Role of the Brain in Mental Processes and Behaviour

Chapter 4

What is brain ablation?

Involves the destruction or removal of a brain part.

• Intentionally done

• Followed by assessment of subsequent changes in behaviour or mental functioning.

• Damaged caused is irreversible

What is brain lesioning?

Involves disrupting or damaging the normal structure/ function of the brain

• Term lesion also used generally to refer to any area of damaged

• Intentionally done

• Followed by assessment of subsequent changes in behaviour or mental functioning

• May involve temporary disruption to brain function

What is a lesion, and can it be caused by an ablation?

A lesion may be generally referred to as any area of damaged tissue so therefore it can also be caused by an ablation.

What are the ethics behind brain ablation and lesioning?

• Brain ablation or permanent lesioning for an experimental research is considered unethical.

• However: may be used to remove a tumour or for debilitating brain-related disorders.

When may a lesion cause temporary disruption?
Provide and example.

When nonsurgical procedures are used.

For example: drugs that are injected into a brain area.

What is an ESB

Electrical stimulation of the brain.

How does an electrical stimulation of the brain (ESB) work?

A small electrified wire (or disc) is inserted or placed onto a specific area of the brain.
The device will then initiate, interfere or inhibit a response,

What are the ethical issues of an ESB?

• Extremely invasive

• Potentially harmful

• risk of physical or psychological harm is unacceptable according to current ethical guidelines

How may an ESB be used ethically?

• Used for therapeutic reasons:

  • help with motor symptoms of Parkinson’s disease.

  • depression in severe cases

What is a split brain surgery?

Involves the cutting the main band of nerves tissues, the corpus callosum connecting the two hemispheres.

What was Roger Sperry able to demonstrate through his split brain studies?

Demonstrated that the 2 cerebral hemispheres clearly ‘specialise’ in some areas and confirmed contralateral arrangement of the body.

Most Notably: the left hemisphere specialises in language expression and comprehension.

Does movement need both sides of the brain to communicate throught the corpus callsoum?

No.

What is the corpus callsoum?

The main nerve tissues connecting the two cerebral hemispheres.
Main communication pathway for neural images

What is hemispheric specilisation?

The dominance or particular control of each hemisphere on differnet particular tasks

Does only one hemisphere that is specialised in that task function whilst doing thee?

No, they may exert ‘dominance’ over a particular function but both hemispheres are often involved.

Functions of the left hemisphere.

• Involved in language and speech

  speech comprehension, fluent and coherant speech

• Analytical functions:

  maths, logic interpreting data

• Controls the right side of the body

Functions of the right hemisphere.

Non-verbal

• Judgement of rythm and time

• Controls left side of the body

• Spatial abilites:
  constructing puzzles, rotating objects

• Processing things as a whole

• Detection and expression of emotions

• Recognition of faces and patterns

• Art apprecitation

• Day dreaming and fantasy

2 categories of neuroimaging/brain scanning

Structual and Functional

What is structural imagining?

Refers to techniques that produce images, or scans of the brains anatomy and structure.

What is functional neuroimaging/dynamic neuroimagining

Refers to techniques that provide views of some aspect of brain function by showing images of the brain ‘at work’.

and provide information about brain structure

What is the purpose of functional neruoimagining?

To allow correlations between brain areas that may be active at the time of a participant’s response.

What is CT?

Computerised tomography

How does computerised tomography work?

uses x-ray equipment:

• participant may be given substance called contrast

  -highlights brains blood vessels

  -enables interpretation of resulting images

What does CT do?

• scan brain at different angles

• shows horizontal cross-section

• more detailed than x-ray

• can be produced in 3-D

What is the purpose of CT?

useful for locating brain abnormalities/injuries

-Location and size of a tumour

-Extent I've damaged caused by brain injury from stroke/hit

-Brain abnormalities in people with mental health disorders

What are the limitations of computerised tomography?

• black-and-white images only

• Only shows brain structure (not as well as scanners that do not use x ray equipment)

• Not very good for imaging tissue

What does MRI stand for?

magnetic Resonance imaging

How does MRI work?

uses harmless magnetic fields to vibrate atoms in the brain neurons to generate a computer image

How are CT and MRI similar?

both taken in metal cylinder both structural

What is more sensitive CT or MRI?

MRI

Because MRIs are more sensitive than CT, what does this entail?

• images are clearer and more detailed

• Produced in full colour

-Assist researchers to distinguish between different brain areas/structures

Examples of subtle changes that an MRI can produce

loss of Myelin protecting nerve fibres

Nerve/tissue degeneration

Blood clot/leaks from strokes and injury

What is FMRI?

functional magnetic resonance imaging

What does FMRI do?

Detects and records brain activity by measuring oxygen consumption across brain through standard MRI technology

Why is FMRI preferred in psychology?

• can take numerous photos in succession and therefore detect brain change as it occurs can

• simultaneous scan the brains of two people as they interact

What does pet stand for?

positron emission tomography

How do pet scans work?

• tracks a glucose solution containing short-lived radioactive tracer that is usually injected into the brain

• Uses colour code to indicate areas of high and low activity

  -looks like a coloured map of someone's brain

Are pet scans functional or structural

functional

What are the limitations of functional neuroimaging?

• more or less blood flow does not necessarily mean more or less brain activity

• similarly does not mean that a brain area is engaged or not engaged

What is the cerebral cortex?

