PSYC110: Brain & Behavior (EXAM 1)

All behaviors can be explained by ______

Physical processes in the brain

5 Principles

1. Mind and brain are inseparable

2. Each mental function is carried out by specialized neural circuits in different regions or networks of regions in the brain

3. All of these circuits are made up of elementary signaling and support cells: neurons; glia

4. Neural circuits use specific ions and molecules to generate and transmit signals

5. These ions and molecules are conserved: worms to flies to humans use the same basic elements in their behaviors

Why is it a great time to study the brain?

• Technology

  • Imaging techniques (can image a brain as we think/act)

  • Neural recording and stimulation techniques (can move a cursor with a thought)

  • Genetic techniques (can make a polyhamous rodent a monogamous one)

• All the above are possible because our understanding of the brain has improved considerably

• But still, so much remains unknown – ‘the final frontier’

  • Cure for brain diseases, addiction alleviation, neural prostheses

What is behavior?

• The planning and execution of a series of goal-directed movements

• Modified by the internal state of the animal (emotions, learning, memory, biological rhythms and hormones)

• Modified by external factors (temperature, light, predator/prey)

4 Major Behavioral Motivations (Four F’s)

• Fight (aggression, competition, territoriality)

• Flight (fear, escape)

• Feed

• Reproduce

Tinbergen: Biological Explanation of Behavior

1. Function: how does the behavior impact the animal’s chances of survival and reproduction?

2. Causation: what are the neural bases of the behavior?

3. Development: how does the behavior change with age? What role do genes and experience play?

4. Evolution: how does the behavior compare with similar behaviors in related species, and how might it have arisen?

Every _____ & ______ is a brain activity

mental experience; behavior

• every encompasses everything from a simple reflex to emotion to consciousness

What evidence do we have for: every mental experience & behavior is a brain activity

• Lesions

• Imaging and neural recording

• Microstimulation: electrical signals in the brain, controlling which neurons are communicating with which and which areas of the brain are activated

• Genetic Manipulations

Case Study: Phineas Gage

• Historically - this case illustrated mental changes can occur with brain changes

  • Also suggested major brain surgeries were possible

• Went from responsible to fitful, indulgent and childlike intellectual capacity

Lesions — Frontal Lobotomies

• Cutting of the brain connections to and from the front part of the brain to cause changes in personality (typically in state mental hospitals)

Lesions — Speech Difficulties: Broca v. Wernicke

• Speech production vs. Comprehension: Broca v. Wernicke

  • Broca, back end of frontal cortex: any damage causes language production difficulties

  • Wernicke (people couldn’t comprehend language): towards the back of the brain” when this region is affected its comprehension difficulties

Hemineglect Syndrome

• Stroke or trauma of right parietal cortex

• Someone sees the whole field but only processes one side

• Lesion experiments:

  • Corpus callosum cut – disconnect left and right hemispheres. A way to see how conscious, unconscious and verbal expressions interact

Neural Recording

what: group of techniques that allow researchers to record neural activity from either a single neuron or a population of neurons

why: allows us to be able to tell if certain treatment has any effect at the level of neural activity

Single-Unit Recording

• record from a single neuron using microelectrodes

• Will be able to see clear action potential wave

• High spatial and temporal resolution

EEG

Neural recording

• record neural activity from population level (thousand or millions of neurons) near the electrode (using macroelectrodes)

• Low spatial and temporal resolution

Microstimulation

• Direct electrical stimulation of different parts of the brain

• Caused movements of distinct parts

• Also elicited memory recalls (even memories from a looonng time ago)

Brain Plasticity: Phantoms in the brain

• The neural connections of the brain can change/expand when regions are removed

What Does the Nervous System Do?

• Reception of sensory input

• Integration, memory, learning, and decision

• Motor action

Neurons & Glia

• Neurons - like a battery with positive and negative ions, causing electrical signals

• Glia - Meant to support the neuron cell, three types

2 Major Specializations of Neurons

1. Shape (processes) axon (tube within white sausage looking structures) and dendrites (appear like tree branches, input process of cell)

2. Excitability (they can produce and transmit voltage changes)

Basic Structures of a Neuron: Soma

•  cell body of a neuron containing the nucleus

Basic Structures of a Neuron: Dendrite

 input information from other neurons (tree branches)

Basic Structures of a Neuron: Axon

• long thin structure that conveys information from the soma of a neuron to its terminal buttons (the tube)

Basic Structures of a Neuron: Terminal Buttons

•  buds at the end of a branch of an axon

Basic Structures of a Neuron: Synapse

•  Junction between the terminal button of an axon and the membrane of another neuron

Supporting Cells: Astrocytes

• Provide support to hold neuron

• Clean up debris

• Blood Brain Barrier (all substance in the blood that enters the body is blocked from plugged blood vessels to the brain

What Are Supporting Cells?

• Supporting cells that glue the nervous system together are known as glial cells (the glue)

• Astrocytes, Oligodendrocytes, Microglia

Supporting Cells: Oligodendrocytes

• Support axons and produce the myelin sheaths

  • Myelin sheath (white sausage wrapping, it is fat)

Supporting Cells: Microglia

• Act as phagocytes and protect the brain from microorganisms

Phagocytes: type of white blood cell; protects body by destroying harmful bacteria

Neurons are ____ cells

excitable

meaning, they hold a charge and can discharge for signals

Because Neurons are excitable they ….

• They have voltage differences across their cell membrane

• This voltage difference can be changed rapidly

• Such changes can be rapidly transmitted across the length of the neuron

Ionic Basis of an Action Potential: Main Players

Na+ ions, K+ ions, and large anions with negative charge

Ionic Basis of an Action Potential: 2 Major Forces

• concentration gradient - Ions flow from high concentration to low

• Electrical gradient – Opposite charges attract

Main Sequence of Voltage Gated Ion Channels Opening

• Na+ channels are activated first

• Na+ channels get inactivated at the same time as K+ channels open

Membrane Potential

• the voltage difference between the inside and the outside of a neuron. The unit is milivolts (mV)

• At rest, the membrane potential is -70 mV (inside more negative than outside)

Ionic Basis of Action Potential: Action Potential

is a rapid change in membrane potential

Voltage-Gated Ion Channels

• No actions (voltage): proteins closed

• Voltage Gated Sodium Channels are very fast; goes into cell; activated first

• Voltage Gated Potassium Channels are lazy, take time to go into cell

What Happens when Voltage Gated Sodium Channels are Opened?

• Positively charged ions in neuron = neuron becoming more positively charged

• There’s a threshold where all the voltage gated sodium channels will be opened

  • Changes membrane potential to be more positive

• Depolarization phase of action potential: where inside of cell membrane becomes less negative and briefly positive due to rapid influx of sodium ions

What Happens when Potassium Ion Channels Open?

• When sodium channels close…they open

• Membrane is still positively charged

• Electrical and concentration forces want to push potassium out

  • Positive charges leave neuron = membrane potential goes toward negative value

    • Repolarization phase

• Potassium leaves the cell making it more negative

• Hyperpolarization phase

More _____ inside than outside; Less _____ inside than outside

Potassium; sodium

LARGE difference of potassium and sodium

At rest, ____ and _____ want to bring _____ in

diffusion gradient; electrical gradient; sodium

Net force is negative

At rest, _____ wants to bring potassium out, ______ wants to bring potassium in

Diffusion gradient; electrical gradient

Net force is 0