Infant Recognition Memory Research Articles

Neurophysiologic evaluation of auditory recognition memory in healthy newborn infants and infants of diabetic mothers

Objectives: We evaluated the integrity of neural pathways for auditory recognition memory in normal newborn infants (n = 32) and infants of diabetic mothers (IDMs, n = 25). IDMs are at risk for fetal metabolic abnormalities that potentially damage recognition memory pathways. We hypothesized that newborn IDMs would have recognition memory deficits that would be correlated with later cognitive development. Study design: Recognition memory was assessed with event-related potentials (ERPs). Neonatal ERPs elicited by the maternal voice were compared with those elicited by a stranger’s voice. The Bayley Scales of Infant Development were administered at 1 year of age. Results: Infants in both the control and IDM groups demonstrated recognition of the maternal voice, but their ERP patterns differed. Both groups demonstrated increased amplitude and latency for the “P2” peak elicited by the maternal voice compared with the stranger’s voice. In the control group the stranger’s voice also elicited a negative slow wave, which was attenuated in the IDMs. The negative slow wave correlated significantly with the 1-year Mental Developmental Index. Conclusions: The presence of a specific neonatal ERP pattern indicated better 1-year cognitive development in infants in the control and IDM groups. ERPs from IDMs demonstrated subtle evidence of recognition memory impairments. (J Pediatr 2000;137:777-84)

Visual Recognition Memory for Objects in Six- and Nine-Month-Old Infants

Developmental trends in recognition memory were examined in typically-developing 6- and 9-month-old infants using the Visual Paired-Comparison task (VPC). The VPC exploits an infant's natural tendency to look longer at a novel stimulus than at a familiar one with which it has been paired. The results show that infants of both ages display a novelty preference (i.e., recognition memory) when the delay interval is 10 seconds or 5 minutes in duration. However, after a delay of 1 week, 6-month-old infants are performing at chance levels of responding while 9-month-old infants tend to look longer at the familiar stimulus. The possibility that the younger infants' performance reflects forgetting while the older infants are updating memory is discussed. The importance of assessing infant recognition memory is discussed in light of recent findings that this measure has predictive reliability for cognitive function in later childhood.

Delayed recognition memory in infants and adults as revealed by event-related potentials

The present study sought to compare adult and infant ERP responses in analogous tests of visual recognition memory. Adults were tested under two test conditions, in which they were given either explicit instructions to respond to a previously-seen stimulus, or no instructions. Testing in both conditions took place after either a 1- or 5-min delay between familiarization and test. Eight-month-old infants were tested under the same ‘passive’ (no instruction) conditions as adults. ERP morphology differed across age groups. Adults evinced a P300 that was larger under ‘active’ as compared to ‘passive’ test conditions, and a late positive slow wave response that was greater to novel than familiar stimuli. There was no evidence in infants of a P300, although infants did demonstrate a late positive slow wave that was greater to familiar than to novel stimuli. Parallels between the infant and adult findings are discussed and in particular, whether the infant slow wave response is the precursor to the adult P300.

The Ebb and Flow of Infant Attentional Preferences: Evidence for Long-term Recognition Memory in 3-Month-Olds

Using paired-comparisons, 3-month-olds' (n= 148) recognition of dynamic visual events was investigated after retention intervals of 1 minute, 1 day, and 1 and 3 months (Experiment 1) and 1 minute, 1 day, and 1 week (Experiment 2). Participants were either tested at each retention interval (Multiple Tests) or tested at one interval (Single Test). The proportion of total looking time to the novel event and the length of the longest look to novel and familiar events in the first 15 s of the retention test revealed significant novelty preferences at 1 minute and 1 day and a null preference at 1 week for Multiple- and Single-Test groups. At 1 month, Multiple- (Proportion of Total Looking Time and Longest Look) and Single-Test groups (Longest Look only) preferred the familiar event. The 3-month test revealed a familiarity preference (both measures) for Single- and a null preference for Multiple-Tests groups. This changing pattern of attentional preferences is consistent with models of infant recognition memory in which novelty, familiarity, and null preferences are considered conjointly and hypothesized to reflect the accessibility of novel and familiar event representations in memory.

Auditory Brain Maturation and Recognition Memory in Newborn Infants of Diabetic Mothers 1237

Infants of diabetic mothers (IDMs) are at increased risk for cognitive impairments, possibly due to alterations in fetal brain growth and development. The purpose of this longitudinal study is to evaluate the neural bases of cognitive impairments in IDMs. In this first phase, we evaluated neonatal brain function in 21 IDMs studied at term and compared with 22 full term healthy control infants using event-related potentials (ERPs). The ERP technique is an electrophysiologic method which can be used to study regional brain maturation and cognitive function.

Neurophysiologic assessment of auditory recognition memory in newborn infants of diabetic mothers

The preferential expression of T-cell receptor (TCR) Vα regions in the CD4+ and CD8+ T-cell subsets suggests that they have a special role in distinguishing recognition of major histocompatibility complex (MHC) class I from class II, or CD4 from CD8. Here, Bee-Cheng Sim, David Lo and Nicholas Gascoigne review recent data indicating the molecular basis for this discrimination, and how polymorphism within Vα subfamilies and between TCR α-chain haplotypes contributes to the T-cell repertoire.

