Director Director FunctionFunction

Stretch Reflex

Withdrawal and Crossed Extensor Reflex

Locomotion

Autonomic Regulation of Cardiovascular Function

Emotional Circuit

Evolution of Brain

Anatomical organization of Cerebrum

Grey Matters

The Association Cortices

Cortical Architecture

Intracortical circuits

Cortical Lamination

Brodmann's cytoarchitectonic mapping of the human brain

Broadman's # NAME FUNCTION

17 Occipital Lobe Visual Projection Cortex

18 Visual Association Cortex

19 Posterior Parietal Lobe Visual Association Cortex

37 Tempero-parietal-occipital area General Sensory Association Cortex

39 Angular Gyrus Word Recognition

40 Supramarginal Lobe Somatosensory Association Cortex

1,2,3 Postcentral Gyrus Somatosensory Projection Cortex

5, 7 Superior Parietal Lobule General Sensory Association Cortex

41, 42 Middle 1/3 of Superior Temporal Cortex Auditory Projection Cortex

22 Superior Temporal Gyrus Auditory Association Cortex

21, 20, 38 Inferior Temporal Cortex General Sensory Association Cortex

4 Precentral Gyrus Primary Motor Cortex

1,2,3 Postcentral Gyrus Somatosensory Projection Cortex

6,8,9 Premotor Cortex Motor Association Cortex

41, 42 Middle 1/3 of Superior Temporal Cortex Auditory Projection Cortex

44,45,46 Broca's Area Motor Association Cortex - Specific to speech

10 Preftontal Cortex General Motor Association Cortex

11 Orbital Gyri General Motor Association Cortex

Input-output relationships of cortex.

Cerebral Cortex and Thalamus

Noradrenergic neurons in the pons

Important for focused attention

Dopaminergic neurons in the brain stem and hypothalamus

Dopamine in the caudate nucleus facilitates posture, whereas dopamine in the nucleus accumbens is associated with an animal's speed (and pleasure).

Serotonergic Cell Groups

Serotonin seems to have distinctive actions contributing to anxiety and impulsive behavior.

Patients with evidence of low serotonin levels have attempted suicide by very dramatic means, such as cutting the throat

Cholinergic Cell Groups (wake sleep cycle)

Sensory Pathway

Visual Pathway

Auditory Pathway

Taste Pathway

Corticospinal tract

Cerebral Cortex: Functional Organization

Association cortices

Pathways to the somatosensory, visual, and auditory association areas

Unimodal sensory inputs converge on multimodal association areas

The Sequence of Information Processing Is Reversed in the Motor System

Sensory Motor Association Cortex

Frontal Lobe is an “Essence of Human being”

Gives our capacity to feel empathy, sympathy, understand humor and when others are being ironic, sarcastic or even deceptive.

Evolution of Human Frontal Lobe

The high, straight forehead that characterizes modern humans, superceding the prominent brow ridges of our ancestors, is due to the expansion of the cortex, and especially the prefrontal cortex, in our species.

1. Australopithecus robustus 2. Homo habilis 3. Homo erectus4. Homo sapiens neanderthalensis 5. Homo sapiens sapiens

Phinease Gage (1848)

On 13th Sept 1848 a railroad

worker hard working,

diligent, reliable, responsible,

intelligent, good humored,

polite god fearing, family

oriented foreman

Following an explosion iron bar

drove into frontal lobe

1. He becomes unreliable and fails to come to work and when present he is "lazy."

2. He has no interest in going to church, constantly drinks alcohol, gambles, and "whores about."

3. He is accused of sexually molesting young children.

4. He ignores his wife and children and fails to meet his financial and family obligations.

5. He has lost his sense of humour. 6. He curses constantly and does so

in inappropriate circumstances. 7. Died of status epilepticus in 1861

Frontal Lobe ablation in Monkey and Dogs (Bianchi)

"The frontal lobes are the seat of coordination and fusion of the incoming and outgoing products of the several sensory and motor areas of the cortex" (Bianchi, 1895)

• Loss of "perceptive power", leading to defective attention and object recognition.

• Reduction in memory. • Reduction in "associative power", leading to lack of coordination of the

individual steps leading towards a given goal, and thus to severe difficulty solving anything but the most simple problem.

• Altered emotional attachments, leading to serious changes in "sociality" [one of the main aspects of Phineas Gage's post-traumatic behaviour].

• Disruption of focal consciousness and purposive behaviour, leading to apathy and/or distractibility [one of the main aspects of Becky's post-operative behaviour].

Bianchi 1922

History

Dandy’s (1936)– following bilateral frontal

lobotomy during removal of meningioma

Feuchtwanger (1923)200 case of frontal lobe injury

– Lack of initiative

– Vacillation

– Euphoria

– Inattentiveness

– Normal intellect and memory

Jacobson (1935)– Premotor lobotomy in

primates ->

– Social indifference

– Tameness

– Placidity

– Forgetfulness

– Difficulty in problem solving

Egas Moniz 1935– Prefrontal lobotomies in

psychotics

Inferiomesial Frontal leukotomyEgas Moniz 1935

Hours– Drowsy– Apathetic– Incontinent– Akinetic– Mute

Days– Decreased initiative– Lack of concern– Freedom from anxiety– Apathetic

Weeks to months– Regained memory and

intellect– With personality changes– Indifferent to the others

problem– No thought to their conduct– Tactless– Distractible– Socially inept– Euphoria and emotional

outburst

Frontal lobe and Psychiatry

Schizophrenia : – Involving dorsolateral

prefrontal cortex– affective changes, impaired

motivation, poor insight. and other "defect symptoms

– Evidence : Neuropathologic studies, (23) in EEG studies, (24) in radiological studies using CT measures, (25) with MRI, (26) and in cerebral blood flow (CBF) studies.

