Frontal Lob Anatomisi İşlevleri

... konulu sunumlar: "Frontal Lob Anatomisi İşlevleri"— Sunum transkripti:

1 Frontal Lob Anatomisi İşlevleri
Prof Dr Süheyla Ünal

2 Functional Frontal Lobe Anatomy
Motor cortex Primary Premotor Supplementary Frontal eye field Broca’s speech area Prefrontal cortex Dorsolateral Medial Orbitofrontal

3 PFK, korteksin en çok bağlantıya sahip bölgesidir
PFK bölgelerinin dış uyaranların işlendiği duyu alanları ile bağlantıları vardır (işlenmiş dış uyaran bilgisi) PFK bölgelerinin emosyonel durumların gözlendiği ve düzenlendiği bölgeler ile bağlantıları vardır (içsel bilgi) PFK bölgelerinin motor işlevlerden sorumlu olan bölgeler ile bağlantıları vardır PFK konumu ve bağlantıları dış uyaranların içsel bilgiler ile entegre edilmesine olanak sağlayacak şekildedir

4 Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press
The prefrontal cortex has expanded over mammalian and primate evolution. A greatly enlarged prefrontal cortex is a distinctively human and primate feature. According to Brodmann (1909), the prefrontal cortex accounts for 29% of total cortex in humans, 17% in the chimp, 11.5% in the macaque, and 3.5% in the cat. While whales and dolphins have large brains, it is the parietal rather than frontal cortex that has expanded in these mammals. Cognition, Brain and Consciousness: An Introduction to Cognitive Neuroscience Edited by Bernard J. Baars and Nicole M. Gage 2007 Academic Press

5 Prefrontal cortex can be divided into lateral (side), medial (midline), ventral (bottom), and dorsal (top) regions. The lateral division divides into dorsal and ventral halves separated by a major horizontal fold, the inferior lateral sulcus

6 Dorsolateral Input mainly from medial, dorsolateral cortical areas. (somatosensory, visuospatial information) Lateral Inputs mainly from ventrolateral and ventromedial cortical areas (auditory, visual pattern information)

7 The dorsomedial thalamic nucleus is a point of convergence, the ‘summit’ of the integration occurring within the specific thalamic nuclei.

8 The Frontal Cortex Confers emotional meaning (semantic content) onto objects in the world Emotional salience (attachment) Seat of the Self and Personality Love, Morality, Decency, Responsibility, Spirituality Conscious “choice”

9 Prefrontal cortex Effortful Control: Involves explicit processing
Delay of gratification Inhibition of dominant responses (overlearned or innate); e.g., turning your head away from a light stimulus (anti-saccade); not peeking at a present for a child Pay close attention to detail (= focused attention) Persevere in unpleasant tasks

10 ventro-medial Prefrontal Cortex
Damasio A, Bechara A: research on patients with vmPFC lesions “Myopia for the future,” cognitive impulsiveness - prefer immediate but disadvantageous rewards over rewards that are delayed but advantageous in the long run - guided primarily by immediate prospects and insensitive to pos or neg future consequences - deny or are unaware of the problem (analogous to “denial”) vmPFC patients are similar to Substance Abusing pts

11 Working memory is The ability to keep information in your mind for a short period of time (seconds) and be able to use this information in your thinking.

12 Working memory is closely linked to the critical role the frontal lobes play in the temporal organization of behavior and controlling the proper sequence in which various mental operations are enacted. Since the selection of information required to solve the problem at hand is made in the frontal lobes, they must ‘know’, at least roughly, where in the brain the information is stored.

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14 Executive system An organism’s ability to guide its behavior by internal representations -- the formulation of plans and then guiding behavior according to those plans 2. An organism’s ability not only to guide its behavior by internal representations, but also the capacity of ‘switching gears’ when something unexpected happens

15 DLPFC

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17 Poor organizational strategies
Poor memory search strategies Stimulus-bound behavior/environmental dependency Impaired set shifting and maintenance

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20 Frontal Lob Anatomisi Motor Korteks Primer Premotor Suplementer
Frontal göz alanı Broca konuşma merkezi

21 Motor korteks Primary motor area Premotor area Supplementary
B4 B6 Central sulcus Supplementary motor area (medially) Frontal eye field B 8 Lateral sulcus/ Sylvian fissure Motor speech area of Broca B 44, 45

22 Prefrontal Korteks Bütün kaynaklardan (duyusal sistemler, limbik sistem, subkortikal yapılar) gelen bilgileri toplar, bütünleştirir, formülleştirir, uygular, denetler, değişiklikler yapar ve yargılar. Sonuçta ortaya çıkarılacak davranışa karar verir

