Biomedical subjects

W D Hopkins

Publications and source records attributed to W D Hopkins.

At least 37 records · Page 2Linked to original sources

PubMed1998

Planum temporale asymmetries in great apes as revealed by magnetic resonance imaging (MRI).

The planum temporale (PT), a portion of Wernicke's area, is important for linguistic functions in humans and is larger in the left compared to the right hemisphere. In this study, we assessed the presence and size of the PT in a sample of non-human primates including 21 great apes, four lesser apes, 11 Old World monkeys and eight New World monkeys using magnetic resonance imaging. The PT was measured in both the sagittal and coronal planes by use of multiplanar reformatting software. The PT could only be identified in the sample of great apes and not in the remaining non-human primate species. Within the great ape sample, the PT was larger in the left hemisphere than in the right in a statistical majority of the subjects. These results are consistent with the notion that the PT evolved as a definable structure about 15 million years ago and may have arisen as a result for selection for greater cortical folding which in turn led to greater gyrification in larger brains.

Animals↗

PubMed1998

Maternal cradling and infant nipple preferences in rhesus monkeys (Macaca mulatta).

This study investigated lateral biases in nipple preferences, maternal cradling, carrying, and retrieval in 41 rhesus macaque (Macaca mulatta) mother-infant dyads living in two captive social groups. Observations were made during the first 6 weeks of infant life using a combination of scan sampling and ad-libitum sampling techniques. Infants exhibited a significant left-nipple preference in the first weeks of life but the bias decreased with infant age. Mothers showed a left-arm bias in carrying their infants but no significant lateral bias in cradling or retrieval. Our results suggest that the left-side cradling bias reported in studies of humans and some other primates reflects a bias in the infant's nipple preference rather than in maternal behavior. The infants' preference for the left nipple is consistent with both Salk's (1960) heartbeat hypothesis and with more recent hypotheses linking this lateral bias with brain asymmetry and hemispheric specialization for mother-infant communication.

Age Factors↗

PubMed1998

Intentional communication by chimpanzees: a cross-sectional study of the use of referential gestures.

This study describes the use of referential gestures with concomitant gaze orienting behavior to both distal food objects and communicative interactants by 115 chimpanzees, ranging from 3 to 56 years of age. Gaze alternation between a banana and an experimenter was significantly associated with vocal and gestural communication. Pointing was the most common gesture elicited; 47 subjects pointed with the whole hand, whereas 6 subjects pointed with index fingers. Thus, communicative pointing is commonly used by laboratory chimpanzees, without explicit training to point, language training, or home rearing. Juveniles exhibited striking decrements in their propensity to communicate with adult male experimenters compared with older chimpanzees. Significantly fewer mother-reared chimpanzees exhibited gaze alternation compared with nursery-reared chimpanzees.

Animal Communication↗

PubMed1998

Lateralized changes in tympanic membrane temperature in relation to different cognitive tasks in chimpanzees (Pan troglodytes).

Lateralized changes in tympanic membrane (TM) temperature were assessed in chimpanzees. Subjects were engaged in 1 of 3 different cognitive tasks, including matching-to-sample, visual-spatial discrimination, and a motor task. During execution of each task, TM temperatures were taken from each ear over a 20-min time period. The TM temperatures at each time interval were subtracted from a baseline measure to assess relative change in blood flow. For the matching-to-sample and visual-spatial discrimination tasks, significant lateralized changes in TM temperature were found, with left-ear temperature increasing and right-ear temperature decreasing. No laterality effects were found for the motor or control tasks. These data provide the first evidence of laterality in physiological functioning in chimpanzees and suggest that transient asymmetries in cognitive functions are associated with changes in cerebral blood flow as assessed by TM temperature change.

Animals↗

PubMed1998

Hand use and gestural communication in chimpanzees (Pan troglodytes).

Hand use in gestural communication was examined in 115 captive chimpanzees (Pan troglodytes). Hand use was measured in subjects while they gestured to food placed out of their reach. The distribution of hand use was examined in relation to sex, age, rearing history, gesture type, and whether the subjects vocalized while gesturing. Overall, significantly more chimpanzees, especially females and adults, gestured with their right than with their left hand. Foods begs were more lateralized to the right hand than pointing, and a greater prevalence of right-hand gesturing was found in subjects who simultaneously vocalized than those who did not. Taken together, these data suggest that referential, intentional communicative behaviors, in the form of gestures, are lateralized to the left hemisphere in chimpanzees.

Animal Communication↗

PubMed1998

Why faces may be special: evidence of the inversion effect in chimpanzees.

