What are mossy fibers in the cerebellum?

Mossy Fibers. Mossy fibers (Fig. 11.9) provide a rich excitatory drive to the cerebellar cortex. They originate from several regions in the brain and spinal cord (Fig.

What are granule cells in the cerebellum?

Cerebellar granule cells form the thick granular layer of the cerebellar cortex and are among the smallest neurons in the brain. (The term granule cell is used for several unrelated types of small neurons in various parts of the brain.)

What are granule cells in the brain?

Granule cells are the smallest and most numerous type of neurons in the brain. They are involved in functions ranging from processing visual and motor information to learning and memory.

How many granule cells does the cerebellum have?

The human brain contains approximately 60 billion cerebellar granule cells1, which outnumber all other brain neurons combined.

What is the function of mossy fibers?

Hippocampal mossy fiber (MF) synapses connect dentate granule cells to CA3 pyramidal neurons and are important for spatial memory formation and consolidation. The transcription factor Bcl11b/Ctip2 is expressed in dentate granule cells and required for postnatal hippocampal development.

Are mossy fibers inhibitory or excitatory?

excitatory
Purpose: Mossy fibers are the sole excitatory projection from dentate gyrus granule cells to the hippocampus, forming part of the trisynaptic hippocampal circuit. They undergo significant plasticity during epileptogenesis and have been implicated in seizure generation.

Are cerebellar granule cells excitatory or inhibitory?

inhibitory
All cells in the cerebellar cortex are inhibitory except granule cells and unipolar brush cells (not shown). The cerebellar cortex receives two excitatory inputs from mossy fibers (MF) originating in various brain stem and spinal cord nuclei and from climbing fibers (CF) originating from the inferior olive (IO).

What is granular cerebral cortex?

the portion of the cerebral cortex that contains granule cells, which are located in layers II and IV of the cortex (see cortical layers). The term refers particularly to primary sensory cortex, in which layer IV (the major input area) is very thick.

Where do mossy fibers originate?

Mossy fibers originate from multiple brainstem nuclei and terminate on granule cells in a layer just below Purkinje cells in the cerebellar cortex.

What role is played by the climbing fibers in the cerebellum and why is their function controversial?

These fibers provide very powerful, excitatory input to the cerebellum which results in the generation of complex spike excitatory postsynaptic potential (EPSP) in Purkinje cells. In this way climbing fibers (CFs) perform a central role in motor behaviors.

What is the mossy fiber pathway?

In the hippocampus, the mossy fiber pathway consists of unmyelinated axons projecting from granule cells in the dentate gyrus that terminate on modulatory hilar mossy cells and in Cornu Ammonis area 3 (CA3), a region involved in encoding short-term memory.