Cerebral Cortex & White Matter 國防醫學院 生命科學研究所 陳建甫 助理教授 2016 Spring 腦與行為課程

Cerebral Cortex & White matter Cerebral Cortex: the outer layer of the Cerebrum ♦ thickness from 2 to 4 mm ♦ surface area ~ 0.12 m 2 gyri Sulci Grey matter 灰質 White matter 白質

Cerebral Cortex & White matter Types of Cerebral Cortex Neocortex ( 新皮質 ) ♦ “new” cortex ♦ 6-layered cortex ♦ covering 90% of the cortex Allocortex ( 異源皮質 ) Paleocortex ♦ 3-layered cortex ♦ Olfactory system ( 嗅覺系統 ) Archicortex ♦ 3-layered cortex ♦ Hippocampus ( 海馬迴 ) ♦ Memory consolidation

Cerebral Cortex & White matter Division of Cerebral Cortex 額葉 顳葉 頂葉 枕葉 Central sulcus Lateral sulcus

Cerebral Cortex & White matter Principal neurons of Cerebral Cortex Pyramidal cell ( 錐體細胞 ) ♦ is an excitatory neuron. ♦ glutamate ( 谷胺酸 ) as the neurotransmitter (glutamatergic). ♦ has a pyramidal shape cell body or soma. ♦ has an apical dendrite and multiple basal dendrites with many dendritic spines on them. ♦ has one axon that projects locally or to long-distance targets. ♦ Betz cells are the largest pyramidal cells found in primary motor cortex. apical dendrite soma basal dendrites

Cerebral Cortex & White matter Interneurons of Cerebral Cortex Glutamate, excitatory GABA, inhibitory

Cerebral Cortex & White matter Laminar organization of Cerebral Cortex ( 視丘 ) Molecular External granular External pyramidal Internal granular Internal pyramidal Multiform Afferent = incoming Efferent = outgoing

Cerebral Cortex & White matter Cytoarchitecture-based area system

Cerebral Cortex & White matter Brodmann areas 布羅德曼分區 Korbinian Brodmann, 1909

Cerebral Cortex & White matter Ways to study Brain Functions ♦ Accidents ♦ Brain surgeries ♦ In Vivo electrical stimulation/recording ♦ EEG (Electroencephalogram) ♦ CT scan (Computerized Tomography) ♦ MRI (Magnetic Resonance Imaging) ♦ PET scan (Positron Emission Tomography) ♦ Functional MRI Invasive Non-invasive

Cerebral Cortex & White matter Phineas Gage ( ) (An accident leading to frontal lobe injury) His personality and behaviors were reported to be drastically changed from before the accident. Since then, he was unable to hold a job. He died in 1860 from status epilepticus, almost 13 years after the accident. A recent study estimates 11% white matter and 4 % cortex of his frontal lobe was damaged (Van Horn 2012). In 1848, a 25-year-old American railroad construction foreman Gage accidently had his head impaled by an iron rod while surprisingly survived this head trauma.

Cerebral Cortex & White matter Electroencephalogram (EEG) 腦電圖

Cerebral Cortex & White matter CT ( 電腦斷層掃描 ) and MRI ( 核磁共振造影 ) Tools for detecting brain morphological changes MRI CT CT MRI X-ray radio frequency radiation magnetic field low cost high cost 30s ~ 5min 10min~2 hr Bone soft tissues *FLAIR: fluid-attenuated inversion recovery *PD: proton density *GRE: gradient echo sequences

Cerebral Cortex & White matter Positron Emission Tomography (PET) 正子斷層掃描造影

Cerebral Cortex & White matter Functional MRI (fMRI) - detecting blood oxygenation-level dependent (BOLD) contrast

Cerebral Cortex & White matter Sensory areas ♦ Primary Somatosensory Cortex (S1; BA 3, 1 & 2) ♦ Primary Visual Cortex (V1; BA 17) Secondary Visual Cortex (V2; BA 18) Associative Visual Cortex (V3, V4 & V5/MT; BA 19) ♦ Primary Auditory Cortex (A1; BA 41, 42) ♦ Primary Gustatory Cortex (G1; BA 43) ♦ Primary Olfactory Cortex (BA 27)

