Psychology AOS 2 - Chapter 4

Grey matter

Pinkish in a living brain due to blood capillaries, made of majorly nerve cell bodies and their local connections to each other. Outer cerebral cortex is entirely grey matter.

White matter

Abundant beneath the cortex, nerve fibres with myelinated axons (that produce a white appearance) connect distant areas of the brain.

Meninges

Three transparent 'skin-like' membranes that cover the brain.

Cerebrospinal fluid

Water-like liquid that circulates between meninges to provide a cushion from some blows

Blood-brain barrier

Formed between capillaries, limits entry of harmful substances in blood

Nerve cell

Ventricles

Cavities filled with cerebrospinal fluid

How many neurons are in the brain?

Roughly 86 billion

Past brain understanding approaches (old to new)

• 2000 years ago - Greek philosophers

• 19th century - scientists dissected animal and donated brains to observe structure, biological perspective

Brain vs heart debate

Whether the brain or the heart is the root of human thoughts, feelings and behaviours

Discoveries of Greek physician Galen

• Worked as gladiator doctor 129-216 CE

• Observed impact on behaviour of head injuries

• Observed nerves from sense organs went to brain

Mind-body problem

Are the mind and body distinct, separate entities, or are they one in the same. Do they interact, and who's in control?

Mind-brain problem

Questions of how brain activity relates to conscious experience

Phrenology

German physician Franz Gall (1758-1828) decided that the brain was made up of different 'brain organs', and he thought the skull's outer features related to personality and behaviours.

Brain ablation

An irreversible, intentionally done procedure where a part of the brain is destroyed or removed, can be used to remove tumours.

Brain lesioning

Naturally occurring or induced disruption or damage to the regular functioning or structure of a part of the brain, can be used to treat debilitating brain disorders as a last resort. Can be reversed.

Electrical stimulation of the brain (ESB)

A small fine wire or disk is placed on a brain area to determine the function associated with that area. It can initiate and also inhibit (block) a brain response. Can be used for therapeutic reasons

Split-brain surgery

American neuropsychologist Roger Sperry (1913-1994) found brain specialisation and used Split-brain surgery to treat severe epilepsy by cutting the corpus callosum. He received a Nobel prize in 1981.

Hemispheric swap

Each of the halves of the cerebral cortex control + receive sensory information from the opposite half of the body

Sperry and Gazzaniga split-brain experiment results

• Left hemisphere is language centre

• Right hemisphere can see and draw things it sees, but can't verbally articulate it alone.

• When asked to articulate something seen in the left visual field, split-brain patients believed they saw nothing at all

Neuroimaging

A computerised technique that captures a picture of the brain

Structural Neuroimaging

(static neuroimaging)
Techniques that produce a scan showing brain structure, e.g. CT and standard MRI

CT (or CAT)

(Computerised tomography)
Structural X-ray based neuroimaging technique that builds a black and white horizontal cross-section of the brain.
Used for tumours, brain damage, abnormalities, and physical changes due to a disorder

MRI

(Magnetic Resonance Imaging) Structural neuroimaging technique using harmless magnetic fields to vibrate neurons, produces coloured image.
Used for very small brain anatomy and tissue changes, myelin loss, nerve degeneration and blood clots or leaks

Functional neuroimaging

(dynamic neuroimaging) Techniques that show some brain function and activity, and can do structure too. E.g. PET and FMRI

PET

(Positron Emission Tomography) Functional neuroimaging technique tracks a short-lived injected radioactive tracker to see brain areas using most blood whilst participant does an activity. 2D or 3D coloured images.

fMRI

(Functional magnetic resonance imaging) Functional neuroimaging technique measures changes in oxygen levels in areas of brain. Rapid succession images, 2D and 3D images. Can scan 2 people at once in dynamic fMRI.

Hindbrain

Lower level structures including pons, medulla and cerebellum. Has areas involved in motor and autonomous functions, as well as sleep and arousal.

Medulla

Lowest brain structure, continuation of spinal cord. Controls automatic + vital body functions, e.g. swallowing, breathing, heart rate, etc. Also some areas in touch sensory info. Damage can be fatal.

Pons

Above medulla, 2.5cm long. Involved in sleep, dreaming and waking up. Also helps with breathing and some muscle movements. 'Bridge' relaying cerebral cortex - cerebellum and medulla - midbrain.

