Angela Bartolo

Humor Comprehension and Appreciation: An fMRI Study

Humor is a unique ability in human beings. Suls [A two-stage model for the appreciation of jokes and cartoons. In P. E. Goldstein & J. H. McGhee (Eds.), The psychology of humour. Theoretical perspectives and empirical issues. New York: Academic Press, 1972, pp. 81100] proposed a two-stage model of humor: detection and resolution of incongruity. Incongruity is generated when a prediction is not confirmed in the final part of a story. To comprehend humor, it is necessary to revisit the story, transforming an incongruous situation into a funny, congruous one. Patient and neuroimaging studies carried out until now lead to different outcomes. In particular, patient studies found that right brain-lesion patients have difficulties in humor comprehension, whereas neuroimaging studies suggested a major involvement of the left hemisphere in both humor detection and comprehension. To prevent activation of the left hemisphere due to language processing, we devised a nonverbal task comprising cartoon pairs. Our findings demonstrate activation of both the left and the right hemispheres when comparing funny versus nonfunny cartoons. In particular, we found activation of the right inferior frontal gyrus (BA 47), the left superior temporal gyrus (BA 38), the left middle temporal gyrus (BA 21), and the left cerebellum. These areas were also activated in a nonverbal task exploring attribution of intention [Brunet, E., Sarfati, Y., Hardy-Bayle, M. C., & Decety, J. A PET investigation of the attribution of intentions with a nonverbal task. Neuroimage, 11, 157166, 2000]. We hypothesize that the resolution of incongruity might occur through a process of intention attribution. We also asked subjects to rate the funniness of each cartoon pair. A parametric analysis showed that the left amygdala was activated in relation to subjective amusement. We hypothesize that the amygdala plays a key role in giving humor an emotional dimension.

Pantomimes are special gestures which rely on working memory

The case of a patient is reported who presented consistently with overt deficits in producing pantomimes in the absence of any other deficits in producing meaningful gestures. This pattern of spared and impaired abilities is difficult to reconcile with the current layout of cognitive models for praxis. This patient also showed clear impairment in a dual-task paradigm, a test taxing the co-ordination aspect of working memory, though performed normally in a series of other neuropsychological measures assessing language, visuo-spatial functions, reasoning function, and executive function. A specific working memory impairment associated with a deficit of pantomiming in the absence of any other disorders in the production of meaningful gestures suggested a way to modify the model to account for the data. Pantomimes are a particular category of gestures, meaningful, yet novel. We posit that by their very nature they call for the intervention of a mechanism to integrate and synthesise perceptual inputs together with information made available from the action semantics (knowledge about objects and functions) and the output lexicon (stored procedural programmes). This processing stage conceived as a temporary workspace where gesture information is actively manipulated, would generate new motor programmes to carry out pantomimes. The model of gesture production is refined to include this workspace.

Double dissociation between meaningful and meaningless gesture reproduction in apraxia

A model of the normal processing of gestures to account for the complexityof the different patterns of apraxia has been proposed by Rothi et al. (1991;1997) and recently refined by Cubelli et al. (2000). This model, in analogy withthe dual-route models of reading (e.g., Coltheart et al., 1993) encompasses threeprocessing components

Exploring the Relationship Between Gestural Recognition and Imitation: Evidence of Dyspraxia in Autism Spectrum Disorders

In this study, the relationship between gesture recognition and imitation was explored. Nineteen individuals with Autism Spectrum Disorder (ASD) were compared to a control group of 23 typically developing children on their ability to imitate and recognize three gesture types (transitive, intransitive, and pantomimes). The ASD group performed more poorly than controls on all tasks of recognition and imitation. Higher performance on tests of working memory was associated with increased odds of successful imitation in both groups. Group differences remained even when working memory was statistically controlled for. An association was revealed in the ASD group between pantomime recognition and imitation but a similar association was not identified for intransitive gestures suggesting that recognition alone is not sufficient for imitation success.

Perceiving What Is Reachable Depends on Motor Representations: Evidence from a Transcranial Magnetic Stimulation Study

Background Visually determining what is reachable in peripersonal space requires information about the egocentric location of objects but also information about the possibilities of action with the body, which are context dependent. The aim of the present study was to test the role of motor representations in the visual perception of peripersonal space. Methodology Seven healthy participants underwent a TMS study while performing a right-left decision (control) task or perceptually judging whether a visual target was reachable or not with their right hand. An actual grasping movement task was also included. Single pulse TMS was delivered 80% of the trials on the left motor and premotor cortex and on a control site (the temporo-occipital area), at 90% of the resting motor threshold and at different SOA conditions (50ms, 100ms, 200ms or 300ms). Principal Findings Results showed a facilitation effect of the TMS on reaction times in all tasks, whatever the site stimulated and until 200ms after stimulus presentation. However, the facilitation effect was on average 34ms lower when stimulating the motor cortex in the perceptual judgement task, especially for stimuli located at the boundary of peripersonal space. Conclusion This study provides the first evidence that brain motor area participate in the visual determination of what is reachable. We discuss how motor representations may feed the perceptual system with information about possible interactions with nearby objects and thus may contribute to the perception of the boundary of peripersonal space.

