Joshua Obermayer graduates!!
On the 3rd of April, Joshua succesfully defended his PhD thesis on "Cholinergic Modulation of Microcircuits in the Cortex."
Thesis synopsis: Neuromodulators enable the brain to change the activity of neuronal networks and their output in a spatially and temporally precise manner. The work presented in this thesis shows that in addition to the cholinergic afferent input from the basal forebrain, ChAT-VIP interneurons act as a local source of ACh and control attention. Since ChAT-VIP neurons are found in rodent cortex, but not in human neocortex, this suggests that cholinergic systems that shape attention behavior rely on different mechanisms in rodent and human brain. When ACh is released in the cortex it modulates synaptic plasticity in a layer specific fashion and enhances lateral inhibition between pyramidal neurons. Joshua provides direct evidence that cholinergic modulation of layer specific synaptic plasticity and lateral inhibition also occur in the human cortex. This indicates that cholinergic modulation of these phenomena is a conserved mechanism across species, which underscores its relevance for cognitive processing.
Dr. Obermayer is continuing his career as Business developer/Project manager at Sylics.
mPFC activity during learned behaviour:
Neural representation of context and behavioral adaptation in rat medial prefrontal cortex during learned behavior
Roel De Haan, Judith Lim, Sven A. van der Burg, Anton W. Pieneman, Vinod Nigade, Huib D. Mansvelder and Christiaan P J De Kock
To identify spiking patterns of mPFC during learned behavior, we extracellularly recorded neuronal action potential firing in the mPFC of rats performing a whisker-based “Go”/“No-go” object localization task. First, we identify three functional groups of neurons, which show different degrees of spiking modulation during task performance. One group increased spiking activity during correct “Go” behavior (positively modulated), the second group decreased spiking (negatively modulated) and one group did not change spiking. Second, the relative change in spiking was context-dependent and largest when motor output had contextual value. Third, the negatively modulated population spiked more when rats updated behavior following an error compared to trials without integration of error information. Finally, insufficient spiking in the positively modulated population predicted erroneous behavior under dynamic “No-go” conditions. Thus, mPFC neuronal populations with opposite spike modulation characteristics differentially encode context and behavioral updating and enable flexible integration of error corrections in future actions.
First sub-types of pyramidal neurons in human neocortex revealed:
Comprehensive Morpho-Electrotonic Analysis Shows 2 Distinct Classes of L2 and L3 Pyramidal Neurons in Human Temporal Cortex.
Yair Deitcher, Guy Eyal, Lida Kanari, Matthijs Verhoog, Guy Kahou, Huibert Mansvelder, Christiaan de Kock*, and Idan Segev*
Cerebral Cortex, 2017. EPub. (https://doi.org/10.1093/cercor/bhx226)
* shared senior authors
We used our database of digital reconstructions from human neocortex L2/L3 pyramidal neurons to address the question whether pyramidal subtypes exist that can be subclassified based on morphology. Using a newly developed algorithm by Lida Kanari (EPFL, Blue Brain Project), we show that we can reliably distinguish profuse-tufted pyramids from slim-tufted pyramids, based on morphological complexity of the apical dendrite. These structural differences translate into functional properties, since profuse-tufted pyramids have increased activity upon current injections relative to slim-tufted pyramids. Thus, our morpho-electrotonic analysis shows 2 distinct classes of human Layer 2/Layer 3 pyramids.
Deitcher et al, CerebCtx 2017
Teaching contribution of our lab in CNCR Minor "Brain and Mind" highlighted in Ad Valvas (VU Amsterdam magazine).
The starting course Cognitive Neuroscience of the Minor is coordinated by Sophie vd Sluis and Christiaan de Kock and serves to explain basic principles of brain structure and function to a broad spectrum of students with no previous training in neuroscience. During the first lecture, student reporter Joeke Berg (secretly) joined the lecture and published a report (in Dutch) in Ad Valvas using her dedicated column "So you think you can teach".
An important goal of our lab is outreach to the neuroscience community, students and layman audiences and we very much appreciate the inspiring exposure for brain research created by this report!
high resolution link: https://issuu.com/advalvas/docs/nr_2_13_september_2017
=>scroll to page 27.
Perspective on function of Posterior Parietal Cortex during whisker somatosensory integration published in Special Issue of the IBRO Journal "Neuroscience". The special issue will be launched in 2017 and features invited contributions from many speakers that appeared during the international meeting BACOFUN 2016, which was held in May 2016, Amsterdam. Editors of the special issue are Heiko Luhmann (Mainz), Miguel Maravall (Sussex) and C. de Kock (Amsterdam).
The Posterior Parietal Cortex as Integrative Hub for Whisker Sensorimotor Information.
Mohan H., de Haan R., Mansvelder H.D., de Kock C.P.J.
Neuroscience. 2018 Jan 1;368:240-245.
doi: 10.1016/j.neuroscience.2017.06.020. Epub 2017 Jun 19.
Our daily life consists of a continuous interplay between incoming sensory information and outgoing motor plans. Particularly during goal-directed behavior and active exploration of the sensory environment, brain circuits are merging sensory and motor signals. This is referred to as sensorimotor integration and is relevant for locomotion, vision or tactile exploration. The somatosensory (tactile) system is an attractive modality to study sensorimotor integration in health and disease, motivated by the need for revolutionary technology that builds upon conceptual understanding of sensorimotor integration, such as brain-machine-interfaces and neuro-prosthetics. In this perspective, we focus on the rat whisker system and put forward the posterior parietal cortex as a potential circuit where sensorimotor integration could occur during active somatosensation.
Illustration by Nicolas Antille,
Blue Brain Project, EPFL.
Mohan et al, 2018, Figure 2
Hemanth Mohan graduates!!
On the 20th of March, succesfully defended his PhD thesis on the "Organizational Principles of Human and Rodent Association Cortex."
Thesis synopsis: Hemanths work offers new insights into both the structural organization as well as the decoding principles used by the association cortex. In behaving rats, he found highly specific coding principles for individual cortical layers during whisker motion and whisker touch, which is comparable to fingertip use when operating the touch screen of a smartphone. He further uncovered the presence of specialized neurons that report the difference between expected and actual sensory information. To directly bridge animal research to human brain and uncover the organizational principles of human association cortex, we made digital reconstructions of individual human neurons in 3D. Hemanth found that individual human neurons are three times larger compared to rodent and monkey neurons with much more complex architecture. This has a large impact on how these neurons form networks and process information. We are convinced that these insights may eventually contribute to the improvement of neural prosthetics or the treatment of brain diseases, including Parkinson or Alzheimer.
Dr. Mohan is continuing his career at Cold Spring Harbor (NY, USA) in the lab of Prof.dr. Josh Huang.
Barrel Cortex Function Meeting
On the 19th and 20th of May, our lab hosted the BACOFUN 2016 meeting with renowned keynote speakers including profs. Gordon Fishell, Adam Kepecs, Moritz Helmstaedter, Michael Stryker, Anthony Holtmaat, David Kleinfeld and Josh Huang. These keynote lectures were supplemented with lectures by (a.o) Randy Bruno, Koen Vervaeke, Michael Brecht, James Poulet, and Fritjof Helmchen.
The meeting was attended by more than 160 participants from 40 different (inter)national institutes.
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