Details of the central nervous system

Name: Gustavo Duarte VianaGroup number:17

Teacher: Okzana Zotova

Function of the Basal Ganglia, thalamus, Limbic system, cerebral

cortex methods of examination of the central nervous system

Kursk State Medical university

Kursk, Russia

2012

The basal ganglia compodes of: consist of corpus striatum ( caudate nucleus and putamen ),

globus palidus, substantia nigra and subthalamic nucleus.located in lateral to the thalamus.    Function of the basal ganglia. Executing pattern of motor activity.----- putamen circuit. > To function in association with the corticospinal system to

control complex patterns of motor activity. ------ writing of alphabets.

> Controlling relative intensities of sequential movements, direction of movements and sequential of multiple movements.

Basal Ganglia

Motor control Learning Sensorimotor integration Reward Cognition

Main functions of the basal ganglia

Interconnecting circuitry through these nuclei

These circuits start from the cortex and ends in the cortex

These circuits are very complex Their effect is excitatory or inhibitory on

motor functions (depending on the neurotransmitter involved)

They also have a role in cognitive functions.

Peculiarities of the Basal ganglia

This circuit functions to control complex patterns of movement in association with the motor cortex

eg. ◦ writing letters of alphabet, ◦ cutting papers with scissors, ◦ hammering nails, ◦ passing a football, ◦ vocalisation

Putamem circuit

Cortex

Putamen

globuspallidus

Thalamus

Starts from all parts of the Cx: frontal, parietal, occpital, temporal. and association Cx

Then to caudate nucleus Then to globus pallidus Then to thalamus Finally to Premotor Cx, SMA This circuit functions in the cognitive control

of movement.

Caudate circuit

Cortex

Caudate

globuspallidus

Thalamus

Some of these circuits are excitatory and some inhibitory

This depends on the neurotransmitter involved.

Inhibitory: dopamine and GABA Excitatory: Ach Others: glutamate (from cortical

projections) enkephalin etc

Process and neurotransmitter involved

Lesions of the substantia nigra lead to the common and extremely severe disease of rigidity, akinesia, and tremors known as Parkinson’s disease.

lesions in the globus pallidus frequently lead to spontaneous and often continuous writhing movements of a hand, an arm, the neck, or the face—movements called athetosis.

Multiple small lesions in the putamen lead to flicking movements in the hands, face, and other parts of the body, called chorea.

A lesion in the subthalamus often leads to sudden flailing movements of an entire limb, a condition called Hemiballismus.

Basal ganglia disorders are also called extrapyramidal disorders

Basal ganglia disorders

Function of thalamus. > Is a switchboard where all the sensory

board lead except olfactory. > Kind of gate of the way of cerebral

cortex through which all info passes from receptors of external and internal environment of org.

> Highest pain center.

Thalamus

Non-specific thalamic nuclei.-fibers give of many branches in various areas of cortex -large number of cortical neuron in excitatory process.-nuclei send signals to subcortical nuclei through which impulses

convert to diff. Parts of cortex.-take part in quick and short activation of cortex.-nuclei organize the attention process in working organism.-have wide reciprocal connection with the relay and association

nuclei.  Specific thalamic nuclei.-fibers terminate in the 3rd and 4th layer of cortex and form synapses

with a limited number of cells in sensory and associative area.-divided in 2 groups:> Relay nuclei> Association nuclei -relay nuclei receive impulses from definite sensory tract.-association nuclei from relay nuclei.

division of specific thalamic nuclei.

-principle nuclei are anterior, ventrolateral, post-ventral, lateral and medial geniculate bodies.

 -anterior thalamic nuclei – receive impulses from olfactory receptors,

viscerareceptor and transmit to limbic.

-ventralateral nucleus receive from cerebellum and transmit to motor area. -post ventral nuclei receive from skin, face, trunk, extremities and send to

somatosensory area.

-lateral geniculate bodies for visual signs. Receive from primary visual centers and send to visual area of cerebral cortex.

 -medial geniculate bodies for auditory tract. Receive from primary auditory

centers and send to auditory cortex.

Relay thalamic nuclei

Association thalamic nuclei.-located in anterior and receive impulses from relay nuclei and send

them to associative area of cortex.

-include lateral, dorsomedial, and pulvinar nuclei. -lateral nuclei send impulses to parietal region of cortex. -lateral part of pulvinar nuclei send to optic associative area in occipital

lobe. -medial part of pulvinar nuclei to the auditory associative area of

temporal lobe. -dorsomedial nuclei connected with cortex of the frontal lobe with

limbic system and hypothalamus.

Association nuclei

Structure of the limbic system.-limbic system is entire neuronal circuitry that controls

emotional behaviour and motivational drives and internal condition of body.

