Event-related potentials study in children with borderline intellectual functioning.

BACKGROUND: Low general cognitive ability is a common cause for learning and academic difficulties. The present study was undertaken to objectively investigate the cognitive functioning of children having borderline intelligence using electrophysiological measures. MATERIALS AND METHODS: The study was conducted on children having borderline intelligence (IQ: 70-85). The cognitive functioning of children was assessed using event-related potentials. RESULTS: Significant prolongation of the latency of P200, N200, and P300 with no significant difference in the amplitudes was seen in the children having borderline intelligence as compared to controls. CONCLUSIONS: Brain systems that are important for stimulus discrimination and using cognitive representation to guide cognition and behavior are impaired in children with borderline intelligence.

Functional status of auditory pathways in children with borderline intellectual functioning: evoked potential study.

The present study was undertaken to determine whether impairment of sensory conduction in the auditory pathway is one of the contributory factors of performance in children with borderline intelligence. The study was conducted on children having borderline intelligence (IQ 71-84). The functional integrity of the central auditory pathway was assessed using Auditory Evoked Responses i.e. Auditory Brainstem response (ABR), Mid Latency Response (MLR) and Slow Vertex Response (SVR). The recordings were done using a computerized evoked potential recorder by 10-20 electrode placement system. There was no significant difference in the absolute peak latencies, the interpeak latencies and amplitude of ABR in the subjects as compared to controls. There was prolongation of the latency of MLR and SVR waves in subjects though not statistically significant indicating no conduction abnormality in the auditory pathway of the study subjects. Electrophysiological methods reveal underlying immaturity or abnormal brainstem timing and may serve as reliable tool in individuals with learning difficulties.

No auditory conduction abnormality in children with attention deficit hyperactivity disorder.

Attention deficit hyperactivity disorder (ADHD) is a neurobehavioral developmental disorder characterized by lack of sustained attention and hyperactivity. It has been suggested that asymmetrical conduction of the auditory stimulus in the brainstem plays a role in the pathophysiological process of ADHD. In the present study, the functional integrity of the central auditory pathway was assessed using the auditory brainstem response (ABR), mid-latency response (MLR) and slow vertex response (SVR). Twenty ADHD children and twenty controls were recruited for the study and recordings were done on a computerized evoked potential recorder using the 10-20 system of electrode placement. There emerged no significant difference in absolute peak latencies, interpeak latencies and amplitude of ABR or latency of MLR in the ADHD children as compared with the controls. Prolongation of the SVR latency was found in the children with ADHD versus the controls, but the difference was statistically insignificant. The present study does not suggest any auditory conduction abnormality as a contributory factor in ADHD.

Event-related potentials study in attention deficit hyperactivity disorder.

Attention deficit hyperactivity disorder (ADHD) is a childhood disorder characterized by lack of sustained attention, hyperactivity and impulsivity. Children with ADHD have functional impairment occurring at multiple levels. In the present study, cognitive status was assessed using auditory event-related potentials (ERPs). Twenty ADHD children and 20 controls were recruited for the study and ERPs were recorded on a computerized evoked potential recorder, using the international 10-20 system of electrode placement. The ADHD children showed a statistically significant N200 latency prolongation and amplitude decrease compared with the controls; the latencies of the other waves, i.e. N100, P200, P300, were prolonged in the ADHD children but the difference versus the controls was statistically insignificant. Reaction time was significantly longer in the ADHD subjects as compared with the controls. The above findings are suggestive of dysfunctions in the discrimination of task-relevant stimuli and a slower motor response in ADHD children.

Visual evoked potential study in slow learners.

Slow learners are individuals with low achievement and comparably low IQ scores. It may be a symptom reflecting a larger underlying problem in them. Sensory neural processing of visual information can be one of the contributory factors for their underachievement. The present study was undertaken to examine the integrity and function of visual pathway by means of Visual Evoked Potential (VEP). Pattern reversal VEP was performed on seventeen slow learners. Fifteen age and sex matched children with good school performance and normal IQ were taken as controls. There was significant prolongation of N75 component of VEP in slow learners. The latencies of P100 and N145 were also increased but could not reach the level of significance. Our findings are suggestive of the presence of a weaker VEP response in slow learners indicative of a deficit early in the visual processing. There is some abnormality in the geniculate afferents to V1 which is consistent with a defect in the magnocellular pathway at the level of Visual Area 1 or earlier.

Functional status of auditory pathways in hypothyroidism: evoked potential study.

Hypothyroidism is known to be associated with mental retardation, motor dysfunction, memory deficits and hearing impairment. In the present study, the functional integrity of the thalamocortical projections to the primary auditory cortex and association cortex has been assessed by using Auditory Evoked Responses i.e Auditory Brainstem (ABR), Mid Latency Response (MLR) and Slow Vertex Response (SVR). Thirty newly diagnosed hypothyroid patients and thirty healthy controls were taken for the study and ABR, MLR and SVR were recorded on computerized evoked potential recorder using 10-20 system of electrode placement. The second recordings for the hypothyroid patients were done 3 months after treatment with attainment of euthyroid states. The present study revealed a slight increase in absolute latency of wave III of ABR in hypothyroid patients and significant decrease in absolute latency of wave III and interpeak latency of I-III after treatment. There was a significant decrease in amplitude of wave V in hypothyroid patients and significant increase in amplitudes of ABR wave I and wave V after treatment. There was a significant increase in latency of wave Na of MLR and wave P2 of SVR in hypothyroid patients. The latencies of waves Na, Pa, Nb of MLR and waves PI and N2 of SVR showed significant improvement with thyroid hormone treatment. The results of the present study indicates that in hypothyroid state there might be slow conduction at the periphery and with treatment there is better recruitment of neuronal pool of the generators of the waves of ABR in the brainstem. We can also conclude that the thalamocortical projections of the auditory pathways are adversely affected in the hypothyroid state and this improves after treatment.