Neural Bases of Languages.

• Supported by post-Supported by post-mortem studiesmortem studies

• No consistent results – No consistent results – different types of aphasia different types of aphasia share similar behavioural share similar behavioural

disturbancesdisturbances

‘‘‘‘Anatamo-clinical principles’Anatamo-clinical principles’

Neuro-linguistics Neuro-linguistics

Studies the relation of Studies the relation of language and language and communicationcommunication to different aspects of to different aspects of brain function.brain function.

It tries to explore how the It tries to explore how the brain brain understands and produces language and understands and produces language and communication. communication.

Neuro linguisticsNeuro linguistics

This involves attempting to combine This involves attempting to combine neurological/ neuro physiological theory (how brain is structured and how it (how brain is structured and how it functions) with functions) with linguistic theory linguistic theory (how (how language is structured and how it functions).language is structured and how it functions).

Studies of language and communication after Studies of language and communication after brain damage brain damage are perhaps the most common are perhaps the most common type of neuro linguistic studiestype of neuro linguistic studies

Let us study

How language is represented in the brain:How language is represented in the brain:

that is, that is,

how and where our brains store our knowledge how and where our brains store our knowledge of the language (or languages) that we speak, of the language (or languages) that we speak, understand, read, and write, understand, read, and write,

what happens in our brains as we acquire that what happens in our brains as we acquire that knowledge, andknowledge, and

what happens as we use it in our everyday lives. what happens as we use it in our everyday lives.

1. What about our brains makes human language possible –why is our communication system so elaborate and so different from that of other animals?

Neurolinguistics

2. Do people who read languages written from left to right (like English or Spanish) have language in a different place from people who read languages written from right to left (like Hebrew and Arabic)?

Neurolinguistics

3. Does language use the same kind of neural computation as other cognitive systems, such as music or mathematics?

Neurolinguistics

4. Where in your brain is a word that you've learned? How does a word ‘come to mind’ when you need it (and why does it sometimes not come to you?)

Neurolinguistics

5. If you know two languages, how do you switch between them and how do you keep them from interfering with each other?

Neurolinguistics

6. If you learn two languages from birth, how is your brain different from the brain of someone who speaks only one language, and why? Is the left side of your brain really ‘the language side’?

Neurolinguistics

NeuroanatomyThe study of the anatomy and stereotyped organization of nervous systems.

Neurochemical The science of

neurochemistry studies the functions of neurochemicals.

A neurochemical is an organic molecule, such as serotonin, dopamine, or nerve growth factor, that participates in neural activity.

NeurophysiologyThe branch of Physiology that deals with the functions of the nervous system.

Neuranatomical correlates of language Functions.

The complexity of human brain and The complexity of human brain and the complexity of language behavior present the complexity of language behavior present a major challenge to anyone trying to a major challenge to anyone trying to explain how the one produces the other.explain how the one produces the other.

Although the sizes and shapes of the Although the sizes and shapes of the brains of different people vary, just as facial brains of different people vary, just as facial features do, the component structures of the features do, the component structures of the brain are common to all the human beings. brain are common to all the human beings.

The Central nervous System (CNS)

Parts of the nervous system that are encased in bone

1. Brain

2. Spinal Cord

The Peripheral nervous System (PNS)

All the spinal nerves that innervate the skin, joints, muscles, etc. and under voluntary control:

Somatic PNS

Neurons that innervate internal organs, blood vessels, glands, etc. and are involuntary:

Visceral PNS or Autonomic Nervous System (ANS)

CNSCNSNuclei (gray matter) vs. nerve tracts (white Nuclei (gray matter) vs. nerve tracts (white

matter)matter)Brain, functional areasBrain, functional areasSpinal cordSpinal cordBlood-brain barrierBlood-brain barrierVentricular systemVentricular systemBlood supplyBlood supply

PNSPNSCranial, cervical to sacral nerves, Cranial, cervical to sacral nerves,

autonomic nervesautonomic nervesmusclesmuscles

CNS vs PNSCNS vs PNS

Describing locations in the brainDescribing locations in the brain

The locations of the layers, nuclei, and The locations of the layers, nuclei, and the pathways of the brain can be described the pathways of the brain can be described by their placement by their placement

with respect to other body parts of the animal, with respect to other body parts of the animal, w.r.tw.r.t to their relative locations and to their relative locations and w.r.tw.r.t to a viewer’s perspective. to a viewer’s perspective.

Main terminologies used in relation to other body parts:

Caudum (Latin: tail)-Caudal Rostum (Latin: beak)- Rostral Dorsum (Latin: back)- dorsal Ventrum (Latin: Stomach)- Ventral

Main terminologies used to describe in relation to one another from the frame of reference of the face:

Anterior/frontal Posterior Lateral(At side) Medial(Centre of between)

Locations

to describe the direction of the cut, or a section, through the brain from the perspective of a viewer.

• Coronal: cut in vertical plane , from the crown of the head down. • Horizontal: cut in the horizon. • Sagittal: cut in lengthways, front to back, viewed from the ides• Ipsilateral: on the same side• Contralateral: opposite to each other.• Bilateral : structures are bilaterally.