Five chimpanzees were tested on their ability to discriminate faces and automobiles presented in both their upright and inverted orientations. The face stimuli consisted of 30 black and white photographs, 10 each of unfamiliar chimpanzees (Pan troblodytes), brown capuchins (Cebus apella), and humans (Homo sapiens). Ten black and white photographs of automobiles were also used. The stimuli were presented in a sequential matching-to-sample (SMTS) format using a computerized joystick-testing apparatus. Subjects performed better on upright than inverted stimuli in all classes. Performance was significantly better on upright than inverted presentations of chimpanzee and human faces but not on capuchin monkey faces or automobiles. These data support previous studies in humans that suggest the inversion effect occurs for stimuli for which subjects have developed an expertise. Alternative explanations for the inversion effect based on the type of spatial frequency contained in the stimuli are also discussed. These data are the first to provide evidence for the inversion effect using several classes of face stimuli in a great ape species.

Animals↗

PubMed1997

Haptic discrimination in capuchin monkeys (Cebus apella): evidence of manual specialization.

Two experiments investigated the effects of haptic and visual discrimination on hand preference in 22 brown capuchin monkeys (Cebus apella). The percentage of left-handed subjects in Experiment 1 were 63.6%, 45.5%, and 18.2% for haptic, bipedal, and quadrupedal reaching, respectively. In Experiment 2, the haptic demands of the task were manipulated by using additional food types and another tactile medium. Left-hand preferences were further strengthened when reaching into water compared to pineshavings in Experiment 1. Reaching with no tactile interference resulted in equal numbers of lateralized and nonlateralized subjects. These results show that when reaching demands the use of haptic cues, as opposed to visual ones, monkeys shift towards greater left hand use. This is consistent with what is known about right hemisphere superiority for haptic discrimination in humans.

Aging↗

PubMed1997

Hemispheric specialization for local and global processing of hierarchical visual stimuli in chimpanzees (Pan troglodytes).

This study examined laterality in global and local processing of hierarchical compound stimuli in seven chimpanzees (Pan troglodytes). A divided visual half-field paradigm was used that allowed for unilateral presentation of compound stimuli to either the left or right hemisphere. Comparison stimuli differing on the basis of their global configuration, local elements or both features followed sample stimulus presentation. Subjects were required to accurately discriminate the comparison stimuli on the basis of these features relative to the sample stimulus. No laterality effects were found for accuracy; however, for reaction time, a significant interaction was found between visual field and processing mode. An overall right visual field advantage was found for local processing but no visual field differences for global processing. The overall results are consistent with previous findings in humans and suggests homologous lateralization in chimpanzees and humans.

Analysis of Variance↗

PubMed1997

Manual specialisation and tool use in captive chimpanzees (Pan troglodytes): the effect of unimanual and bimanual strategies on hand preference.

Hand preference for tool use was assessed in a sample of captive chimpanzees (Pan troglodytes). Whether the subjects solved the tool task using either a unimanual or coordinated bimanual strategy was manipulated in the chimpanzees. No population-level hand preference was found for tool use when unimanual strategies were used by the chimpanzees. However, a population-level right-hand bias was found when coordinated bimanual actions were required of the chimpanzees. A significant correlation was found in hand use for the two hand preference testing conditions. Neither sex nor rearing was found to significantly affect the direction or strength in hand preference. These results may explain discrepancies in hand preference reported in captive and wild chimpanzees with regard to tool use and other manual activities.

Journal Article↗

PubMed1997

Children's lateralization on a finger-localization task.

The effect of stimulus orientation and hand use on performance on a finger-localization task was assessed in a sample of 40 children, including 20 boys and 20 girls. Experimenters stimulated a single finger on either the left or right hand, and the participants were required to identify the stimulated finger displayed on a drawing of a hand. The model drawing was displayed in either an isomorphic or reversed orientation relative to the stimulated hand. Analysis indicated that 4-yr.-olds performed significantly better than 3-yr.-olds. Also, participants were significantly better at identifying the middle finger when the left hand was stimulated than the right hand.

Child, Preschool↗

PubMed1996

Video-task acquisition in rhesus monkeys (Macaca mulatta) and chimpanzees (Pan troglodytes): a comparative analysis.

This study describes video-task acquisition in two nonhuman primate species. The subjects were seven rhesus monkeys (Macaca mulatta) and seven chimpanzees (Pan troglodytes). All subjects were trained to manipulate a joystick which controlled a cursor displayed on a computer monitor. Two criterion levels were used: one based on conceptual knowledge of the task and one based on motor performance. Chimpanzees and rhesus monkeys attained criterion in a comparable number of trials using a conceptually based criterion. However, using a criterion based on motor performance, chimpanzees reached criterion significantly faster than rhesus monkeys. Analysis of error patterns and latency indicated that the rhesus monkeys had a larger asymmetry in response bias and were significantly slower in responding than the chimpanzees. The results are discussed in terms of the relation between object manipulation skills and video-task acquisition.