Personality disorder: Antisocial

Personality disorder with impulsivity of

frontal lobe

Attention deficit syndrome with

distractibility of frontal lobe

Attention skills

Selective attention: the ability to efficiently 'filter' information; to detect

information that is relevant and ignore irrelevant or distracting

information.

Sustained attention: the ability to actively attend to a task, goal, or own

behavior despite there being little stimulation for such continued

processing.

Divided attention: the ability to monitor or attend to two things at once.

Shifting attention: the ability to shift attention between two or more

tasks.

Thinking skills

Organization: the ability to arrange or place things in a meaningful system.

Planning: the ability to create a 'blueprint' or strategy for reaching goals or completing a task.

Time management: the ability to effectively estimate how much time one has, how to spend that time, and how to stay within time limits and meet deadlines.

Working memory: the ability to hold information in immediate awareness while performing a mental operation on that information.

Metacognition: the ability to think about one's own thoughts, behaviors, and feelings in a given situation. It involves being able to self-monitor or evaluate one's skills.

Monitoring skills

Response inhibition: the ability to think before acting. Doing so, gives one the time to evaluate a situation and determine how one's behavior might affect it.

Self-regulation of affect: the ability to manage emotions in order to achieve goals, complete tasks, or control and direct behavior.

Task initiation: the ability to start a task without procrastinating.

Flexibility: the ability to revise plans or directed behavior when there are obstacles, setbacks, new information, or mistakes; adapting to environmental changes.

Goal-directed persistence: the ability to self-motivate and see things

through to completion or reaching of a goal.

~ 1/3 of cortical surfaceMost recently evolvedWell developed only in primates

– the advent of the human species: "age of the frontal lobe"

develops late in ontogeny– differentiation through age 1 – maturation through age 6

Prefrontal cortex

Input from association cortex(occipital, parietal, temporal & olfactory areas)

convergence of higher-order input from all modalities.

Reciprocal connections:prefrontal processing modulates perceptual processing.

LIMBIC connections(memory/emotion)

Input to premotor areas -controls/programs behavior.

Connectivity of Prefrontal regions

Premotor & Motor Areas

Premotor areas (6) - input from prefrontal regions and parietal association areas (5,7).

Area 4: primary motor cortex

– input from premotor area (6) and area 44

– sends output to spinal cord, and other motor structures (basal ganglia)

Frontal network controls voluntary, planned actions.

“Planning Neurons” in the Monkey Frontal Cortex

Neuron Firing in the Principal Sulcus track the working Memory

Working Memory

Imaging of Working Memory

Interaction Among Association Areas

Beyond Motor Planning

Frontal lobe has evolved from being the main motor planner/organizer

to a higher level behavioral/strategic planner/organizer.

Mental model, considering options, selecting behaviors based on

context, feedback, stored knowledge

Making predictions about what will work.

Impaired divergent thinking

Decreased consideration of alternative strategies/ behaviors; reduced

flexibility

Decreased spontaneity, initiative, may appear lazy, unmotivated

Knowledge/intelligence may seem intact (e.g. IQ) but its not used to

generate strategies or solve problems efficiently

Decreased Inhibition

Problems inhibiting incorrect/ineffective responses & switching to a

new strategy

Perseverates; not responsive to feedback or changes in environment

Violates rules, expectancies; takes risks

Not adaptable

Decreased social inhibitons as well

Impaired association learning

Reduced response to consequences

Impaired on delayed response tasks

Impaired responsiveness to social & contextual cues

Impaired temporal learning

Impaired memory for order

Could affect problem-solving, planning and impair systematic,

organized behaviours

Personality and emotional changes

Apathetic, indifferent, loss of initiative, lack of emotion or somewhat

depressed, little verbal output. Most common after left frontal damage;

called "pseudodepression"

Lack of tact & restraint, immature, coarse,lack of social graces,

inappropriate sexual behavior, increased motor activity. More

common after right frontal damage; called "pseudopsychopathic"

Memory defect

Part of more general disturbance in thinking

Can recall the details of problem, error in trying to solve

Could not put them to use in the correction of further performance.

Cannot categorizes series of item in group for recall

Frontal lobe and arousal

Right frontal lobe exerts bilateral influences on arousal

The right frontal lobe is also larger than the left suggesting a greater

degree of interconnections with other brain tissue, and it appears to

exert bilateral inhibitory influences on attention and arousal

However, because the right frontal lobe appears to exert bilateral

inhibitory influences, whereas the influences of the left are unilateral

and excitatory, when the left frontal region is damaged, the right may

act unopposed and there may be excessive left cerebral inhibition or

reduced activity

Personality and behavior

Lack of initiative and spontaneity

Placidity: worry, anxiety, self concern, hypochondriasis, and pain reduces

Psychomotor retardation: number of movements, spoken words and thought per unit of time diminish. Mild form abulia and severe akinetic mutism.

Organic driveness: brief but intense meaningless activity.

Loss of ego strength: Witzelsucht or moria : socially uninhibited and lack aunawerness of their abnormal behavior.

Loss of regards to social conventions , only interested in personal gratification.

Disinhibited sexuality

It is not unusual for a hypersexual, disinhibited frontal lobe injured

individual to employ force.

Seizure activity arising from the deep frontal regions have also been

associated with increased sexual behaviour, including sexual

automatisms, exhibitionism, genital manipulation, and masturbation

Summary Frontal lobe function

Motor Cognitive Behavior Arousal

Voluntary movements

Memory Personality

Language Expression

Problem solving Social and sexual

Eye movements Judgment Impulse control

Initiation

Spontaneity

Abstract thinking

Mood and affect

Attention