Latest findings by Szeged researchers: intelligence could be determined by human-specific brain characteristics and, in turn, as the Achilles heels of the brain these could also be responsible for the development of certain brain disorders.
The neocortex is dedicated to higher-order cognitive functions such as language use. This part of the brain has a very similar microstructure in humans and in species used for animal tests. However, the latest results of two research groups in Szeged University, headed by Gábor Tamás and Karri Lamsa respectively, suggest that the human neocortical network has unique properties.
Gábor Tamás’s research group together with Zoltán Nusser (Institute of Experimental Medicine of the MTA) has published an article in eLife on the unique properties of excitatory and inhibitory neurons of the human cerebral cortex. These interneuron connections are so effective that a single action potential of a single neuron may activate several other neurons. The authors suppose that this property specific to the human cerebral cortex might have evolved in order to foster more effective information processing. The publication of Gábor Tamás and his colleagues shows that several synaptic vesicles release neurotransmitters owing to neural activity in these very effective interneuron connections. The cerebral cortex of other species does not exhibit a similar phenomenon, which entails the possibility that this has evolved in humans only.
Viktor Szegedi and Karri Lamsa (Department of Physiology, Anatomy and Neuroscience, University of Szeged) published an article in Plos Biology, which is closely connected to the topic above. The article claims that these very effective connections are rather flexible and plastic, i.e. their effectiveness can be more readily changed than that of the interneuron connections of rats, which were examined as a baseline. These strong interneuron connections can be changed due to learning, and thus are able to activate another neuron system in the human cerebral cortex. These results are also important because the regulation of the neocortical neural network is indispensable during higher-order cognitive functions, such as learning.