Locations

Space restrictions force cerebral hemispheres to grow Space restrictions force cerebral hemispheres to grow posteriorly over rest of brain, enveloping itposteriorly over rest of brain, enveloping it

Cerebral hemispheres grow into horseshoe shape (b and c)Cerebral hemispheres grow into horseshoe shape (b and c) Continued growth causes creases, folds and wrinklesContinued growth causes creases, folds and wrinkles

Brain protection1.Meninges2. Cerebrospinal fluid3. Blood brain barrier

Meninges1.1. Dura materDura mater: 2 layers of fibrous connective tissue, : 2 layers of fibrous connective tissue,

fused except for dural sinusesfused except for dural sinuses Periosteal layer attached to bonePeriosteal layer attached to bone Meningeal layer - proper brain coveringMeningeal layer - proper brain covering

2.2. Arachnoid materArachnoid mater3.3. Pia materPia mater

Note superiorNote superiorsagittal sinussagittal sinus

Dura mater - dural partitionsSubdivide cranial cavity & limit movement of brain

Falx cerebriFalx cerebri In longitudinal fissure; In longitudinal fissure;

attaches to crista galli of attaches to crista galli of ethmoid boneethmoid bone

Falx cerebelliFalx cerebelli Runs vertically along Runs vertically along

vermis of cerebellumvermis of cerebellum Tentorium cerebelliTentorium cerebelli

Sheet in transverse Sheet in transverse fissure between fissure between cerebrum & cerebellumcerebrum & cerebellum

Arachnoid materArachnoid mater Between dura and arachnoid: Between dura and arachnoid: subdural spacesubdural space Dura and arachnoid cover brain looselyDura and arachnoid cover brain loosely Deep to arachnoid is Deep to arachnoid is subarachnoid spacesubarachnoid space

Filled with CSFFilled with CSF Lots of vessels run through (susceptible to tearing)Lots of vessels run through (susceptible to tearing)

Superiorly, forms arachnoid villi: CSF valvesSuperiorly, forms arachnoid villi: CSF valves Allow draining into dural blood sinusesAllow draining into dural blood sinuses

Pia materPia mater Delicate, clings to brain following convolutionsDelicate, clings to brain following convolutions

Cerebrospinal FluidCSF

Made in choroid plexuses (roofs of ventricles)Made in choroid plexuses (roofs of ventricles)Filtration of plasma from capillaries through Filtration of plasma from capillaries through

ependymal cells (electrolytes, glucose)ependymal cells (electrolytes, glucose) 500 ml/d; total volume 100-160 ml (1/2 c)500 ml/d; total volume 100-160 ml (1/2 c) Cushions and nourishes brainCushions and nourishes brain Assayed in diagnosing meningitis, bleeds, MSAssayed in diagnosing meningitis, bleeds, MS Hydrocephalus: excessive accumulationHydrocephalus: excessive accumulation

CSF circulation: through ventricles, median and lateral apertures, subarachnoid space, arachnoid villi, and into the blood of the superior sagittal

sinus

CSF:-Made in choroid plexus-Drained through arachnoid villus

HydrocephalusHydrocephalus

Blood-Brain Barrier

Tight junctions between endothelial cells of Tight junctions between endothelial cells of brain capillaries, instead of the usual brain capillaries, instead of the usual permeabilitypermeability

Highly selective transport mechanismsHighly selective transport mechanisms Allows nutrients, O2, CO2Allows nutrients, O2, CO2 NotNot a barrier against uncharged and lipid a barrier against uncharged and lipid

soluble molecules; allows alcohol, nicotine, soluble molecules; allows alcohol, nicotine, and some drugs including anestheticsand some drugs including anesthetics

Blood-brain barrierendothelial cells (tight junctions in-between), pericytes, and astrocytes (end-foot processes)

Anatomical classification Cerebral hemispheresCerebral hemispheres DiencephalonDiencephalon

ThalamusThalamus HypothalamusHypothalamus

Brain stemBrain stem MidbrainMidbrain PonsPons MedullaMedulla

CerebellumCerebellum

Spinal cordSpinal cord

Parts of Brain

CerebrumCerebrumDiencephalonDiencephalonBrainstemBrainstemCerebellumCerebellum

Usual pattern of gray/white in CNS

White exterior to grayWhite exterior to gray Gray surrounds hollow Gray surrounds hollow

central cavitycentral cavity Two regions with Two regions with

additional gray called additional gray called “cortex”“cortex” Cerebrum: “cerebral cortex”Cerebrum: “cerebral cortex” Cerebellum: “cerebellar cortex”Cerebellum: “cerebellar cortex”

_________________

____________________________

_____________________________

Gray and White Matter Like spinal cord but Like spinal cord but

with another layer of with another layer of gray outside the whitegray outside the white Called Called cortexcortex Cerebrum and Cerebrum and

cerebellum havecerebellum have Inner gray: “Inner gray: “brain brain

nucleinuclei” (not cell nuclei)” (not cell nuclei) Clusters of cell bodiesClusters of cell bodies

Remember, in PNS Remember, in PNS clusters of cell bodies were clusters of cell bodies were called “ganglia”called “ganglia”

More words: brains stem is caudal (toward tail) to the more rostral (noseward) cerebrum

Ventricles

Central cavities expandedCentral cavities expanded Filled with Filled with CSFCSF (cerebrospinal fluid) (cerebrospinal fluid) Lined by ependymal cells (these cells lining Lined by ependymal cells (these cells lining

the choroid plexus make the CSF: see later the choroid plexus make the CSF: see later slides)slides)

