Functional Neuroanatomy • Neuroanatomy text and atlas. Martin JH, third edition 2003. • Neuroanatomy through clinical cases. Blumenfeld H, 2002. • Readings to be specified.

General structural features of the nervous system • • • • • •

General description of the brain and its parts Subdivisions of the nervous system Cellular elements Meninges – protective covers Ventricular system Conventions for describing relative position of brain structures

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Overview of the nervous system

Autonomic nervous system

Cellular elements: Neurons

Cellular elements: astrocytes

Cellular elements: Oligodendroglia, Schwann cells and Myelin

Microglia

Meninges of the brain

The ventricular system of the brain

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Overview of brain organization

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The brain stem

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1-8 The limbic system: amygdala and hippocampus

The basal ganglia: The striatum in relation to the lateral ventricle.

Lobes of the cerebral cortex

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Lateral view of the brain

1-9b Mid-sagittal view of the brain

1-10a Ventral view of the brain

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Dorsal view of the brain

Methods of Functional Neuroanatomy • Electrophysiology (stimulate and record) • Histology – staining of tissue elements: cell types, myelin, special proteins. • Tracing of connections between brain regions. • Neuro-imaging: Structural, Functional

Nissl stains: Detection of cell bodies of both neurons and glia

Myelin stain

Immunohistochemistry: detecting specific proteins – subsets of cells

Tracing connections in the nervous system Tracing degenerating axons

Tracing connections in the nervous system Tracing transported molecules

CT images • CT (roentgen-ray computed tomography) A beam of x-rays is shot straight through the brain. • Blunting or "attenuation" of the x-ray comes from the density of the tissue encountered along the way.

www.med.harvard.edu/AANLIB/home.html

Magnetic resonance imaging Schizophrenia: enlarged ventricles, shrunken hippocampus

Control: normal volunteer

SPECT/PET (single photon/positron emission computed tomography) When radiolabeled compounds are injected in tracer amounts, their photon emissions can be detected much like x-rays in CT. The images made represent the accumulation of the labeled compound.

Temporal and spatial scales in functional neuroanatomy

Functional MRI • MRI signal changes result from variations in the oxygenation state of venous vasculature. • Accuracy of millimeters and temporal resolution of seconds. • The method is also called the ‘BOLD’ (blood oxygenation level dependent) method.

Types of structure-function correlations in Functional Neuroanatomy • Structure-function correlations under normal conditions: development, sexdifferences, species comparisons, hemispheric asymmetry and lateralization of function, etc. • Structure-function correlations under abnormal conditions: aging-associated neurodegeneration, stroke, epilepsy, etc.

Examples of localization of language functions

Cerebral asymmetry and lateralization of speech

Lateralization of auditory processing in monkeys • Monkeys listen to social vocalizations. • Monkeys get radiolabeled 2-fluoro-2-

deoxyglucose • Lateralization depended on the corpus callosum. • After sectioning of the corpus callosum the right hemisphere was as active as the left.

Evolution of language: Neural circuits for imitation

Functional Neuroimaging • Activity during a “specific cognitive process” minus activity during a “control process”. • Variations in cerebral blood flow (CBF) reflect changes in neuronal activity. • Patterns of CBF are reliable even though they depict physiology (sensitive to time day, drugs, fatigue, etc.) • Increased CBF reflects excitatory processes. • The higher the increase in CBF the higher the contribution of the cerebral area to the realization of the task. • Increase in the participation of structure in a task is reflected by the same CBF increase in all cerebral structures. • Absence of CBF change implies no change in cerebral activity.

Example of functional PET neuroimaging The task: decide whether a single letter presented visually sounds like ‘ee’. Substractions of different control tasks presented in A and B.

Control task: decide whether a single letter was in normal or inverted orientation.

Control task: decide whether a single object was natural.