Lecture 2 - Foundations Flashcards

1
Q

Models of the mind

A

Models are representations of structures or processes that help us simplify, visualise or explains the respective structure or process
- structure models represent structures in the brain that are involved in specific functions
- process models illustrate how a process operates

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2
Q

Process models

A

Breaking processes down into units and subprocesses
Help us to understand input and output
Can help us to visualise behaviour of those who have impairments to things such as attention or memory issues
- almost always flow diagrams
Example, learning:
Attention -> encoding -> storage -> retrieval

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3
Q

Structural models

A

Models that represent certain structures
Very common in neuroscience to represent the brain and its different regions
Useful for localisation, visualisation and brain comparison

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4
Q

Cognitive neuroscience

A

Brain <-> behaviour (the connection between the brain and behaviour - the basis of cognitive neuroscience)
The study of the physiological basis of cognition
Involves an understanding of both nervous system and the individual units that comprise that system

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5
Q

Levels of analysis

A
  • Brain -
    Context
    Indivual differences
    Experience
    Emotions
    Brain regions
    Neural connunication
    Hormones
  • Behaviour -
    There are different points of views (“levels”) in understanding cognitive phenomena e.g. socio-cultural, phenomenological, cognitive, behavioural, biological
  • g there are different processes and aspects going into behaviour, as well as a hierarchy with certain aspects
    We try to understand both behavioural and physiological aspects of the functioning of the mind
    From studying the whole brain, to studying networks or individual structures of the brain, to the chemicals that create electrical signals within these structures of the brain, to the chemicals that create electrical signals within these structures
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6
Q

Quick brain facts

A

The human brain weighs ~3 lbs and has an estimated amount of 86 billion neurones
It is nearly 60% fat and the remaining 40% is a combination of water, protein, carbohydrates and salts
It isn’t fully developed until around 25 +/- 2 years of age
First cognitive relaxes start slowly eroding at around 25 years, but risk management and long-term planning abilities finally kick into high gear
While the brain represents just 2% of a person’s total body eight, it accounts for 20% of the body’s energy use
Sufficient sleep, hydration, carbohydrates and fatty acids are crucial for optimum brain function

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7
Q

Building blocks of the nervous system v

A

Neurones: cells specialised to create, revive and transmit information in the nervous system
Aspects of neurones:
Axon - outgoing signals
Dendrites - incoming signals
Cell body - contains mechanisms to keep cell alive
Dendrites - multiple branches reaching from the cell body, receive information from other neurones
Axon - tube filled with fluid that transmits electrical signals to other neurones
Terminal buttons - form functions with other cells
Myelin sheath - covers the axon of some neurones and helps speed neural impulses
Action potential - electrical signal travelling down the axon

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8
Q

Nerve nets and the neurone doctrine

A

Early concept of interconnected neurones creating a nerve net
- continuously interconnected
- equal connection
- this allows for almost nonstop, continuous communication of signals throughout the network
Contradicted by the neurone doctrine
- proposed by Physiologist Ramon y Cajal
- arguing that nerve nets are not continuous, but rather made up of individual cells that transmit in the nervous system
- neurones form connections only to specific neurones resulting in groups of interconnected neurones, which together form neural circuits
- extremely high levels of specification within the neurones, so some neurones can’t connect with other neurones
Neurones that receive information from outside (“the senses”) are called receptors

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9
Q

How we measure how neurons communicate with each other

A

Once we figured out how neurones are structured, we needed to figure out how they did this
We need electronic amplifiers that are sensitive enough to pick up and amplify a single neurone firing
First recorded by Edgar Adrian in the 1920s with microelectrodes (earning him a Nobel prize) placed near axons
- used muscle stretch neurones in frogs

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10
Q

How neurones communicate with each other

A
  1. When a nerve is at rest, there is a negative charge in the inside compared to the outside of the axon, called the resting potential (-70mV)
  2. As the nerve impulse passes the electrode, this inside of the fibre near the electrode becomes more positive (+40mV)
  3. As the nerve impulse moves past the electrode, the charge in the fibre becomes more negative
  4. Eventually the neurone returns to its resting state

Resting potential (-) is when the nerve is at rest
Action potential
- neurone receives signal from environment (impulse) which briefly raises the relative voltage in the neurone
- information travels down the axon of the neurone to the dendrite of another neurone
- the size of the action potential is always the same, but the firing rate depends on stimulus intensity
~ low-intensity = slow firing
~ high-intensity = fast firing
Synapse:
- space between axon of one neurone and dendrite or cell body of another
- when the action potential reaches the end of the axon, synaptic vesicles open and release chemical neurotransmitters
- synaptic transmission is not an electrical transport of signals, but a biochemical one
Neurotransmitters:
- chemicals that affects the electrical signal of the receiving neurone, cross the synapse and bind with the receiving dendrites

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11
Q

The principle of neural representation

A

Mind = system that creates representations of the world, so we can act on it to achieve goals
If there is something our brain scale cannot perceive, we will not be able to experience it e.g. UV light
Everything a person experiences is based on representations in the person’s nervous system
- = everything you experience is reflected/represented somewhere in the neural system
And all information is represented via action potential

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12
Q

If all action potential are the same, how do we differentiate between different inputs?

