J. Lauwereyns, Ph.D.ProfessorGraduate School of Systems Life SciencesKyushu University

jan@sls.kyushu-u.ac.jp

Basic neuroscience

Anatomy

The neuron

DNA

Detection Chemical release

Transport

Insulation

Glia

In mammals: Axons are myelinated

Neuron communication

Neurons: 1. detect external environment 2. convert this sensory

information into cellular ‘language’

Simple reflex

Simple reflex

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

Simple reflex

Dendrites ofa sensory neuronsignal the painfulstimulus

Simple reflex

This triggersan action potentialin the axon

Simple reflex

This activatesan inter-neuronin the spinal cord

Simple reflex

This activatesan inter-neuronin the spinal cord,which, in turn,activates a motor neuron

Simple reflex

Now the motor neuron sends aseries of action potentialsto 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

Data from a neuron in visual cortex

Visual stimulus

Neu

ron

’s r

esp

on

se

Visualstimulus

Neuron’sresponse(actionpotentials)

Back to the present…

The neuron

DNA

Detection Chemical release

Transport

Insulation

Glia

In mammals: Axons are myelinated

DNA

mRNA

Protein

Transcription

Translation

‘Central dogma’ of molecular biology

The axon and its terminal

Close up of terminal button

Following anaction potential:Neurotransmitterswill be released in the synaptic cleftand influence thepost-synapticneuron…

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 human2 monkey3 cat4 pigeon5 possum6 dog

rostral caudal

dorsal

ventral

neuraxis

lateralmedial

anterior

posterior

rostral

caudal

ventral dorsal

mediallateral

neuraxis

dorsal

ventral

rostral caudal

coronal

transversal

sagittal

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Cranial nerves

Meninges

Spinal cord

Ribs

Spinal nerves Kidney

Lung

(Cauda equina)

Dorsal

Ventral

Spinal nerve

VertebraFattissue

Dura materArachnoid membrane

Pia mater

Sub-arach-noid space

Dorsal

Ventral

Afferent axon

Efferentaxon

Dorsal rootganglion

Dorsal root

Ventral root

To brain

Motorneuron

Spinal nerve

VertebraFattissue

Dura materArachnoid membrane

Pia mater

Sub-arach-noid space

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Cranial nerves

Meninges

Spinal cord

Ribs

Spinal nerves Kidney

Lung

(Cauda equina)

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Let’s take a look

The meninges

Dura mater

Arachnoidmembrane

Subarachnoid space

Pia mater

Surface of the brain

(Arachnoid trabeculae)

Subdural space

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Lateral ventricle

FourthventricleCerebral

aqueduct

Massaintermedia

Third ventricle

Ventricular system: flotation, shock absorption

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Nervous system1 Central Nervous System2 Peripheral Nervous System3 The cranial nerves4 The meninges5 The ventricular system

Forebrain

Midbrain

Hindbrain

(Telencephalon)

(Diencephalon)Thalamus

Hypothalamus

(Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…)

(Metencephalon)

(Myelencephalon) Medulla

Pons

Cerebellum

Limbic structures

Cerebral cortex

Basal ganglia

Forebrain

Midbrain

Hindbrain

(Telencephalon)

(Diencephalon)Thalamus

Hypothalamus

(Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…)

(Metencephalon)

(Myelencephalon) Medulla

Pons

Cerebellum

Limbic structures

Cerebral cortex

Basal ganglia

Cerebral cortex

PrimaryVisual cortex

PrimaryAuditorycortex

PrimaryMotor cortex

PrimarySomatosensorycortex

Cerebral cortex

Frontal lobeParietal lobe

Occipitallobe

CerebellumSpinal cord

MedullaTemporal lobe

PrimaryVisual cortex

PrimaryAuditorycortex

PrimaryMotor cortex

PrimarySomatosensorycortex

Right hemisphere

Left hemisphere

PrimaryMotorcortex

PrimarySomatosensory cortex

PrimaryAuditory cortex

PrimaryVisual cortex

Right hemisphere

Left hemisphere

PrimaryMotorcortex

PrimarySomatosensory cortex

PrimaryAuditory cortex

Central sulcusCalcarine fissure

Lateral fissure

PrimaryVisual cortex

Fissure, sulcus: groove (major, minor)Gyrus: a convolution of the cortex (separated by sulci or fissures)

Forebrain

Midbrain

Hindbrain

(Telencephalon)

(Diencephalon)Thalamus

Hypothalamus

(Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…)

(Metencephalon)

(Myelencephalon) Medulla

Pons

Cerebellum

Limbic structures

Cerebral cortex

Basal ganglia

Corpuscallosum

Cerebellum

Spinal cordMedulla

Pons

(largestcommissure,

connecting the two

hemispheres)

Pituitary gland

Hippocampus

Limbic cortex

Amygdala

Limbic structures

Forebrain

Midbrain

Hindbrain

(Telencephalon)

(Diencephalon)Thalamus

Hypothalamus

(Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…)

(Metencephalon)

(Myelencephalon) Medulla

Pons

Cerebellum

Limbic structures

Cerebral cortex

Basal ganglia

Caudate nucleusand putamen

Tail of caudate nucleusGlobuspallidus

(can’t see:

Substantia nigra)

Basal ganglia

Thalamus

Hypothalamus

+ (Diencephalon)

Forebrain

Midbrain

Hindbrain

(Telencephalon)

(Diencephalon)Thalamus

Hypothalamus

(Mesencephalon) Tectum (Substantia nigra, Superior colliculus,…)

(Metencephalon)

(Myelencephalon) Medulla

Pons

Cerebellum

Limbic structures

Cerebral cortex

Basal ganglia