Neuroanatomy Flashcards
Voltage changes during Action Potential - draw chart
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WHAT ARE EPSPS ANS IPSPS?
EPSPs and IPSPs are graded (they may have different intensities). They spread and collect in the hillock, where they add up (= neural summation)
If the sum of EPSPs and IPSPs crosses a certain threshold (e.g. -50 mV),
an ACTION POTENTIAL will occur.
(the membrane depolarizes) EXCITATORY POST-SYNAPTIC POTENTIAL (EPSP)
(the membrane hyperpolarizes) This is called an INHIBITORY POST-SYNAPTIC POTENTIAL (IPSP).
DISTRIBUTION OF IONS ACROSS MEMBRANE
When the neuron is “at rest” (no inputs), ions are NOT evenly distributed across the membrane.
Na+ and Cl- are more highly concentrated outside the cell, whereas K+ is more highly concentrated inside the cell.

WHAT IS CYTOARCHITECTONICS?
Even though all neocortex is composed of 6 cortical layers, neurons in different areas of cortex (and elsewhere) have different structure (size shape, etc.)
The study of the structure of neurons is called cytoarchitectonics (cyto = cell)
Cells within a particular functional region tend to have similar cytoarchitecture.
One important aim of cytoarchitectonics is to identify potential functional regions by looking at the cytoarchitecture of neurons.
Major subcortical structures
WHAT ARE THEY (LIST)
THEY ARE ALL ______
Consist of gray matter nuclei beneath the cortex (a nucleus is a
cluster of densely packed neurons)
They include:
- Basal ganglia
- Limbic system
- Dienchephalon (Thalamus + Hypothalamus)
- Cerebellum
- Brainstem
•Pattern of gyri & sulci
–e.g., inferior frontal gyrus
HOW DO NEURONS COMMUNICATE?
The most common way in which neurons communicate with one another is by sending a chemical signal, known as neurotransmitter.

Intro to Neuronal Communication
•The primary purpose of the brain is to sense, interpret and ultimately act upon the environment.
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•This is achieved through the interaction of neurons in neural circuits.
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•For neurons to interact they need to communicate with each other.
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•Neurons have evolved ways of communicating with one another by generating electrical and chemical signals.
Voltage gated ion channels
(See slides) Voltage gated and ???? Gated?
How does it get back to the resting membrane potential?
Remember that at rest, there’s more Na+ outside the cell than inside, whereas for K+ the opposite is true…
But at the end of the action potential, lots of Na+ have entered the cell and lots of K+ have exited, so the proportions have reversed.
How do we return to the resting-potential concentrations?
Na+/K+ pumps!
Human Cortex contains:
dips/infoldings (Sulci), if very deep, called Fissures
raised surfaces/convolutions (Gyri)
LIMBIC SYSTEM
Major structures:
Amygdala
Hippocampus
Cingulate Gyrus
Mammilary bodies
Major functions
relating the organism to present and past environment
Emotion
Memory

Useful terms to refer to sections (slices) of the brain -
- Horizontal (or Axial)
- Coronal
- Sagittal
Put it all together: what are all the different ways we can talk about one brain region
Brodmann areas (cytoarchitectonic maps)
Gross anatomy
Function
•There are several ways to describe the anatomy of the brain
–Gross neuroanatomy
–Cytoarchitecture
–Functional divisions
•As a result, the same brain region may be described in different ways
Sodium Potassium Pump - Draw diagram!

– Sympathe)c
• Responds to stress, mediates fight-flight response (heart races, dilate muscle blood vessels, hormones are released)
Function
–e.g., primary visual cortex
–Difficult for higher cortical regions
Glia
• support cells; around the same glia cells-to-neurons proportion
Produce Myelin:
Fatty substance surrounding axons of many neurons; speeds electrical transmission of output along the axon

CEREBELLUM
Cerebellum (“little brain”)
2 lobes
attached to hindbrain
Major functions
integrates information about motor commands with sensory feedback
enables smooth movement and dexterity

Medial vs. lateral

WHAT IS ACTION POTENTIAL?
When an action potential occurs (AC), we say the neuron “fires”.
What it means is that the neuron has itself “decided” to send a signal to other neurons downstream.
The AP consists of a quick wave (≈2 ms) of depolarization (immediately followed by repolarization) that propagates (spreads) down the axon.
Unlike EPSPs and IPSPs, which are graded, APs either occur or not (we say the AP is an “all-or-none” event, because it either occurs fully o not at all)
sodium potassium pump (Na+/K+ pumps)
Works against the concentration gradient and therefore requires energy.

Na+/K+ pumps not only make the concentration of Na+ and K+ ions different across the membrane, but also create a difference in electrical potential across the membrane (voltage).
Ions carry positive or negative charge
- Na+ and K+ carry positive charge
- Cl- carries negative charge
We say we have a membrane electric potential when the distribution of positive and negative charges across the membrane is different (e.g. the inside of neuron is more negative than the outside)







































