Anatomy Basic neuroscience J. Lauwereyns, Ph.D. Professor Graduate School of Systems Life Sciences Kyushu University jan@sls.kyushu-u.ac.jp

The neuron Chemical release Detection Transport DNA Insulation Glia In mammals: Axons are myelinated

Neuron communication Neurons: detect external environment convert this sensory information into cellular ‘language’ PIC BEFORE slide 5

Simple reflex

Simple reflex Touching a hot iron; muscles of the arm contract, withdraw the arm

Simple reflex Dendrites of a sensory neuron signal the painful stimulus

Simple reflex This triggers an action potential in the axon

Simple reflex This activates an inter- neuron in the spinal cord

Simple reflex This activates an inter- neuron in the spinal cord, which, in turn, activates a motor neuron

Simple reflex Now the motor neuron sends a series of action potentials to the muscle, which contracts

Simple reflex Note: for simplicity, only 3 neurons and 1 muscle are shown. In reality, even this simple reflex involves many hundreds of neurons, and groups of muscles…

How does this work?? Action potentials (or nerve impulses) form the language of the brain, like computer bits or Morse code Cells that can generate and conduct action potentials have an excitable membrane When such cells are not generating impulses, the membrane is at its resting potential

Flash forward!

Action potentials: The brain’s information code Neuron’s response (action potentials) Visual stimulus Neuron’s response Visual stimulus Data from a neuron in visual cortex

Back to the present…

The neuron Chemical release Detection Transport DNA Insulation Glia In mammals: Axons are myelinated

‘Central dogma’ of molecular biology DNA Transcription mRNA Translation Protein

The axon and its terminal

Close up of terminal button

Following an action potential: Neurotransmitters will be released in the synaptic cleft and influence the post-synaptic neuron… To be continued

Neuron communication Two components: Within the neuron (action potentials) Between neurons (neurochemical release)

The logic of + and – in the brain Inhibitory “-” Excitatory “+”

Simple reflex Touching a hot iron; muscles of the arm contract, withdraw the arm

The advantage of inhibitory control… Returning to the example of the simple reflex, and a desire not to let go of the hot casserole

1 human 2 monkey 3 cat 4 pigeon 5 possum 6 dog

dorsal posterior caudal rostral anterior ventral lateral medial neuraxis dorsal posterior rostral caudal anterior ventral lateral medial

rostral lateral neuraxis medial ventral dorsal caudal

dorsal coronal ventral sagittal rostral caudal transversal

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Meninges Spinal cord Cranial nerves Ribs Lung Spinal nerves Kidney (Cauda equina)

Dorsal Ventral Dura mater Arachnoid membrane Pia mater Spinal nerve Sub- arach- noid space Vertebra Fat tissue Ventral

Dorsal Ventral To brain Dorsal root Dura mater Dorsal root ganglion Afferent axon Arachnoid membrane Pia mater Ventral root Spinal nerve Efferent axon Motor neuron Sub- arach- noid space Vertebra Fat tissue Ventral

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Meninges Spinal cord Cranial nerves Ribs Lung Spinal nerves Kidney (Cauda equina)

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

The meninges Let’s take a look Dura mater Arachnoid Subdural membrane space Subarachnoid space (Arachnoid trabeculae) Pia mater The meninges Surface of the brain

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Ventricular system: flotation, shock absorption Lateral ventricle Third ventricle Massa intermedia Fourth ventricle Cerebral aqueduct

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Nervous system 1 Central Nervous System 2 Peripheral Nervous System 3 The cranial nerves 4 The meninges 5 The ventricular system

Not the two hemispheres present; narrowing of the medulla and fattening of the cerebellum

Cerebral cortex (Telencephalon) Limbic structures Basal ganglia Forebrain Midbrain Hindbrain Thalamus (Diencephalon) Hypothalamus (Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…) Cerebellum (Metencephalon) Pons (Myelencephalon) Medulla

Cerebral cortex (Telencephalon) Limbic structures Basal ganglia Forebrain Midbrain Hindbrain Thalamus (Diencephalon) Hypothalamus (Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…) Cerebellum (Metencephalon) Pons (Myelencephalon) Medulla

Primary Motor cortex Primary Somatosensory cortex Cerebral cortex Primary Visual cortex Primary Auditory cortex

Primary Motor cortex Primary Somatosensory cortex Cerebral cortex Parietal lobe Frontal lobe Primary Visual cortex Primary Auditory cortex Occipital lobe Temporal lobe Medulla Cerebellum Spinal cord

Primary Somatosensory cortex Primary Motor cortex Right hemisphere Primary Visual cortex Primary Auditory cortex Left hemisphere

Primary Somatosensory cortex Primary Motor cortex Right hemisphere Central sulcus Calcarine fissure Primary Visual cortex Lateral fissure Primary Auditory cortex Left hemisphere Fissure, sulcus: groove (major, minor) Gyrus: a convolution of the cortex (separated by sulci or fissures)

Cerebral cortex (Telencephalon) Limbic structures Basal ganglia Forebrain Midbrain Hindbrain Thalamus (Diencephalon) Hypothalamus (Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…) Cerebellum (Metencephalon) Pons (Myelencephalon) Medulla

Limbic structures Limbic cortex Corpus callosum (largest Hippocampus commissure, connecting the two hemispheres) Hippocampus Pituitary gland Cerebellum Amygdala Pons Spinal cord Medulla

Cerebral cortex (Telencephalon) Limbic structures Basal ganglia Forebrain Midbrain Hindbrain Thalamus (Diencephalon) Hypothalamus (Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…) Cerebellum (Metencephalon) Pons (Myelencephalon) Medulla

Tail of caudate nucleus Globus pallidus Basal ganglia Caudate nucleus and putamen + (Diencephalon) Thalamus Hypothalamus Tail of caudate nucleus Globus pallidus (can’t see: Substantia nigra)

Cerebral cortex (Telencephalon) Limbic structures Basal ganglia Forebrain Midbrain Hindbrain Thalamus (Diencephalon) Hypothalamus (Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…) Cerebellum (Metencephalon) Pons (Myelencephalon) Medulla