Chapter 1- The Cellular Foundations of Behaviour

Question 1

physiological explanation

Answer 1

relates behaviour to the activity of the brain and other organs. It deals with the machinery of the body, for example, the chemical reactions that enable hormones to influence brain activity and the routes by which brain activity controls muscle contractions.

Question 2

ontogenic explanation

Answer 2

describes how something develops. For example, if we want to explain why males and females differ on average in some regard, we might examine behaviour at ages and relate it to changes in the nervous system.

Question 3

evolutionary explanation

Answer 3

reconstructs the evolutionary history of a structure or behaviour. The characteristic features of an animal are almost always modifications of something found in ancestral species. For example, bat wings are modified arms; quills are modified hairs. Evolutionary explanations call attention to behavioural similarities among related species

Question 4

functional explanation

Answer 4

describes why a structure or behaviour evolved as it did. Within a small, isolated population, a gene can spread by accident through a process called genetic drift. Example: dominant male with many offspring spreads all his genes, including some that may have been irrelevant or even disadvantageous.

Question 5

biological psychology

Answer 5

the study of the physiological, evolutionary, and developmental mechanisms of behaviour and experience

Question 6

monism

Answer 6

the belief that the universe consists of only one kind of substance
-mental activity and certain types of brain activity are insperable

Question 7

dualism

Answer 7

the belief that mind and body are different kinds of substance that exist independently

Question 8

Camillo Golgi

Answer 8

The nervous system is composed of a network of interconnected fibres- one big mess of wires

Question 9

Santiago Ramon y Cajal

Answer 9

The nervous system is made of discrete cells
Neuron Doctrine (Neuron Hypothesis)
Neurons are the units of brain function

Question 10

Neurons

Answer 10

cells that receive information and transmit it to other cells
Carry out the brain’s major functions
86 billion
69B Cerebellum
16B Cortex
<1B Other
1B Spinal cord
Continuously changes their shape
New dendritic branches and lose old ones
New connections
Neuroplasticity
Some new neurons appear throughout life, but most of your neurons are with you for life and are never replaced.

Question 11

Glia

Answer 11

Aid and modulate neuron activities
40-50 billion

Question 12

Endothelial cells

Answer 12

• BBB
• 13-17 billion

Question 13

dendrites

Answer 13

Receive info from other neurons
1 - 20+
Dendritic spines

Question 14

cell body/ soma

Answer 14

The core region; contains the nucleus
Integrates the information

Question 15

axon

Answer 15

Transmits info to other cells
Only one axon
Axon hillock, buttons, synapses,
Myelin sheath
Nodes of Ranvier

Question 16

what does a single neuron do?

Answer 16

Most behaviours are produced by networks (groups of 100s or 1000s of neurons)
When an ensemble of neurons are all transiently active to some thought, feeling, process, etc., they are all referred to as a cell assembly.
If a cell assembly is responsible for a specific process or content of thought, then what sort of information is “coded” by a single neuron within the cell assembly?
Grandmother cells

Question 17

sensory neurons

Answer 17

Info concerning the environment (from the peripheral nervous system) is transmitted to the central nervous system
Bipolar, unipolar neurons

Question 18

interneurons

Answer 18

Bridge sensory and motor neurons
E.g. Purkinje cell is one type of interneuron
Modulate functioning between sensory and motor neurons
Multipolar interneuron

Question 19

motor neurons

Answer 19

Transmit signals from the central nervous system to muscles
Multipolar neuron

Question 20

efferent

Answer 20

going away

Question 21

afferent

Answer 21

accepting, toward the brain

Question 22

“language” of neurons

Answer 22

Excitation and inhibition
Each neuron receives thousands of excitatory and inhibitory signals per second.
Neurons sum these signals and respond accordingly: they become active or not (like a democracy)
From the simple “yes-no” language of neurons emerges enormous possibilities for behaviour.

Question 23

glial cells

Answer 23

From the Greek “glue,” supportive role for neurons
10-50 glia for every neuron? Maybe not
The best estimate is 1:1 or 0.7:1

Question 24

types of glia

Answer 24

Ependymal cells
Microglia
Astrocytes
Oligodendrocytes
Schwann cells
Radial cells

Question 25

ependymal cells

Answer 25

Found on the walls of the ventricles
Produce Cerebral spinal fluid
These cells form the choroid plexus
If CSF is blocked, hydrocephalus (“water brain”) results

Question 26

microglia

Answer 26

Found within the central nervous system
Clean up dead neurons or glia because such debris may interfere with neural functioning
Quite mobile, they originate in the blood, and they travel to the site of an injury to provide growth factors to aid repair and for phagocytosis (“cell-eating”)
Phagocytosis: scavenge debris

Question 27

astrocyte (astroglia)

