Performance on test conditions
In a preliminary analysis ‘Cohort’ was included as a second
between-subject factor to establish if there were any differences
regarding the two cohorts. The only main effect of cohort was for the
Dark condition (p<0.05), and no other main effects or
interactions involving this factor were observed (all Fs< 4.00; all ps > 0.06).
Therefore, the cohort data were pooled and analysed together for each
separate condition, though the Dark condition data received extra
scrutiny.
In the following analyses, ‘Drug’ refers to saline or clozapine (within
subject) while Group refers to iDREADDs or GFP infusions (between
subject).
Standard T-maze: There was a significant main effect of Drug:F 1,20 = 7.01, p = 0.015,ηp2 = 0.25, but not a main
effect of Group or Drug × Group interaction: Fs< 0.85, ps > 0.37,ηps2 < 0.04 (Figure
6). This set of results showed that clozapine did not exert a greater
effect in the active viral group when compared with the control viral
group.
Start T-maze: There was a main effect of Drug:F 1,20 = 5.76, p = 0.03,ηp2 = 0.22, but no main effect
of Group or Drug × Group interaction: Fs< 3.48, ps > 0.08,ηps2 < 0.15 (Figure
6). This pattern of results corresponded to that seen for the Standard
condition.
Rotation T-maze: There was a significant main effect of Drug:F 1,20 = 12.02, p = 0.002,ηp2 = 0.37 but also a Drug ×
Group interaction: F 1,20 = 6.8, p = 0.016,ηp2 = 0.25. Simple main effects
analyses revealed a significant decline in performance following
clozapine infusions within the iDREADDs group that was not seen in the
GFP control group: F 1,13 = 25.36,p< 0.0001 (Figure 6). All other tests were
non-significant: Fs < 2.75,ps > 0.11.
Opposite arm T-maze: As in the Rotation condition, there was a
significant main effect of Drug: F 1,20 = 7.7,p = 0.01, ηp2 = 0.278
and a Drug × Group interaction: F 1,20 = 4.55,p = 0.045, ηp2 = 0.18.
Again, there was decline in performance following clozapine infusions in
the iDREADDs group that was not seen in the GFP control group:F 1,13 = 16.6, p <0.001 (Figure
6). All other tests were non-significant: Fs< 0.89, ps > 0.35.
Dark T-maze: The behavioural analyses revealed a significant
Drug × Group interaction: F 1,20 = 7.8, p =
0.011, ηp2 = 0.28, however,
there was no main effect of Drug or Group: Fs< 0.036, ps > 0.85.
Follow-up simple main effects analyses showed that again iDREADDs
animals’ performance declined following the clozapine infusions relative
to saline: F 1,13 = 5.8, p = 0.025. All
other tests were non-significant: Fs <
2.84, ps > 0.10 (Figure 6). For this
one condition, there was a significant main effect of Cohort
(F 1,18 = 10.6, p = 0.004). Overall, Cohort 1 had
lower scores, possibly reflecting the absence of an additional saline
trial. Nevertheless, the key intervention comparisons were
within-subject (saline vs clozapine), being effective across both
Cohorts.