1 - 3 pm, GAFO 05/425, Jonas Rose (Tierphysiologie, Universität Tübingen): Capacity and control of working memory.
Fakultät für Psychologie
Phone: +49 234 - 32 28213
Fax: +49 234 - 32 14377
News & Views
Functional organization of telencephalic visual association fields in pigeons
Birds show remarkable visual abilities that surpass most of our visual psychophysiological abilities. In this study, scientists from the biopsychology investigated visual associative areas of the tectofugal visual system in pigeons. Similar to the condition in mammals, ascending visual pathways in birds are subdivided into parallel form/color vs. motion streams at the thalamic and primary telencephalic level. However, we know practically nothing about the functional organization of those telencephalic areas that receive input from the primary visual telencephalic fields. The current study therefore had two objectives: first, to reveal whether these visual associative areas of the tectofugal system are activated during visual discrimination tasks; second, to test whether separated form/color vs. motion pathways can be discerned among these association fields. To this end, pigeons were trained to discriminate either form/color or motion stimuli. The immediate early gene protein ZENK was used to capture the activity of the visual associative areas during the task. Indeed, several visual associative telencephalic structures could be identified by activity pattern changes during discriminations. However, none of these areas displayed a difference between form/color vs. motion sessions. The presence of such a distinction in thalamo-telencephalic, but not in further downstream visual association areas opens the possibility that these separate streams converge very early in birds, which possibly minimizes long-range connections due to the evolutionary pressure toward miniaturized brains.
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Reconsolidation in the Immune System
When memories are recalled, they enter a transient labile phase in which they can be impaired or enhanced followed by a new stabilization process termed reconsolidation. Meanwhile, we have more information on the neural processes that constitute this constant updating of memories stored in the synaptic weights of our brain. But we have multiple memory systems and some of them do not reside in the nervous system. It is unknown, however, whether reconsolidation is restricted to neurocognitive processes or can also be found in peripheral physiological functions as well. To answer this question, a group of psychoimmunologists from Essen and biopsychologists from Bochum used a paradigm of behaviorally conditioned taste aversion in rats to study memory-updating in learned immunosuppression. The administration of sub-therapeutic doses of the immunosuppressant cyclosporin A together with the conditioned stimulus (CS/saccharin) during retrieval blocked extinction of conditioned taste aversion and learned suppression of T cell cytokine (interleukin-2; interferon-c) production. This conditioned immunosuppression is of clinical relevance since it significantly prolonged the survival time of heterotopically transplanted heart allografts in rats. Collectively, these findings demonstrate that memories can be updated on both neural and behavioral levels as well as on the level of peripheral physiological systems such as immune functioning. A huge wide door has been opened by these insights. Memory updating seems to be a widespread process that is in no way restricted to our brain.
Hadamitzky, M., Bösche, K., Wirth, T., Buck, B., Beetz, O., Christians, U., Schniedewind, B., Güntürkün, O., Engler, H., Schedlowski, M., Memory reconsolidation abrogate extinction of learned immunosuppression, Brain, Behavior, and Immunity, 2016, 52: 40-48.
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CATEGORIES IN THE PIGEON BRAIN: A REVERSE ENGINEERING APPROACH
Pigeons are well capable to categorize visual stimuli. Now scientists of the biopsychology adopted a reverse engineering approach to study categorization learning in a novel way. Instead of training pigeons on predefined categories, they simply presented stimuli and analyzed neural output in search of categorical clustering on a solely neural level. They presented artificial, easily distinguishable colored shapes and grating while recording from the nidopallium frontolaterale (NFL), a higher visual area in the avian brain. They computed representational dissimilarity matrices to reveal categorical clustering based on the neural data. This revealed that colored shapes and gratings were differentially represented in the brain. This study gives proof-of-concept that this reverse engineering approach – namely reading out categorical information from neural data – can be quite helpful in understanding the neural underpinnings of categorization learning.
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‘Wanting’, ‘liking’, and their relation to consciousness
Most animal and human behaviors emanate from goal-directedness and pleasure seeking, suggesting that they are primarily under conscious control. However, ‘wanting’ and ‘liking’ are believed to be adaptive core subcortical processes working at an unconscious level and responsible for guiding behavior towards appropriate rewards. Here we examine whether ‘wanting’ is an inherent property of conscious goals and ‘liking’ an intrinsic component of conscious feelings. We argue that ‘wanting’ and ‘liking’ depend on mechanisms acting below the level of consciousness, explaining why individuals often struggle to enhance or refrain their motivations and emotions by means of conscious control. In particular, hyperreactivity of subcortical ‘wanting’ systems has been tied to pathological behaviors such as drug addiction and gambling disorder. In addicts, cognitive processes intended to curb drug-seeking wage a constant battle against subcortical urges to take more drug that often ends in relapse following repeated assaults. Nevertheless, we suggest that in non-pathological contexts, ‘wanting’ and ‘liking’ interact with major cognitive processes in order to guide goal-directed actions.
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Are birds “natural split-brains”? – Anatomical analysis of the anterior commissure in pigeon
In birds which do not possess a corpus callosum the anterior commissure (AC) constitutes the main interhemispheric pathway at telencephalic level. However no detailed description of the topographic organization of the AC has been performed till now. This information is not only necessary for a better understanding of interhemispheric transfer in birds, but also for a comparative analysis of the evolution of commissural systems in the vertebrate classes. Therefore researchers from the Biopsychology Department examined the fiber connections of the AC. The main differences in the interhemispheric connectivity between birds and mammals are found at two levels of structural organization. First, the AC in birds differs from the corpus callosum and the AC of mammals in its proportion of homotopic reciprocal to heterotopic unidirectional projections. In contrast to the situation in mammals, in birds only a small amount of cells interconnect the two hemispheres in a homotopic and reciprocal fashion. Instead, most of the cells project heterotopically and in unidirectional manner. Second, in birds the absolute majority of pallial areas do not participate by themselves in interhemispheric exchange. Instead, a rather small cluster of cells is key for commissural interactions. Thus, the colloquial statement that birds are “natural split-brains” is wrong, when the pallial areas are considered that interhemispherically interact via the AC. It is true, however, when taking into account how small the proportion of pallial neurons is that constitutes interhemispheric exchange.