23 Prefrontal korteks 2- Medial prefrontal korteks
1- Dorsal prefrontal korteks 2- Medial prefrontal korteks 3- Ventral orbitofrontal korteks Dış dünyayla ilgili algılar, dünya hakkındaki düşünceler, bedenin kendisindeki olaylar bu bölgelerden gelen bilgiler aracılığı ile oluşturulur

24 Ventromedial Prefrontal Cortex and Somatic Markers
Somatic marker “biasing signals” are regulated by VM premotor cortex; these signals help regulate decision-making in uncertainty

25 The somatic marker hypothesis posits that deficits in emotional signalling (somatic states) lead to poor judgment in decision-making, especially in the personal and social realms. Similar to this hypothesis is the concept of emotional intelligence, which has been defined as an array of emotional and social abilities, competencies and skills that enable individuals to cope with daily demands and be more effective in their personal and social life. Patients with lesions to the ventromedial (VM) prefrontal cortex have defective somatic markers and tend to exercise poor judgment in decision-making, which is especially manifested in the disadvantageous choices they typically make in their personal lives and in the ways in which they relate with others. Furthermore, lesions to the amygdala or insular cortices, especially on the right side, also compromise somatic state activation and decision-making. This suggests that the VM, amygdala and insular regions are part of a neural system involved in somatic state activation and decision-making.

26 the prefrontal cortex is an ability to deal with cognitive novelty.
The dark areas in this composite brain image show regions that control novel actions, but which lose activity when the identical actions becomes automatic with practice.

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28 Ayna Nöronlar Class of neurons in F5 (BA 44) and ventral premotor cortex that discharge both: when animal performs object-directed action when animal observes OD action in others Subset appear to be “communicative” motor neurons Functions Imitation Action understanding Potentially important for understanding social learning and imitation effects

29 To do that, you must have the capacity to form an internal representation of the other person’s mental life -- or as it is called in cognitive psychology, to have a theory of mind. Your actions will be chosen under the influence of your theory of the other person’s mind formulated in your own mind. This makes the executive processes required for success in an interactive environment much more complex than those required in a solitary situation.

30 The prefrontal cortex 1) orbitofrontal cortex 2) lateral prefrontal cortex 3) ventromedial (sub-genual) cortex 4) limbic system 5) anterior cingulate cortex

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33 Ingvar (1985) coined the phrase ‘memories of the future‘ referring to one of the most important functions of advanced organisms: making plans and then following the plans to guide behavior. Unlike primitive organisms, humans are active, rather than reactive, beings. We are able to form goals, our visions of the future. Then we act according to our goals. In order to guide our behavior in a sustained fashion, these mental images of the future must become the content of our memory: thus the ‘memories of the future’ are formed

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35 Orbito-frontal cortex : processing site fpr learmed associations between affective stimuli and their reinforcement value (reward/punishment), thus playing a crucial role in subsequent decision making; role is in repeated learning; impulse control and social cognitive skills including theory of mind tasks Severe lesions: oblivious to social and emotional cues, poor decision making capacity, sociopathic tendencies, loss of fear regulation: inhibition of inappropriate thoughts and actions. Anterior cingulate: experience of emotion, helps to focus attention and may be required to properly integrate emotion and cognitionto tune in on one’s own thoughts

36 Orbitofrontal cortex inhibits hypothalamus, the area responsible for basic appetitive behaviors such as feeding, fighting, fleeing, and mating.

37 The amygdala and orbitofrontal cortex influence autonomic and endocrine function via their connections with the brainstem and hypothalamus. He does not agree that “somatic states” generate emotions (i.e., James-Lange Theory or Damasio’s Somatic Marker Hypothesis) but rather thinks that these states prepare the animal for different types of action including fight, flight, feeding and sex. The amygdala and orbitofrontal cortex can influence the selection of behavioral actions through 1) brain systems that operate implicitly and have been present in primates and some other mammals for millions of years, such as the ventral striatum and other parts of the basal ganglia; and in humans 2) higher cortical systems that can process multiple “If..the” statements to implement a plan to obtain a reward or avoid punishment. Deferring action may be part of the plan.

38 Lesions to the ventral frontal lobes can result in difficulties altering behavioral strategies in response to a change in environmental reinforcement contingencies (Rolls, 2000) Damage is associated with changes in social behavior (disinhibition) and problems identifying vocal and facial emotional expression (Rolls, 2000; Phillips, 2003) Studies described later indicate that bilateral orbitofrontal lesions cause more severe problems with social and emotional functions, but that unilateral lesions cause some subtle difficulties. Problems also appear to be more severe in patients with more diffuse damage (e.g., caused by head trauma or stroke versus surgical lesions) Results of studies are inconsistent regarding whether the laterality of the lesion is important in symptom presentation (Honak et al., 2003; Tranel et al., 2002.

