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					PHYSIOLOGY DEPARTMENT
  CENTRAL NERVOUS SYSTEM
   PHYSIOLOGY. LECTURE #2.

PHYSIOLOGY OF ‘DIENCEPHALON’

   CEREBELLUM PHYSIOLOGY




        Ass. Prof. VASTYANOV Rooslan
ATTENTION !!!
               DIENCEPHALON
Diencephalon is the part of the forebrain that locates more rostral
     compared with the brain cortex and subcortical nuclei.


  The 'diencephalon' includes the hypothalamus, thalamus
                       and subthalamus.
        Thalamus and the reticular formation

Motor (frontal) cortex                           Sensoric cortex




   To the
limbic system
  Thalamus
  Hypothalamus
        Amygdala
          Reticular formation

                         Tractus Spinothalamicus
                             Ganglion spinalis

                                                     Spinal cord
                     Sensor fiber
        Pain receptor
    The main thalamic nuclei
 Specific nuclei         Relying

                       Associative

                         Motor

Nonspecific nuclei
                  Specific thalamic nuclei

    Relying                 Associative                 Motor
    Ventrobasal              Mediodorsal
                                                    N.N. frontolateral
     complex                   nucleus
                                                    and ventrolateral
      Tactile,               Projections to
  proprioceptive,
                              frontal lobes
                               Putamen                 Signals rely
    temperature,
                                                    from cerebellum
  pain, gustatory         Projections to tempo-         and basal
   inputs to brain        ral and occipital lobes
                                                    gangles to motor
  somatosensory
                           Nucleus lateralis              cortex
       cortex                   dorsalis
                             Projections to
N.geniculatum int.
                             temporal lobe
                           Nucleus frontalis
 Audial information in-
to brain audial centers       Projection to
                              limbic cortex
N.geniculatum ext.

Visual information in-
to brain visual centers
Thalamus
   rely
 function
  All sensory pathways have direct
projections to thalamic nuclei, which
 convey the information to restricted
     areas of the sensory cortex.




Coordination and integration of peripheral
  sensory stimuli occur in the thalamus
  «… thalamus serves as the rely station,
       where all the external stimuli,
 coming together, change their expression
and go to subcortical and cortical centers».




                                   А. К. Walker
HYPOTHALAMUS and its main nuclei
      FUNCTIONS of hypothalamus N1

1. Water and electrolyte balance regulation
(supraoptic and paraventricular nuclei).


2. Secretion of hypothalamic releasing factors
(arcuate and periventricular nuclei and parvocellular cells of the
paraventricular nucleus).


3. Temperature regulation
(the anterior and posterior hypothalamic nuclei).



4. Activation of the sympathetic nervous system
   and adrenal medullary hormone secretion
(the dorsal and posterior hypothalamus).
      FUNCTIONS of hypothalamus N2

5. Thirst and drinking regulation
(lateral hypothalamus).


6. Hunger, satiety and the regulation of eating behavior
(the arcuate nucleus, ventromedial nucleus, and lateral hypothalamic area).



7. Regulation of sexual behavior
(the anterior and preoptic hypothalamic areas).



8. Regulation of circadian rhythms.
Sleep-wakefullness cycle
(the suprachiasmatic nucleus of hypothalamus).
Experiment with hypothalamus self-irritation (Olds)
Circadian
 Rhythms
Regulation
      FUNCTIONS of hypothalamus N3

9. Aggressive behaviour regulation
(the anterior hypothalamic area).
      Hypothalamus is the important
integrative center of vegetative, somatic
         and endocrinal functions,
    that is responsible for the complex
    homeostatic reactions realization
and serves as the key structure within the
  hierarchically organized brain system
    that regulates visceral functions.
CEREBELLUM
The cerebellum ("small or diminutive brain")
  consists of two cerebellar hemispheres
             joined by a vermis.



   Cerebellar cortex, only a few mm thick,
              lies in the surface.




   Deep to the cortex lies the white matter.
    Within the white matter, masses of gray
   matter, called cerebellar nuclei, are found.
               Mossy fibers (spino-, reticulo-,
              vestibulo- and corticocerebellar)
Cerebellar      make complex multicontact
   inputs        synapses jn granule cells.
 (afferent)
               Climbing fibers arise from the infe-
              rior olive, a nucleus in the medulla.
                 Each climbing fiber synapses
                     directly on the dendrites
                 of a Purkinje cell and exerts a
                   strong excitatory influence.

               Adrenergic fibers arise from the
                locus coeruleus, a basal ganglia
                   structure. These fibers are
                     considered to perform
                       the trophic function.
The layers of cerebellar cortex
     Types of the cerebellar cortical cells

Basket cells     their projections terminate on the Purkinje cells bodies

Stellate cells   their projections terminate on the Purkinje cells
                 dendrites


Purkinje cels    their dendrites reach upward into the molecular layer

                 their axons go downward and make synapses with
                 cerebellar nuclei

                 some axons terminate on vestibular nuclei


 Golgi cells     their dendrites reach upward into the molecular layer,
                 their axons go the the granular cells

Granular cells   their axons reach upward into the molecular layer and
                 make synapses with Purkinje, basket and stellate cells
 Purkinje cells constantly generate IPSP

        This is critically important for the cerebellar
         nuclei activity inhibition because they are
              constantly generate tonic activity


   Purkinje cells excitation through     Both stellate cells and basket
 climbing and mossy fibers results in    cells – induced Purkinje cells
IPSP generation increasing that lead    activity inhibition results in their
  in turn more expressed cerebellar     activation that lead to cerebellar
        nuclei activity inhibition.         nuclei activity increasing.
TOPOGRAPHIC CLASSIFICATION OF
 CEREBELAR CORTEX AND NUCLEI
              1. MEDIAL zone –
              has projections on the fastigial n.



              2. INTERMEDIATE zone –
              has projections on the interposed n.



              3. LATERAL zone –
              has projections on the dentate n.
                  Functions of cerebellum
1. Posture and muscular tone regulation


           2. Slow aimed movements correction
           and their coordination with
           the postural reflexes


                                    3. Sensorimotor coordination of quick aimed
                                    movements performed from the commands
                                    out of brain cortex.



1. MEDIAL zone     – n. gastigial – medulla oblongata, vestibular nuclei


2 INTERMEDIATE zone         – interposed n. – red n. + brain cortex.


3 LATERAL zone     – dentate n. – thalamus – brain cortex motor zone
Cerebellar lesions
THANKS FOR
ATTENTION !

				
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posted:3/25/2012
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Description: Physiology