Continuous with each other and central Continuous with each other and central canal of spinal cordcanal of spinal cord

Lateral ventriclesLateral ventriclesPaired, horseshoe shapePaired, horseshoe shape In cerebral hemispheresIn cerebral hemispheresAnterior are close, separated only by thinAnterior are close, separated only by thin

Septum pellucidumSeptum pellucidum

Third ventricleThird ventricle In diencephalonIn diencephalonConnectionsConnections

Interventricular foramenInterventricular foramenCerebral aqueductCerebral aqueduct

Fourth ventricleFourth ventricle In the brainstemIn the brainstemDorsal to pons and top of medullaDorsal to pons and top of medullaHoles connect it with subarachnoid spaceHoles connect it with subarachnoid space

Subarachnoid space

Aqua blue in this picAqua blue in this pic Under thick Under thick

coverings of braincoverings of brain Filled with CSF alsoFilled with CSF also Red: choroid plexusRed: choroid plexus

(more later)(more later)

________

Surface anatomy

Gyri Gyri (plural of (plural of gyrusgyrus))Elevated ridgesElevated ridgesEntire surfaceEntire surface

Grooves separate gyriGrooves separate gyriA A sulcussulcus is a shallow is a shallow

groove (plural, groove (plural, sulcisulci))Deeper grooves are Deeper grooves are

fissuresfissures

Gyri Gyri (plural of (plural of gyrusgyrus))Elevated ridgesElevated ridgesEntire surfaceEntire surface

Grooves separate gyriGrooves separate gyriA A sulcussulcus is a shallow groove (plural, is a shallow groove (plural, sulcisulci))Deeper grooves are Deeper grooves are fissuresfissures

simplified…simplified…

Back of brain: perceptionBack of brain: perceptionTop of brain: movementTop of brain: movementFront of brain: thinkingFront of brain: thinking

Cerebral hemispheres: note lobes Divided by Divided by longitudinal fissurelongitudinal fissure into right & left into right & left

sidessides Central sulcusCentral sulcus divides frontal from parietal divides frontal from parietal

lobeslobes

Lateral sulcusLateral sulcus separates temporal lobe from separates temporal lobe from parietal lobeparietal lobe

Parieto-occipital sulcusParieto-occipital sulcus divides occipital and divides occipital and parietal lobes (not seen from outside)parietal lobes (not seen from outside)

Transverse cerebral fissureTransverse cerebral fissure separates cerebral separates cerebral hemispheres from cerebellumhemispheres from cerebellum

coronal section Note: longitudinal fissure, lateral sulcus, insulaNote: longitudinal fissure, lateral sulcus, insula Note: cerebral cortex (external sheet of gray), Note: cerebral cortex (external sheet of gray),

cerebral white, deep gray (basal ganglia)cerebral white, deep gray (basal ganglia)

Cerebral hemispheres Lobes: under bones of same nameLobes: under bones of same name

FrontalFrontal

ParietalParietal

TemporalTemporal

OccipitalOccipital

Plus: Insula (buried deep in lateral sulcus) Plus: Insula (buried deep in lateral sulcus)

Cerebral cortex Executive functioning capabilityExecutive functioning capability Gray matter: of neuron cell bodies, dendrites, short Gray matter: of neuron cell bodies, dendrites, short

unmyelinated axonsunmyelinated axons 100 billion neurons with average of 10,000 contacts each100 billion neurons with average of 10,000 contacts each

No fiber tracts (would be white)No fiber tracts (would be white) 2-4 mm thick (about 1/8 inch)2-4 mm thick (about 1/8 inch) Brodmann areas (historical: 52 structurally different Brodmann areas (historical: 52 structurally different

areas given #s)areas given #s) Neuroimaging: functional organizationNeuroimaging: functional organization

(example later)(example later)

Prenatal life: genes are responsible for creating the Prenatal life: genes are responsible for creating the architecture of the brainarchitecture of the brain Cortex is the last to develop and very immature at birthCortex is the last to develop and very immature at birth

Birth: excess of neurons but not inter-connectedBirth: excess of neurons but not inter-connected 11stst month of life: a million synapses/sec are made; this is genetic month of life: a million synapses/sec are made; this is genetic

11stst 3 years of life: synaptic overgrowth (connections) 3 years of life: synaptic overgrowth (connections) After this the density remains constant though some grow, some dieAfter this the density remains constant though some grow, some die

Preadolescence: another increase in synaptic formation Preadolescence: another increase in synaptic formation Adolescence until 25: brain becomes a reconstruction siteAdolescence until 25: brain becomes a reconstruction site

Connections important for self-regulation (in prefrontal cortex) are Connections important for self-regulation (in prefrontal cortex) are being remodeled: important for a sense of wholenessbeing remodeled: important for a sense of wholeness

Causes personal turbulenceCauses personal turbulence Susceptible to stress and toxins (like alcohol and drugs) during these Susceptible to stress and toxins (like alcohol and drugs) during these

years; affects the rest of one’s life years; affects the rest of one’s life The mind changes the brain (throughout life)The mind changes the brain (throughout life)