Cerebral Cortex & White matter Primary Somatosensory Cortex (Postcentral gyrus of parietal lobe)

Cerebral Cortex & White matter Somatosensory Homunculus Penfield and Rasmussen 1950 SomatosensoryMotor

Cerebral Cortex & White matter Wilder Penfield – first to identify motor and somatosensory homunculus Wilder Penfield Penfield and Boldrey 1934

Cerebral Cortex & White matter Data from the original paper Penfield and Boldrey 1934

Cerebral Cortex & White matter Primary Visual Cortex (striate cortex of occipital lobe)

Cerebral Cortex & White matter Where and What Visual Pathways V3: colors V4: objects V5: movement ♦ Posterior Parietal Cortex (PPC; BA 5, 7)

Cerebral Cortex & White matter Primary Auditory Cortex (Temporal lobe )

Cerebral Cortex & White matter Primary Auditory Cortex

Cerebral Cortex & White matter Primary Gustatory Cortex

Cerebral Cortex & White matter Primary Olfactory Cortex Periamygdaloid, Pirifrom and Entorhinal cortex Vaughan & Jackson 2014

Cerebral Cortex & White matter Motor areas ♦ Primary Motor Cortex (M1; BA 4) ♦ Premotor Cortex (PMA; BA 6) ♦ Supplementary Motor Cortex (SMA; BA 6) ♦ Frontal Eye Fields (FEF; BA 8) ♦ Broca’s area (BA 44, 45)

Motor areas ♦ Primary Motor Cortex: movement of body parts ♦ Premotor Cortex: postural stability ♦ Supplementary Motor Cortex: motor planning Akinesia: inability to initiate movement ♦ Frontal Eye Fields (FEF; BA 8): voluntary saccades ♦ Broca’s area (BA 44, 45): speech production

Cerebral Cortex & White matter Higher Order Association areas ♦ Prefrontal cortex (PFC; BA 9, 10, 11, 12, 46, 47) ♦ Language areas Broca’s area (BA 44, 45) Wernicke’s area (BA 22) ♦ Fusiform face area (FFA; BA 37)

Cerebral Cortex & White matter Prefrontal Cortex Representing your human qualities abstract thinking, thought analysis, data analysis, regulating behavior, making choices between right and wrong, predicting possible outcome, attention, intelligence, short-term memory satisfaction, reward, food flavor.

Cerebral Cortex & White matter Language areas Aphasia ( 失語症 ) : language and speech disorder often caused by damages to language areas (generally left hemisphere) Broca’s aphasia ♦ Impaired speech fluidity ♦ Intact comprehension ♦ Expressive aphasia Wernicke’s aphasia ♦ Impaired comprehension ♦ Intact speech fluidity but incomprehensible ♦ Receptive aphasia

Cerebral Cortex & White matter Fusiform Face Area (Fusiform gyrus of temporal lobe) Prosopagnosia ( 臉盲症 ) : Face blindness, unable to recognize faces (including one’s own face), caused by damage to occipital and/or fusiform face areas. Apperceptive prosopagnosia ♦ is unable to recognize “face”. ♦ may be able to recognize a person via other cues such as voice and clothing. Associative prosopagnosia ♦ is able to recognize face but is unable to associate the face with any information.

Cerebral Cortex & White matter White matter ♦ contains myelinated axons. ♦ Association fibers connect cortical areas of the same hemisphere. ♦ Commissural fibers connect cortical areas of the opposite hemisphere and go across corpus callosum ( 胼胝體 ) and anterior commissure. ♦ Projection fibers go to subcortical areas including basal ganglia, thalamus and spinal cord.

Cerebral Cortex & White matter Myelin ♦ is lipid-based substance that provides insulation to axons of neurons and helps electrical transmission. ♦ Myelination is done by oligodendrocytes (central) and schwann cells (peripheral). ♦ Demyelination is the loss of myelin sheath of the neurons and may result from autoimmune problems.

Cerebral Cortex & White matter Questions