Telencephalon and Limbic System

3 main tracks traveling into/out of cerebral cortex

3 main types of axons traveling in/out cerebral cortex: 1. Association bundles: one gyrus to neighboring gyrus 2. Commissural Bundle: commissures - crossing from one brain hemisphere to the opposite side. 3. Projection Fibers (axons): axons projecting/traveling a long way. - ex. corticospinal tracts (motor cortex to spinal cord)

Telencephalon Functionality

4 General Functions of Telencephalon 1. Sensory 2. Motor 3. Unimodal Association Cortex: higher level processing relevant to that specific sensory modality. - ex. feeling paper clip vs. quarter - ex. telling faces apart 4. Multimotor association cortex: receives from several different sensory modalities to create a complete experience to the surroundings - Allows communication through language - reason/predict future events based on present experiences - Make complex/long range plans - Imagine + create things that never existed.

Agnosia

Agnosia: usually involves 1 single sensory modality - I.e: visual agnosia (cannot recognize faces) Lesion in sensory association cortex Appreciation of Space (Cortical Deficits)

Alzheimer's Disease

Alzheimer's Disease: excessive neuronal cell death not attributed to normal aging and thus causing severe cognitive dysfunction and death. Neurofibrillary Tangles + Neuritic Plaques: destroy the function of neuron. Hippocampus + Nucleus Basalis of Meynert: first areas to show evidence of Alzheimer's disease

Amygdala

Amygdala: fear center Located deep within the uncus of the parahippocampal gyrus

Anterior Paracentral Lobule

Anterior Paracentral Lobule: UMN that innervate contralateral knee, leg + foot.

Appreciation of Space

Appreciation of Space: Located in Parietal Association Cortex in non-dominant hemisphere. Right sided parietal association cortical lesion: 1. Contralateral Neglect: Deficit in attention, unaware of objects in left half of surrounding space - ie forget to do makeup on left side, put on left shoe 2. Construction Apraxia: inability to manipulate objects in space 3. Disorders of Affect: can't appreciate humor, prosody of speech

Apraxia

Apraxia: disorder of motor control Lesion to parietal association cortex, premotor cortex, supplementary motor cortex - there is no paralysis or decrease in muscle strength, but pt cannot perform motor activities (ie. skipping) Appreciation of Space (Cortical Deficits)

Brodmann's Map of Cortical Functional Areas

Area 4: Primary motor cortex - precentral gyrus Area 6: Premotor, supplemental motor cortices Area 3,2,1: Primary somatosensory cortex - postcentral gryus Area 17: Primary Visual Cortex - occipital lobe Area 22, 39 + 40: Wernicke's Area - Speech center Areas 41 + 42: Primary Auditory Cortex - transverse temporal gyri

Brain Lobes

Cerebral Brain Lobes 1. Frontal 2. Parietal 3. Temporal 4. Occipital 5. Insular 6. Limbic

Deep Groups of Telencephalic Nuclei

Deep Groups of Telencephalic Nuclei 1. Basal Nuclei: support motor systems 2. Nucleus Accumbens 3. Nucleus Basalis of Meynert 4. Hippocampus 5. Amygdala

What causes Global Aphasia

Global Aphasia: Total loss of language Middle Cerebral Artery Stroke: Knocks out everything seen in left brain (broca's + wernicke's)

Hippocampus

Hippocampus: to consolidate long term memories from immediate and short term memories In Parahippocampal Gyrus: older and newer part located in temporal lobe

Kluver-Bucy Syndrome

Kluver-Bucy Syndrome: Lesion in temporal lobe mainly affecting the amygdala - Amygdala Lesion Signs/Symptoms: 1. Visual Agnosia: can't recognize what you're seeing. 2. Hyperorality: 3. Hypermetamorphisis: easily distracted 4. Hyperphagia: eating things normally not in diet 5. Placidly - not fear or anger 6. Hypersexuality

Korsakoff Syndrome

Korsakoff Syndrome: caused by thiamine deficiency + seen in chronic alcoholics. Neuronal degeneration is seen in mammillary bodies, fornix, hippocampus + dorsomedial nucleus of thalamus. Signs/Symptoms: Dementia, Confabulation, Memory loss, Confusion, Cerebellar damage (ataxia) Wernicke-Korsakoff Syndrom: signs/symptoms listed above plus Wernicke's aphasia (receptive, fluent aphasia)

Language

Language - function of multimodal association cortex Located in Left Brain Hemisphere: 1. Wernicke's Area (parietal + temporal): language comprehension Lesion: Receptive, fluent aphasia - Aphasia: unable to understand what is being said - Alexia: unable to read - Agraphia: unable to write - Display fluent, clear non-sensical speech (Word Salad) 2. Broca's Motor Speech Area (inferior frontal gyri): Speech - turning thought/concept into sound Lesion: Expression or non-fluent aphasia - Short, habitual phrases - Slow, labored speech - Poor enunciation Patients do understand spoken/written langauge, so can get depressed, frustrated by deficit Conduction Aphasia: Lesion in connection from Wernicke's to Broca's Lesion - Normal comprehension, fluent expression, but has problems translating what was said to them into a normal reply.