Where brain activation occurs, synapses happenWhere brain activation occurs, synapses happen When pay attention & focus mind, neural firing occurs and brain When pay attention & focus mind, neural firing occurs and brain

structure changes (synapses are formed)structure changes (synapses are formed) Human connections impact neural connections (ongoing experiences Human connections impact neural connections (ongoing experiences

and learning include the interpersonal ones)and learning include the interpersonal ones)adapted from Dr. Daniel Siegel, UCLA

Cerebral cortex

All the neurons are All the neurons are interneuronsinterneuronsBy definition confined to the CNSBy definition confined to the CNSThey have to synapse somewhere before the They have to synapse somewhere before the

info passes to the peripheral nervesinfo passes to the peripheral nerves Three kinds of functional areasThree kinds of functional areas

MotorMotor areas: movement areas: movementSensorySensory areas: perception areas: perceptionAssociationAssociation areas: integrate diverse areas: integrate diverse

information to enable purposeful actioninformation to enable purposeful action

Controlling our behaviour in Controlling our behaviour in response to the social or environmental response to the social or environmental situation that we are in – situation that we are in – Considerable skillConsiderable skill

Fontal lobeFontal lobe

Controls our behaviour with respect to Controls our behaviour with respect to time and space.time and space.

(only with all the relevant sensory and mnemonic i.e., (only with all the relevant sensory and mnemonic i.e., memory information).memory information).

Subdivisions of the frontal lobe

In the human brain, the frontal lobes In the human brain, the frontal lobes includes all the tissue anterior to the central includes all the tissue anterior to the central sulcus. sulcus.

It constitutes 20% of the neo-cortex and It constitutes 20% of the neo-cortex and made up of several distinct regions are made up of several distinct regions are grouped grouped

The motor cortex: Area 4The motor cortex: Area 4 Pre motor cortex: Pre motor cortex:

Lateral Area 6: pre motor cortexLateral Area 6: pre motor cortexMedial Area 6: Supplementary motor cortex.Medial Area 6: Supplementary motor cortex.Area 8: frontal eye field. Area 8: frontal eye field. Area 8A: Supplementary eye field.Area 8A: Supplementary eye field.

In humans, the lateral pre motor area In humans, the lateral pre motor area expanded as Broca’s area. (Area 44) expanded as Broca’s area. (Area 44) developed. developed.

The frontal cortex The frontal cortex are multimodal. Cells are multimodal. Cells responsive to responsive to combinations of combinations of visual, auditory, and visual, auditory, and somatic stimuli are somatic stimuli are found in the lateral found in the lateral pre motor cortex pre motor cortex Area 6 and Area 46.Area 6 and Area 46.

Connections of the frontal lobe.

The motor and pre motor area are part of a The motor and pre motor area are part of a functional system to control movements functional system to control movements directly.directly.

The motor cortex projects to the spinal motor The motor cortex projects to the spinal motor neurons to control limb, hand, and foot, and neurons to control limb, hand, and foot, and digit movements and to the appropriate digit movements and to the appropriate cranial-nerve motor neuron to control facial cranial-nerve motor neuron to control facial movements. It connects with basal ganglia, movements. It connects with basal ganglia, and the red nucleus.and the red nucleus.

The pre motor cortex influences movements The pre motor cortex influences movements directly through cortico spinal projections directly through cortico spinal projections or indirectly through projections to the or indirectly through projections to the motor cortex. It receives projections from motor cortex. It receives projections from the posterior parietal areas.the posterior parietal areas.

The pre motor regions are connected to The pre motor regions are connected to areas concerned with the execution of limb areas concerned with the execution of limb and eye movements.and eye movements.

Functions

The temporal organization of behavior and The temporal organization of behavior and the sequential organization is the general the sequential organization is the general function of the frontal lobe. function of the frontal lobe.

The frontal lobe contains control systems that The frontal lobe contains control systems that implement different behavioral strategies in implement different behavioral strategies in response to both internal and external cues. response to both internal and external cues.

These temporal systems are called as These temporal systems are called as ‘executive functions’ in recent days. ‘executive functions’ in recent days.

Motor cortexMotor cortex: Provides a mechanism for : Provides a mechanism for executing individual movementsexecuting individual movements

Pre motor cortexPre motor cortex. . Selects the movements to be executed. Selects the movements to be executed. The movements can be the response to The movements can be the response to

either internal or external environmental either internal or external environmental cues or stimuli.cues or stimuli.

Richard Passingham (1993) suggested that Richard Passingham (1993) suggested that the pre motor regions functions primarily to the pre motor regions functions primarily to choose behavior in response to external choose behavior in response to external cues cues

Supplementary motor cortex:Supplementary motor cortex: contribution contribution to selection of behavior for internal stimuli to selection of behavior for internal stimuli or when there is no any external cues. or when there is no any external cues.

The limb and eye movements for a stimulus The limb and eye movements for a stimulus directed (Area 8) or for internal cues are made directed (Area 8) or for internal cues are made (Area 8A). (Area 8A).

Per Roland (1980): Supplementary motor Per Roland (1980): Supplementary motor region plays a special role in the selection and region plays a special role in the selection and direction of motor sequences. (More activation direction of motor sequences. (More activation for 16 sequential movement of a finger than for 16 sequential movement of a finger than repetitive movements of the finger). repetitive movements of the finger).

The production of the movement sequence The production of the movement sequence was self –paced, or internally driven. was self –paced, or internally driven. (Counting , days in week, months in (Counting , days in week, months in calendar etc, or slokas). calendar etc, or slokas).