Cognitive Approach to the Assessment of Limb Apraxia

A new instrument for the assessment of the different levels of gesture processing, as identified by recent cognitive models of apraxia, is presented. The battery comprises thirteen tasks—eight assess the production of meaningful gestures both on command and on imitation, four tasks assess the ability to recognize and identify gestures, and one task assesses imitation of meaningless gestures. The battery encompasses a novel test of gesture production on visual command. A total of 60 healthy British volunteers were tested with the entire battery. On the whole, participants made more errors with pantomimes than with other tasks. Their scores served as norms.

Relationship between Object-Related Gestures and the Fractionated Object Knowledge System

The praxic semantic system comprises a conceptual knowledge system, which stores functional information about objects, and an action knowledge system, which stores information about the correct manipulation of objects. Moreover, mechanical problem solving abilities permit to take advantages from objects structure to use unfamiliar tools or discover alternative ways of using familiar tools. This study aims at investigating whether conceptual knowledge, action knowledge and mechanical problem solving abilities intervene in the production of gestures with objects (i.e. pantomimes and object use) by testing a group of brain damaged patients. Results showed that the mechanical problem solving abilities are not sufficient to produce pantomimes and that only severe deficits in the praxic semantic system would affect the production of these gestures. Furthermore, a double dissociation was observed between mechanical problem solving abilities and the capacity to use multiple objects. Overall, the results indicate that the praxic semantic system can be disrupted at different levels, suggesting that the semantic system for object has to be conceived as fractionated in different entities.

Case report: selective deficit in the production of intransitive gestures in an individual with autism

Left-hemisphere brain damage may result in limb apraxia, a deficit in the processing of gestures ([Rothi et al., 1991] and Cubelli et al., 2000 R. Cubelli, C. Marchetti, G. Boscolo and S. Della Sala, Cognition in action: Testing a model of limb apraxia, Brain and Cognition 44 (2000), pp. 144-165. Abstract | PDF (353 K) | View Record in Scopus | Cited By in Scopus (53)[Cubelli et al., 2000]) which may be transitive (i.e., actual object use), intransitive (i.e., communicative), pantomime (i.e., a gestures that describe the object use), or meaningless gestures (i.e., arbitrary gestures that have no semantics).

Linguistic and spatial information for action.

Motor acts can be triggered according to either semantic or spatial objects attributes, which are thought to predominantly involve the ventral and the dorsal stream of the visual system, respectively, but with different time constraints. To date, no study has specifically addressed the issue of a possible interaction between spatial and semantic information when responding according to linguistic stimuli. In particular, it is not well established whether a motor response to a linguistic stimulus may remain immune to the influence of concurrent spatial information. In this vein, we tested the influence of the presentation of congruent and incongruent spatial information on a right-left motor response made towards a linguistic stimulus, and also the reverse condition. Results showed that the time to respond to a linguistic stimulus was greater than that observed to react to a spatial stimulus. Furthermore, we found an absence of interference of linguistic information on response accuracy and reaction time when responding to spatial stimuli. In fact, a strong interference of spatial information in the form of an increase in reaction time and misdirected responses was observed when responding to the linguistic stimulus, but predominantly for responses with short reaction times (300-500 ms) and in presence of incongruent spatial information. In the latter condition, correct responses showed in addition a tendency to veer away from the distracting spatial stimulus. We conclude that response selection can be influenced by irrelevant visual information. This suggests that information that is processed within the ventral and the dorsal visual streams compete very early under different time constraints, in order to specify the relevant visual signal for action.

The perception of peripersonal space in right and left brain damage hemiplegic patients.

Peripersonal space, as opposed to extrapersonal space, is the space that contains reachable objects and in which multisensory and sensorimotor integration is enhanced. Thus, the perception of peripersonal space requires combining information on the spatial properties of the environment with information on the current capacity to act. In support of this, recent studies have provided converging evidences that perceiving objects in peripersonal space activates a neural network overlapping with that subtending voluntary motor action and motor imagery. Other studies have also underlined the dominant role of the right hemisphere (RH) in motor planning and of the left hemisphere (LH) in on-line motor guiding, respectively. In the present study, we investigated the effect of a right or left hemiplegia in the perception of peripersonal space. 16 hemiplegic patients with brain damage to the left (LH) or right (RH) hemisphere and eight matched healthy controls performed a color discrimination, a motor imagery and a reachability judgment task. Analyses of response times and accuracy revealed no variation among the three groups in the color discrimination task, suggesting the absence of any specific perceptual or decisional deficits in the patient groups. In contrast, the patient groups revealed longer response times in the motor imagery task when performed in reference to the hemiplegic arm (RH and LH) or to the healthy arm (RH). Moreover, RH group showed longer response times in the reachability judgment task, but only for stimuli located at the boundary of peripersonal space, which was furthermore significantly reduced in size. Considered together, these results confirm the crucial role of the motor system in motor imagery task and the perception of peripersonal space. They also revealed that RH damage has a more detrimental effect on reachability estimates, suggesting that motor planning processes contribute specifically to the perception of peripersonal space.