frontal lobe

Frontal lobe

1. FRONTAL LOBE - Dr. Sriram.R

2. INTRODUCTION The  frontal lobe  is one of the four major lobes of the cerebral cortex. Located at the front of each cerebral hemisphere and positioned anterior to parietal lobe. Superior and anterior to the Temporal lobes. Separated from the parietal lobe by a space between tissues called the central sulcus . Separated from the temporal lobe by a deep fold called the lateral ( Sylvian ) sulcus .

3. The precentral gyrus , forming the posterior border of the frontal lobe, contains the primary motor cortex, which controls voluntary movements of specific body parts. In humans, the frontal lobe reaches full maturity around the late 20s ( Giedd et al., 1999) A small amount of atrophy, however, is normal in the aging person’s frontal lobe. A decline in frontal lobe volume of approximately .5% every year seemed to be average. ( Fjell , 2009) These findings corroborate those of Coffey, who in 1992 indicated that the frontal lobe decreases in volume approximately 0.5%-1% per year.

4. Leukotomy and lobotomy (1935 – Egas Moniz)

5. STRUCTURE OF FRONTAL LOBE On the lateral surface of the human brain, the central sulcus  separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe. The frontal lobe bottom can be divided into a  lateral, polar, orbital (above the orbit; also called basal or ventral), and  medial part.

6. Each of these parts consists of particular  gyri and the gyri are separated by  sulci Lateral part:  Precentral gyrus , lateral part of the  superior frontal gyrus ,  middle frontal gyrus ,  inferior frontal gyrus . Polar part:  Transverse frontopolar gyri ,  frontomarginal gyrus . Orbital part:  Lateral orbital gyrus ,  anterior orbital gyrus ,  posterior orbital gyrus ,  medial orbital gyrus ,  gyrus rectus . Medial part: Medial part of the  superior frontal gyrus ,  cingulate gyrus .

7. LATERAL SURFACE ORBITAL (VENRAL SURFACE)

8. MEDIAL SURFACE

9. The orbitofrontal cortex is divided into ventromedial (reddish in the anterior view: above and yellow in the convex-lateral and median-sagittal view) and the lateral orbitofrontal cortex (green)

10. BLOOD SUPPLY of FL – MCA and ACA The  middle cerebral artery  (MCA) is one of the three major paired  arteries  that supply  blood  to the  cerebrum . The MCA arises from the  internal carotid  and continues into the  lateral sulcus  where it then branches and projects to many parts of the lateral cerebral cortex. To the frontal lobe, it gives off 4 branches - Lateral frontobasal  ( orbitiofrontal ) Prefrontal arteries Pre- Rolandic artery  ( precentral ) Rolandic arteries  (central)

11. The  anterior cerebral artery  ( ACA ) is one of a pair of arteries on  the brain  that supplies oxygenated blood to most medial portions of the  frontal lobes  and  superior medial parietal  lobes. The two anterior cerebral arteries arise from the internal carotid artery  and are part of the  Circle of Willis . The ACA supplies the frontal lobe in the following areas – - The medial surface of the  frontal lobe  by the medial orbito -frontal artery. - Approximately 1 inch of the lateral surfaces of FL

12. ACA – MEDIAL SURFACE OF BRAIN

13. LATERAL SURFACE OF THE BRAIN PINK - REGION SUPPLIED BY MIDDLE CEREBRAL ARTERY BLUE – REGION SUPPLIED BY ANTERIOR CERBRAL ARTERY

14. CYTOARCHITECTURE, FUNCTIONS and TESTS of FRONTAL LOBE

15. Cytoarchitecture  ( Greek   κύτος = "cell" +  αρχιτεκτονική = "architecture"), also known as  cytoarchitectonics , is the study of the cellular  composition of the body's tissues under the microscope. Refers to the arrangement and characteristic organization of  neuronal   cell bodies  in the  brain  and  spinal cord . The birth of the cytoarchitectonics of the  human cerebral cortex  is credited to the Viennese psychiatrist  Theodor Meynert  (1833-1892)

16. Korbinian Brodmann  (1868-1918) in Berlin, working on the brains of diverse mammalian species, developed a division of the cerebral cortex into 52 discrete areas (of which 44 in the human , and the remaining 8 in non-human primate brain.