The pre motor cortex is activated when movement The pre motor cortex is activated when movement sequences are paced externally by a cue. (Speaking sequences are paced externally by a cue. (Speaking to the rhythm of a pulse). to the rhythm of a pulse).

Not only are motor acts paced by cues, but they also Not only are motor acts paced by cues, but they also can become associated with cues. can become associated with cues.

When the subjects are trained for arbitrary When the subjects are trained for arbitrary

associations there is increase in functional activity associations there is increase in functional activity in the pre motor cortex. (Learning of traffic signals).in the pre motor cortex. (Learning of traffic signals).

Functions of the Pre frontal cortex

Controls cognitive processes so that Controls cognitive processes so that appropriate movements are selected at the appropriate movements are selected at the correct time and place. correct time and place.

It can be due to internal cues or external It can be due to internal cues or external cues or may be made in response to context or cues or may be made in response to context or self-knowledge. self-knowledge.

Internal cues: Internal cues: Temporal memory, a neural record of recent events Temporal memory, a neural record of recent events

and their order related to things or to movements and their order related to things or to movements and thus derive their information from the object- and thus derive their information from the object- recognition or motor streams of sensory processing. recognition or motor streams of sensory processing.

The dorsolateral areas are especially engaged in the The dorsolateral areas are especially engaged in the selection of behavior based on the temporal memory. selection of behavior based on the temporal memory.

External cues:External cues:People whose memory is defective become People whose memory is defective become

dependent on environmental cues to determine dependent on environmental cues to determine their behavior. their behavior.

Frontal lobe injury leads to inability to inhibit Frontal lobe injury leads to inability to inhibit behavior directed to external stimuli. behavior directed to external stimuli.

Learning by association is controlled Learning by association is controlled by orbitofrontal cortex. by orbitofrontal cortex.

Contextual cues:Contextual cues:The choice of behaviors in context requires detailed The choice of behaviors in context requires detailed

information which is conveyed to the inferior frontal information which is conveyed to the inferior frontal cortex from the temporal lobe. cortex from the temporal lobe.

Context also means effective context and is Context also means effective context and is contributed by amygdala. contributed by amygdala.

Persons with orbitofrontal lesions, which Persons with orbitofrontal lesions, which are common in TBI, closed head injury have are common in TBI, closed head injury have difficulty with context, especially in social difficulty with context, especially in social situations. situations.

Autonoetic awarenessAutonoetic awareness Lifetime experiences and goals can also Lifetime experiences and goals can also

influence our behavior. influence our behavior.

Tulving (2002) called this autobiographic Tulving (2002) called this autobiographic knowledge as autonoetic awareness. i.e., knowledge as autonoetic awareness. i.e., self-knowledge. self-knowledge.

This allows one to bind together the This allows one to bind together the awareness of oneself as a continuous entity awareness of oneself as a continuous entity through time. through time.

Impairment results in a deficit in the self Impairment results in a deficit in the self regulation of behavior. regulation of behavior.

Our behavior is influenced by our Our behavior is influenced by our personal past experiences and life goals for the personal past experiences and life goals for the future. future.

Such that we interpret the whole world in Such that we interpret the whole world in our daily life with in our own our daily life with in our own frame of referenceframe of reference. .

Patients with ventral frontal injury often Patients with ventral frontal injury often loose this self-knowledge and have difficulty in loose this self-knowledge and have difficulty in daily living.daily living.

Asymmetry of frontal lobe function

The asymmetry of functions is relative rather The asymmetry of functions is relative rather than absolute. than absolute.

Right frontal lobe: Right frontal lobe: role in non verbal movements such as role in non verbal movements such as

facial expressions.facial expressions. More engagement in retrieval of More engagement in retrieval of

information.information.

Left frontal lobe: Left frontal lobe: role in language, Speech. role in language, Speech. Encoding information into memory Encoding information into memory

Laterality of function disturbed by frontal –Laterality of function disturbed by frontal –lobe lesions are less striking than the lobe lesions are less striking than the posterior lobes.posterior lobes.

Heterogeneity of frontal lobe functions

Any individual patient is unlikely to show all Any individual patient is unlikely to show all the symptoms and the severity of the the symptoms and the severity of the symptoms may vary with lesion location. symptoms may vary with lesion location.

However , in recent homogeneity of However , in recent homogeneity of functions are favored i.e., at least in the functions are favored i.e., at least in the orbitofrontal cortex there is evidence of orbitofrontal cortex there is evidence of discrete localization of functions. discrete localization of functions.

Symptoms of frontal lobe lesions

Disturbance of motor function

Damage to Primary motor cortexDamage to Primary motor cortex:: Chronic loss of the ability to make fine, Chronic loss of the ability to make fine,

independent finger movements , presumably independent finger movements , presumably owing to a loss of direct corticospinal owing to a loss of direct corticospinal projections onto motor neurons.projections onto motor neurons.Loss of speed and strength in both hand and Loss of speed and strength in both hand and

limb movements in the contralateral limbs. limb movements in the contralateral limbs. Loss of strength : Area4, lesions restricted to Loss of strength : Area4, lesions restricted to

prefrontal cortex.prefrontal cortex.

Movement programming. Movement programming. Removal of supplementary motor cortex- Removal of supplementary motor cortex-

Transient disruption of all voluntary Transient disruption of all voluntary movements. movements.

