lectura obligatoria, Ejercicios de Psicología

¡Descarga lectura obligatoria y más Ejercicios en PDF de Psicología solo en Docsity! 231 Recent studies have begun to elucidate the roles played in social cognition by specific neural structures, genes, and neurotransmitter systems. Cortical regions in the temporal lobe participate in perceiving socially relevant stimuli, whereas the amygdala, right somatosensory cortices, orbitofrontal cortices, and cingulate cortices all participate in linking perception of such stimuli to motivation, emotion, and cognition. Open questions remain about the domain-specificity of social cognition, about its overlap with emotion and with communication, and about the methods best suited for its investigation. Addresses The University of Iowa, Department of Neurology, Division of Cognitive Neuroscience, 200 Hawkins Drive, Iowa City, IA 52242, USA; e-mail: ralph-adolphs@uiowa.edu Current Opinion in Neurobiology 2001, 11:231–239 0959-4388/01/$ — see front matter © 2001 Elsevier Science Ltd. All rights reserved. Introduction The ability to recognize, manipulate, and behave with respect to socially relevant information requires neural systems that process perception of social signals and that connect such perception to motivation, emotion, and adaptive behavior (Figure 1). Social cognition guides both automatic and volitional behavior by participating in a variety of processes that modulate behavioral response: memory, decision-making, attention, motivation and emotion are all prominently recruited when socially relevant stimuli elicit behavior. Although social cognition has been investigated for some time within developmental, comparative and social psychology, recent findings from neurobiology shed light on its neural underpinnings, and several studies are beginning to integrate neurobiological and psychological approaches [1,2•,3•]. This review will focus on work in mammals, especially primates, on the visual system and on those aspects of social cognition closely related to emotion; as such, the review will omit aspects of social communica- tion such as language. Evolution and development of social cognition Many species live in societies of multiple individuals, giving rise to opposing factors that shape the evolution of their social behavior: on one hand, groups can offer better prospects for survival; on the other hand, groups can generate within-group competition between individuals. A reconciliation of these factors is found in two distinct evolutionary solutions: rigid, eusocial behavior, typically seen in insects such as bees (but also found in the rare case of the mammalian naked mole rat), or the highly complex, flexible social behavior exemplified by primates. The latter solution requires social cognition: the ability to construct representations of the relations between oneself and others, and to use those representations flexibly to guide social behavior. Are the information-processing demands made by social cognition different from those made by non-social cogni- tion? In general, brains provide an advantage to survival in environments in which many factors change rapidly over time, by permitting organisms to extract complex patterns that aid prediction. Compared to the physical environment in general, the social environment is more complex, less predictable, and, critically, more responsive to one’s own behavior (this applies already to the broadest and most primitive social relation — that between predator and prey). These factors, and especially the reciprocity inherent in the last one, are thought by some to have driven the evolution of our cognitive abilities. To the extent that social cognition has been shaped by evolution, it is important to keep in mind that the environment in which such evolution took place differed from our present environment [4]: early human social groups were smaller, humans were hunter–gatherers, and, of course, humans did not have available all of the modern technology that dramatically widens the scope of our social abilities. Our understanding of the evolution of social behavior, especially of phenomena such as cooperativity and altruism, has also benefited from mathematical modeling, which has demon- strated the emergence of behaviors that are stable in a population even though they may not be rational from the point of view of the individual (see e.g. [5•]). A final phenomenon worth considering is the evolution of social relationships between different species: for instance, it has been speculated that a complete account of the evolution of human social cognition could include the reciprocal social behaviors that evolved to tie humans and wolves into cooperative dual-species societies [6•]. No less important to consider is the development of social cognition, influenced by two heritable components: genes and culture. Current models of personality acknowledge the importance of innate, biological factors, but emphasize that their developmental trajectory depends on the particular cultural and social context within which a person