Answer 27

Star-shaped appearance, found in the central nervous system
Neural synchronization
Structural support
Without astrocytes, neurons would be floating around unanchored within extracellular-fluid
Synchronizes the activity of neurons it supports
Blood-brain barrier
Form connections with the blood supply (end-feet of astrocyte) and neurons to transfer glucose and nutrients to neurons.
Neurons “request” more oxygen/glucose from the blood supply via the astrocytes

Question 28

oligodendria

Answer 28

myelinate axons in the central nervous system
ms & amyotrophic lat. sclerosis

Question 29

schwann cells

Answer 29

myelinate axons in the peripheral nervous system
multiple sclerosis
amyotrophic lateral sclerosis

Question 30

myelin

Answer 30

glial coating that surrounds axons: 80% lipids (fats), 20% protein

Question 31

oligodendrocytes(CNS)

Answer 31

myelinate many (-15) neurons
provide some structural stability

Question 32

schawnn cells(PNS)

Answer 32

One cell myelinates only one neuron
it takes many schwann cells to myelinate a neuron
can guide regrowth of damaged neurons

Question 33

radial glia

Answer 33

Guide migrating neurons during development
After neural migration, some become neurons, others become astrocytes, ependymal cells, or oligodendrocytes.

Question 34

blood-brain barrier

Answer 34

Blood-Brain Barrier (BBB)
Body
Endothelial cells in capillaries are not tightly joined
Brain
Endothelial cells are tightly joined
Astrocytes (type of glia) play a role
BBB surrounds the brain and blocks most chemicals from entering
It blocks incoming viruses, bacteria, etc. from entering the nervous system
Regions without BBB: pineal gland, pituitary, area postrema

Question 35

active transport

Answer 35

The protein-mediated process that expends energy to pump chemicals from the blood into the brain
Glucose, certain hormones, amino acids, and a few vitamins are brought into the brain via active transport.
Although BBB is essential to protect the brain, it can pose a difficulty in allowing chemicals (drugs, chemotherapy, etc.) for to pass the barrier for treatment.

Question 36

glucose and the BBB

Answer 36

Glucose can pass through the BBB
Neurons need a steady supply of oxygen
20% of all oxygen consumed by the body is used by the brain
The body needs thiamine (b1) to use glucose
Prolonged thiamine deficiency leads to death of neurons (as in Korsakoff’s syndrome)

Question 37

the internal structure of a cell

Answer 37

Extracellular (outside cell)
Intracellular (inside cell)

Question 38

outside the cell

Answer 38

Cl-
Na+

Question 39

in the cell

Answer 39

K+
Proteins (A-)
Within the cell, the environment is more negative than it is outside the cell bc distribution of ions and proteins

Question 40

cell membrane

Answer 40

Separates the intracellular and extracellular fluid
Regulates the movement of ions, molecules, and other substances into and out of the cell
Most substances do not pass through the membrane
Proteins within the membrane permit substances to pass into and out of the cell

Question 41

hydrophilic head

Answer 41

water-loving and polar

Question 42

hydrophobic tail

Answer 42

water hating and nonpolar
lipids (fat molecules)

Question 43

the action potential

Answer 43

A large, brief reversal in polarity of an axon
Lasts approx. 1 millisecond (ms)
All-or-none (i.e., it is NOT graded)
Rate law: stimulus intensity- increased firing rate

Question 44

threshold of excitation

Answer 44

Voltage on a neural membrane at which an action potential is triggered
Opening of Na+ and K+ voltage-sensitive channels
-50mV relative to the extracellular surround

Question 45

axon hillock

Answer 45

It is very rich in voltage-sensitive channels, and this is where EPSPs and IPSPs will summate (temporally or spatially). If the sum of activity is greater than -50mV, then this summed activity will generate an AP

Question 46

absolute refractory period

Answer 46

The depolarizing (rising) and repolarizing phase
A new action potential cannot be elicited

Question 47

relative refractory period

Answer 47

The state of an axon in the later phase of an action potential
During this hyperpolarization, another action potential is possible with stronger stimulation

Question 48

action potential in 5 steps

Answer 48

Step 1: resting state (-70mV)
Step 2: slight depolarization to threshold (-50mV) followed by a massive depolarization (“rising phase”)
Na+ channels open, Influx of Na+ due to electrostatic pressure… K+ channels open … lastly, Na+ channels close
Step 3: repolarization
Efflux of K+, slow closing of K+
Step 4: hyperpolarization
Continued efflux of K+ (overshoot)
Step 5: back to resting state- random movement of ions and Na+/K+ Pumps

Question 49

nerve impulse: AP propogation

Answer 49

Refers to the propagation of an action potential on the membrane of an axon
Why does an AP move?
The voltage difference is 100mV during the AP, but only 20mV is required to bring resting potential to the threshold.
Neighbouring parts of the axons will receive sufficient voltage change to bring it to the threshold.

Question 50

nodes of ranvier

Answer 50

Part of an axon that is not covered by myelin
Richly endowed with voltage-sensitive channels