BOLD signals in functional magnetic resonance imaging do not always reflect what nerve cells are doing.
There are few topics as controversial as research involving experiments on animals in general and primates in particular.
Although its duration is brief, short term memory is a complex network of neurons in the brain that includes different brain regions. To store the information, these regions must work together. Researchers from the Max Planck Institute for Biological Cybernetics in Tübingen have now discovered that the participating regions must be active at the same time to enable us to form short-term memories of things that happen.
Functional magnetic resonance images reflect input signals of nerve cells.
At least two regions of the brain decide what we perceive.
Tübinger neurophysiologists develop new method to study widespread networks of neurons responsible for our memory.
New findings support the view that the content of consciousness is not localised in a unique cortical area.
Max Planck scientists discover brain cells in monkeys that may be linked to self-awareness and empathy in human.
Scientists from Tübingen discovered new functions of brain regions that are responsible for seeing movement.
Scientists have now discovered how different brain regions cooperate during short-term memory.
Specific nerve cells process vocal information from conspecifics.
|Similar structures for face selectivity in human and monkey brains|
Using functional magnetic resonance imaging (fMRI), scientists at the Max Planck Institute for Biological Cybernetics in Tübingen have now discovered that the circuitry for face processing in the brain is remarkably similar in both macaques and humans. Consequently, macaque monkeys could be suitable model organisms for studying human disorders such as autism or prosopagnosia, so-called "face blindness".
Perceptual changes - a key to our consciousness
Recognition at first glance
|June 2010 |
How to read brain activity?
|Dec. 2009 |
|Regions of the brain can rewire themselves|
Scientists in Tübingen have proven for the first time that widely-distributed networks of nerves in the brain can fundamentally reorganize as required.
|March 2009 |
|Here`s looking at you, fellow!|
Humans and monkeys are experts in face recognition making them even more akin than previously thought.
|Feb. 2009 |
|Whose voice is that|
Max Planck scientists discover a "voice" area in the brain of a nonhuman primate.
|Feb. 2008 |
|A neural mosaic of tones|
Max Planck researchers map out numerous areas in the brain where sound frequencies are processed.
|June 2006 |
|New insights in brain tomography|
Functional imaging signals indicate weakening in brain activity.
|April 2006 |
|Smart Contrast Agents for functional Magnetic Resonance Imaging|
Modern medical diagnostics and brain research would be unthinkable without magnetic resonance imaging (MRI). In addition to traditional imaging, which reveals anatomical structures, functional MRI (fMRI) has become a valuable tool. It comes close to allowing us to watch the brain at work and has contributed considerably to the advances in human cognitive neuroscience. However, fMRI is an indirect method, as it measures a surrogate signal, based on hemodynamics. Smart contrast agents (SCAs) shall overcome this limitation and allow a direct access to neuronal activity.
|Integration of Touch and Sound in Auditory Cortex|
New results demonstrate that those regions of the brain uniquely devoted to the processing of a single sense are rarer than classically thought. Instead, most of the brain is concerned with merging information across senses and creating a coherent percept.