17. BROCA’S AREA Broca's area  or the  Broca area is a region in the  frontal lobe  of one  hemisphere  (usually the left), named after Pierre Paul Broca . Broca's area in the left hemisphere and its homologue in the right  hemisphere  are designations usually used to refer to  pars triangularis  ( PTr ) and  pars opercularis  ( POp ) of the inferior frontal  gyrus . Represented in  Brodmann's   cytoarchitectonic map  as areas  44  and  45  of the dominant hemisphere. Leborgne was a patient of Broca's . Almost completely unable to produce any words or phrases, he was able to repetitively produce only the word  tan . Lelong was another patient of Broca's . He also exhibited reduced productive speech. He could only say five words, 'yes,' 'no,' 'three,' 'always,' and ' lelo '

18. FUNCTIONS OF BROCA’s area Language production and language comprehension/use syntax to determine meaning of sentences. Plays a role in interpreting action of others – Action recognition and production. Speech-associated gestures could possibly reduce lexical or sentential ambiguity, comprehension should improve in the presence of speech-associated gestures. As a result of improved comprehension, the involvement of Broca's area should be reduced

19. FRONTAL-SUBCORTICAL CIRCUITS There are 5 parallel, separate circuits (Alexander et al, 1986) 1. a motor circuit originating in the motor cortex and pre-motor cortex 2. an oculomotor unit originating in the frontal eye fields 3. the dorsolateral prefrontal circuit, which underpins executive functions 4. the anterior cingulate circuit which underpins motivation 5. the orbitofrontal circuit which underpins impulse control and social behavior. Neurology Psychiatry

20. Frontal lobes: Subcortical connections - Thalamus dorsomedial Dorsolateral prefrontal Dorsolateral caudate Lateral dorsomedial Globus Pallidus VA & MD Thalamus Ventromedial caudate Medial Globus pallidus Anterior Cingulate Nucleus accumbens Rostrolateral Globus Pallidus MD Thalamus Orbital prefrontal VA & MD Thalamus

21. Frontal lobes: Subcortical connections Thalamus

22. Frontal lobes: Subcortical connections White matter uncinate fasciculus long tracts to posterior association areas cortical u-fibers

23. Frontal lobes: Cortical connections

24. Functional regions of the frontal lobes I. Primary motor area II. Premotor area III. Frontal eye fields IV. Dorsolateral prefrontal cortex V. Orbital and basal areas VI. Supplementary motor area and anterior cingulate gyrus area

25. I. Primary motor area Brodmann area 4 Input from ventral lateral thalamic nucleus, primary somatosensory area in parietal lobe Output to internal capsule Pyramidal motor functions Although designated a “motor” cortex, this area is also involved with somatosensory perception

26. CORTICAL HOMUNCULUS (Primary motor) A  cortical homunculus  is a pictorial representation of the anatomical divisions of the primary motor cortex.

27. Primary motor dysfunction Initially flacid hemiparesis or hemiplegia on contralateral side Later spastic hemiparesis or hemiplegia

28. Bedside tests for Primary motor cortex: Motor strength of hand grip - The patient is asked to grip the examiners fingers. Strength should be roughly equal, with greater strength on the dominant side. It should be difficult for the examiner to free her/his fingers. 2. Motor speed as in finger tapping has also been listed as a useful test (Malloy & Richardson, 1994) but such tests do not discriminate from the premotor cortex. Diagnostically, poor performances suggest local lesions such as vascular or neoplastic pathology, or a generalized lesion such as a degenerative disease. (Peripheral nerve lesion must, of course, be excluded.)

29. II. Premotor area Brodmann area 6 Input from ventral anterior thalamic nucleus and secondary somatosensory area Output to motor area and connections via corpus callosum to contralateral premotor area Integration of sensory and motor information Praxis

30. Premotor dysfunction Apraxia Preserved postural praxis via basal ganglia Contralateral fine motor deficits Difficulty using sensory feedback

31. Bedside tests for premotor cortex: 1. Sensorimotor abilities are tested by asking the patient touch each finger to the thumb in succession as rapidly as possible. Watch for speed and dexterity. 2. Apraxia can be tested by asking the patient to "blow a kiss" / demonstrate the use of a shovel / draw a cube / draw a star / light a cigarette etc. Poor performance carries the diagnostic implications as for the motor cortex above. (i.e. the area is affected by vascular insult/neoplasm)

32. EFFECTS of LESIONS AFFECTING BOTH Primary motor and Premotor cortex Motor – Contralateral spastic paresis; loss of fine motor control Reduced verbal fluency Impaired spelling Others effects – (GROUPS) Gegenhalten / Paratonia Primitive reflexes (grasp/sucking/ palmar -mental/ glabellar tap) Optic atrophy ( Ipsilateral ) Urinary incontinence Perseveration Seizures ( Jacksonian )

33. III. Frontal eye field Brodmann area 8 (posterior portion of middle frontal gyrus ), with some area 9 and 6 Volitional eye movement in contralateral visual field Active visual search Voluntary eye movements are of two types - Pursuit movement occurs when the eyes to follow moving objects. Saccadic eye movements are used to follow imaginary points.

