Flocculus

The flocculus is contained within the flocculonodular lobe which is connected to the cerebellum. The cerebellum is the section of the brain that is essential for motor control. As a part of the cerebellum, the flocculus plays a part in the vestibulo-ocular reflex system, a system that controls the movement of the eye in coordination with movements of the head. The anatomy of the flocculus shows that it is composed of two disjointed lobes or halves. The “halves” of the flocculus refer to the caudal half and the rostral half, and they indicate from where fiber projections are received and the path in which a signal travels. The caudal half of the flocculus receives mossy fiber projections mainly from the vestibular system and tegmental pontine reticular nucleus, an area within the floor of the midbrain that affects the axonal projections or images received by the cerebellum. Vestibular inputs are also carried through climbing fibers that project into the flocculus, stimulating Purkinje cells. Leading research would suggest that climbing fibers play a specific role in motor learning. The climbing fibers then send the image or projection to the part of the brain that receives electrical signals and generates movement. From the midbrain, corticopontine fibers carry information from the primary motor cortex. The rostral half of the flocculus also receives mossy fiber projections from the pontine nuclei; however, it receives very little projection from the vestibular system. ==Function==

The flocculus is a part of the vestibulo-ocular reflex system and is used to help stabilize gaze during head rotation about any axis of space. Neurons in both the vermis of cerebellum and flocculus transmit an eye velocity signal that correlates with smooth pursuit. Flocculus role In learning basic motor functions The idea that the flocculus is involved in motor learning gave rise to the “flocculus hypothesis.” This hypothesis argues that the flocculus plays a key role in the vestibulo-ocular system, most importantly the ability for the vestibular system to adapt to a shift in the visual field. ==Location==

Constituted by two disjointed-shaped lobes, the flocculus is positioned within the lowest level of the cerebellum. There are three main subdivisions in the cerebellum and the flocculus is contained within the most primitive the vestibulocerebellum. Its lobes are linked through a circuit of neurons connecting to the vermis, the medial structure in the cerebellum. Extensions leave the base of the follucular's lobes which then connect to the spinal cord. The cerebellum, which houses the flocculus, is located in the back and at the base of the human brain, directly above the brainstem. ==Clinical significance==

The flocculus is most important for the pursuit of movements with the eyes. Lesions in the flocculus impair control of the vestibulo-ocular reflex, and gaze holding also known as vestibulocerebellar syndrome. The deficits observed in patients with lesions to this area resemble dose-dependent effects of alcohol on pursuit movements. Bilateral lesions of the flocculus reduce the gain of smooth pursuit, which is the steady tracking of a moving object by the eyes. Instead, the bilateral lesions of the flocculus result in saccadic pursuit, in which smooth tracking is replaced by simultaneous rapid movements, or jerking motions, of the eye to follow an object toward the ipsilateral visual field. These lesions also impair the ability to hold the eyes in the eccentric position, resulting in gaze-evoked nystagmus toward the affected side of the cerebellum. ==Additional images==

File:Human cerebellum anterior view description.JPG|Human cerebellum anterior view File:Slide2SEER.JPG|Cerebellum. Inferior surface. File:Slide3EER.JPG|Cerebellum. Inferior surface. File:Slide4SER.JPG|Cerebellum. Inferior surface. ==References==