Evaluation of memory in persons with mesial temporal lobe sclerosis: A combined fMRI and VBM study

Persons with drug refractory TLE have the option of being managed by surgery. They may develop memoryimpairment with specific etiology of mesial temporal sclerosis and anterior temporal lobe resection (ATLR).The study evaluated the semantic verbal memory outcomes in pre- and post-surgery temporal lobe epilepsy(TLE) patients using functional MRI and voxel morphometric methods. Twenty consecutive persons withdrug-resistant epilepsy (DRE) and 20 healthy controls were recruited after obtaining the institute ethicsapproval. The fMRI scans were performed on a 1.5 T MR Scanner using standardized semantic verbal memorytasks using a native Hindi paradigm, before and after an anterior temporal lobectomy (in cases). A task-basedfunctional connectivity (FC) was estimated using a conn toolbox. Data analysis was carried out using thestatistical parametric imaging (SPM12) and CAT12 toolbox. Post-surgery TLE group showed increased robustFC in the right middle and posterior temporal regions as compared to pre-surgery session. A significantreduction in grey matter volume was observed in the left temporal lobe post-operatively as compared to presurgery and healthy control groups. In the post-surgery TLE group, neuropsychological scores were reduced inspecific PGI domains such as visuospatial, working memory, and executive functioning. Our results may helpin understanding of memory reorganization in TLE post-operatively.

Mechanism of selective attention: fMRI study of face-word stroop task performance.

Selective attention is the cognitive process of selecting and processing the task relevant information and ignoring the task irrelevant information. Though the neural substrates involved in this cognitive process are well established, the mechanism of selection process is the point of contention. To study the effect of selection process on the information processing we performed functional neuroimaging on 23 healthy righthanded male subjects while performing a modified face word stroop task. The word processing area did not show any attention dependent changes in the level of activity whereas the activity of face processing area was higher when the faces were target, but there was no decrease in baseline activity when faces were distractors. Our results suggest that during selective attention there is no biasing of sensory processing for automatically processed stimuli like words whereas there is amplification of task relevant information when stimuli are processed in controlled manner.

Soft drinks: Are they really soft.

We report a case of epileptic seizures following heavy consumption of a cola and caffeine containing soft drink. The probable cause for seizures could be due to a combination of hyponatraemia, water intoxication, and high dose of caffeine and aspartame from the soft drink.

Cortical activation during finger tapping in thyroid dysfunction: a functional magnetic resonance imaging study.

Thyroid dysfunction is associated with attention deficit and impairment of the motor system (muscle weakness and fatigue). This paper investigates possible motor function deficit in thyroid patients,compared to the controls. Functional MRI studies (fMRI)were carried out in five hypo and five hyperthyroid patients and six healthy volunteers. Whole brain imaging was performed using echo planar imaging (EPI)technique, on a 1.5T whole body MR system (Siemens Magnetom Vision). The task paradigm consisted of 8 cycles of active and reference phases of 6 measurements each, with right index finger tapping at a rate of 120 taps/min. Post-processing was performed using statistical parametric mapping on a voxel-by-voxel basis using SPM99. Clusters of activation were found in the contralateral hemisphere in primary somatomotor area (M1), supplementary motor area (SMA), somatosensory,auditory receptive and integration areas, inferior temporal lobe, thalamus and cerebellum. Increased clusters of activation were observed in M1 in thyroid subjects as compared to controls and with bilateral activation of the primary motor cortex in two hyperthyroid patients. The results are explained in terms of increased functional demands in thyroid patients compared to volunteers for the execution of the same task.