34. Frontal eye field dysfunction Failure to move eyes volitionally to contralateral visual field Intact passive eye movement Poor visual search

35. Bedside test for frontal eye field: Ask the patient to follow the movement of a finger from left to right and up and down. 2. Ask the patient to look from left to right, up and down (with no finger to follow). Note inability to move or jerky movement.

36. IV. Dorsolateral PFC

37. Brodmann areas 46,45,47,8,9,10 . A compromise position is that the DLPFC is composed of Brodmann area 9 and the lateral aspect of 10 and most of area 46. Executive functions - (“Executive” in frontal lobe means cognitive system that controls and manages other cognitive processes. ) Integration of multimodal sensory information Generation of multiple reponse alternatives to environmental challenges Selection of most appropriate response, self evaluation of responses and selection of a replacement response if first response fails Maintenance of task set, persistence Sequential ordering of data Set shifting, flexibility Spatial working memory FUNCTIONS OF DLPFC

38. The executive functions largely determine the ability of the individual to cope with the continuous, but ever changing challenges of the environment. Thus, the patient’s ability to make an appointment and to arrive on time is valuable information. So too,is the ability of the patient to give a comprehensive account of her/himself and the reasons for the consultation. It is believed by some authors that formal thought disorder arises from a lack of executive planning and editing (McGrath, 1991). In thought disorder there are frequent examples of failure to maintain set (distractibility), sequentially order information, and to ensure that the listener is comprehending. Note - formal thought disorder is also known to involve the left superior temporal sulcus and the left temporal pole (Horn et al, 2010).

39. Dorsolateral PFC dysfunction Difficulty integrating sensory information Generation of few, stereotyped response alternatives Poor judgement in response selection Impersistence Perseveration

40. Head injury and dementing illnesses may result in severe impairment of the executive functions. Schizophrenia often has thought disorder as a major feature and the executive functions tests are usually also affected. Depressive disorder may be associated with poor performance on verbal fluency tests during the acute phase, which normalizes with remission ( Trichard , et al., 1995).

41. Bedside tests for DLPFC: Is the patient able to make an appointment and arrive on time? 2. Is the patient able to give a coherent account of current problems and the reason for the interview? Is there evidence of thought disorder? 3. Digit span , days of the week or months of the year backwards. Here the patient has to retain the task and simultaneously manipulate information. 4. Controlled oral word association test (COWAT): the patient is asked to produce as many words as possible, in one minute, starting with F,then A, then S. Proper nouns and previously used words with a different suffix are prohibited (Benton, 1968). 5 . Other categorical fluency tests include naming animals, fruits and vegetables ( Monsch et al, 1992).

42. 6. Alternating hand sequences . These can be devised by the examiner. One example is that one hand is placed palm upwards and the other is place palm downwards, and the patient is then asked to reverse these positions as rapidly as possible. Another example is that the backs of the hands are both placed downwards, but one hand is clenched and the other is open, then the patients is asked to close the open hand and open the closed hand, and keep reversing the posture of the hands as rapidly as possible. A final example is that the patient taps twice with one fist and once with the other, then after the rhythm is established, the patient is asked to change over the number of beats (the fist which first tapped twice now taps only once). Patients with frontal lobe deficits usually perform poorly on these tests , often being unable to follow the relatively simple instructions 7. Formal neuropsychological may be necessary where uncertainty remains. Commonly employed tests include Controlled Oral Word Association Test (Benton, 1968) and the Wisconsin Card Sorting Tests (Heaton, 1985).

43. Dorsolateral tests Figural fluency

44. Dorsolateral tests Luria’s reciprocal hand movements & graphic designs

45. Dorsolateral tests Perseverations within and between Lurian tasks

46. Dysexecutive effects on other tests

47. Frontal lobes Poor organization of learning and recall (Ray Osterrieth ) Copy Free recall

48. V. Orbital and Basal areas Brodman areas 10,11,12,13,14 Input from limbic and olfactory systems ( amygdala , temporal pole, entorhinal cortex, olfactory nerve); inferotemporal lobe areas, ventral visual pathways Output to autonomic musculature and endocrine system (basal forebrain cholinergic system, caudate, and autonomic system )

49. FUNCTIONS OF OFC Modulation of affective and social behavior; “...preservation of behavioral regulation by external stimuli and its dissolution in the absence of external stimulation.” It mediates empathic, civil and socially appropriate behavior (Mega and Cummings, 1994). Working memory for feature information Integration of memory and emotional valence Smell discrimination Much of the personality change described in cases of frontal lobe injury ( Phineas Gage being the most famous) is due to lesions in this area. Patients may become irritable, labile, disinhibited and fail to respond to the conventions of acceptable social behavior

50. Dr. Harlow – Surgeon Who treated Phineas Gage

51. OFC dysfunction Disinhibition , socially inappropriate behavior Failure on feature working memory tasks Anosmia Confabulation Increased concern about social behavior and contamination has been associated with increased orbitofrontal and caudate metabolism. This has been reported with lesions of the globus pallidus and in obsessive compulsive disorder.

