brain and behaviour
TRANSCRIPT
Brain and Behaviour
Prepared By:
Sharad Agarwal
The Neuraxis
Anterior Posterior
Dorsal
Ventral
The Neuraxis
Anterior
Posterior
Dorsal
Dorsal Ventral
A few definitions
Dorsal (back) refers to the top of the head and the back
The ventral (front) surface faces the ground
These directions are somewhat more complicated in humans because our neuraxis bends, so that the top of the head is now perpendicular to the back
A few definitions
Slices of the brain Transversely, like a loaf of bread - also called
frontal or cross sections Parallel to the ground, giving us horizontal sections Perpendicular to the ground and parallel to the
neuraxis - sagittal section - midsagittal plane divides the brain in half along the longitudinal fissure
Because of our upright posture, cross sections of
our spinal cord are actually parallel to the ground
Transverse/ Cross section
Horizontal section
Sagittal section
Brain anatomy
The Brainstem
• Consists of all structures from the thalamus to the spinal cord
• Regulatory functions: Eating, drinking, body temperature, sleep and waking, basic movement and learning
• Generally speaking, these structures rule functions that are hard-wired, automatic, and not very plastic
The Brainstem
The Brainstem
• Thalamus: A relay centre for sensory information (touch, vision, hearing); located near the middle of the cerebral hemispheres. – Fibres project to primary sensory areas in neocortex
– There are separate nuclei for vision, touch, hearing
– Not a “passive” structure because the majority (80%) of its connections are not from sensory neurons, but from the neocortex (including motor areas).
The Limbic Cortex
• Developmental origin is earlier
• Primarily known for its role in emotion, (emotional) learning and memory
• Also plays a role in spatial learning and olfaction (memories of odour)
The Limbic Cortex
The Chemical Synapse
A (chemical/electrical) device that connects
axon of neuron A to dendrites of neuron B
Dendrites of neuron B
Axon of neuron A (note varicosities)
A chemical synapse formed between axons and dendrites
Axonal terminal
(pre-synaptic)
Dendritic spine
(post-synaptic)
Synapse
(with gap)
Typical morphology of a neuron
soma
dendrites
axon
nodes of Ranvier
Inter-node myelin
no myelin
Axon terminals (pre-synaptic site)
axon initial segment (AIS) “HOT” region
generating “spikes”
Poliak & Peles
Nature Reviews Neuroscience 4, 968-980 (December 2003)
Neurons communicate with each other primarily through synapses
The chemical synapse
Axon cell A
(small vesicles)
Spine: cell “B”
SPIKE at axon (digital - “all or none)
Excitatory synaptic potential
(analog/graded)
excitatory
synapse
axon
Spiny dendrite
The Chemical Synapse
When two cells fire together the synapse between them strengthens
Cell A Dendrite of Cell B Axon of Cell A
Receptors binding neurotransmitter
Vesicles containing neurotransmitter molecules
Intracellular injection of Lucifer Yellow in fixed cortical tissue
Layer II
Layer V
Human pyramidal
neuron from the
neocortex
Spines
spines
20 mm
1 mm
Courtesy of Javier DeFelipe, University Madrid
The Chemical Synapse
A (chemical/electrical) device that connects
axon of neuron A to dendrites of neuron B
Dendrites of neuron B
Axon of neuron A (note varicosities)
A chemical synapse formed between axons and dendrites
Axonal terminal
(pre-synaptic)
Dendritic spine
(post-synaptic)
Synapse
(with gap)
The chemical synapse
Axon cell A
(small vesicles)
Spine: cell “B”
SPIKE at axon (digital - “all or none)
Excitatory synaptic potential
(analog/graded)
excitatory
synapse
axon
Spiny dendrite
The Chemical Synapse
When two cells fire together the synapse between them strengthens
Cell A Dendrite of Cell B Axon of Cell A
Receptors binding neurotransmitter
Vesicles containing neurotransmitter molecules
Motor function