introduction to neuroanatomy russell m. bauer, ph.d
TRANSCRIPT
Introduction to Neuroanatomy
Russell M. Bauer, Ph.D.January 9, 2006
Caveats
• What you need to know about anatomy– Changes with each individual case– Involves both local and global knowledge– Depends on your practice and referral
question
• What I can give you in 90 minutes– Conceptual understanding of organization– Tools to think about deeper levels of analysis– Ways of decomposing deficits
Key Concepts
• Functional Systems: patterns of connectivity
• Localized damage has systemic effects
• Segregated patterns of inputs and outputs
• Excitatory and inhibitory control• Parallel vs. serial processing
Cerebral Cortex
Horizontal (Axial)
SagittalCoronal
Directions Directions andand
Planes of Planes of SectionSection
Blumenfeld, 2002
• The layer of gray matter covering
the entire surface of cerebral hemisphere
• Migration of neurons from inner mantle layer of• neural tube
• Accommodates enormous number of neurons
- Large surface area accommodates
more neurons than deep nuclei
- Gyri and sulci also increase surface area
- Laminar organization also accommodates
enormous number of neurons
Cerebral CortexCerebral CortexCerebral CortexCerebral Cortex
Won Taek Lee, M.D., Ph.D.
Numerical DataNumerical Data
Total surface areaTotal surface area: : 2200 cm2200 cm22 (2.5 ft (2.5 ft22))
about 1/3 ------ surface areaabout 1/3 ------ surface area about 2/3 ------ hidden in the sulciabout 2/3 ------ hidden in the sulci
ThicknessThickness: : 1.5 mm (V I) - 4.5 mm (M I)1.5 mm (V I) - 4.5 mm (M I)
Generally, thickest over the crest of the Generally, thickest over the crest of the convolution and, thinnest in the depth of sulciconvolution and, thinnest in the depth of sulci
WeightWeight: : 600 gm (40 % of total brain weight)600 gm (40 % of total brain weight)
180 gm --------- neurons180 gm --------- neurons 420 gm --------- glial cells420 gm --------- glial cells
CerebralCerebral CortexCortexCerebralCerebral CortexCortex
Won Taek Lee, M.D., Ph.D.
Numerical DataNumerical Data
Number of neuronal cells in cerebral cortexNumber of neuronal cells in cerebral cortex
neurons ----------- neurons ----------- 10-15 billion10-15 billion
glial cells ----------glial cells ---------- 50 billion50 billion
Estimation of number of cortical neuronsEstimation of number of cortical neurons
von Economo and Koskinas (1925) von Economo and Koskinas (1925) 14.0 billion 14.0 billion
Shariff (1953)Shariff (1953) 6.9 billion 6.9 billion
Sholl (1956)Sholl (1956) 5.0 billion 5.0 billion
Pakkenberg (1966)Pakkenberg (1966) 2.6 billion 2.6 billion
CerebralCerebral CortexCortex
Won Taek Lee, M.D., Ph.D.
Subdivision of Cerebral CortexSubdivision of Cerebral Cortex
AllocortexAllocortex
Archicortex (hippocampal formation)Archicortex (hippocampal formation)
Palaeocortex (Paleopallium)Palaeocortex (Paleopallium)
IsocortexIsocortex
Neocortex (Neopallium)Neocortex (Neopallium)
Won Taek Lee, M.D., Ph.D.
Isocortex – typical 6 layered cortex
I. I. Molecular LayerMolecular Layer
II. II. External Granular LayerExternal Granular Layer
III.III. External Pyramidal LayerExternal Pyramidal Layer
IV.IV. Internal Granular LayerInternal Granular Layer
V. V. Internal Pyramidal LayerInternal Pyramidal Layer
VI. Polymorphic LayerVI. Polymorphic Layer
Won Taek Lee, M.D., Ph.D.
1. Pyramidal Cell1. Pyramidal Cell
2. Fusiform Cell 2. Fusiform Cell
3. Granular (Stellate) Cell3. Granular (Stellate) Cell
44. . basket cellbasket cell
5. double bouquet cell 5. double bouquet cell
6. chandlier cell 6. chandlier cell
7. neurogliform cell7. neurogliform cell
8. Horizontal Cell of Cajal8. Horizontal Cell of Cajal
9. Cells of Martinotti9. Cells of Martinotti
a: axona: axon
CerebralCerebral CortexCortex
Won Taek Lee, M.D., Ph.D.
Blumenfeld, 2002
Blumenfeld, 2002
A. A. pyramidal neuronpyramidal neuron
B. excitatoryB. excitatorygranular cellgranular cell
C.C. inhibitoryinhibitorygranular cellgranular cell
1. 1. afferentafferent fiber fiber
2.2. efferent fiberefferent fiber
3.3. corticothalamic fibercorticothalamic fiber
Columnar Cortical Unit and Cortical CircuitryColumnar Cortical Unit and Cortical CircuitryColumnar Cortical Unit and Cortical CircuitryColumnar Cortical Unit and Cortical Circuitry
Won Taek Lee, M.D., Ph.D.
