Altered EEG spectral activity and attentional behavioral deficits following prolonged febrile seizures: a pilot study.

The consequences of febrile seizures (FSs) in infants are still a matter of debate. It is important to develop non-invasive tools to determine markers of brain function that could have predictive value for the outcome of FSs infants.Pattern visual evoked potentials (pVEPs) were recorded in 18 FS infants (mean age of seizure 15.97 months). Spectral density and coherence analyses were performed in infants evaluated at 1.1 month (n = 4), 5.75 months (n = 4) or 30.33 months (n = 6) following a prolonged FS and compared to age-matched healthy controls. The impact of severity of seizures was assessed by comparing the children who had prolonged FSs to 4 infants that had experienced a simple FS. Cognitive tests (Bayley, Stanford-Binet) were administered at the time of testing in FS and control children. Behavioural measures (Achenbach Child Behavior Check List) were administered two years after the FS. pVEP responses and coherence measures failed to yield significant differences between the FS groups and healthy controls. However, spectral density measures showed a significant increase in delta band activity in both FS groups and a reduced high frequency density only in the prolonged FS groups that was seen up to 39 months post-seizure. Behavioural and cognitive measures revealed cognitive development within average, but lower attentional capacities in the FS infants. The persistent changes in spectral density patterns seen in children with prolonged FS may reflect seizure induced alterations in the developing brain or a result of a complex mode of inheritance. Further studies are needed to determine whether these observations can be used as a marker to predict the vulnerability of the child in developing behavioral deficits or epilepsy.

Development of visual texture segregation during the first year of life: a high-density electrophysiological study.

There are important developmental changes occurring during infancy in visual cortical structures that underlie higher-order perceptual abilities. Using high-density electrophysiological recording techniques, the present study aimed to examine the development of visual mechanisms, during the first year of life, associated with texture segregation. Forty-two normal full term infants were tested at 1, 3, 6 or 12 months of age. Visual-evoked potentials to low-level stimuli varying in orientation (oriVEP) and higher-level textured stimuli (texVEP) were recorded from 128 scalp electrodes. Difference potentials were obtained to extract the VEP component associated specifically with texture segregation (tsVEP). Results show a clear developmental pattern regarding amplitude, latency and scalp distribution of tsVEP, which appears at around 3 months but does not reach maturity by 12 months of age. A reduction in latency is particularly evident between 3 and 6 months, whereas amplitude shows a gradual increase with a marked increment between 3 and 6 months for low-level orientation stimuli and between 6 and 12 months for higher-level textured stimuli. These developmental patterns are attributed to neural maturational processes such as myelination and synaptogenesis. The differential developmental rates can be explained by delayed maturational processes of brain regions involved in more complex visual processing.

Electrophysiological markers of voice familiarity.

Our ability to discriminate and recognize human voices is amongst the most important functions of the human auditory system. The current study sought to determine whether electrophysiological markers could be used as objective measures of voice familiarity, by looking at the electrophysiological responses [mismatch negativity (MMN) and P3a] when the infrequent stimulus presented is a familiar voice as opposed to an unfamiliar voice. Results indicate that the MMN elicited by a familiar voice is greater than that elicited by an unfamiliar voice at FCz. The familiar voice also produced a greater P3a wave than that triggered by the unfamiliar voice at Fz. As both the MMN and the P3a were elicited as participants were instructed not to pay attention to incoming stimulation, these findings suggest that voice recognition is a particularly potent preattentive process whose neural representations can be objectively described through electrophysiological assessments.