Lateral Occipital Temporal Cortex Research Articles

Action Observation Network Activity Related to Object-Directed and Socially-Directed Actions in Adolescents.

The human action observation network (AON) encompasses brain areas consistently engaged when we observe other's actions. Although the core nodes of the AON are present from childhood, it is not known to what extent they are sensitive to different action features during development. Because social cognitive abilities continue to mature during adolescence, the AON response to socially-oriented actions, but not to object-related actions, may differ in adolescents and adults. To test this hypothesis, we scanned with functional magnetic resonance imaging (fMRI) male and female typically-developing teenagers (n = 28; 13 females) and adults (n = 25; 14 females) while they passively watched videos of manual actions varying along two dimensions: sociality (i.e., directed toward another person or not) and transitivity (i.e., involving an object or not). We found that action observation recruited the same fronto-parietal and occipito-temporal regions in adults and adolescents. The modulation of voxel-wise activity according to the social or transitive nature of the action was similar in both groups of participants. Multivariate pattern analysis, however, revealed that decoding accuracies in intraparietal sulcus (IPS)/superior parietal lobe (SPL) for both sociality and transitivity were lower for adolescents compared with adults. In addition, in the lateral occipital temporal cortex (LOTC), generalization of decoding across the orthogonal dimension was lower for sociality only in adolescents. These findings indicate that the representation of the content of others' actions, and in particular their social dimension, in the adolescent AON is still not as robust as in adults.SIGNIFICANCE STATEMENT The activity of the action observation network (AON) in the human brain is modulated according to the purpose of the observed action, in particular the extent to which it involves interaction with an object or with another person. How this conceptual representation of actions is implemented during development is largely unknown. Here, using multivoxel pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data, we discovered that, while the action observation network is in place in adolescence, the fine-grain organization of its posterior regions is less robust than in adults to decode the abstract social dimensions of an action. This finding highlights the late maturation of social processing in the human brain.

Sex Differences in the Neural Correlates of Spatial Context Memory Decline in Healthy Aging.

Aging is associated with episodic memory decline and alterations in memory-related brain function. However, it remains unclear if age-related memory decline is associated with similar patterns of brain aging in women and men. In the current task fMRI study, we tested the hypothesis that there are sex differences in the effect of age and memory performance on brain activity during episodic encoding and retrieval of face-location associations (spatial context memory). Forty-one women and 41 men between the ages of 21 and 76 years participated in this study. Between-group multivariate partial least squares analysis of the fMRI data was conducted to directly test for sex differences and similarities in age-related and performance-related patterns of brain activity. Our behavioral analysis indicated no significant sex differences in retrieval accuracy on the fMRI tasks. In relation to performance effects, we observed similarities and differences in how retrieval accuracy related to brain activity in women and men. Both sexes activated dorsal and lateral PFC, inferior parietal cortex, and left parahippocampal gyrus at encoding, and this supported subsequent memory performance. However, there were sex differences in retrieval activity in these same regions and in lateral occipital-temporal and ventrolateral PFC. In relation to age effects, we observed sex differences in the effect of age on memory-related activity within PFC, inferior parietal cortex, parahippocampal gyrus, and lateral occipital-temporal cortices. Overall, our findings suggest that the neural correlates of age-related spatial context memory decline differ in women compared with men.

Assessment of gray and white matter structural alterations in migraineurs without aura

BackgroundMigraine constitute a disorder characterized by recurrent headaches, and have a high prevalence, a high socio-economic burden and severe effects on quality of life. Our previous fMRI study demonstrated that some brain regions are functional alterations in migraineurs. As the function of the human brain is related to its structure, we further investigated white and gray matter structural alterations in migraineurs.MethodsIn current study, we used surface-based morphometry, voxel-based morphometry and diffusion tensor imaging analyses to detect structural alterations of the white matter and gray matter in 32 migraineurs without aura compared with 32 age- and gender-matched healthy controls.ResultsWe found that migraineurs without aura exhibited significantly increased gray matter volume in the bilateral cerebellar culmen, increased cortical thickness in the lateral occipital-temporal cortex, decreased cortical thickness in the right insula, increased gyrification index in left postcentral gyrus, superior parietal lobule and right lateral occipital cortex, and decreased gyrification index in the left rostral middle frontal gyrus compared with controls. No significant change in white matter microstructure was found in DTI analyses.ConclusionThe significantly altered gray matter brain regions were known to be associated with sensory discrimination of pain, multi-sensory integration and nociceptive information processing and were consistent with our previous fMRI study, and may be involved in the pathological mechanism of migraine without aura.

Reach Out and Touch Someone: Anticipatory Sensorimotor Processes of Active Interpersonal Touch

Anticipating the sensorimotor consequences of an action for both self and other is fundamental for action coordination when individuals socially interact. Somatosensation constitutes an elementary component of social cognition and sensorimotor prediction, but its functions in active social behavior remain unclear. We hypothesized that the somatosensory system contributes to social haptic behavior as evidenced by specific anticipatory activation patterns when touching an animate target (human hand) compared with an inanimate target (fake hand). fMRI scanning was performed during a paradigm that allowed us to isolate the anticipatory representations of active interpersonal touch while controlling for nonsocial sensorimotor processes and possible confounds because of interpersonal relationships or socioemotional valence. Active interpersonal touch was studied both as skin-to-skin contact and as object-mediated touch. The results showed weaker deactivation in primary somatosensory cortex and medial pFC and stronger activation in cerebellum for the animate target, compared with the inanimate target, when intending to touch it with one's own hand. Differently, in anticipation of touching the human hand with an object, anterior inferior parietal lobule and lateral occipital-temporal cortex showed stronger activity. When actually touching a human hand with one's own hand, activation was stronger in medial pFC but weaker in primary somatosensory cortex. The findings provide new insight on the contribution of simulation and sensory prediction mechanisms to active social behavior. They also suggest that literally getting in touch with someone and touching someone by using an object might be approached by an agent as functionally distinct conditions.