Hippocampal Lesions

Lesion to Hippocampus: Impairs ability to form long term memories Less severe lesions: impairment to learn new things easily, or may forget to return to a previously started task if interrupted.

Limbic Lobe -

Limbic Lobe: Makes a ring around the medial rim of the hemisphere 1. Subcallosal Area 2. Cingulate Gyrus 3. Parahippocampal Gyrus 4. Uncus

Limbic System Overview

Limbic System: involves structures not only in the limbic lobe, but also from telencephalon, diencephalon + brainstem Participates in complex + interrelated behaviors such as learning and memory and social interactions - instinctual brain - very old part of brain

Cerebral Hemispheres

Longitudinal Fissure: Divides Cerebrum into right and left cerebral hemisphere

Limbic Lobe

Lumbus: ring, border, edge. Limbic Lobe: Learning, memory, moods, behaviors - Structure in this lobe make a ring around the medial rim of each hemisphere 1. Subcallosal Area (yellow) 2. Cingulate Gyrus (blue) 3. Parahippocampal Gyrus (green) 4. Uncus (pink)

3 Main cortical functions that require use of multimodal association cortex (to test it can assess these):

Multimotor association cortex: receives from several different sensory modalities to create a complete experience to the surroundings 3 Main cortical functions that require use of multimodal association cortex (to test it can assess these): 1. Language 2. Appreciation of Space 3. Planning a Behavior

Cytoarchiteture of Cerebral Cortex

Neocortex contains 6 unique cell layers Layer 4: receives sensory information Layer 5: pyramidal cell bodies (motor neurons) which project to brainstem + spinal cord. Thickness matters: - All same thickness: does a lot of integration - Layer 4 thicker: More sensory info (ex. visual cortex) - Layer 5 thicker: More motor (ex. precentral gyrus)

Nucleus Accumbens

Nucleus Accumbens: "Pleasure Center" and plays a role in addictive behaviors

Nucleus Basalis of Meynert

Nucleus Basalis of Meynert: sustains significant neuronal cell death in Alzheimer's disease. Located inferior to anterior commissure

Papez Circuit

Papez Circuit: Important role in learning + memory and expression of emotion. - originates + terminates in the hippocampus 1. Hippocampal Cell bodies project axons (fornix - over thalamus and down) to 2. Mammillary body projects up via mammillothalamic tracts to 3. Anterior thalamic nucleus (thalamus) project up through Anterior limb of the internal capsule to 4. Cingulate gyrus that projects back down and around to synapse on hippocampus

Planning a Behavior - function of multimodal association cortex

Planning of behavior occurs in the prefrontal association cortex Prefrontal association Cortex Coordinates: Judgement, foresight, sense of purpose, sense of responsibility, sense of social propriety Lesions to prefrontal association cortex will cause: - Highly distractible - Lack of foresight - Unusually stubborn term-33 - Lack of ambition - Loss of sense of responsibility

Postcentral Gyrus

Postcentral Gryus: contralateral somatosensory neurons from face to hip Parietal Lobe

Posterior Paracentral Lobule

Posterior Paracentral Lobule: contralateral somatosensory neurons representing knee leg and foot

Pre-central Gyrus

Pre-central Gyrus: Contralateral Upper motor neurons from face to the hip Frontal Lobe

Primary Visual Cortex

Primary Visual Cortex: Lower part of Cuneus gyrus and upper part of Lingual gyrus Lesion: Contralateral homonymous hemianopsia (blindness in right or left of both eyes contralateral to injury) - if lesion is vascular in nature, there will be macular sparing as well Occipital Lobe - Area 17

Septal Nuclei

Septal Nuclei: Project emotional olfactory information to the Habenular Nuclei of diencephalon Lesion: Rage behavior

Telencephalon Overview

Telencephalon: 85% of the brain's weight All modalities (somatosensory, motor, visual) represented here Contains regions with specific functions that connect to association cortices to interrelate information Damage can cause complex neurological deficits

Insular Lobe

The lobe tucked away in the lateral sulcus.

Transverse Temporal Gyri

Transverse Temporal Gyri / Heschl's Gyrus / Primary Auditory Area: Final destination for auditory pathway. Lesion: cause difficulty interpreting sound but not deafness Temporal Lobe

Gray vs. White matter in cerebrum

Yellow: Cerebral Cortex - Gray Matter (cell bodies) Pink: Subcortical white matter (axonal connections) Green: Deep groups of cell bodies (Nuclei) - gray matter