Mismatch Negativity and article compare/contrast

Wikepedia (see link on the side) explains what Mismatch Negativity (MMN)is. MMN is basically a deviant sound played within a series of similar sounds. The article I chose did not have a good definition or I didn't relate it properly. I apologize. They cite that "MMN is thought to reflect an automatic neuronal response to a change in auditory input." (Dunn, Gomes, Gravel, 2008, p. 53). It has also been described as the "separation between the waveforms in response to the standard and deviant tones" (p. 57) on an event related potential (ERP). I personally liked viewing the data in a graph then comparing responses in milliseconds. The majority of research has been done with adults with ASD and is typically recorded while the individual is engaged by another activity such as watching a video. (Dunn et al., 2008). This study found that MMN in children was not as large as in adults. They also mention that they need to be able to focus their attention on different sounds. As we focused on attention this week, we can begin to make connections. A younger child may only be able to focus on one thing and block others out. That could be a possibility for the studies' results. The authors state that MMN is not related to language (p. 61) however that may be only from this study. They cite "impaired discriminative ability or abnormal automatic processing of infrequent changes in auditory information" as potential reasons for the lack of or little change in response. (Dunn et al., 2008, p. 61). I believe that children with ASD lack the ability to isolate sounds and that they either over respond behaviorally or tune all sounds out. "Normally if important auditory information is present in the environment but outside a child's current attentional spotlight, automatic auditory processing allows the child to register that information and rapidly shift attention if need be." (Dunn et al., 2008, p. 68). The younger child may only be able too focus attention on one thing at a time or need controlled attention (Lynch, 2009). They also may be unable to automatically switch their focus as an older individual who has had intervention or more time for development can. Younger children with ASD need to develop this ability for safety, communication, socialization and cognition (Dunn et al., 2008, p. 68).
Wikepedia mentions MMN in visual terms as well as auditory.

I'd also like to compare and contrast the findings of my articles. I had used them independently to gather information and had not noted any similarities or differences. In Dunn et al. (1980) the children had activation of different brain regions than the typical group. When given an auditory stimulus, they had a "large negativity over the frontal central areas. The children with autism evidence a bilateral negativity, which was larger laterally." (Dunn et al., 2008, p. 54) rather than bilaterally in the supratemporal plane of the auditory cortex (Alho, 1995; Scherg, Vajsar & Picton, 1989, in Dunn et al., 2008, p. 53). They exhibited a smaller variance than the typical group. Boddaert et al (2004) sis their measurements at rest and through passive listening. They used PET scans rather than MMN. They found similar but not exactly the same areas of the brain to be engaged while listening. "We found significant activation of the auditory cortex in the bilateral superior temporal gyrus (Brodmann's area 22 in both groups while subjects were listening to speech-like stimuli" and that "the control children activated the superior temporal cortex billaterally with left based asymmetry." (Boddart et al, 2004, p. 2119). "The left dominance was not observed in the autistic group. In addition, austistic children had additional significant activation outside the auditory cortex: the left temporal pole (Brodmann's area 38), the bilateral cingulum (Brodmann's area 38), the bilateral posterior parietal (Brodmann's area 19), the cerebellar hemispheres, and the brainstem." (p. 2119). Boddart et al.(2004) did link the location activation ( or non activation of speech areas) to meaningful speech where Dunn et al. (2008) did not. In Boddart et al. (2004), they found that this decreased activation could lead to word processing issues. In Bigler et all. (2007), they focus on the superior temporal gyrus (STG) since it is involved in auditory processing and language more so than the others. They look at the "relationship between head size, total brain volume, regional brain volume and neurophsyical function of the region" (p. 219). The authors also reviewed " IQ, language and total and regional brain volumes" as well as dimensional variable, language and IQ" and " neurobiological heterogeneity." (p. 220). Bigler at al. (2007) also used a standard assessment tool(Clinical Evaluation of Language Fundamentals- Third Edition or CELF-3) where the other two had not.

The second study by Boddaert et al., (2004) also used children as subjects. Both studies found less activation in the speech centers than typical children. Both studies had some differences found between adults and children. The third article I used, Bigler et al. (2007)while it also used children focused more on language. I has used it mainly for that intent as well. I did not find many similarities between the three studies excpet for the focus on autism.