|Functional Magnetric Resonance Imaging of the Monkey Brain|
Our research concentrates on the neural mechanisms of cognitive functions in the primate. Specific projects include investigations aiming to elucidate (a) how brain areas involved in object recognition interact and integrate information that is critical for the task at hand, (b) what kind of neural activity in the association visual cortices, e.g. the inferior temporal cortex, underlies the ability of subjects (be they humans or monkeys) to assess object similarity and perform categorization and recognition, and (c) how brains accomplish the perceptual organization involved in visual cognition. We also study the ability of networks of neurons to reorganize in response to extensive familiarity or deafferentation, that is, deprivation of their sensory input. Results from such investigations over the last decade strongly suggest that stimulus or task-related neural activity is distributed over large parts of the brain, covering different cortical and subcortical areas whose synergistic co-activation probably d termines the neural states underlying various conscious behaviours. Attempts to understand the organization of such global networks are hampered by the large gaps that exist between the different kinds of investigations of the nervous system. Neuroimaging studies in humans are highly inclusive, in that one can record activity from all brain areas at the same time, but they lack the ability to tell us anything about the local processes underlying the observed stimulus-induced activation patterns. Physiological studies, on the other hand, can record the activity patterns of single neurons or of small neural assemblies with outstanding spatial and temporal resolution, but are unable to capture the concurrent activation of other brain parts, and thus are often ambiguous as to the exact role of single units in various behaviours. An ideal strategy would be to find a way to combine spatiotemporally resolved functional magnetic resonance imaging (fMRI) with intracortical electrophysiology conducted with single or mu tiple microelectrodes. Convinced of the benefits of such an integrated approach, we recently developed an fMRI system for the nonhuman primate and used it to show that this neuroimaging technique can be used in monkeys to obtain (a) high resolution activity maps of their brain with excellent spatial localization, (b) a view of the organization of networks involved in scene, motion, and visual form analysis, (c) ultra-high resolution fMRI with intraosteally implanted radio frequency coils, (d) detailed connectivity patterns and tracings of pathways crossing several synapses in the living animal with injections of paramagnetic agents, and (e) excellent retinotopic mapping of extrastriate cortex. This methodology is currently used to answer fundamental question regarding visual perception and object recognition.
|The Eyes Hear, Too|
Our brain, more than anything else, determines what we hear. How it does that is a question that researchers in the Department for the Physiology of Cognitive Processes at the Max Planck Institute for Biological Cybernetics in Tübingen are trying to answer. Led by Nikos K. Logothetis, the scientists study not only brain areas that are used for this, but also how the acoustic information is combined with the brain's impressions.
|A Mosaic of Tones |
The brain filters what we hear. One of the reasons it is able to do this is because particular groups of neurons react only to specific sound frequencies. Neurobiologists at the Max Planck Institute for Biological Cybernetics in Tübingen used high-resolution functional magnetic resonance imaging (fMRI) of nonhuman primates to create a frequency map for 11 exceptionally small auditory fields in the brain. They did this by identifying neuronal fields that are activated either by single frequencies (tones) or by combinations of frequencies. Many of the findings will now aid in human imaging, which for more than a decade has had difficulty doing such a large-scale mapping as was accomplished here in some of our closest primate relatives.
|A Mature Brain Does Not Adapt|
To what extent are nerve cells in the cortex able to reorganize themselves to compensate for damage following a stroke or other defects? From experiments with macaques, neurobiologists at the Max Planck Institute for Biological Cybernetics in Tübingen have now discovered that no reorganization of nerve cells in the primary visual cortex takes place after damage to the retina. This result contradicts previous concepts that primary sensory systems in the brain cortex retain plasticity and can compensate for damage up to adulthood.
|Seeing by Learning|
Cross-linkage of nerve cells in the higher cognitive regions of the brain enables people to remember other people, objects and events. Thanks to the plasticity of such networks, we can continuously store new content. Researchers at the Max Planck Institute for Biological Cybernetics in Tübingen have now discovered that learning also has a feedback effect on the neurons of the brain’s visual centers themselves. And that this optimizes interaction and feedback between sensory and associative brain areas, in addition to the “upward” information flow from visual areas.
|Monkeys Read Faces too|
Investigating the link between facial and vocal expressions is a prerequisite for understanding human speech perception. Scientists at the Max Planck Institute for Biological Cybernetics in Tübingen have now shown that not only humans, but also rhesus monkeys are able to understand the connection between their own species’ facial and vocal expressions. The researchers see this ability in monkeys as an evolutionary precursor to human speech perception.
|Inside the Chamber |
The development of magnetic resonance imaging (MRI) is one of basic research’s success stories. Nowadays it is a fundamental part of medical diagnostics. Yet this research has been a lengthy process – it is over fifty years since physicists first began investigating so-called nuclear magnetic resonance. By adopting new methods, max Planck scientists in Tübingen have succeeded in considerably extending their understanding of the basic principles of functional MRI, thereby advancing cognitive neurobiology.