Kursk State Medical UniversityNormal Physiology Deparment

Functions of basal ganglia, thalamus, limbic system and central cortex,

methods of examination the funcitons of CNS

Alef Kotula AraujoZootova Oksana M.

Group 11

PLAN:1) THE BASAL GANGLIA:a) It is structure and localization.b) Functions of basal gangliac) The putamen circuit.d) The caudate circuit.e) Functions of specific neurotransmitter in basal ganglia system.

2) THE THALAMUS.a)Functions and structure of the thalamus.b) Specific thalamic nuclei.c) Non-specific thalamic nuclei.

3)FUNCTIONAL ANATOMY OF THE LIMBIC SYSTEMa) Vegetative and endocrine control functions f the hupothalamusb) “Reward” and “Punishment” center and their importancec) Functions of hippocampusd) Functions of amydalae) Functions of the limbic cortex

4) PHYSIOLOGIC ANATOMY OF THE CEREBRAL CORTEXa) Distribution of functions in the córtex.b) Motor córtex.c) Somatosensory cortex.d) Association areas and their functions.e) Role of the brain cortex in communication and speech.f) Concept of the dominant hemisphere.

The Basal Ganglia

Definition• Basal ganglia: A region of the base of the brain that consists of

three clusters of neurons (caudate nucleus, putamen, and globus pallidus) that are responsible for involuntary movements such as tremors, athetosis, and chorea. The basal ganglia are abnormal in a number of important neurologic conditions, including Parkinson's disease and Huntington's disease.

http://www.medicinenet.com/script/main/art.asp?articlekey=10030

Composition of basal ganglia• The basal ganglia is composed of 1)Caudate nucleus2)Puttamen3)Globus pallidus4)Subthalamic nucleus5)Substantia nigra

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The basal ganglia inputs •  The largest component, the striatum (dorsal and ventral),

receives input from many brain areas beyond the basal ganglia, but only sends output to other components of the basal ganglia. The pallidum receives input from the striatum, and sends inhibitory output to a number of motor-related areas. The substantia nigra is the source of the striatal input of the neurotransmitter dopamine, which plays an important role in basal ganglia function. The subthalamic nucleus receives input mainly from the striatum and cerebral cortex, and projects to the globus pallidus.

• https://en.wikipedia.org/wiki/Basal_ganglia

The cognitive control of sequences of motor patterns

The term cognition means the thinking processes of the brain, using both sensory input to the brain plus information already stored in the memory. Most of our motor actions occur as a consequence of thoughts generated in the mind, a process called cognitive control of motor activiy. The caudate nucleus plays a major role in this cognitive control of motor activity.

Caudate Circuit through the basal ganglia from the

cognitive planning of sequential and parallel motor

patterns to achieve specific conscious golas.

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Putamen circuit• Functions of putamen circuit:1) Assosciation with the corticospinal

system to control the complex pattern of motor activity

2) Destruction of globus pallidus: inability of the trunck muscle to maintain postural support

3) Destruction of subthalamic nucleus: spontaneous tembling of limbs called hemiballismus

4) Destruction of striatum: produce diferente motor syndromes related to a release of inhibition called chorea

5) Destruction of substantia nigra- Parkinson’s disease(domapine)

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Caudate circuitCognitive control of sequence of motor patter (the thinking process of the brain, using both the sensory in the brain and the informations already stored in the brain (Eg. Writting of alphabet)

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Associated function of the cerebellum and associated function of basal gangliaThe basal ganglia and cerebellum are sub-cortical structures that receive input from wide areas of the cerebral cortex and direct their output, through the thalamus, back to more precisely defined regions. The cerebellum corrects the errors in each movement command and imparts motor skills. It does so based on input from motor areas, somatosensory areas and parietal association areas, and directs corrections to motor areas. As well, it receives input from and sends corrections to the spinal cord. The basal ganglia release appropriate movements from the premotor and motor areas. As well, they release appropriate behaviors from the prefrontal association areas. Damage to the basal ganglia is in part responsible for Tourette's syndrome, which results in the release of inappropriate utterances.