Visual event-related brain potentials in 4-month-old infants at risk for neurodevelopmental impairments.

The recording of event-related potentials (ERPs) is an electrophysiologic technique that has been used to evaluate the functional maturation of neural pathways responsible for recognition memory systems in infants and children. The purpose of this study was to evaluate ERP correlates of visual recognition memory in 4-month-old infants at risk for later cognitive impairments. We compared ERPs using a test of shape recognition at 4 months of age (adjusted for prematurity) in 16 high-risk, neonatal intensive care unit (NICU) survivors and 16 healthy full-term infants. ERPs were recorded while infants were familiarized with one stimulus (a red cross, 15 trials), then tested with 60 trials of this familiar stimulus and a novel stimulus (a red corkscrew). Both the NICU and control groups' ERPs demonstrated evidence of differential processing of the two stimuli, but the NICU groups' ERP patterns were distinctly different from those of the control group. In the NICU group, the novel stimulus elicited parietal positivity at 1000-1700 ms poststimulus, whereas in the control group the novel stimulus elicited occipital and frontal negativity at 500-1700 ms poststimulus. The ERP pattern demonstrated by the NICU group was atypical as it has not been previously described in healthy infants. The results of the study indicate that the ERP technique can be used to demonstrate altered patterns of neural activity during tasks of visual recognition memory in high-risk infants. We speculate that the atypical ERP patterns described in this study may indicate that patterns of synaptic organization were altered by neonatal events.

Feeding formula without arachidonic acid and docosahexaenoic acid has no effect on preferential looking acuity or recognition memory in healthy full-term infants at 9 mo of age

Preferential looking acuity and novelty preference (a test of recognition memory) were determined by using Teller Acuity Cards and the Fagan Test of Infant Intelligence, respectively, for 399-433 healthy full-term infants at 39 +/- 1 wk of age. Duration of breast-feeding and age of infant at introduction and amount and type of formula were determined by questionnaire. Seventy-four infants (17%) were never breast-fed; another 92 infants (21%) were still receiving breast milk as the milk source at 39 wk of age. There were no differences in visual acuity or novelty preference among the infants when they were stratified by incidence or duration of breast-feeding. The formulas met current Canadian guidelines with > or = 0.7% of energy as linolenic acid, but had no docosahexaenoic or arachidonic acid. The studies indicate that formulas containing adequate linoleic and linolenic acids, without arachidonic or docosahexaenoic acid, impose no measurable deficits in performance in these visual and cognitive developmental tests at 9 mo of age in healthy full-term infants.

Delayed recognition memory in newborn infants

Delayed recognition memory in newborn infants

Predictive validity of infant recognition memory and processing speed to 7-year IQ in an inner-city sample

Predictive validity of infant recognition memory and processing speed to 7-year IQ in an inner-city sample

Event-related potential measures of 24-hour retention in 5-month-old infants.

Two experiments using event-related potentials (ERPs) investigated 24-hr recognition memory in infants. In each, ERPs were recorded to 100 identical stimuli in 5-month-olds. After 24 hr, 50 of these familiar stimuli and 50 novel stimuli were presented. In Experiment 1, the 2 stimuli were a tone and a click. The amplitude of a negative peak (N2 ; approximate latency = 350 ms) of the auditory ERP was larger on Day 2 for the familiar stimuli compared with ERPs for both Day 1-familiar stimuli and Day 2-novel stimuli. Trial-to-trial latency variability of N2 decreased from Day I to Day 2 for the familiar stimuli. In Experiment 2, 2 tones differing only in frequency (pitch) were used. The results replicated those of Experiment 1. In addition, an earlier positive peak (P2 ; approximate latency = 200 ms) showed larger amplitudes and smaller latency variability to the familiar stimulus on Day 2.

Preliminary findings confirming effects of prenatal PCB exposure on infant recognition memory: JACOBSON, S.W., H.C. KO, B.L. YAO, J.L. JACOBSON, F.M. CHANG, and C.C. HSU, Department of Psychology, Wayne State University, Detroit, Michigan, and Departments of Psychiatry and Obstetrics and Gynecology, National Cheng Kung University Medical College, Tainan, Taiwan

Preliminary findings confirming effects of prenatal PCB exposure on infant recognition memory: JACOBSON, S.W., H.C. KO, B.L. YAO, J.L. JACOBSON, F.M. CHANG, and C.C. HSU, Department of Psychology, Wayne State University, Detroit, Michigan, and Departments of Psychiatry and Obstetrics and Gynecology, National Cheng Kung University Medical College, Tainan, Taiwan

Visual recognition memory in drug-exposed infants.