39 Thayer and Lane (2000) propose that the ACC serves as a point of integration for viseral, attentional and affective information that is critical for self-regulation and adaptability. The ACC seems to be associated with the conscious allocation of attention (I.e. including inhibition of irrelevant informaton). The ventral and rostral regions of the ACC are associated with affective, motivated and autonomic behavior; whereas the dorsal region is associated with response selection as well as pain

40 PFK alt alanları Dorsolateral: 9,46 Ventrolateral: 44,45,47
Orbitofrontal: 10,11 - Anterior: 8, 10 - Medial: 11, 25, 32

41 İşlevsel Frontal Lob Anatomisi
Frontal-Subkortikal Döngüler Globus Pallidus & Substantia Nigra Striatum Caudate & Putamen Thalamus DM & CM nuclei Frontal cortex

42 5 Frontal-Subkortikal Döngü
1-Motor döngü 2- Okulomotor döngü 3- Dorsolateral döngü 4- Lateral orbitofrontal döngü 5- Limbik döngü

43 1. Motor Döngü SMA, Premotor,Motor Putamen VL Globus Pallidus
Dil 1. Motor Döngü SMA, Premotor,Motor Putamen VL Globus Pallidus VL, VA, CM Thalamus Hypo-thalamus Suplementar Motor & Premotor: motor programların planlanması, başlatılması ve depolanması, hareketlerin ince ayarı Motor: hareketin plana göre yönetilmesi Konuşma

44 1. Motor Döngü

45 2. Okulomotor Döngü Frontal Eye Field Central Caudate DM Globus
Pallidus Substantia Nigra VA, MD Thalamus İstemli tarayıcı göz hareketleri Bağımsız görsel uyaranlar

46 3. Dorsolateral Prefrontal Döngü
DL Caudate DM Globus Pallidus Substantia Nigra VA, MD Thalamus Yönetsel işlevler: motor planlama, dikkati yönlendirme, bilişsel setleri değiştirme Dikkat ve işlem belleği aracılığı ile davranışı monitorize etme ve uyumlandırma

47 Dorsal prefrontal korteks
İşlem belleği ve motor planlama ile ilişkilidir.

48 dorsal system (incl. hippocampus, dorsal ACC & dorsolateral PFC)
Dorsal ACC: involved in target & motor response selection, error detection & performance monitoring, novelty detection, motivational valence assignment & reward based decision making if not working properly likely difficulty in becoming motivated or interested in new things & looking forward to rewards

49 DLPFC: things held in mind here, working memory, with volition; integrating the outcome of two or more separate cognitive operations in pursuit of a higher behavioural goal” in addition to executive function at an abstract level; Ventromedial PFC: involved in extinction of fear responses

50 4. Lateral Orbitofrontal Döngü
VM Caudate DM Globus Pallidus Substantia Nigra VA, MD Thalamus Infero-lateral prefrontal Orbito-frontal Duygusal yaşam ve kişilik yapısı Uyarılma, motivasyon, duygu, çeldirici uyaranların baskılanması Bilinçlilik, ödül sistemi Sosyal biliş

51 Frontal lobe syndromes - Orbitofrontal
The orbitofrontal syndrome is in many ways the opposite of dorsolateral syndrome: the patients are behaviorally and emotionally disinhibited. Their affect is rarely neutral, constantly oscillating between euphoria and rage, with impulse control ranging from poor to non-existent. Their ability to inhibit the urge for instant gratification is severely impaired: they do what they feel like doing, when they feel like doing it, without any concern for social taboos or legal prohibitions.

52 orbitofrontal cortex (OFC): centre for sensory integration, modulation of autonomic reactions & anticipation in learning, prediction & decision-making for emotional and reward-related behaviours reward value & expected reward value, & even subjective pleasantness of food & other reinforcers are represented in OFC

53 5. Anterior Singulat Döngü
Cingulate Gyrus Ventral Striatum RL Globus Pallidus Substantia Nigra MD Thalamus Motivasyon, eyleme yönelme, kızgınlık, irritasyon

54 PFK’nın işlevleri Farkındalık, bilinçlilik

55 Prefrontal Cortex Involved with intellect, cognition, recall, and personality Contains working memory needed for judgment, reasoning, persistence, and conscience Development depends on feedback from social environment

56 Attentional functions might may be influenced bu the frontal lobes as well as an ‘attentional loop’ combining frontal, brainstem, and posterior cortex. Breakdown anywhere along this loop may interfere with attention, thus producing a form of attention deficit disorder. Thus, any damage to the prefrontal cortex or its pathways may result in attentional impairment.