www.tutis.ca/NeuroMD/L6CerBG/CerBG.pdf

Clinic syndromes caused by damages in the basal ganglia

Parkinson’s disease is the results from widespread destruction of that portion of the substantia nigra (the pars compacta) that sends dopamine-secreting nerve fibers to the caudate nucleus and putamen. The disease is characterized by 1)rigidity of much of the musculature of the body 2) involuntary tremor of the involved áreas even when the person is resting at a fixed rate of 3 to 6 cycles per second, and 3)serious difficulty in initiating moviment, called akinesia.

Huntington's disease, or chorea, is a hereditary disease of unwanted movements. It results from degeneration of the caudate and putamen, and produces continuous dance-like movements of the face and limbs. A related disorder is hemiballismus, flailing movements of one arm and leg, which is caused by damage (i.e., stroke) of the subthalamic nucleus. 

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Thalamus

Definition• Thalamus: the brain is composed of many parts. They are defined by

their locations, functions, and anatomy. The thalamus is a structure in the middle of the brain. It is located between the cerebral cortex and the midbrain. It works to correlate several important processes, including consciousness, sleep, and sensory interpretation.

http://study.com/academy/lesson/thalamus-definition-functions-location.html

Specific and nonspecific nuclei of the thalamus

Specific nuclei: a) Fibers (specific thalamic tracts) terminate in the 3 and 4 layers of the

cortex.b) Form synapses between a limited number of cells in the sensory and

association areas of the cortex.Non-specific nuclei:c) Fiber (non-specific thalamic tracts) give off many banches in different

areas of the cortex, send signal to the subcortical nucleid) Involve a large number of cortical neurons in excitatory process

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Relay nuclei and association nuclei of the thalamus

Relay nuclei: Receive impulses coming from a definite sensory tracts

Association nuclei:

Receive impulses from relay nuclei and send impulsation to the cortex

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Characteristics of relay thalamic nuclei

1)Posterior ventral2)Medial geniculate body3)Lateral geniculate body 4)Ventro-lateral5)Anterior nuclei

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Functions of nonspecific thalamic nuclei

• Non-specific thalamic nuclei take part in a quick and short-lived activation of cortex. They also particapate in organization the attention process in the waking organism. Has wide reciprocal connection between relay association nuclei and between subcortical formation.

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The Limbic System

Definition• The limbic system is a grouping of structures in the brain that sits

between in the most primitive part of the forebrain called the rhinecephalon. This is a doughnut-shaped network of neurons that inlfuences many deep-rooted drives and emotions including pain, anger, hunger, sex, thirst, and pleasure. The thalamus, hypothalamus, amygdala, fornix, mammiliary bodies, and septal areas are all parts of the limbic system.

http://www.alleydog.com/glossary/definition.php?term=Limbic%20System

Functions of the limbic system

1)Behavioral function: The actions or reactions of na organism usually in relation between environment

2)Emotion function: The mental physiological state associated with a wide variety of feelings, thoughts and behaviour

3)Motivation function: The set of reasons that determine one to engage in particular behavior

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Subcortical and cortical structures included in the limbic system

The limbic system is typically divided in two categories: subcortical structures and cortical structures. The cortical regions include the hippocampus, areas of neocortex, the orbital frontal cortex, the subcallosal and cingulate gyrus, and the parahippocampal gyrus. Subcortical portions of the limbic system include the olfactory bulb, hypothalamus, amygdala, septal and thalamic nuclei, the anterior nucleus, and the dorsomedial nucleus. Of these the main regions are the hypothalamus, the amygdala, and the hippocampus.