Visual recognition memory testing in high-risk infants has been shown to have significant predictive ability for later cognitive deficits. This study evaluated cognition in infants exposed prenatally to illicit stimulant drugs compared with nonexposed controls with a standardized test of visual recognition, the Fagan Test of Infant Intelligence (FTII). Thirty-six healthy, full-term infants with prenatal exposure to cocaine and/or amphetamines and 26 infants with no drug exposures, matched for race and socioeconomic status, were tested. Average FTII scores were significantly lower and the percentage testing at risk significantly higher in the drug-exposed group (p less than .01). Differences between groups were also noted in behaviors dealing with attention, distractibility, and activity level. These data support recent evidence from longitudinal studies showing that infants exposed to drugs prenatally may be at risk for later subtle neurological abnormalities and suggest these difficulties may be identifiable long before the children reach school age.

Proactive interference in infant recognition memory

Preference for novel photographs of faces was tested in 5- to 7-month-old infants following three different proactive interfering conditions that replicated those in which retroactive interference had previously been demonstrated by Fagan (1973). One group of infants was presented with three successive presentations of upside-down caricatures of faces prior to the familiarization and novelty test, whereas the other two groups experienced three successive presentations of either upside-down or upright photographs of faces. Consistent with demonstrations of retroactive interference, preference for novelty existed following presentation of the rotated caricatures but not following rotated photographs. However, contrary to the effects due to retroaction, upright photographs did not lead to a preference for novelty. This differential disruption of preference for novelty is discussed as indicating either the existence of proactive interference in which the effects of perceptual similarity are different from those of retroaction, or the presence of a differential release from proactive interference that does not operate in retroaction.

Effects of in utero exposure to polychlorinated biphenyls and related contaminants on cognitive functioning in young children

Because prenatal exposure to polychlorinated biphenyls (PCBs) and related contaminants has been associated with reduced birth weight, neonatal behavioral anomalies, and poorer recognition memory in infants born to women who have consumed Lake Michigan sports fish, 236 children, previously evaluated for PCB-related deficits in infancy, were assessed at 4 years of age. Prenatal exposure (indicated by umbilical cord serum PCB level) predicted poorer short-term memory function on both verbal and quantitative tests in a dose-dependent fashion. These effects cannot be attributed to a broad range of potential confounding variables, the impact of which was evaluated statistically. Although much larger quantities of PCBs are transferred postnatally via lactation than prenatally across the placenta, exposure from nursing was unrelated to cognitive performance. The data demonstrate the continuation of a toxic impact received in utero and observed initially during infancy on a dimension of cognitive functioning fundamental to learning.

Visual recognition memory in IUGR and normal birth-weight infants

Recognition memory as measured by visual novelty preference was studied in 20 7-month-old term intrauterine growth retarded (IUGR) infants and 20 matched normal birth-weight infants. Preference for novelty was significantly lower for the IUGR group, p<.0017, and there was a significant correlation between birth weight and novelty preference, r.55, p<.0002. The results indicate that IUGR infants can now be added to the list of biologically at-risk groups that can be expected to differ from normal infants on measures of recognition memory during infancy.

Electrophysiological Correlates of Infant Recognition Memory

Event-Related Potentials were recorded from 6-month-old infants in order to examine the electrophysiological correlates of recognition memory. In 1 study, infants were shown 1 face briefly, followed by the same face presented with high probability, and a novel face presented with low probability. 2 components were observed that distinguished between the novel and familiar events. Differences between these components in latency, polarity, and scalp topography led to the suggestion that 2 processes were involved in recognizing the stimuli. In a second study infants were again presented with 1 face briefly, followed by the same face and a novel face presented with equal probability. 1 component at central scalp distinguished between the novel and familiar events. In a third study, infants were simply presented with 2 previously unseen faces equally often. Infants responded as if the faces were identical, suggesting that previous experience with 1 stimulus directs infants' attention to the novel stimulus during the test portion of the task. The extent to which the observed responses reflect the updating of working memory is discussed, as is the extent to which infants' electrophysiological response to stimulus novelty and uncertainty resembles the adult's.

Electrophysiological Correlates of Infant Recognition Memory

Electrophysiological Correlates of Infant Recognition Memory

The Segregation of Items into Categories by Ten-Month-Old Infants

2 experiments were conducted investigating infants' use of structural relations (i.e., correlated attribute values) in dividing or segregating items into categories. Rosch argued that attribute values do not occur in all possible combinations in the real world. Even though values of attributes may vary continuously across objects, some combinations are more likely to occur than others, forming breaks or discontinuities between clusters of correlated values. Within a well-controlled laboratory context, using artificial categories and a standard infant-recognition memory procedure, the present experiments demonstrated 10-month-old infants' sensitivity to structural information like that proposed by Rosch to exist in the real world, and their ability to segregate items into categories on the basis of clusters of correlated attribute values.

Visual recognition in infant pigtailed macaques after a 24-hour delay.

Comparative studies of memory in monkey and human subjects suggest similarities in visual recognition memory across human and nonhuman primates. In order to investigate developmental aspects of visual recognition memory in monkey infants, the familiarization-novelty procedure, developed for use with human infants, was employed with pigtailed monkey infants to study long-delay recognition memory. Subjects were familiarized with a black-and-white abstract pattern. Twenty-four hours later they were tested with the familiar pattern paired with a novel one. Results indicated a significant visual preference for the novel stimulus, providing evidence for recognition memory. These results parallel those obtained with human infants, suggesting further similarities in the development of visual recognition memory.