matures [7]. The idea that the influence of genes on behavior is very context-sensitive is corroborated by studies in mice, which have documented profound differences in behavioral traits despite genetic identity [8•]. The development of social cognitive abilities is tied closely to the development of emotion and of its communication between infant and mother, a topic that has seen enormous research from devel- opmental social psychology. Recent neurobiological studies have demonstrated that maternal behavior directly influ- ences social development. In rats, susceptibility to stress and anxiety in the infant is influenced by the mother’s The neurobiology of social cognition Ralph Adolphs behavior (grooming and nursing); moreover, these personal- ity traits in the infant remain stable across the lifespan and are transmissible to future offspring [9,10]. Specific neural structures that are involved in social cognition have been shown to subserve somewhat different functions during different stages of development: damage to the frontal lobes early during development results in a more severe impair- ment of moral knowledge than similar damage during adulthood [11•], and the amygdala’s role in aversive condi- tioning only switches on some time after birth, permitting early attachment regardless of parental behavior [12]. At the genetic level, there is evidence that specific sets of genes contribute to the development of aspects of social cognition with a particular timecourse, as found in genetic diseases such as Williams syndrome [13•]. Developmental and evolutionary approaches to under- standing social cognition are now being fused in some studies that combine experiments in human infants with experiments in nonhuman primates. These studies have emphasized that humans quickly develop cognitive capac- ities (around three to four years of age) that no other primate shares: notably, only humans appear able to adopt the point of view of another individual [14••,15], a capacity whose rudiments may already be evident in the ability of newborns to mimic some facial gestures, and that may be the catalyst for the generation of culture. Social perception: faces and the superior temporal sulcus How are socially relevant stimuli and signals perceived? Most mammals use olfaction and touch as key sensory channels for social communication: rat mothers identify their pups by smell, and maternal and sexual behaviors are mediated by a specialized olfactory organ, the vomeronasal organ. Auditory communication is based on often complex signals that are adapted to a species’ particular environ- ment: whale songs that can travel enormous distances underwater, ultrasonic separation cries of small mammals that are inaudible to many predators, and highly complex songs of birds that permit distinctions to be made among many cohabiting species. Arguably, species-specific communication signals are the most common source of stimuli for social perception, a large topic that has been extensively reviewed [16,17]. Not surprisingly, the perception of social stimuli in pri- mates has been studied most in the sensory system we understand best: vision. Single-unit studies in monkeys have demonstrated neuronal responses in temporal visual cortices that appear to encode information about highly specific social aspects of stimuli. A proportion of cells in monkey inferotemporal cortex show visual responses that are relatively selective for faces [18], for direction of gaze, for body orientation, or for intended action [19]. These findings have now been complemented by studies in humans. Electrophysiological studies in epileptic patients have found regions of the temporal cortex that respond to socially salient parts of faces, such as eyes and moving mouth parts. A collection of regions in the superior tempo- ral sulcus is activated in response to biologically and socially salient visual motion stimuli (for a review, see [20]). Functional imaging studies have also found responses to static faces specifically in the fusiform gyrus, which have sparked a debate: are there systems in the human brain for processing specific social stimuli, such as faces [21], or are there only systems that carry out more domain-general processing, on which social and face processing may draw 232 Cognitive neuroscience Figure 1 Component processes of social cognition. At the input end, social cognition draws upon neural mechanisms for perceiving, recognizing, and evaluating stimuli, which together provide the information required to construct complex central representations of the social environment. Regions in temporal lobe, such as the fusiform gyrus and the superior temporal sulcus, work together with a network of structures that includes amygdala, orbitofrontal cortex, anterior and posterior cingulate cortices, and right somatosensory-related cortices. Central processes of social cognition in turn modulate effector systems, which include motor and premotor cortices and basal ganglia, as well as systems more involved in emotional output, such as hypothalamus and