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Way does the hypothalamus regulate most of the endocrine functions

Hypothalamus is the major control headquarters-It sends output in 3 directions:1)Downward to brainstem2)Upward toward many higher areas of the diencephalon and cerebrum3)Into the hypothalamic infundibulum ( pituitary gland release many hormones)

- Hypothalamus contains osmoreceptor, thermoreceptor influence on:1)Cardiovascular system 4) Water-salt balance2) Gastrointestinal system 5) Carbohydrates, protein, fat metabolism3)Thermal regulation 6) Endocrine system

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Functions of the hippocampus 1) Provide drive that cause translation of short term memory into long term memory

2) Stimulation of any part of hippocampus can cause almost any diferent

3) Give prolanged output signal even under normal functional condition

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Functions of amygdala and limbic cortex

The functions of amygdala are:1)Control fear and anxiety2)Control sexual desires3)Take part in memory process4) Help pattern of the person behavior response so that is appropriate for each occasion

The functions of limbic cortex:

1)Anterior temporal cortex: Same as amydala

2) Posterior orbrital frontal cortex: Promote sleep, calm emotion

3) Anterior angulate gyri and subcollosol gyri: Control rage centers of septum and hypothalamus

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Functional characteristics of motor cortex

1)Primary motor cortex: Controlling in the activity of muscle

2)Suppleentary area: regulate bilateral muscle contractions( Eg. Grasping movements, rotation of diferente parts of the body, positional movement of head and eyes)

3)Promotor area: generate complex “pattern” of the movement and sends signals to the primary motor cortex or to basal ganglia and after signals from the thalamus come back to primary motor cortex.

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Functional characteristics of the somatosensory areas I and II

Somatosensory area I : 1)High degree of localization of diferente parts of body2)Receive and differentiate the sensation from opposite side of body

Somatosensory area II : 1)Low degree of localization of diferente parts of body2) Receive signals from somatosensory area I, brain stem, visual and auditory areas.

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Subareas of the parieto-occiptotemporal association area

Parieto-occiptotemporal association area:1) Analysis for spatial cordination of body2) Area language comprehesion 3) Area for initial processing of visual language (Reading)4) Area of naming of objects

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“Wernicke’s area” in the communication

- General interpretative area, knowing area, tertiary A.A- Plays gretest single role of any part of cerebral cortex in high

comprehensive levels of brain function (intelligence) and it interpreting the complicated meaning of the different patterns of sensory experiences.

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Functions of the limbic association area

Limbic association area is primarily concerned with behavior, emotion, motivation. Is associated with the limbic system that provides most of the emotional drives for setting the other areas of the brain into action and even provides the motivational drive for the process of lerning itself.

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Functions of the pre-frontal association area

1) Association between motor cortex to plan complex patterns and sequence of motor movements

2) Carrying out thought processes in mind3) Participate in working memory

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Concept of dominat hemisphere-General interpretation function of Wernike’s area and the angular gyrus as well as functions of the speech and motor control areas are usually much more developed in one cereral hemisphere than in other. 95y of population have left dominant hemisphere.-Dominat hemisphere is concerned between (rate organization and symbolization). Non-dominat (representative) participate in (visio-spatial relation). Destruction of categorical hemisphere produce language disordes. Destruction of non-dominant produce (inability to identify objects)-Patients between probable dominant hemisphere know about their disability and often depressed.Patients between probable non-dominat hemisphere presente in euphoric state.

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The Central Nervous System

Definition• The central nervous system (CNS) is comprised of the brain and

spinal cord. The CNS receives sensory information from the nervous system and controls the body's responses. The CNS is differentiated from the peripheral nervous system, which involves all of the nerves outside of the brain and spinal cord that carry messages to the CNS.

http://psychology.about.com/od/cindex/g/def_cns.htm

Methods of examining the functions of the CNS

1) Stimulation (electrical and chemical)2) Removal and secretion of various part of the CNS3) Electrophysialogical methods4) Electroencephalography5) Neuro-humoral method

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Methods of extirpation and local demage

Extirpation:

Provide information about functional importance of the diferente parts of brain and spinal cord and are used in acute and chronic experiment. They help to clarify which function of CNS dissapear after surgical operation and which are ratained.