Brodmann’s cytoarchitectorial map (Lateral Brodmann’s cytoarchitectorial map (Lateral
surface)surface)
Brodmann’s cytoarchitectorial map (Medial Brodmann’s cytoarchitectorial map (Medial surface)surface)
Blumenfeld, 2002
Order of Cortical MaturationOrder of Cortical Maturation
11
2233
33
33
22
11
11
S I (3, 1, 2 ; postcentral gyrus)
afferents: ventrobasal complex (VPLc, VPM)
discrimination of position and intensity of sensation
S II (superior bank of lateral fissure)
Somesthetic Association Cortex (5, 7; parietal
lobe, precuneus)
afferents: S I, LP of thalamus
integration of general sensation with past experience
tactile agnosia, astereognosis
Somesthetic AreaSomesthetic AreaSomesthetic AreaSomesthetic Area
Sensory HomunculusSensory HomunculusSensory HomunculusSensory Homunculus
ThalmocorticalThalmocortical
connectionconnection
(VPLc (VPLc S I)S I)
Central region
--- cutaneous (3b, 1)
Peripheral region
--- deep (3a, 2)
PrimaryPrimarySomestheticSomesthetic
AreaArea
PrimaryPrimarySomestheticSomesthetic
AreaArea
Secondary
Somesthetic
Area (SII)
superior bank of
lateral fissure
Kaas JH & Catania, KC (2002). How do features of sensory representations develop? Bioessays, 24, 334-343.
primary Motor Area (M I)
Premotor Area (PM)
Supplementary Motor Area (SMA)
Frontal Eye Field
Motor AreasMotor AreasMotor AreasMotor Areas
Motor HomunculusMotor HomunculusMotor HomunculusMotor Homunculus
Language Areas: 22, 39, 40, 44, 45Language Areas: 22, 39, 40, 44, 45
Posterior Parietal Association Area: Posterior Parietal Association Area: 5, 75, 7 (39, 40)(39, 40)body imagebody image
Temporal Association Area: Temporal Association Area: 20, 21, 37, 20, 21, 37, 38 38 (22)(22)
multisensory integration, conceptualmultisensory integration, conceptual
ideationideation
Prefrontal Association Area:Prefrontal Association Area: 9, 10, 11, 12, 46, 9, 10, 11, 12, 46,
47 (44,45) executive skills, judgment,47 (44,45) executive skills, judgment,
planning, emotion-regulationplanning, emotion-regulation
Association AreasAssociation Areas
Unimodal and Polymodal AssociationUnimodal and Polymodal AssociationUnimodal and Polymodal AssociationUnimodal and Polymodal Association
Neuropsychological Manifestations of Temporal Lobe Lesions
Lateral (20,21,38,37)
A) Posterior: visual recognition disturb-ances (severity depends on whether unilateral or bilateral
B) Anterior: anomia for objects (left), anomia for facial expressions (right), full-blown anomia, retrograde memory disturbance (bilateral)
Mesial (27,28 and limbic structures)
Anterograde amnesia for verbal (left) or nonverbal (right) material; bilateral lesions produce severe material non-specific defect
Tranel, 1992
Neuropsychological Manifestations of Occipital Lobe Lesions
Dorsal(17,18,19,39,7)
Partial or mild Balint’s syndrome (unilateral), severe Balint’s syndrome (bilateral), defective motion perception, astereopsis, severe visuospatial disturbance, simultanagnosia
Ventral (17,18,19)
Hemiachromatopsia (unilateral), pure alexia (left), apperceptive visual agnosia (unilateral, R>L), defective imagery
Bilateral lesions produce severe agnosia, prosopagnosia
Bilateral lesions of Area 17 produce cortical blindness (may be transient or evolving)
Tranel, 1992
Neuropsychological Manifestations of Parietal Lobe Lesions
Temporoparietal Junction (including posterior superior temporal gyrus, 22, inferior 39,40)
A) Left: Wernicke’s aphasia
B) Right: Amusia, defective music recognition, ‘phonagnosia’
C) Bilateral: auditory agnosia
Inferior Parietal Lobule (39,40)
A) Left: Conduction aphasia, tactile agnosia
B) Right: neglect, anosognosia, tactile agnosia, anosodiaphoria
C) Balint’s syndromeTranel, 1992
Neuropsychological Manifestations of Frontal Lesions I
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
Tranel, 1992
Neuropsychological Manifestations of Frontal Lobe Lesions II
Inferior Mesial Region
A) Orbital Region (10, 11)
Lesions in this region produce disinhibition, altered social conduct, “acquired sociopathy”, and other disturbances due to impairment in fronto-limbic relationships
B) Basal Forebrain (posterior extension of inferomesial region, including diagonal band of Broca, nucleus accumbens, septal nuclei, substantia innominata
Lesions here produce prominent anterograde amnesia with confabulation (material specificity present, but relatively weak)
Tranel, 1992
Neuropsychological Manifestations of Frontal Lobe Lesions III
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
Tranel, 1992
Blumenfeld, 2002
Blood Supply to Cortical and Deep Structures
Blumenfeld, 2002