Verbal functions Vocabulary Verbal comprehension Reading comprehension Verbal abstraction Visual–spatial functions Visuo-motor integration Mental rotation Visual discrimination Assessed construct Visual recognition Visual reproduction Episodic memory Semantic memory Short-term memory 4.5 3.5 4.5 3 4 11 11 7 11 11 7 3 4 9 7 4 11 4 9 9 7 11 3–5 6.5 9 4 11 11 11 7 7 Cohorta Oswego Michigan Faroe Islands Netherlands Michigan Michigan Faroe Islands Oswego Michigan Netherlands Faroe Islands Michigan Michigan Cohorta Oswego Michigan Michigan Germany Netherlands Netherlands Faroe Islands Michigan North Carolina Netherlands Michigan Faroe Islands Months 6, 12 7 7 Age Boucher et al. observed in the German study. Visual rec­ ognition memory was also affected at 4 years of age in the Michigan study. On the other hand, in the Netherlands, the delayed repro­ duction of the Rey Complex Figure was unaf­ fected in children 9 years of age. The apparent contradictory results between the Michigan and the Netherlands studies might first be explained by the age difference. Second, both studies differed with regard to the functions assessed in both tests: The Sternberg Memory task (Michigan) has time pressure and requires sustained attention and working memory more manifestly than the Rey Complex Figure delayed copy (Netherlands). Moreover, the Table 4. Study results for verbal and visual–spatial functions. Sternberg Memory has a strong verbal compo­ nent, whereas the Rey Complex Figure essen­ tially relies on visual–spatial memory. Episodic memory refers to contextualized memories of one’s own experiences and learn­ ing (Lezak et al. 2004; Mazeau 2003). For example, one can remember a day spent in Rome and the name of a person met on that day, as well as what was for dinner. Such con­ textualized memories were assessed in two of the nine selected studies: the Dutch and the Faroese. In the Dutch study, the most severely exposed children were not different from the least exposed on the AuditoryV­erbal Learning Test, which contained both immediate and delayed recalls of verbal information. The chil­ dren of the Faroese cohort were assessed with the California Verbal Learning Test, a test of list learning and verbal memory comparable to the Auditory­Verbal Learning Test. The absence of association between episodic mem­ ory and PCB exposure found in the Dutch study was corroborated in the Faroese cohort. Thus, episodic memory does not appear to be particularly affected by prenatal PCB exposure, despite the relatively high PCB concentrations observed in both cohorts. Whereas episodic memory is contextualized, semantic memory refers to the general knowl­ edge one possesses, which is disconnected from Age (years) Effect Measurement Abbreviations: ↓, statistically significant decreased performance on the measure; –, absence of significant effect. Tests: BNT, Boston Naming Test (Kaplan et al. 1983); BTVMI, Beery Test of Visual Motor Integration (Beery 1967); KMFF, Kagan Matching Familiar Figures (Kagan 1965), Mental Rotation (Kail 1986); PPVT, Peabody Picture Vocabulary Test (Dunn and Dunn 1981); Rey Complex Figure Test copy (Rey 1941); RLDS, Reynell Language Development Scales (Van Eldik et al. 1995); WRMT, Woodcock Reading Mastery Tests (Woodcock 1987). aCohorts are presented in ascending order of median prenatal PCB exposure. bDecreased performance as a function of prenatal PCB exposure was significant before controlling for MeHg. cEffect is significant among non-breast-fed children only. Table 5. Study results on verbal and visual memory. Years Effect Abbreviations: ↓, statistically significant decreased performance on the measure; –, absence of significant effect. Tests: AVLT, Auditory-Verbal Learning Test (Kalverboer and Deelman 1964); Corsi Spatial Span (Corsi 1972); CVLT, California Verbal Learning Test (Delis et al. 1994); FTII, Fagan Test of Infant Intelligence (Fagan and McGrath 1981); Sternberg Memory [adap- tation from Sternberg (1969)]. aCohorts are presented in ascending order of median prenatal PCB exposure. bThis adaptation of the Sternberg Memory Test emphasizes visual recognition memory rather than working memory. cAuthors do not report associations with the different subtests of the Memory Scale. dEffect significant in children of younger mothers and parents with lower verbal IQ scores only. eEffect significant in non-breast-fed children only. 10 ovlume 117 | number 1 | January 2009 • Environmental Health Perspectives ↓ ↓ ↓ – – – – ↓ – ↓d – ↓ ↓e – ↓ – – ↓ – – ↓ ↓ – b c ↓ ↓ ↓ – ↓ – – – – – – MSCA Word Knowledge MSCA Word Knowledge PPVT WISC-R Vocabulary WRMT Word Comprehension BNT RLDS WRMT Reading Comprehension WISC-R Similitudes WISC-R Similitudes MSCA Block Building MSCA Block Building BTVMI Rey Complex Figure Test copy WISC Block Design Mental Rotation KMFF Measurement FTII FTII FTII Sternberg Memoryb Rey Complex Figure Test recall AVLT long delay recall CVLT long delay recall WISC Information MSCA Memory Scalec MSCA Memory Scalec AVLT short delay recall MSCA Memory Scale WISC-R Digit Span Corsi Spatial Span Sternberg Memory WISC-R Digit Span Forward CVLT short delay recall Reference Stewart et al. 2003b Stewart et al. 2003b Jacobson et al. 1990 Jacobson and Jacobson 1996 Jacobson and Jacobson 1996 Grandjean et al. 2001 Patandin et al. 1999b Jacobson and Jacobson 1996 Jacobson and Jacobson 1996 Grandjean et al. 2001 Stewart et al. 2003b Stewart et al. 2003b Jacobson et al. 1990 Vreugdenhil et al. 2004a Grandjean et al. 2001 Jacobson and Jacobson 2003 Jacobson et al. 1992 Reference Darvill et al. 2000 Jacobson et al. 1985 Jacobson et al. 1992 Winneke et al. 1998 Vreugdenhil et al. 2004a Vreugdenhil et al. 2004a Grandjean et al. 2001 Jacobson and Jacobson 1996 Gladen and Rogan 1991 Vreugdenhil et al. 2002 Vreugdenhil et al. 2004a Jacobson et al. 1990 Jacobson and Jacobson 2003 Jacobson and Jacobson 2003 Jacobson and Jacobson 2003 Grandjean et al. 2001 Grandjean et al. 2001