OADES, R. D., ROEPCKE,
B., & SCHEPKER, R. (1996). A test
of conditioned blocking and its development in childhood and adolescence:
relationship to personality and monoamine metabolism. Developmental
Neuropsychology, 12, 207-230.
(request a copy) . (view).
Introduction:
Conditioned blocking (CB) is the undermining of conditioning to a
stimulus by conjoint exposure to a stimulus already associated with
the unconditioned stimulus. CB is one of several tests of "learned
inattention" in which performance has been found to depend on certain
features of personality and on monoamine activity recorded in animals
performing CB.
Methods:
In part 1, the performance of 25 healthy young adults (mean
age 21.6 years) on a new test form for demonstrating CB is described
("mouse-in-house"). The personality inventories used included the
Hamburger neuroticism/extroversion scale (HANES) and the short version
of the Minnesota multiphasic personality inventory (MMPI). From 24h
urine samples collected at the time of testing the levels of four
monoamine and three of their metabolites were measured as an indicator
of the overall level of neurotransmitter activity. In part 2,
the development of CB was studied across children and adolescents
clustered into 4 age groups (means 10, 14, 17 and 22 years of age).
Results:
Part 1 demonstrated CB in normal healthy young adults and the
expression of CB correlated with extroversion and increased catecholamine
utilisation (turnover).
Part 2 showed CB was least marked prepubertally,
but developed across adolescence independent of IQ. Although performance
did not correlate with developing personality features, like the adults,
CB was positively correlated with dopamine activity. Unlike adults
CB was inversely correlated with noradrenaline activity. Figure
1 shows the development of CB in the 4 age-groups and correlations
with monoamine activity.
Figure 2 shows how the measures of the 3 monoamines,
their metabolites and their activity (turnover) develops across age-groups.
Conclusions:
The maturation of attention related information processing is discussed
in terms of the development and maturation of structures in the limbic
part of the central nervous system and, in particular, the separate
function of dopamine in switching between and noradrenaline in tuning
in/out stimulus features during selection processes. |