Disrupts copying of the facial movements. Disrupts copying of the facial movements.

Voluntary gaze and visual search tasks.Voluntary gaze and visual search tasks. Corollary discharge or reafferenceCorollary discharge or reafference

Teuber (1972), argued that voluntary Teuber (1972), argued that voluntary movements require two sets of signals. movements require two sets of signals.

A movement command through motor A movement command through motor system, effects the movement and a system, effects the movement and a signal(Corollary Discharge) from the frontal signal(Corollary Discharge) from the frontal lobe to the parietal and temporal lobe to the parietal and temporal association cortex presets the sensory association cortex presets the sensory system to anticipate the motor act. system to anticipate the motor act.

Speech

Broca’s areaBroca’s area: : word retrieval on the basis of an object, word, word retrieval on the basis of an object, word,

letter, or meaning. It is like the premotor area’s letter, or meaning. It is like the premotor area’s role in other behaviors.role in other behaviors.

Broca’s area selects words on the basis of cues.Broca’s area selects words on the basis of cues.People with Broca’s area damage are impaired People with Broca’s area damage are impaired

in their ability to use verbs and to produce in their ability to use verbs and to produce appropriate grammar, symptom of appropriate grammar, symptom of Aggrammatism.Aggrammatism.

Supplementary Motor Area: Supplementary Motor Area: Retrieval of words without external cues, which also is Retrieval of words without external cues, which also is

consistent with the general function of supplementary consistent with the general function of supplementary motor area. motor area.

Damage to supplementary area extended to left medial Damage to supplementary area extended to left medial frontal region are often mute. frontal region are often mute.

Ability to speak usually returns in unilateral region than Ability to speak usually returns in unilateral region than in bilateral lesion. in bilateral lesion.

Because of bilateral participation of supplementary Because of bilateral participation of supplementary motor area in movement selection. motor area in movement selection.

Loss of divergent thinking

List of possible uses of Cup, a frontal List of possible uses of Cup, a frontal lobe injury interferes with the process lobe injury interferes with the process required for divergent thinking.required for divergent thinking.

Behavioral Spontaneity Behavioral Spontaneity

Loss of Spontaneous Speech , word fluency Loss of Spontaneous Speech , word fluency test test

( Patients are asked to write or say as ( Patients are asked to write or say as many as words starting with a given letter many as words starting with a given letter as they can think of in 5 minutes and as as they can think of in 5 minutes and as many as four letter word of a given letter in many as four letter word of a given letter in 4 minutes).4 minutes).

Damage to left orbitofrontal and right Damage to left orbitofrontal and right orbitofrontal region leads to marked orbitofrontal region leads to marked reduction in verbal fluency. reduction in verbal fluency.

The spontaneity loss can be in daily routine The spontaneity loss can be in daily routine activities and lethargic too.activities and lethargic too.

Strategy formation:Strategy formation:

Impairment in developing novel cognitive Impairment in developing novel cognitive plans or strategies for solving problems. plans or strategies for solving problems.

Environmental control of

behaviour

Response inhibitionResponse inhibition

Frontal lobe damage leads to perseverations on Frontal lobe damage leads to perseverations on responses. responses.

Difficulties in shifting response strategies. Difficulties in shifting response strategies.

Poor performance in Poor performance in stroop task. stroop task.

Risk taking and rule breaking Risk taking and rule breaking Orbitofrontal cortex is part of neural decision Orbitofrontal cortex is part of neural decision

making circuit that evaluates degrees of making circuit that evaluates degrees of uncertainty in the world.uncertainty in the world.

Self regulation Self regulation The loss of biographic knowledge clearly makes The loss of biographic knowledge clearly makes

it difficult to put ongoing life events in context it difficult to put ongoing life events in context and leads to difficulties in regulating behavior and leads to difficulties in regulating behavior flexibly. flexibly.

Difficulty in regulating own behavior because of Difficulty in regulating own behavior because of loss of autonoetic awareness.loss of autonoetic awareness.

Poor temporal memory.Poor temporal memory.There is unequivocal role of the frontal cortex in There is unequivocal role of the frontal cortex in

short term memory processes.short term memory processes.Different regions of the prefrontal cortex Different regions of the prefrontal cortex

control the storage of different types of control the storage of different types of information.information.

Area 46 likely plays an important role in Area 46 likely plays an important role in providing an internal representation of spatial providing an internal representation of spatial information, and the medial regions likely play a information, and the medial regions likely play a similar role in object formation. similar role in object formation.

Cells in these area are active during the Cells in these area are active during the intervals in delayed-response tests, and their intervals in delayed-response tests, and their activity ends abruptly when an animal activity ends abruptly when an animal responds. responds.

Gabriel Leonard (1988) had reported that patients Gabriel Leonard (1988) had reported that patients with frontal lobe lesions perform normally on the with frontal lobe lesions perform normally on the recognition trials, but they are impaired in judging recognition trials, but they are impaired in judging the relative recency of two previously seen items.the relative recency of two previously seen items.Asymmetry in functionsAsymmetry in functionsRight frontal lobe: important for memory for non-verbal, Right frontal lobe: important for memory for non-verbal,

or pictorial, recency or pictorial, recency Left frontal lobe: important for verbal recency.Left frontal lobe: important for verbal recency.