• Covers the cerebrum, outer layer of cerebrum

• Involved in high order thinking

  -perception, learning, memory, language, problem-solving

What is a motor area?

related to initiating and executing voluntary movements

What is a sensory area?

receive processed information from five senses

-made of sensory neurons

What are association areas?

surround sensory and motor areas

-deal with complex functions

That require integration of information from multiple or different areas

Frontal lobe

Located at the front of this cerebral hemispheres

Associated with voluntary movement, speech production, sophisticated mental abilities, personality, decision making

4 areas of the frontal lobe

prefrontal cortex

Pre-Motor cortex

primary motor cortex

Brocas area

Function of the prefrontal cortex

reasoning planning

problem-solving

decision-making

symbolic thinking

regulation of emotions

expression self-awareness

aspects of personality

plans required motor sequences and send instructions to motor cortexes

primary motor cortex

• initiates and controls voluntary movement

• contralateral arrangement

• amount of cortex devoted to body part corresponds to complexity or fineness of movements

location of primary motor cortex

strip of neural tissues located at the rear of each frontal lobe

function of Boroc’s area

• crucial role in production of articulate speech that is clear & influent

• coordinates messages to lips, jaws, tongue, vocal cords

function of parietal lobe

receives some processes somatosensory (bodily) information

• touch and temperature

• information about muscle movement & body position

about the primary tomato sensory cortex

receives and processes somatosensory (bodily) information

• touch and temperature

• information about muscle movement & body position

what is the amount of cortex in the primary somatosensory cortex represent?

The amount of cortex represents sensitivity

Function of occipital lobe

Almost exclusively devoted to the sense of vision

Explain the contralateral arrangement of the occipital lobe

left half of each eye receives info from the r ½ of visual field and sends information only to the visual cortex in L occipital lobe

Function of primary visual cortex

Neurons within are are specialised to respond to different features of visual infromation

What different features of visual information does the primary visual cortex respond to?

features of orientation

edges

motion

colour

shape

what is the temporal lobe involved with?

auditory perception

speech comprehension

important role in memory

parts of visual perception (recognising faces/objects)

emotional responses to memories/sensory information

what are the distinct regions of the temporal lobe?

wernicke’s area (left side)

primary auditory coretx

why is the primary auditory cortex an example of hemispheric specilistation?

left processes verbal sounds e.g: comprehends language
right side process non-verbal soundse.g: music

What is the function of wernicke’s area?

crucial role in comprehension of speech
involved in production of meaningful and cohernt speech

What is neuroplasticity?

The ability of the brain and other parts of the nervous system to change in response to experience,

includes the brain ability to recover/ compensate for loss of function from injury

where does neuroplasticity change occur?

at a cellular level, typically at the synpase

t/f the brain shape changes during neuroplasticity?

false, brain shape does not change

what may cause neurons to change?

during brain developtment

during learning

certain drugs

in response to injury

how do neurons change during neuroplasticity?

form new neural pathways, with existing neuros, interconnect

what causes the reorganiation of neurons?

base do

when and which areas have the highest plasticity

what is experience dependant plasticity

involves brain change that modifies some part of neural structure that is already present.

depends on exposure to various enviormental experiences that are unique to individual

-may occur during lifetime
-no crucial period

-evident in everyday life

what is the end result after brain injury?

brain function lost through injury is rerouted via new connections

what is brin injury?

any type of brain damage or disorder that impairs/ interferes with normal functioning, either temporarily or permanently

acquired brain injury

temrn most commonly used in realtion to damage or disorders that occur after birth

sudden onset

occurs abruplty

insidious onset

gradually develops

what is traumatic brain injury?

type of brain injury that occurs when external force causes damage to brain

what may happen to neurons from a traumatic brain injury

may be killed outright
or slowly starved of oxygen & nutrients

what is asphsia?

language disorders that results from acquired brain injury

fluent aphasia

speech is easily produced and flows freely but sentences do not make sense
person usually has difficulties understanding what is heard/said

non fluent aphasia

difficulty speaking clearly, often in short sentences

pure aphasia

specific impairments in reading ,writing or recognising spoken words

broca’s aphasia

damage to broca’s area
considerable difficulty producing speech
+reading and writing impaired

aware of language difficulties

difficulty understanding complex speech, understand everyday conversation

wernicke’s aphasia

considerable difficulty understanding spoken, written language and speaking in a meaningful way

What is a stroke

occurs when blood supply to part of the brain is interrupted

what are the two types of strokes

ischemic, haemorrhagic

what are ischaemic strokes?

when blood supply is restricted/stopped in 1 blood vessel because its blocked
typically caused by blood clot forming somewhere else and travelling up

what are hemorrhagic strokes?

when a blood vessel supplying the brain becomes weak and bursts
causes bleeding in the brain

what typically causes hemorrhagic strokes?

high blood pressure

Risk factors of strokes that cannot be controlled

• older age

• male

• family

• history

• already experinced a stroke

Factors that can be controlled that contribute to the likelihood of a stroke

• high cholesterol

• high blood

• smoking

• overweight/obese

• lack of exercise

• drugs/alchol

• door diet(too much saturated fats/too salty)

what is the effect of a stroke?

During a stroke neurons within the brain may die due to lack of oxygen and nutrients.

Symptoms of a stroke

•numbness or weakness in the face, arm or leg, especially on one side of the body

•speech disturbance, such as slurring or decreased speech fluency or comprehension

•trouble walking, dizziness, loss of balance or lack of coordination

•trouble seeing in one or both eyes

•headache, usually severe with no known cause

•difficulty swallowing

•nausea or vomiting.

Explain the effects of a stroke

the effects of a stroke will be different for all, as the impact will be based off of the:

location, amount of neurons that die, time of deprevation

if the cerebellum was impacted by a stroke what would it cause?

codination issues

if the pons, thalamus, was affected during a stroke what would happen?

Permanet coma

if the hypothalamus was effected during stroke

body temp & sleep regulation become irregular

Motor cortex damage in the right hemisphere

paralysis on L side of body