Animals↗

PubMed1996

Indexical and referential pointing in chimpanzees (Pan troglodytes).

The spontaneous index finger and other referential pointing in 3 adult, laboratory chimpanzees (Pan troglodytes) who have not received language training is reported. Of 256 total observed points, 254 were emitted in the presence of a human to objects in the environment; therefore, the points were communicative. Indicators of intentional communication used by the subjects included attention-getting behaviors, gaze alternation, and persistence until reward. Thus, pointing by these chimpanzees was intentionally communicative. These data imply that perspective-taking and referential communication are generalized hominoid traits, given appropriate eliciting contexts. Index finger pointing was more frequent with the subjects' dominant hands. This study refutes claims that indexical or referential pointing is species-unique to humans or dependent on linguistic competence or explicit training.

Adult↗

PubMed1995

Asymmetries in spontaneous head orientation in infant chimpanzees (Pan troglodytes).

Behavioral laterality in head orientation while sleeping in either a supine or prone posture was examined in 43 chimpanzees (Pan troglodytes) for the first 3 months of life. An overall significant right-side lateral bias was found for head orientation in the supine posture. A trend toward greater right-side bias in females compared with males was observed but failed to reach significance. These data suggest that asymmetries in head orientation are present early in life in chimpanzees, and they may be correlated with functional asymmetries observed in adulthood.

Animals↗

PubMed1995

Hand preferences for a coordinated bimanual task in 110 chimpanzees (Pan troglodytes): cross-sectional analysis.

Hand preference for a coordinated bimanual task was assessed in a sample of 110 chimpanzees (Pan troglodytes). Subjects were presented with opaque tubes, the inside of which was coated with peanut butter. The hand and finger used to extract the peanut butter was recorded in 2 test sessions. A population right-hand bias was found. Juvenile and adolescent subjects were less lateralized than adults. All subjects primarily used their index finger to extract peanut butter. Use of the index finger was higher in adults and adolescents compared with juveniles. The results suggest that coordinated bimanual tasks (a) elicit strong hand preferences at the individual level and (b) elicit population level right-handedness.

Age Factors↗

PubMed1994

Hand preferences for bimanual feeding in 140 captive chimpanzees (Pan troglodytes): rearing and ontogenetic determinants.

Hand preference in bimanual feeding was assessed in 140 captive chimpanzees (Pan troglodytes). Bimanual feeding was defined as the active use of one hand for feeding with the opposite hand holding other food items. In terms of strength of hand preference, adults were more lateralized than sub-adults. Additionally, mother-reared chimpanzees were more lateralized than nursery-reared chimpanzees. The number of subjects with no hand preference was more prevalent in sub-adults compared with young and older adults. Of those subjects with a significant hand preference, a larger proportion exhibited a right-hand preference. These results are discussed in relation to previous reports of handedness and bimanual feeding in gorillas and bonobos.

Aging↗

PubMed1994

Do right- and left-handed monkeys differ on cognitive measures?

Twelve left- and 14 right-handed monkeys were compared on 6 measures of cognitive performance (2 maze-solving tasks, matching-to-sample, delayed matching-to-sample, delayed response using spatial cues, and delayed response using form cues). The dependent variable was trials-to-training criterion for each of the 6 tasks. Significant differences were found between left- and right-handed monkeys on the 2 versions of the delayed response task. Right-handed monkeys reached criterion significantly faster on the form cue version of the task, whereas left-handed monkeys reached criterion significantly faster on delayed response for spatial position (p < .05). The results suggest that sensitive hand preference measures of laterality can reveal differences in cognitive performance, which in turn may reflect underlying laterality in functional organization of the nervous system.

Animals↗

PubMed1994

Videotape-versus pellet-reward preferences in joystick tasks by macaques.

Andrews and Rosenblum (1993) convincingly demonstrated the effectiveness of live-social-video reward for joystick-task performance by bonnet macaques. We performed a similar series of experiments with quite different results. Taken together, these experiments emphasize the importance of the variability in individual preferences for reward effectiveness.

Animals↗

PubMed1994

Handedness and approach-avoidance behavior in chimpanzees (Pan).

The relationship between hand preference and approach-avoidance behavior was examined in 49 chimpanzees (Pan). Ss were presented with 2 sets of novel objects on 4 consecutive days. The objects were presented for 2 hr during each session, and latency to touch any object was recorded for each S. Latency scores were then compared for chimpanzees that had been determined to be non-right- or right-handed. Right-handed Ss approached and touched the objects significantly faster than non-right-handed Ss did. In addition, males touched the objects significantly faster than did females. Correlations in approach-avoidance behavior were significant across stimulus sets and days of testing. The overall results support recent theoretical models linking hemispheric specialization with the expression of positive and negative affective behaviors.

Affect↗