Functional specificity in the human brain: A window into the functional architecture of the mind

Abstract

Is the human mind/brain composed of a set of highly specialized components, each carrying out a specific aspect of human cognition, or is it more of a general-purpose device, in which each component participates in a wide variety of cognitive processes? For nearly two centuries, proponents of specialized organs or modules of the mind and brain-from the phrenologists to Broca to Chomsky and Fodor-have jousted with the proponents of distributed cognitive and neural processing-from Flourens to Lashley to McClelland and Rumelhart. I argue here that research using functional MRI is beginning to answer this long-standing question with new clarity and precision by indicating that at least a few specific aspects of cognition are implemented in brain regions that are highly specialized for that process alone. Cortical regions have been identified that are specialized not only for basic sensory and motor processes but also for the high-level perceptual analysis of faces, places, bodies, visually presented words, and even for the very abstract cognitive function of thinking about another person's thoughts. I further consider the as-yet unanswered questions of how much of the mind and brain are made up of these functionally specialized components and how they arise developmentally.brain imaging | modularity | functional MRI | fusiform face area U nderstanding the nature of the human mind is arguably the greatest intellectual quest of all time. It is also one of the most challenging, requiring the combined insights not only of psychologists, computer scientists, and neuroscientists but of thinkers in nearly every intellectual pursuit, from biology and mathematics to art and anthropology. Here, I discuss one currently fruitful component of this grand enterprise: the effort to infer the architecture of the human mind from the functional organization of the human brain.The idea that the human mind/brain is made up of highly specialized components began with the Viennese physician Franz Joseph Gall (1758-1828). Gall proposed that the brain is the seat of the mind, that the mind is composed of distinct mental faculties, and that each mental faculty resides in a specific brain organ. A heated debate on localization of function in the brain raged over the next century (SI Text), with many of the major figures in the history of neuroscience weighing in (Broca, Brodmann, and Ferrier in favor, and Flourens, Golgi, and Lashley opposed). By the early 20th century, a consensus emerged that at least basic sensory and motor functions reside in specialized brain regions.The debate did not end there, however. Today, a century later, two questions are still fiercely contested. First, how functionally specialized are regions of the brain? The concept of functional specialization is not all or none but a matter of degree; a cortical region might be only slightly more engaged in one mental function than another, or it might be exclusively engaged in a single mental function. Many neuroscientists today challenge the strong (exclusive) version of ...

Top-down attention switches coupling between low-level and high-level areas of human visual cortex

“…information by modulating the visual area that is most specialized for processing this kind of information, both in terms of its evoked response (3,(6)(7)(8)(9)(10) and how it interfaces with frontoparietal cortex (14,17,18,33). The present findings suggest that attention can also influence visual areas not specialized for this information (e.g., retinotopic human area V4 during category-based attention to faces/scenes), increasing their coupling with more specialized areas.…”

“…At early stages, occipital cortex decomposes visual images into simple features, such as form and orientation (2). At later stages, ventral temporal cortex combines these features into complex objects, such as faces and scenes (3). Although this hierarchy is hard-wired (4), human vision is flexible: our goals and intentions determine what we see via top-down attention (5).…”

Functional specificity for high-level linguistic processing in the human brain

“…To conclude, discoveries of linguistic specificity provide answers to the longstanding question of whether high-level cognitive functions are supported by dedicated neural machinery (45) and provide important clues into the mental operations supported by these regions. Future work will (i) test the engagement of regions that support high-level linguistic processing in yet other nonlinguistic processes (e.g., amodal conceptual processing, action representation, or hierarchical sequence processing) as well as examine other language regions that support phonological and discourse-level processes, (ii) identify the precise linguistic computations conducted in each of these regions, and (iii) characterize the interactions between these regions and other parts of the brain that enable uniquely human cognition.…”

Spatiotemporal dynamics in understanding hand—object interactions

“…On the basis of these findings, it was proposed that neural substrate crucial for visual perception is represented by the higher-order visual areas of the inferior temporal lobe (6)(7)(8). Functional MRI (fMRI) data obtained in humans confirmed these findings (9,10). These data also suggested that the temporal lobe poles are an even higher integration center, where conceptual object properties (e.g., how an object is commonly used) are represented (11)(12)(13).…”