A

Feature detectors:
Neurones that respond best to a specific stimulus
Discovered by Huber and Wiesel (1960s) in research with visual stimuli in cats
You are never going to have a neurone that reacts to multiple things
- a neurone that reacts to shape cannot react to colour
Each neurone in the visual area of the cortex responded to a specific type of stimulation
- colour, light, lines, shape (all working together)
This means that multiple feature detectors represent different aspects of objects

Electrical signals are recorded from the visual system of an anaesthetised cat that is viewing stimuli presented on thr screen
The lens in front of the cat’s eye ensures that the images on the screen are focused on the cat’s retina
Different types of stimuli that cause different neurones in the cat’s visual cortex to fire

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13
Q

Highly specialised feature detectors

A

Fusiform gyrus is in the temporal cortex and has many highly specialised feature detector areas (face, word, object, shape, body, place and many others)

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14
Q

Feature detectors development

A

Experience-dependent plasticity
- the structure of the brain changes with experience
Kitten exposed to vertical-only stimuli over time could only perceive verticals in normal stimui
- demonstrated that perception is determined by neurones that fie to specific qualities of a stimulus
Speech sounds: any baby can produce all sounds that are used in any existing language
The older e get, the harder it gets to produce sounds that are not in our own languages

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15
Q

Hierarchal processing

A

Example: spoken language comprehension
When we perceive language, we do so in a specific order that moves from lower to higher areas if the brain
When we perceive different objects, we do so in a specific order that moves from lower to higher areas of the brain
The ascension from lower to higher areas of the brain corresponds to perceiving objects that range from lower (simple) to higher levels of brain complexity

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16
Q

Sensory coding

A

The problem of neural representations for the senses
Sensory coding refers to how neurones represent various characteristics of the environment
Three types of sensory coding:
- specificity coding - representation of a stimulus by the firing of specifically tuned neurones specialised to respond only to a specific stimulus grandmother cells/neurones
- population coding - representation of a stimulus by the pattern of firing neurones
- sparse - representation of a stimulus by a pattern of firing of only a small group of neurones, its most neurones remaining silent

17
Q

Localisation of function

A

Specific functions are served by specific areas of the bran
Cognitive functioning declines in specific ways when certain areas of the brain are damaged (e.g. by age, disease or trauma)
Cerebral cortex (3 mm thick layer covering the brain) contains mechanisms responsible for most cognitive functions

18
Q

Functions of different areas of the brain

A

Frontal lobe:
Motor cortex
- motor control
- action
- knowledge
- ‘muscle memory’
Executive control
- focus/conscious attention
- knowledge coordination
- evaluating of information
Abstract thinking and problem solving
Frontal lobe/cortex is anterior to the parietal core t and superior to the temporal lobes

Parietal lobe:
Sensory cortex
Attention - one of the largest networks for attention
Imagination and creativity
Knowledge integration
It is posterior to the frontal lobe and superior to the temporal and occipital cortex

Occipital lobe:
Visual cortex
- visual perception categorisation
Posterior and inferior to the partial cortex and posterior to the temporal cortex

Temporal lobe:
Memory and remembering
- knowledge categories
Language
- auditory perception and parsing
Hearing
Anterior to the occipital cortex and inferior to the partial and frontal cortex

Cerebellum:
Movement and coordination
Balance
Rhythm
Proprioception
Inferior to the temporal and occipital cortex

Brain stem:
Basic biological functions
- breathing
- heart rate

19
Q

Language localisation

A

Areas specialised for language:
Broca’s area in the frontal lobe - language production is impaired by damage to this area
Wernicke’s area, in the temporal lobe - language comprehension is impaired by damage to this area
Fusiform word form area - recognise written words
Word memory - middle and inferior temporal cortex
Temporoparietal junction - combines meanings of words

20
Q

Double dissociation

A

When damage to just one part of the brain causes function A to be absent while function B is present and damage t another areas causes function B to be absent while function A is present
Allows us to identify functions that are controlled by different parts of the brain