periaqueductal gray (PAG). Importantly, social perception and social behavior are causally connected as aspects of social communication, as indicated at the bottom of the figure: an organism’s production of social behavior in turn functions as an important source of perceptual input. SS, somatosensory; STS, superior temporal sulcus. Stimulus Current Opinion in Neurobiology Processing of stimulus features Emotion Cognition Motivation Social behavior Sensory and association cortices (fusiform gyrus, STS) Amygdala, orbitofrontal cortex, cingulate cortex, right SS cortex Motor cortex, basal ganglia, hypothalamus, brainstem (PAG) Social perception Social behavior Social cognition mechanism by which we acquire, represent, and retrieve the values of our actions. This mechanism relies on gener- ating somatic states, or representations of somatic states, that correspond to the anticipated future outcome of deci- sions. Such ‘somatic markers’ steer the decision-making process toward those outcomes that are advantageous for the individual, on the basis of the individual’s past experi- ence with similar situations. Such a mechanism may be of special importance in the social domain, where the enor- mous complexity of the decision space typically precludes an exhaustive analysis. Another model for explaining the function of the prefrontal cortex in social cognition is that this region serves to regulate and inhibit processes in other brain regions, for example by inhibition of amygdala activity; possibly such inhibition could contribute to con- trol over impulsive, aggressive and violent social behaviors [55]. The role of the prefrontal cortex in regulating social behavior is corroborated by findings that there is a lower prefrontal gray-matter volume in subjects that meet criteria for antisocial personality disorder and psychopathy than in control subjects [56]. Like the orbitofrontal cortex, the cingulate cortex, includ- ing both anterior and posterior sectors (as well as the posteriorly adjacent retrosplenial cortex), plays a key role in emotion and in social behavior [57,58]. Damage to the anterior cingulate cortex can result in a gross loss of motivation (akinetic mutism), and this region is activated in normal subjects by emotional versions of the Stroop task [59], supporting the idea that it helps to monitor errors and response-conflicts. Most intriguing are recent findings at the single-cell level. Large, spindle-shaped neurons have been found exclu- sively in layer Vb of the anterior cingulate cortex of primates; moreover, the density of such neurons is highest in humans, next highest in chimpanzees, lower in other apes, and absent in all other species, correlating well with phylogenetic relatedness [60•]. Nothing is known of the function of these neurons, but their size and location make it plausible that they serve to connect different regions that are spatially distant in large brains; possibly, they participate in the integration of sensory, cognitive, and motivational information that is a hallmark of anterior cingulate cortex function. Another interesting finding from this brain region was recently obtained in neurosur- gical patients. Single-unit responses were found that resulted from the subject experiencing pain directly, and that also resulted when the subject simply observed another person in pain [61]. Such responses may be analogous to the responses of so-called ‘mirror neurons’ that have been found in monkey prefrontal cortex [46,62], which respond both when the monkey executes an action and when it views another individual performing the same action. These findings may constitute further hints of systems that construct socially relevant knowledge by simulation, as described above in relation to right hemisphere cortices. Molecular and genetic factors The molecular and genetic underpinnings of social cogni- tion are an underexplored domain that is seeing rapid progress. Several neurotransmitters appear to play a disproportionate role in social behaviors. The hypothalam- ic peptides oxytocin and vasopressin mediate affiliative and sexual behaviors in several mammalian species. Voles show different mate affiliation (monogamous versus polygamous) as a result of different oxytocin systems in their brains [63], and oxytocin-knockout mice show abnormalities in their social behavior, including a social memory impairment that is specific for the odors of con- specifics [64]. It has been speculated that abnormalities in oxytocin neurotransmission may contribute to the social pathology of autism [65]. Serotonin is another neurotrans- mitter linked to social behavior, especially social status and dominance in primates [66]. In fact, selective reuptake inhibitors for serotonin influence social behavior in humans [67], an issue that has implications for the prescription of drugs such as Prozac. Serotonin has also received recent interest specifically in relation to its role in modulating aggressive social behavior [55], a role supported by the finding that genetic diseases affecting serotonin metabolism can