Book of abstracts - British Neuroscience Association

69.06
Comparison of data analysis techniques for direct
pharmacological challenge fMRI (phMRI)
McKie S (1), Lees J (1), Richardson P(1), Elliott R(1), Anderson I (1),
Deakin B (1), Williams S(2)
(1) Neuroscience and Psychiatry Unit (2) Imaging Science and
Biomedical Engineering, , University of Manchester
Direct pharmacological challenge-fMRI (direct phMRI) is used to study
the dynamic effects of drugs on brain haemodynamics. A common
analysis approach is to use subjective-ratings (subjective effects
scales, SES) to measure subject-specific changes while a drug is
being infused. However, there are several problems with this method.
Therefore, we have developed an alternative based on the
conventional block analysis of fMRI data – the pseudo-block analysis
method (p-block).
The infused drugs were mCPP and ketamine. Each subject underwent
a 9 minute fMRI scan during which they self-assessed their mental
state using SES. After 1 minute the drug/saline was infused. Images
were acquired on a 1.5T Philips scanner with a multi-slice, single shot
EPI sequence to achieve whole brain coverage. Data were analysed
using SPM5. The SES analysis involved creating a regressor based
on significant ratings from the SES and a random effects two-sample
t-test. The p-block analysis involved dividing the 9 minute fMRI scan
into 9 one-minute time-bins (T0 to T8). The average signal for each
time-bin (Tn) was compared to the pre-infusion average (T0) and a
random effects ANOVA was used to investigate significant signal
changes.
Both analysis methods resulted in the detection of similar areas for
each drug, however more areas were present in the p-block analysis.
This is thought to be due to individual differences in drug-induced
BOLD signal time courses as well as latency effects between different
brain regions. The p-block method can also be applied when no
regressor is available such as animal studies.
69.07
Structural correlates of autistic features in young people with special
educational needs: a voxel-based morphometric analysis
Spencer M D, Moorhead T W J, Hoare P, Muir W J, Owens D G C, Lawrie
S M, Johnstone E C
Division of Psychiatry, Royal Edinburgh Hospital, Morningside Park,
Edinburgh, EH10 5HF, UK
Background: A strong association exists between intellectual disability
and autism spectrum disorders (ASD). Although previous studies have
investigated the neural correlates of ASD in intellectually unimpaired
subjects, the present study is the first to address these issues in
intellectually impaired subjects.
Methods: We used structural MRI and voxel-based morphometry to study
63 intellectually disabled adolescents receiving additional learning support,
recruited via their place of education. Participants comprised 34 males and
29 females with mean age 16.0 years (SD: 1.8 years) and mean IQ 59.7
(SD: 7.7). We used the Social Communication Questionnaire to classify
participants according to their parentally reported degree of autistic
features, as scoring 1) below the threshold for ASD (n=32); 2) within the
pervasive developmental disorder (PDD) range (n=16); and 3) above the
threshold for autism (n=15). Groups did not differ significantly in terms
of gender, age or IQ. We report tissue density differences at cluster level
with adjustment for underlying smoothness.
Results: We detected a reduction in grey matter density in the thalamus of
subjects with autistic features scoring within the PDD range as compared to
subjects below the threshold for ASD (p