52. Bedside tests for OFC: 1. Does the patient dress or behave in a way which suggests lack of concern with the feelings of others or without concern to accepted social customs? (Frontal Systems Behavior Scale – FrSBe can be used) 2. Test sense of smell - coffee, cloves etc. (UPSIT can be used) Go/no-go Test. The patient is asked to make a response to one signal (the Go signal) and not to respond to another signal (the no-go signal). The most basic is to ask the patient to tap their knee when the examiner says, “Go” and to make no response when the examiner says, “Stop”. Note - The task may be made more demanding by reversing the customary meaning of signals. An example is to ask the patient to tap the knee when the examiner says "Stop" and not to tap when the examiner says "Go" (Malloy and Richardson, 1994).

53. 4. The Stroop Test ( Stroop , 1935). This is a neuropsychological test which examines the ability of the patient to inhibit responses . Patients are asked to state the color in which words are printed rather than the words themselves. Failure of response inhibition is seen in - Head injury, other destructive lesions (including dementing processes) and schizophrenia. Impulse control and personality disorder (particularly of the antisocial type) Depressive disorder may manifest irritability, and has been associated with poor performance on the Stroop Test ( Trichard et al, 1995). Obsessive compulsive disorder in which there is excessive concern and caution is associated with increased metabolism in the orbitofrontal cortex (which may result from subcortical pathology; Hampson et al, 2012).

54. Changes in smell with aging - UPSIT

55. Disinhibition and intrusion in drawing

56. Prefrontal region and its importance Dorsolateral + Basomedial area = Prefrontal region Damage to prefrontal region can impair Intelluctual functions (Sequencing, Processing, attention, concentration and execution) as well as cause Personality changes ( Pseudosychopathic or Pseudodepressive ) Connections with thalamus Magnocellular region (medial part of dorsomedial nucleus of thalamus ) to Basomedial /OF region (damage can cause Pseudopsychopathic syndrome ) Parvicellular region (lateral part of dorsomedial nucleus of thalamus) to Dorsolateral region of PFC (damage can cause Pseudodepressive syndrome )

57. Pseudopsychopathic personality – (CDEFGH) Childish excitement ( Moria ) Disinhibition and promiscuity Euphoria Familiarity Garrulousness (excessive talk) Humorous punning ( Witzelsucht ) Pseudodepressive personlaity – (RAPID) Retardation (Psychomotor) Apathy Placidity Indifference (lack of concern) Diminished drive (lack initiative)

58. VI. SMA/ Cingulate area SMA – medial aspect of BA 6 and and Ant. Cingulate gyrus is BA 24 , 32 These areas are involved in drive and motivated behavior (Mega and Cummings, 1994), initiation and goal-directed behavior ( Devinsky et al, 1995) Connections with older cortical and deep limbic structures Environmental exploration Complex attention

59. Cingulate /SMA dysfunction Akinetic mutism occurs with gross lesions (e.g., meningioma ) of the anterior cingulate . Such patients are profoundly apathetic, generally mute and eat and drink only when assisted. They do not respond to pain and are indifferent to their circumstances. Lesions of the supplementary motor area are associated with the alien hand syndrome (Goldberg & Bloom, 1990). The apathy of schizophrenia and the immobility of depressive disorder may be associated with defects in associated circuits. At present there are no office or neuropsychological tests to measure the functional status of these areas.

60. NEUROLOGICAL DISORDERS AFFECTING FRONTAL LOBE Neoplasms (90% brain tumor patients with psychiatric problems have frontal lobe involvement) Cerebrovascular diseases Multiple sclerosis Trauma Degenerative diseases – Alzheimer’s, FTD

61. FRONTAL LOBE SYNDROME Dysexecutive syndrome consists of a number of symptoms which tend to occur together (hence it being described as a syndrome). Broadly speaking, these symptoms fall into three main categories; cognitive, emotional and behavioural . Cognitive - Short  attention span , Poor  working memory , Poor  short term memory , Difficulty in  planning  and  reasoning , Environmental dependence syndrome Emotional - Difficulty in inhibiting emotions, anger, excitement, sadness etc., Depression , Occasionally, difficulty in understanding others' points of view, leading to anger and frustration. Behavioural - Utilization behaviour , Perseveration   behaviour Inappropriate  aggression , Inappropriate  sexual behaviour , Inappropriate humour and telling of pointless and boring stories ( Witzelsucht )

62. THANK YOU