result in severely altered aggression [68]. Another class of neuropeptides that figures prominently in social behavior is the endogenous opiates, which modulate circuits involved in social bonding, separation anxiety, and play. An overview of the various neurotransmitter systems involved in social behavior is given in [69]. Genetic contributions to social cognition are being explored as well. There is evidence to suggest that at least some of the differences in social cognition between males and females are genetic, as borne out by studies of indi- viduals with Turner’s syndrome [70]. There is good evidence from genetic diseases that certain sets of genes can contribute disproportionately to social cognition, rather than to other aspects of cognition. Autism (which is partly heritable) and Williams syndrome [13•] (which is entirely genetic in etiology) both feature disproportionate changes in social cognition relative to general cognition (impaired social cognition and spared social cognition, respectively). The findings are consonant with reports that over 50% of the variability in performance on theory-of-mind tasks is heritable [71], a figure similar to that for the heritability of personality (e.g. as derived from studies of monozygotic twins separated since birth; cf. [7]). As described in the Introduction, genetic and environmental factors interact in a complex fashion that often makes it impossible to trace an aspect of social cognition only to one or the other. A systems-level view of social cognition The processing of social information is centrally distrib- uted in both space and time. As Figure 1 indicates, the sequence of events leading from perception of a socially relevant stimulus to the elicitation of a social behavior is complex and involves multiple interacting structures. At least three general possibilities exist for how structures The neurobiology of social cognition Adolphs 235 such as those shown in Figure 2 interact with other brain regions: first, they may directly modulate cognition by virtue of their extensive connectivity with high-level neo- cortex; second, they may modulate emotional state, which in turn can be used indirectly to modulate cognition; and third, they may directly modulate perceptual processing via feedback. The latter possibility may be a major component of aspects of social cognition such as the recog- nition of facial expressions, and deserves some more discussion. Initially, perceptual processing of a socially relevant stimulus (e.g. a conspecific’s facial expression) in visual cortices would feed into structures such as amygdala and prefrontal cortex. The early information that these higher structures receive may be sufficient only to distin- guish a few categories (for instance, threatening versus not threatening in the case of the amygdala); moreover, initial, rapid processing may be entirely outside the scope of con- scious awareness (as supported by the finding that the amygdala can be activated by subliminally presented facial expressions [72]). The response in prefrontal cortex could be modulated by the amygdala’s input regarding vigilance, threat, and ambiguity concerning the stimulus (as borne out by single-unit studies in animals); and the amygdala’s response may, in turn, be modulated by the contextual and habituating input from the prefrontal cortex (see [73] for such a scheme). However, the prefrontal cortex–amygdala network does not classify the social significance of the stimulus in isolation. Rather, it feeds back onto visual cortices and contributes to the temporal evolution of a fine-grained perceptual representation there. Single-unit studies in monkeys have shown directly that neurons in inferotemporal cortex signal information about different aspects of a stimulus at different times, such that social information about a face is encoded at a later point in time than coarser information that simply distinguishes a face from a non-face stimulus [74•]. It is thus plausible that the unfolding representation of the stimulus in visual and asso- ciation cortices in temporal lobe relies in part on top-down influences from structures such as amygdala and prefrontal cortex that provide information regarding the social relevance of the stimulus. Conclusions and future directions Social cognition is a domain with fuzzy boundaries and vaguely specified components. Its processes overlap substantially with those that fall under the rubrics of ‘moti- vation’, ‘emotion’, and ‘communication’. Structures involved in social cognition include: sensory and associa- tion neocortex for social perceptual processing (e.g. superior temporal sulcus and fusiform gyrus in the case of vision); a network consisting of amygdala, prefrontal cortex, cingulate cortex, and right somatosensory-related cortices for mediating between perception and various cognitive processing components; and hypothalamus, brainstem nuclei, basal ganglia, and motor cortices in order to effect the social behavior (Figure 1). Questions for the future are both conceptual and method- ological. To