In contrast, lesions in temporal lobe lesions are In contrast, lesions in temporal lobe lesions are impaired in the recognition test but not in the impaired in the recognition test but not in the recency test.recency test.

Impaired social and sexual behaviors.Impaired social and sexual behaviors.Social and Sexual behaviors require flexible Social and Sexual behaviors require flexible

responses that are highly dependent on responses that are highly dependent on contextual cues. contextual cues.

Frontal lobe damage leads to a marked change Frontal lobe damage leads to a marked change in social behavior and personality. e.g., Phineas in social behavior and personality. e.g., Phineas Gage case reported by John Harlow in 1868. Gage case reported by John Harlow in 1868.

Pseudodepression/ PseudopsychopathyPseudodepression/ PseudopsychopathyOutward apathyOutward apathyIndifference, loss of initiative, reduced sexual Indifference, loss of initiative, reduced sexual

interest, little overt emotion, little or no verbal interest, little overt emotion, little or no verbal output.output.

General lack of social graces.General lack of social graces.

Spatial Defecit Spatial Defecit

The dorsolateral frontal lobe The dorsolateral frontal lobe plays an important role in the visuomotor plays an important role in the visuomotor guidance of movements in space and in guidance of movements in space and in mental rotation. ( Per Roland and Lars mental rotation. ( Per Roland and Lars Friberg,1985).Friberg,1985).

Damage to Frontal Facial AreaDamage to Frontal Facial Area

- Unilateral removal of the cortical area - Unilateral removal of the cortical area representing the face results in no representing the face results in no significant chronic loss in sensory or motor significant chronic loss in sensory or motor control of the face, presumably because of control of the face, presumably because of the face’s bilateral representation in the the face’s bilateral representation in the cortex.cortex.

- It does result in chronic deficits in - It does result in chronic deficits in phonetic discrimination, spelling, verbal phonetic discrimination, spelling, verbal fluency and design fluency (Taylor, 1971).fluency and design fluency (Taylor, 1971).

Diseases affecting the frontal lobe

SchizophreniaSchizophrenia Parkinson’s diseaseParkinson’s disease Korsakoff’s syndrome ( Chronic alcoholism Korsakoff’s syndrome ( Chronic alcoholism

induced metabolic disorder)induced metabolic disorder) Drug addiction (Inability control drug Drug addiction (Inability control drug

seeking behavior) – leads to changes in the seeking behavior) – leads to changes in the structure of neurons in both the structure of neurons in both the orbitofrontal and the medial fontal regions.orbitofrontal and the medial fontal regions.

Frontal Lobe

LocationLocation

Brodmann Area 6 - Area Brodmann Area 6 - Area 1010

Reciprocal connections Reciprocal connections with thalamuswith thalamus

FunctionFunction

Control of fine movementsControl of fine movements

Cognitive functions Cognitive functions (Reasoning/Decision (Reasoning/Decision making/Planning)making/Planning)

Frontal Lobe

LocationLocation

Brodmann area – 44 ,Brodmann area – 44 ,

45 (BA 44,45)45 (BA 44,45)

Connection with Connection with Wernicke’s areaWernicke’s area

FunctionFunction

Sentence generationSentence generation Overt verbal fluencyOvert verbal fluency

Linguistic processingLinguistic processing Phonological ProcessingPhonological Processing

Parietal Lobe

1,2,3 and 43- 1,2,3 and 43- Somatosensory cortexSomatosensory cortex

39,40, 5, 7-Posterior 39,40, 5, 7-Posterior Parietal cortexParietal cortex

12

3 40

75

39

43

Object RecognitionObject Recognition Guidance movementGuidance movement Sensorimotor Sensorimotor

transformationtransformation Spatial NavigationSpatial Navigation

Parietal LobeLocationLocation

Central sulcus to Occipital Central sulcus to Occipital lobelobe

Superior to temporalSuperior to temporal lobelobe

FunctionFunction

Integration of sensory Integration of sensory informationinformation

Visual recognition ofVisual recognition of

actionaction

12

3 40

75

39

43

Angular Gyrus

LocationLocation

Brodmann area - 39Brodmann area - 39

“ “Association cortex forAssociation cortex for

association cortices”association cortices”

FunctionFunction

Recognition of visual Recognition of visual symbolssymbols

ReadingReading Sound spelling Sound spelling

correspondencescorrespondences

Supramarginal Gyrus

LocationLocation

Brodmann area - 40Brodmann area - 40

Posterior end of Lateral Posterior end of Lateral fissurefissure

Sensory association areaSensory association area

FunctionFunction

Integration of kinestheticIntegration of kinesthetic

memories with auditory memories with auditory commandscommands

Phonological processingPhonological processing

Semantic representationSemantic representation

AcalculaliaAcalculalia

““my son’s wife” and “my my son’s wife” and “my wife’s son”wife’s son”

““tap” and “pat” have the tap” and “pat” have the same letters, but the same letters, but the spatial organization is spatial organization is different.different.

