Vertebrate brain theory

7.2    The inclusion of signal class 3 in the Pontocerebellum

With the formation of signal divergence in the primary cortex areas, especially in the temporal, parietal and occipital lobes, the output shifted from the class 5 neurons to the class 3 neurons, and the signals ascending to the cortex arrived at the axons of the class 4 neurons and ended on class 4 cortical neurons. These could not project further upwards in the cortex cortex cortex, so they transformed into interneurons and transmitted the incoming signals to class 3 neurons, which projected to the motor side of the cortex, but also descending to the substantia nigra pars compacta, the striatum and also via the bridge nuclei into the Pontocerebellum.

This reveals a possible communication problem. Class 3 neurons projected downward. However, to do this they had to use class 5 neurons. With the transition from a class 3 neuron to a class 5 neuron, there was no change in signal class. After the formation of the signal divergence, the class 3 signals were extreme value-coded signals. They remained so, even though their descending projection was on axons that were assigned to the class-5 neuron.

Likewise, the output of the cerebellum was extreme coded after the beginning of the signal divergence in the nucleus olivaris. This signal class 3 also had to pull headward on axons of class 4. However, they remained extreme value coded signals.

Neurons of classes 4 and 5 can therefore not only transport analog signals, but also extreme value-coded signals and, in the case of the pontocerebellum, also complex signals. This must not be forgotten.

Associated with the strong signal divergence was an equally strong increase in class 3 neurons and, in parallel, an increase in the number of class 6 cortical mean neurons, resulting in a strong growth of the Pontocerebellum. Not all species of vertebrates were able to achieve such a development. Therefore, there are vertebrates today with varying degrees of cerebellar development. The Pontocerebellum is best developed in mammals, and especially in Homo sapiens. The strong increase in cortical mean neurons was associated with a strong increase in the number of Purkinje cells and thus also in the number of Purkinje groups. Since each Purkinje group could learn its own complex signal, the number of learnable signals in the cerebellum also increased.

In the plane divergence grids in the primary cortex areas, an additional extreme value coding of the different parameters, such as the angle of inclination of a short line through the orientation columns in the primary visual cortex, was performed. These were already maximum coded. But also minimum coded signals could be converted into maximum coded signals by signal inversion. In the cerebellum, these maximum-coded signals could be combined to complex signals that were learned and later recognized. The cerebellar output again reached the secondary cortex areas, where angles or shapes, but also colors and brightness could be analyzed. These areas are called association areas.

It was not the task of this monograph to fully show the origin of the intelligence of vertebrates and especially of humans. Rather, the aim was to clarify the order in which the evolution of the central nervous system of vertebrates might have taken place and which algorithms represent the most elementary foundations of this intelligence. It seems that this development began in earliest primeval times with the emergence of the segmented Bilateria, which produced a segmented, rope ladder-like nervous system that was also bilaterally present. The formation of neuronal interactions between the two rope ladder systems - especially contralateral inhibition - formed the basis for further developments. The key event for future vertebrates was the change of the vestibular system from paleo- to neovestibular sense. The equal treatment of vestibular and sensory signals led to the formation of the spinocerebellum, which initially served purely as a signal inversion. The formation of signal divergence in the nucleus olivaris formed the basis for further cerebellum development. The incorporation of mean signals into the cerebellum opened the way to learning ability.