what extent does social cognition differ from non-social cognition? Are there neural systems that evolved to guide social behavior, and that are specialized to process socially relevant stimuli? What is unique about human cognition — is it to be found in our social cognitive abilities? Answers to these questions will require inputs 236 Cognitive neuroscience Figure 2 Neuroanatomy of social cognition in humans (see [3•,86]). Only some of the most central structures are shown for clarity: the amygdala (blue), the ventromedial prefrontal cortex (red), the cingulate cortex (yellow), and somatosensory-related cortices in the right hemisphere (green). Not shown are the sectors in the temporal lobe, such as the fusiform gyrus and the superior temporal sulcus, that are involved in the visual perception of social stimuli; nor does the figure show structures closer to the output end that are involved in directly triggering social and emotional behaviors, such as the hypothalamus, periaqueductal gray, and other brainstem nuclei. Also not shown are additional structures involved in social cognition that are intimately connected with the structures shown: dorsolateral prefrontal cortex, frontal polar cortex, temporal polar cortex. Segmented structures shown in color were co-rendered onto a partially transparent brain to obtain the images shown (right lateral view of whole brain at top, medial view of the right hemisphere at bottom). R Adolphs, H Damasio, Human Neuroimaging and Neuroanatomy Laboratory. from multiple disciplines, and will require the integration of data from human and nonhuman animals. Our under- standing will also require a better operationalization of what is to count as ‘social’, and better ways of measuring social behavior; these are issues that ethologists have confronted for some time. As we come to better understand the mech- anisms and causes behind social cognition and behavior, it also becomes important to consider their impact on social policy issues — to what extent can they inform guidelines for raising children, for prescribing what is permissible, and for therapeutic intervention when the regulation of social behavior breaks down in pathological cases? Acknowledgements The author’s work is supported by grants from the National Institute of Neurological Disorders and Stroke, The National Institute of Mental Heath, the Sloan Foundation, the EJLB Foundation, and the Klingenstein Fund. References and recommended reading Papers of particular interest, published within the annual period of review, have been highlighted as: • of special interest ••of outstanding interest 1. Ochsner KN, Schacter, DL: A social cognitive neuroscience approach to emotion and memory. In The Neuropsychology of Emotion. Edited by Borod JC. New York: Oxford University Press; 2000:163-193. 2. Cacioppo JT, Berntson GG, Adolphs R, Carter CS, Davidson RJ, • McClintock MK, McEwen BS, Meaney MJ, Schacter DL, Sternberg EM et al. (Eds): Foundations in Social Neuroscience. Cambridge, MA: MIT Press; 2001. A diverse collection of recent important papers relevant to social cognition, encompassing psychological as well as neurobiological approaches. The collection focuses on papers published within the last three to four years, and covers genetic, physiological, and psychological studies in both humans and animals. The emphasis, however, is on systems-level cognitive neuro- science in humans. 3. Adolphs R: Social cognition and the human brain. Trends Cogn Sci • 1999, 3:469-479. A review that provides a more in-depth treatment of many of the same issues raised in the present article, with an emphasis on questions of interest to cognitive scientists. The focus is almost exclusively on humans, and much of the review deals with the amygdala, orbitofrontal cortex, and right somatosensory cortices. 4. Barkow JH, Cosmides L, Tooby J (Eds): The Adapted Mind: Evolutionary Psychology and the Generation of Culture. New York: Oxford University Press; 1992. 5. Nowak MA, Page KM, Sigmund K: Fairness versus reason in the • ultimatum game. Science 2000, 289:1773-1775. A recent installment in a series of papers by Sigmund, Nowak and co-workers that describe game-theoretic models of the evolution of social behaviors such as altruism. This paper discusses the Ultimatum Game, in which two players are offered a chance to win a certain sum of money by agreeing on how to divide it. The proposer suggests how to split the sum, and the responder can accept or reject the deal. If the deal is rejected, neither player gets anything. The rational solution is for the proposer to offer the smallest possible share and for the responder to accept it. If humans play the game, however, the most fre- quent outcome is a fair share. An evolutionary model of this situation shows that fairness will evolve if the proposer can obtain some information on what deals the responder has accepted in the past. Hence, the evolution of fairness, similarly to the evolution of cooperation, is linked to reputation. 