Temporal Lobe

LocationLocation

Brodmann area - 41, 42Brodmann area - 41, 42

Lies within lateral sulcusLies within lateral sulcus

FunctionFunction

Auditory ProcessingAuditory Processing

Superior Temporal Gyrus

LocationLocation

Brodmann Brodmann Area - 38, 22Area - 38, 22

BA 22 - BA 22 - Wernicke’s Wernicke’s areaarea

Reciprocal Reciprocal connections connections with with thalamusthalamus

FunctionFunction

Auditory Auditory language language associationassociation

Analysis & Analysis & elaboration of elaboration of speech soundsspeech sounds

Phonological Phonological processingprocessing

Buchsbaum, 2001Buchsbaum, 2001

Middle & Inferior TemporalGyrus

LocationLocation

Brodmann Area - 21, 20Brodmann Area - 21, 20FunctionFunction

• • Listening to Listening to sentencessentences

• • Reading tasksReading tasks

• • Lexical semanticLexical semantic

processingprocessing

Superior Temporal Gyrus

LocationLocation

Brodmann Brodmann Area - 38, 22Area - 38, 22

BA 22 - BA 22 - Wernicke’s Wernicke’s areaarea

Reciprocal Reciprocal connections connections with with thalamusthalamus

FunctionFunction

Auditory Auditory language language associationassociation

Analysis & Analysis & elaboration of elaboration of speech soundsspeech sounds

Phonological Phonological processingprocessing

Buchsbaum, 2001Buchsbaum, 2001

Temporal lobeTemporal lobe

Language formulation areaLanguage formulation area Basal temporal language Basal temporal language

areaarea Lexical–phonological Lexical–phonological

retrievalretrieval Semantic processingSemantic processing Retrieval of the name of a Retrieval of the name of a

conceptconcept

Mummery et al, 1999Mummery et al, 1999

Posterior Temporoparietal Posterior Temporoparietal CortexCortex

Auditory processing for Auditory processing for speech like stimulispeech like stimuli

Lexical processingLexical processing Short term acoustic Short term acoustic

storagestorage

Occipital Lobe

Visual Visual sensationsensation

Ventral Ventral pathway - pathway - object object recognitionrecognition

FunctionFunction

Dorsal Dorsal pathway - pathway - visually guided visually guided actionsactions

Letter by letter Letter by letter readingreading

Shmuelof & Zohary 2005

Arcuate Fasciculus

LocationLocation

Posterior Posterior temporoparietal temporoparietal

junctionjunction frontal cortexfrontal cortex

Part of Part of superior superior longitudinal longitudinal fasciculusfasciculus

FunctionFunction

Broca’s area Broca’s area WernickesWernickes

Generation &Generation &

UnderstandingUnderstanding

Sub cortical structures &

Language

Thalamus

LocationLocation

FunctionFunction

Anterior ventrolateral – Anterior ventrolateral – Production of repeated Production of repeated

erraneous wordserraneous words

Medial ventrolateral – Medial ventrolateral – PerseverationPerseveration

Posterior ventrolateral – Posterior ventrolateral – Misnaming, OmissionsMisnaming, Omissions

Basal Ganglia

LocationLocation FunctionFunction

Distinct role in Language Distinct role in Language ProcessingProcessing

Phonological Phonological processingprocessing

Syntactic processingSyntactic processing

Monitoring the Monitoring the semantic and lexical semantic and lexical

aspectsaspects

Hippocampus

LocationLocation

FunctionFunction

Bottleneck for language Bottleneck for language developmentdevelopment

Verbal memoryVerbal memory

Language learningLanguage learning

Knecht 2004Knecht 2004

Brain stem

Language dependent Language dependent operations begin at this operations begin at this

level before signal reaches level before signal reaches cortexcortex

FunctionFunction

Early stages of processing Early stages of processing of linguistic & of linguistic &

nonlinguistic inputsnonlinguistic inputs

Krishnan et al, 2005Krishnan et al, 2005

Cerebellum & Language

Non - motor cognitive abilitiesNon - motor cognitive abilities

Phonological processingPhonological processing

Verb generationVerb generation

Antonym generationAntonym generation

Gebhart, Petersen & Thach’02 , Walter & Joanette’07

Task Specific Representation

Phonology

Task Specific Representation

Frontal Operculum

Anterior STG BA 44/45 Posterior

STG/STS Left Inferior

Frontal Gyrus – phrase structure

Syntax processing

Non-Syntax processing

Frontal activation

Semantic processing Müller et al.

(2003)

Phonological processing

Fiez et al. (1995)

Semantics

Semantic Word Processing

Visual processing

Area

•Striate cortex

•Prestriate area

Word processing

Auditory processing Area

• 1°auditory cortex,• Temporo-parietal• Ant. Sup. temporal• Inf. Ant. cingulate

Naming

Damasio et al, 1996

Prosody

Right HemisphereRight Hemisphere

FunctionFunction

Left hemisphereLeft hemisphere Supra Marginal GyrusSupra Marginal Gyrus Inferior Temporal GyrusInferior Temporal Gyrus

(Ackermann et al., 2001; Zatorre et al., 2002)

Pragmatics

Pragmatics

Reading/Writing

Repetition

Repeating a spoken word

Repeating a written word

fMRI: functional magnetic resonance imagingfMRI: functional magnetic resonance imaging Cerebral cortex of person speaking & hearingCerebral cortex of person speaking & hearing Activity (blood flow) in posterior frontal and Activity (blood flow) in posterior frontal and

superior temporal lobes respectivelysuperior temporal lobes respectively

Homunculus – “little man” Body map: human body spatially representedBody map: human body spatially represented

Where on cortex; upside downWhere on cortex; upside down