57 Working memory is closely linked to the critical role the frontal lobes play in the temporal organization of behavior and controlling the proper sequence in which various mental operations are enacted. Since the selection of information required to solve the problem at hand is made in the frontal lobes, they must ‘know’, at least roughly, where in the brain the information is stored.

58 Dikkat İşlevi Uyaranın keşfedilmesi (odaklanma)
Saptanan uyaranın kodlanması veya işlenmesi İlgili uyarana dikkat devam ederken diğer uyaranların filtre edilmesi Uygun olduğunda dikkatin kaydırılması İstemsiz kaymaların engellenmesi (distraktibilite) Giren bilgiye bir yanıt oluşturulması

59 Algı Adlandırma Anlam oluşturma

60 Bellek İşlevleri İşlem belleği Bilginin organizasyonu (sol DLPFK)
İstekler arasında seçim yapma (sol DLPFK) Kodlama Sözcük kodlama (sol posterior VLPFK) Anlamsal-algısal kodlama (sol anterior VLPFK) Yeni epizodik kodlama Epizodik anımsama (sağ APFK) Kaynak denetleme (sol APFK ve DLPFK) Bilme (sağ DLPFK) İşlem belleği Bilgi sağlama ( VLPFC) Bilginin yönetilmesi ( DLPFC)

61 Yönetsel işlevler Dorsolateral PFK (yönetsel) Caudate v Ventromedial
PFK and Singulat (değerlendirici) v Caudate Putamen

62 Difficulties with academic performance are due to weaknesses in the core executive processes:
Problems with any process will affect learning: Planning & Goal Setting Self-Monitoring & Checking Organizing Prioritizing Shifting Flexibly Memorizing From: Meltzer, 2007

63 Yönetsel işlevleri Bedenden ve dış dünyadan gelen duyuları birleştirmek Kendine yönelik konuşmanın içselleştirilmesi Motivasyon ve uyanıklık durumu Yeniden yapılandırma

64 Yönetsel İşlevleri Gelecekteki eylemin sonuçlarını öngörebilme
Uygun motor tepkiyi seçmek, karar verme Yeni sorunlara çözüm üretme Davranışı planlamak ve düzenleme Davranışların zaman içindeki ardışıklığını sağlama

65 Yönetsel işlevleri Duyguları kontrol etme Yargılama Soyutlama
Dürtüleri denetleme Kendilik kavramı, kimlik duygusu Ruhsallık (Spirituality)

66 The orbitofrontal cortex is not the only part of the frontal lobes linked to socially mature behaviors: the anterior cingulate cortex (ACC) is closely linked to the prefrontal cortex and has been linked to emotion and regulation of distress.

67 The ACC appears to be active during situations of social rejection: in a task designed to evoke the sense of social rejection (as felt by a child in a ball game), the frontal part of the cingulate ‘lights up’.

68 Frontal lob hasarları

69 Motor Korteks Primer motor korteks hasarları: Karşı taraf motor işlevleri / tonus; kuvvet Premotor korteks hasarları: Karşı taraf proksimal kaslarda orta derecede güçsüzlük Suplementer motor hasarlarda mutizm, akinezi Frontal göz alanı destrüktif hasarlarında gözler hasar tarafına, irrite edici hasarlarda göz karşı tarafa deviye olur. Broca konuşma merkezinin hasarlarında motor afazi

70 Prefrontal Attention-Perception Motility Memory
Low alertness; sensory neglect, distractibility, disorders of visual search/control, difficulty w/ sustained attention, internal interference, defective set maintenance Motility Hypokinesia, hyperkinesia (?posterior orbital?) Memory Organization, monitoring, temporal integration, ‘source memory’

71 Attentional functions might may be influenced bu the frontal lobes as well as an ‘attentional loop’ combining frontal, brainstem, and posterior cortex. Breakdown anywhere along this loop may interfere with attention, thus producing a form of attention deficit disorder. Thus, any damage to the prefrontal cortex or its pathways may result in attentional impairment.

