemporal surgeries (chi-square = 3.93; P < or = 0.05). Somatoform disorder was significantly more common in right anterior temporal lobectomy (n = 9) than left anterior temporal lobectomy (n = 1) (chi-square = 6.5; P < or = 0.025). Our findings suggest that right temporal resection contributes to the development of somatoform disorders in our patients and that right temporal dysfunctions may contribute to idiopathic somatoform disorders.