Event archive

Host: Max Planck Research Group "Neuroanatomy and Connectivity" Location: Max Planck Institute for Human Cognitive and Brain Sciences
The search for the structures underlying human cognition, and their corresponding neural substrates, has preoccupied many psychologists and neuroscientists in recent decades. How should scientists best carve up the many dimensions of cognition, emotion, and action into distinct functions or faculties? Do the terms "working memory" and "executive control" reflect the same or different underlying processes? Are there such things as "basic" emotions, and if so, how many? Such questions are difficult to answer but important to ask. Unfortunately, none of them will be directly addressed in this talk. Instead, I will focus on a number of important methodological and conceptual issues surrounding our collective efforts to study the structure of the human mind via brain imaging methods. These include low sensitivity and specificity, poor construct validity, and a lack of isomorphism between constructs at different levels of description. Drawing on a series of recent studies, I demonstrate how large-scale meta-analyses of thousands of published fMRI studies can help us overcome many, but perhaps not all, of these issues. I conclude with a speculative discussion of the short-term and long-term prospects for a fully realized cognitive neuroscience of the human mind. [more]

Dr Chris Lewis | Cortical feedback and repetition enhance sensory coding in primary visual cortex

Guest Lecture
Identical sensory stimulation results in highly dynamic response patterns in primary sensory cortex, despite the physical constancy of external factors. This response modulation is thought to be partly attributable to activity intrinsic to the brain itself, such as behavioral state and previous experience. Two prominent factors contributing to intrinsic brain activity are feedback signals from higher order areas and the history of coactivation amoung sensory cells. I will discuss a series of experiments that investigate the effects of cortical feedback and stimulus repetition on sensory coding in the primary visual cortex. We find that both feedback activity and sensory experience increase the amount of sensory information retrievable from population responses without changing the average activity of single cells or the mean activity across the population. Specifically, the information is encoded in the distributed pattern of activity across the population, as predicted by population coding and Hebbian plasticity. These findings suggest that early sensory cortices provide a highly flexible representation of external variables which reflects both the current state of higher order brain areas, as well as the history of previous stimulation. Time permitting, I will also discuss recent progress in our attempts to increase the spatial coverage of in vivo electrophysiology, while simultaneously acquiring signals at multiple spatial scales: from single neurons to whole brain areas. [more]
Go to Editor View