pre frontal presentation

7/28/2019 Pre Frontal Presentation

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Pre frontal cortex


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Frontal lobe

Frontal lobe is an area of brain of mammals. It islocated in front of each cerebral hemisphere &

positioned anterior to parietal lobe & above andanterior to temporal lobes. It lies in front ofcentral sulcus & above the posterior ramus oflateral sulcus. It forms about 1/3rd of corticalsurface. On the basis of its function, it is divided

into 2 main areas:

pre central cortex

pre frontal cortex


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Frontal lobe contains most of the dopamine-

sensitive neurons in the cerebral cortex. The

dopamine system is associated with pleasure,long-term memory, planning & drive.

Dopamine tends to limit & select sensory

information arriving from the thalamus to the

fore brain. A gene variant that reduces dopamine

activity in the pre frontal cortex is related to

poorer performance & slightly inefficient

function of the brain region during workingmemory tasks & to slightly increased risks for

Schizoprenia.


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Major brodmanns areas

Area 8frontal eye fields

Area 9dorsolateral prefrontal cortex

Area 10anterior prefrontal cortex

Area 11OFC(superior frontal gyrus & inferior

rostral gyrus)

Area 44pars opercularis( part of brocas area)

Area 45pars triangularis(brocas area)

Area 46dorso lateral prefrontal cortex

Area 47inferior prefrontal gyrus


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Pre frontal cortex

It is an anterior part of the frontal lobe of the

brain, lying in front of motor & pre motor areas.The important components are Superior frontalgyrus, Middle frontal gyrus, & Inferior frontalgyrus. It is supplied by anterior cerebral &

middle cerebral artery & superior sagittal sinus.


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Pre frontal is divided into 3 basic

areas

Orbitofrontal (OFC) & ventromedial areas(Vm-PFC)

The Dorsolateral prefrontal cortex (dl-PFC)

The Anterior & Ventral cingulate cortex

this brain region has been implicated in planningcomplex cognitive behaviors, personalityexpression, moderating correct social behaviors.The basic activity is considered to be

orchestration of thoughts & actions.


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Orbitofrontal cortex (OFC)

The name of this region is based upon theregions location with in the frontal lobes,

resting above the orbit of the eye. It is defined

as a part of pre frontal cortex that receives

projections from the magno-cellular, medialnucleus of the medio-dorsal thalamus.
http://en.wikipedia.org/wiki/Image:OFC.JPG


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Function of Orbitofrontal cortex

Orbitofrontal cortex is among the least understood

regions of human brain, but it has been proposed

that OFC is involved in sensory integration, inrepresenting the affective value of reinforcers &

in decision making & expectation. In particular,

this region is thought to regulate planning

behaviour associated with senstivity to reward &punishment.


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Dorsolateral prefrontal cortex

Dorsolateral prefrontal cortex is the last area (45th)to develop in the human cerebrum. Acc. To the

broader definition, dl-PFC consist of lateral

portion of brodmanns area 9-12, area 45, 46 &sup. part of area 47. Mainly receive their bloodsupply from the Middle cerebral artery. This areais connected to OFC, to the variety of brain areas,

which thalamus, part of basal ganglia (dorsalcaudate nucleus), the hippocampus & primary &secondary association areas of neocortex,including posterior temporal, parietal, & occipital

areas.


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Functions of dl-PFC

It serves as the highest cortical area responsible

for motor planning, organization & regulation.

Plays an an important role in the integration ofsensory & mnemonic information.

Regulation of intellectual functioning & action.

it is not exclusively responsible for the executivefunction.


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Cingulate cortex A part of brain situated in the medial aspect of

the cortex. It is extended from corpus callosumbelow to the cingulate sulcus above, atleastanteriorly.

Based on brodmanns architectonics, has beendivided into brodmanns areas 23, 24, 26, 30, 31,32. The areas 26, 29, 30 are referred asRetrospinal areas.

subdivisions are:

Anterior cingulate cortex

Posterior cingulate cortex

Cingulum


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Anterior cingulate cortex

This corresponds to area 24 of brodmann.it is

cyto architectonically agranular.it has gyral part

on the surface & sulcul part. ACC receives its afferent axons from the anterior

nucleus of the thalamus. The nucleus anterior

receives mamillo-thalamic afferences.the

mamillary neurons receive axons rom subiculum.

The whole forms a part of papez circuit.

ACC sends axons to the anterior nucleus & thru

the cingulum to the Brocas limbic areas.


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Posterior cingulate cortex

This corresponds to area 23 of brodmann. It is

granular. It is followed posteriorly by retrospinal

cortex(area 29). Dorsally is the granular area 31. PCC receives great part of afferent axons from

superficial nucleus of thalamus which itself

receives axon from subiculum.

To some extent it thus duplicates papez circuit.


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Cingulum

At the base of cingulate cortex is the thickparasagittal bundle, the cingulum is used for the

connection of the 2 subdivisions described above& with the Parahippocampal gyrus.


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Connections of pre frontal cortex Afferents to pre frontal cortex come from:

Dorsomedial nucleus of thalamus project on to area 9-12 on thelateral & adjacent medial surface & areas 44-47 in the inferior frontalgyrus. Since the dorsomedial nucleus of the thalamus,receivesafferents from posterior hypothalamus .

Anterior nuclei of thalamus project on to cingulate gyrus (area 23, 24,29, 32).

Efferents from pre frontal cortex go to: Thalamus: fibres from area 9&10 go to ventral & medial thalamic

nuclei.

Tegmental reticular formation: fibres from area 9&10 go to reticular

formation inthe tegmentum.

Pontine nuclei: fibres from area 10 pass to the pontine nuclei & henceto the cerebellum.

Caudate nucleus: the inhibitory area 8 & 2, 4, 5 discharge to thecaudate nucleus.

Mammillary bodies: fibres from area13, the hippocampus, uncus &amygdala project via the fornix to the mammillary bodies of thehypothalamus.


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Functions of pre frontal cortex

Centre forplanned actions,

Centre forhigher fuctions like emotions,

learning, memory & social behaviour. Seat forintelligence:short-term memories are

registered in pre frontal cortex. Has an ability tokeep track of many bits of info.(an organ of

mind) Control of intellectual activities:

To plan the future,


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Allow a person to concentrate on central theme of

thought. Helps in depth & abstractness of thought.

Allow to delay action in response to incomung

sensory signals so that sensory info. can be

weighed until the best response is obtained.

It allows to consider the consequence of motor

actions before their performance.

Plays role in solution of complicated

mathematical, legal & philosophical prroblems.

To control ones activity according to the moral

laws.


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pre frontal presentation

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