6. Allman JM: Evolving Brains. New York: Scientific American Library; • 1999. Beautifully illustrated and very readable, this book ranges broadly to cover the evolution of brains, but its emphasis is on primate evolution including the possible effects of social factors. It is a good general introduction to allo- metric issues, and reviews some of the key issues in relating brain size to environmental factors. 7. McCrae RR, Costa PT, Ostendorf F, Angleitner A, Hrebickova M, Avia MD, Sanz J, Sanchez-Bernardos ML, Kusdil ME, Wodfield R et al.: Nature over nurture: temperament, personality, and life span development. J Per Soc Psychol 2000, 78:173-186. 8. Crabbe JC, Wahlsten D, Dudek BC: Genetics of mouse behavior: • interactions with laboratory environment. Science 1999, 284:1670-1672. An important study that showed that genetically identical mice could show quite different behavioral traits when tested in different laboratories, even when the task was made as similar as possible. Apparently, such behavioral traits can be extremely sensitive to even small differences in environment that cannot be controlled for, an issue that is especially applicable to the development of social behaviors. 9. Francis D, Diorio J, Liu D, Meaney MJ: Nongenomic transmission across generations of maternal behavior and stress responses in the rat. Science 1999, 286:1155-1158. 10. Liu D, Diorio J, Day JC, Francis DD, Meaney MJ: Maternal care, hippocampal synaptogenesis and cognitive development in rats. Nat Neurosci 2000, 3:799-806. 11. Anderson SW, Bechara A, Damasio H, Tranel D, Damasio AR: • Impairment of social and moral behavior related to early damage in human prefrontal cortex. Nat Neurosci 1999, 2:1032-1037. Two patients with developmental prefrontal damage showed impaired knowl- edge of morality on tasks, as well as impaired social behavior in real life. These impairments were more severe than when similar damage is sustained in adulthood — further evidence that structures involved in social cognition are critical for the normal development of social and emotional behaviors. 12. Sullivan RM, Landers M, Yeaman B, Wilson DA: Good memories of bad events in infancy. Nature 2000, 407:38-39. 13. Bellugi U, St George M (Eds): Linking cognitive neuroscience and • molecular genetics: new perspectives from Williams syndrome. J Cogn Neurosci 2000, 12 (suppl 1). An up-to-date and comprehensive review of Williams syndrome, including its relation to social behavior. The disease results from deletion of a somewhat- variable small set of genes on chromosome 7. The phenotype features a pecu- liar facial morphology, heart abnormalities, and an intriguing cognitive profile. Although the subjects are generally mentally retarded and are severely impaired in visuospatial processing, they appear remarkably capable socially. They are able to perform many social tasks, including linguistic ones, normally; in fact, they appear hypersocial in terms of their real-life interaction with adults. The disease provides something close to the converse of autism, in which sub- jects can have high general intelligence despite poor social functioning. 14. Tomasello M: The Cultural Origins of Human Cognition. Cambridge, •• MA: Harvard University Press; 1999. A controversial thesis proposing that humans possess cognitive abilities dif- ferent from those of any other primate, including the ability to adopt another person’s point of view. It is proposed that this ability was initially enabled by only one or a few genetic changes, but consequently laid the foundations for the possibility of cultural evolution. The book reviews psychological and anthropological data, but not neurobiological data. 15. Reaux JE, Theall LA, Povinelli DJ: A longitudinal investigation of champanzees’ understanding of visual perception. Child Dev 1999, 70:275-290. 16. Hauser MD: The Evolution of Communication. Cambridge, MA: MIT Press; 1996. 17. Hauser MD, Konishi M (Eds): The Design of Animal Communication. Cambridge, MA: MIT Press; 1999. 18. Perrett DI, Rolls ET, Caan W: Visual neurons responsive to faces in the monkey temporal cortex. Exp Brain Res 1982, 47:329-342. 19. Perrett DI: Visual cells in the temporal cortex sensitive to face view and gaze direction. Proc R Soc Lond B Biol Sci 1985, 223:293-317. 20. Allison T, Puce A, McCarthy G: Social perception from visual cues: role of the STS region. Trends Cogn Sci 2000, 4:267-278. 21. Kanwisher N: Domain specificity in face perception. Nat Neurosci 2000, 3:759-763. 22. Tarr MJ, Gauthier I: FFA: a flexible fusiform area for subordinate- level visual processing automatized by expertise. Nat Neurosci 2000, 3:764-769. 23. Haxby JV, Hoffman EA, Gobbini MI: The distributed human neural • system for face perception. Trends Cogn Sci 2000, 4:223-233. A recent review of face processing in humans. The authors propose that pro- cessing the invariant features of faces may underlie our ability to recognize the identity of people, whereas processing changeable features of faces, such as eye gaze and expression, plays a larger role in social communication. They review The neurobiology of social cognition Adolphs 237