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Local Damage:

1) Mechanical – pricking between needle of scapel

2) Electrical – Inserting thin electrodes into the brain through which direct current is passed produce more destruction of the tissue

3) Freezing and termal coagulation – also between electrodes

4) Intense x-ray or ultrasonic vibration: Portion of brain tissue which can be demaged equal 3mm.Nerve patway can be damaged by vitrations of intensity of that does not effect nerve cell

5) Proton radiation – Not invasive methot ( destroy just nerve)

Practical work: Removal of diferente parts of the frog’s brain

For the work it is necessary to have: a frog, a set of intruments for preparation, ether.1) Cerebral hemisphere removal. The succession of the work. Cut the head skin in a frog T-figuratively and

ablate the lips. Be careful, not to touch the brain, dissect the skull. Remove with the help of the scalpel the cerebral hemisphere. The frog limbs will stretch forward, the head will be raised a little after the operation. Aftera while the frog will take a normal pose. The arbitrary movements are absent in the frog. The attempt to change the body position of the frog, will lead to it’s taking the initial position. For example, if the frog’s limb is drawn aside the frog will pull the previous position. The frog replies to squeezing its limb with fórceps by cordinated jumps(jerks).

2) Removal of diencephalon and midbrain. The diencephalon and midbrain take part in the involuntary regulation of the muscular activity for keeping the body position. The succession of the work. Cut off the loves and the cerebellum and remove them with fórceps. In thirty minutes after the operation repeat the observations just as in the experimente”1”. Be certain that of all locomotion and adjusting reflexes only the turn-over reflex remains.

3) Removal of medula oblongata. Medulla oblongata regulates the blood circulation, breath, digestion. Fibers of all descending and ascending tracts of spinal cord pass through the medula oblongata. After the removal of the medula oblangata the turn-over reflex disappears and all the muscles relax. Locomotion reactions are preserved in the spinal of animals( for example in a frog)

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Sterotaxis techniqueTechnique used to implant electrod or the microinstruments accuratelly in deeper structures of the brain. The method is based on detailed anatomical examination of position of diferente brain structures in relation with definite parts of position of diferente brain structures in relation with definite parts of the skull. Localization of structures is expressed in special 3 coordinate system by means of which the concrete positon of nerve certes are determined.

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Methods of stimulation1) Electrical ( apply a weak electrical current to definite part of the CNS) –

weak electrical stimulation of definite areas of the animal cortex produce different motor reactions. After this method in experiment on animal, it was also used in neurosurgery of humans

2) Chemical (by introduction of diferente chemical substance to stimulate different part of CNS – Techique of electrophoretic microinjection)

3) A small micropipette filled between solution been tested is troduced into the nerve center. One smal electrode is inserted into the micropipette. Another electrode is applied to the surface of the body.

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Induces potentials of the brainElectrical reaction of parts of CNS in response to afferent impulses induced by stimulation of receptor. Have greatest amplitude and shortest latent period in nerve certes that receive afferent impulsation from this group of receptorsBi-phasic potentia with amplitude between 400-600mv. 1) Arise negative electrical event lasting 15-20msec. 2) Positive eletrical changes last 10-12msec

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ElectroencephalographyEEG are the methods of registration of electrical activity of the brain Monopolar method – One electrode is applied to cortical region,

another is applied to the ear-lobe in man or nasal boné in animal Bipolar technique – Two recordinh electrodes are applied to cortex.

The encephalograph record the potential diferences of cortical áreas beneath the electrodes

The amplitude of action potential in human varies from 5-300mv. Frequency from 0,5-70 action potential per second

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Origin of the waves in the EEG

References Lecture of Prof. Avdeev Elena V. Arthur C. Guyton charpters 45-58

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