72 orbital pathway Arousal changes: Adynamia or agitation:
Likely due to orbital frontal damage, usually extensive. ACA territory lesions and adynamia Low motivation; decreased initiative: Probable loss of reward/motivation due to decreased striatal input Reduced insight. Concept of “theory of mind” recent data on role of anterior medial frontal gyrus in TOM, may underlie deficits in insight. Control of attention and selection in anterior cingulate damage. Reduced impulse control; deficits in response inhibition in OF lesions

73 Dorsal yol Eye motor control deficits: Frontal Eye fields direct EM based on spatial information from PL Working memory impairment: Lesions in DLPFC ; also single unit studies in monkey PFC; delayed component; manipulation component; response selection component Reasoning, problem solving deficits; poor “fluid” reasoning Integration of information Perseveration: 46/44 direct stimulation produces perseveration deficits Appears separate from WM

74 Dorsolateral - Spatial delayed response - Spatial delayed alternation task - No deficit in discrimination Lateral - Object alternation - Delayed non-match to sample Orbital - Deficits in olfactory, taste, visual and auditory discrimination - Discrimination reversal learning.

75 Lateral Prefrontal Region (8,9,46)
Lesions in this region produce impairment in a variety of “executive” skills that cut across domains. Some degree of material-specificity is present, but relatively weak. A) Fluency: impaired verbal fluency (left) or design fluency (right) B) Memory impairments: defective recency judgment, metamemory defects, difficulties in memory monitoring C) Impaired abstract concept formation and hypothesis testing D) Defective planning, motor sequencing E) Defective cognitive judgement and estimation

76 Frontal Operculum (44,45,47) A) Left: Broca’s aphasia B) Right: ‘expressive’ aprosodia Superior Mesial (mesial 6, 24) A) Left: akinetic mutism B) Right: akinetic mutism Bilateral lesions of mesial SMA (6) and anterior cingulate (24) produce more severe form of akinetic mutism

77 Prefrontal alanların lezyonunda
Genel zeka, algı, uzun süreli bellek sağlam kalırken, günlük yaşamı sürdürmek için gerekli olan plan yapma ve günlük aktiviteleri düzenleme becerisi bozulur. Hareketi başlatma sorunları Zihinsel ve davranışsal değişiklikler yapabilme zorlukları Durdurma sorunları Kişisel farkındalıkta yetersizlik Somut ve açık tavır

78 Dorsolateral prefrontal hasar
Dikkatte azalma, çelinebilirlikte artma İlgi azlığı Duygusal tepkide azalma Yönetsel işlevlerde bozulma İşlem belleğinde ve anımsamada bozulma Perseverasyon

79 Most common symptoms of dorsolateral syndrome are perseverative behavior, field-dependent behavior, and mental rigidity. These patients often typically have a flat affect: an emotionless voice and facial expression. Perseverative behavior: a patient will have an inability to initiate behaviors. Once behaviors are initiated, the patient is equally unable to terminate or change the behavior.

80 Field-dependent behavior highlights the distractibility seen with frontal lobe injury. A patient will drink from an empty cup, put on a jacket belonging to someone else, or scribble with a pencil on the table surface, merely because the cup, jacket, and pencil are there, even though these actions make no sense.

81 Dorsolateral Mental rigidity is a frequent symptom of frontal lobe injury. Mental flexibility is a critical aspect of frontal lobe processing. These patients will show an inability to change their mental state or approach to a problem. The Wisconsin Card Sorting task is frequently used to asses mental rigidity in frontal lobe patients.

82 Dorsomedial prefrontal hasarlarda
Uyanıklılık ve farkındalıkta azalma, Apati, yavaşlama Motivasyon azlığı Spontan davranışta azalma Amaca yönelik davranışta azalma

83 Anterior singülat hasarı
Akinetic Mutizm Apatik Spontan konuşma yokluğu Aynı heceyi tekrarlama Duygusal tepki yokluğu

84 Orbital prefrontal korteks hasarları
Duygusal tepkide uygunsuzluk, labilite Dürtüleri inhibe edememe Davranışlarının sonuçlarını önemsememe Aşırı hareketlilik, huzursuzluk Dikkatte bozulma

85 Orbitofrontal The orbitofrontal syndrome is in many ways the opposite of dorsolateral syndrome: the patients are behaviorally and emotionally disinhibited. Their affect is rarely neutral, constantly oscillating between euphoria and rage, with impulse control ranging from poor to non-existent. Their ability to inhibit the urge for instant gratification is severely impaired: they do what they feel like doing, when they feel like doing it, without any concern for social taboos or legal prohibitions.

86 Involved in social and emotional functioning Damage produces:
Disinhibition Hyperactivity Emotional lability Aggressiveness Reduced self-awareness

87 Sahte psikopati İmmatür davranış Kaba davranış, sınırsızlık
Küfürlü konuşma Seçimsiz cinsel davranış Motor aktivitede artma Sosyal kurallara uymama