-major part is the hypothalamus.-central is the hypothalamus and surrounds are other

subcortical structure of limbic system ----- septum, anterior nuclei of thalamus, basal ganglia, hippocampus, amygdala and parolfactory area.

-surrounding subcortical limbic is limbic cortex compose of a ring------- orbitofrontal cortex, subcallosal gyrus, cingulated gyrus, parahippocampal gyrus and uncus.

Limbic system

vegetative functions:> Cardiovascular regulation- excitation can cause increase and decrease of arterial pressure, heart rate- stimulation in posterior and lateral hypothalamus cause increase in arterial pressure and heart

rate- stimulation in preoptic area (anterior) cause decrease.- Transmitted mainly through cardiovascular control center. > Regulation of body temperature.- preoptic area (anterior)- an increase and decrease of temperature of blood flowing through this area sense the charges. > Regulation of body water - in 2 ways: 1. by creating the sensation of thirst---- thirst centers in lateral hypothalamus.-when electrolyte inside neuron become too concentrated, cause desire to drink.2. by controlling the excretion of water into urine.-control in supraoptic nucleus-when body fluid become too concentrated, the neuron become stimulated.-posterior pituitary gland secre ADH.-cause reabsorption. > Regulation of uterine contractility and milk ejection by breast.- stimulation of paraventricular nucleus secrete oxytocin.- Cause contractile of uterine and milk ejection. > GI and feeding regulation.1. hunger ---- lateral hypothalamus area2. satiety center ---- ventromedial nucleus3. mammilary bodies ---- feeding reflexes such as licking the lips and swallowing.

Vegetative function of the limbic system

> in anterior pituitary gland, releasing and inhibitory hormones are secreted into blood

> hormone transported to ant pituitary gland, and act on glandular cells.

> Cell bodies tht secrete this hormones located in medial basal nuclei of hypothalamus especially in periventricular zone, arcuate nucleus and part of ventromedial nucleus.

> These axons project to median eminence.> Here secretion of inhibitory and excitatory

hormone take place.

Endocrine function of the limbic system

Reward center lateral and ventromedial nuclei of hypothalamus (main) secondary cemters are septum, amygdala, certain area of thalamus and

basal ganglia and extending downward into basal tegmentum of mesencephalon.

 Punishment center

- in central gray area surrounding the aqueduct of Sylvius in mesencephalon and extending upward into periventricular zones of hypothalamus.

- Less --- amygdala and hippocampus.- Can take preceding over reward centers. -if no reward and punishment, repetition of stimuli will cause habituation and

therefore will cause the animal to ignore it.-if got reward and punishment effect, stimuli will be reinforced and animal will

build up strong memory trace.-so this 2 effect are important in learning and memory.-so selection of information do take place.

Reward and punishment

Function of hippocampus.-any type of sensory activate hippocampus and its

distribute to anterior thalamus and hypothalamus.> Additional channel through which incoming

sensory signals lead to appropriate behavior.> Hippocampal also hyperexcitable ---- give

prolonged output signals even under normal condition.

> Important in learning new information and prevent anterograde amnesia.

> Important in reward and punishment process --- can transfer short term memory into long term.

Hypocampus

Fuction of the amigdalareceive neuronal signals from all limbic cortex, neocortex esp

visual and auditory.effect of stimulating amygdala :Regulate arterial pressure, heart rate, GI motality and secretion,

defecation and micturation, pupillary dilationa nd constriction, piloerection etc

 -also involving involuntary movement:

> Tonic movement, circling, rhythmic, licking, chewing and swallowing.

-also stimulate sexual activities ---- destruction will cause Kluver-Bucy syndrome.

Amigdala

-poorly understood -function as transitional zone through which

signals transmitted from cortex into limbic system.

-functional as cerebral association area for control of behaviour.

-if damage can cause,, --- kluver-bucy syndrome, development insomnia, motor restlessness,

- so cortex mainly as intermediate associative positions between function of cerebral cortex and limbic system.

Limbic cortex

The cerebral cortex is divided into Archiocortex: include the olfactory bulbes

which receive afferentation from olfactory epithelium, olfactory tracts and olfactory tubules

Paleocortex: comprises the gyrus cinguli, Hyppocamal gyrus and amygdala

Neocortex: include all the other regions

Cerebral cortex

In the cerebral cortex is present sex layers 1 Molecular layer2 External granular layer3 External pyramidal layer cells4 Internal granular layer5 Internal pyramidal layer cells 6 Fusiform or polymorphic cells

Histological structure of the cerebral cortex

-anterior to central sulcus, posterior 1/3 of frontal lobes.divided into:

A. primary motor cortex-controlling hand & speech musleB. premotor area-control of body’s complex pattern of

coordinated muscle activityC. supplementary area-bilateral movement,fine motor

controlD. Specialized area: 1.Broca’s area & speech 2.voluntary eye movement field 3.head rotation area 4. area for hand skills

Motor cortex

-posterior to central sulcus -anterior half of parietal, concerned with reception & interpretation posterior with higher level of interpretation of sensory signals-divided into A. somatosensory areas I-representation of specific sensory sensation-judgment of pressure, weight, shapes & texture-appreciation of spatial relationship (space localization, higher degree of

sensation >B. somatosensory areas II -have no good localization of body portion -transmit signal from brain stem, primary sensory area & visual @ auditory

area to secondary somatic area -each side of cortex receives sensory information from opposite side of body -representation of sound & discrimination mainly present in temporal lobe -perception of taste-involve large area of temporal cortex & insula -destruction of this area: reduce ability to discriminate btw flavors

Somatosensory cortex

>localization: in parietal & occipital cortical; anterior-somatosensory posterior-visual cortex>general function: provide high level of interpretive meaning for signal from surroundingsensory area>functions : I) analysis of spatial coordination #Localization: begin in parietal cortex, extending into superior occipital cortex, provides continuous

analysis of spatial coordinates of all body parts & surrounding of body #receive ~visual sensory information from post occipital cortex ~simultaneous somatosensory information from anterior parietal cortex thus, computes of visual, auditory & body surrounding II) area for language comprehension=Wernicke’s area #localization:behind primary cortex in posterior part of superior gyrus of temporal #function:higher intellectual information( intellectual function is language based) III) area for initial processing of visual language(reading) #localization: posterior to language comprehension area, in angular gyrus #function: >make meaning out of visually perceived words >in its absent, will have excellent language comprehension through hearing but not through

reading  IV) area for naming objects @ word formation #localization: most lateral of both anterior occipital lobe & posterior temporal lobe. #function: >naming of objects >names are learned through auditory input >physical natures learned through visual input >names essential for both auditory & visual language comprehension & intelligence(function

of Wernicke’s area) located superior to auditory ‘names’ region

Parieto-occipitotemporal association area

>prefrontal function in close association with motor cortex to plan complex pattern & sequences if motor movement

>provides sequential & parallel movement > carry out thought processes in mind plan motor activity capable of processing non-motor & motor

information thus, achieving non motor & motor types of thinking. important for elaboration of thoughts- store short term basis ‘working

memories’ that used to analyzed new thoughts when entering brain. > Broca’s area: localization-partly in posterior frontal cortex, premotor area functions- provide neural circuitry for word formation plans & motors patterns for expressing individual words,

phasesare initiated & executed work with Wernicke’s area

Prefrontal area

>localization: anterior of temporal lobe, ventral of frontal lobe

in cingulated gyrus lying deep in longitudinal fissure on midsurface of each cerebral hemisphere

>functions:+behavior, emotion, motivation +provide emotional drives for setting other area of

brain into action & provides motivating drive for process of learning

+recognition of faces emotion= individual psyche reaction which related

to reward & punishment center ; important for social life & communication

motivation= arise from positive aim to maintain homeostatic parameter

limbic association area

It is a special region in the frontal cortex, providing the neuronal circuit for word formation.

Play the motor pattern for the expressing individual words or even short phrases can be excuted.

Broca’s area

General interpretative area, knowing area, tertiary association area.

It plays the greatest single role in any part of cerebral cortex in the high comprehensive levels of the brain functions that we call intelligence and it interpreting the complicated meanings afferent patterns of the sensory experience.

Wernicke’s area

Showing the broca’s and wernicke’s area

the general interpretative function of the wernicke’s area and angular gyrus as well as the function of the speech and the motor control areas usually are much more developed in one hemisphere then in the other one

95% of the human population has the left dominant hemisphere

Concept hemisphere of dominant

Methods of investigation of the electrical activity of brain. Electroencephalograophy, it’s role in medicine:▸ a) To detect problems and compare with standards▸ b) To find out the localisation of problem, used for correction▸ c) Record EEG changes during sleep▸ d) Determine electrical activity of brain-stressed, relaxed Steretaxic method: To investigate coordinates/localisation of diff. points/

portions of brain. Determine:▸ a)The A-A horizontal plane which passes through the centres of the external

auditory meatus and the inferior points of the orbital margins. This is called the ‘principal horizontal line’ and used for reading stereotaxic coordinates.

▸ b)O-horrizontal line, 1cm above A-A hori.line▸ c)O-frontal plane, lying along the line connecting the centres of the ext.

Auditory meatus and perpendicular to the horizontal plane.▸ d)O-sagital plane, lying in the medius sagital cranial line, perpendicular to

the horizontal and frontal planes.

Electroencephalography

Thank you for attention