Cerebellum

Attached to brain stem, cauliflower shaped. 10% brain mass, 80% brain neurons. Fine muscle coordination, posture, balance. Rapid muscle calculations, adjusts for smooth movement. Processes/temporarily stores info when learning motor skills, e.g. speaking. Maybe involved in spatial awareness.

Midbrain

2.5cm. Neural pathways connect upper + lower. Structures involved with movement, auditory, visual and tactile processing, sleep and arousal. Info from eyes and ears used for orienting movement, e.g. turning head to loud noise. Contains reticular formation.

Reticular Formation

Runs through centre of midbrain and hindbrain. Screens incoming info for overload directs attention, consciousness, arousal, muscle tension. Reticular Activating System is a component. Damage can cause coma.

Reticular activating system

Component of the Reticular Formation, a webbing of brain-wide neural pathways that regulates arousal in response to info from other areas. Some anaesthetics target it. Ascending pathways release steady impulses to keep upper brain alert. Descending pathways modify movement to tense or relax muscles.

Forebrain

Largest area, includes hypothalamus, thalamus and cerebrum. Works with other areas for complex cognitive functions, personality and memory.

Hypothalamus

Grape-sized, below thalamus. Controls pituitary gland to release hormones for homeostasis, influences behaviours to do with survival needs. Connects with amygdala and hippocampus as limbic system for emotions like anger and fear.

Amygdala

Production and regulation for emotions like fear

Hippocampus

Formation of new long-term memories

Thalamus

1 in each hemisphere. Relay centre between sensory receptors (except nose) and relevant brain areas. Messaging between cerebral cortex and lower structures. Attention, crucial in arousal with Rec. Formation.

Cerebrum

Contains outer cerebral cortex and masses of neural tissue. Cerebrum and cortex are responsibility for a lot of what we think, feel and do. Cerebrum is split into 2 hemispheres divided by longitudinal fissure and connected by corpus callosum. Each hemisphere has 4 lobes (in cerebral cortex)

Cerebral cortex (Grey matter)

Layer covering cerebrum. Functions of its areas can be organised into 3 broad categories. Has 4 broad lobes

'Higher order' cognitive functions, e.g. perception, learning, memory, language, thinking and problems. Also processes incoming sensory info and involved with planning and controlling voluntary movements.

3 categories of cerebral cortex functions

Sensory Areas - Receive and process sensory information, made of sensory neurons
Motor Areas - Initiates and executes voluntary movements, made of motor neurons
Association Areas - Surrounds sensory and motor areas, deals with functions requiring integration of inputs from multiple areas.

Neocortex

Makes up most of cerebral cortex, found in all mammals. Largest and most recently evolved part of the cortex. Has 6 layers of neurons.

Hemispheric specialisation

the idea that one hemisphere has specialised functions or exerts greater control over a particular function

Left cerebral hemisphere specialisations

Verbal functions:

• speech production

• comprehension

• reading

• writing

Analytical functions

• maths

• sequential tasks

• evaluation

• logical reasoning

Controls voluntary movement and receives and processes sensory info for right side of body

Right cerebral hemisphere specialisations

Non-verbal tasks not dependant on language:

• Processing the 'whole' rather than in bits

• Creativity and Fantasy

• Art & music appreciation

• Recognising and expressing emotions

• Rhythm and time

Spatial and Visual functions:

• Puzzle solving

• Recognising patterns and faces

• Map reading

• Visualising a location

Controls voluntary movement and receives and processes sensory info for left side of body

Lobes of the cortex

FPOT: Frontal, Parietal, Occipital, Temporal

Frontal lobe

The largest lobe voluntary muscle movements and involved in thinking, planning, and emotional control. Contains prefrontal cortex, premotor cortex, primary motor cortex and Broca's area (LEFT SIDE ONLY).

Prefrontal cortex

Association area behind forehead doing sophisticated mental abilities such as: reasoning, planning, problem solving, decisions, symbolic thinking, attention, expression of emotions, self awareness, and prohibiting inappropriate behaviour.

Mental process of voluntary behaviour

Prefrontal cortex plans motor sequence ---> premotor cortex prepares appropriate movement sequence ---> Primary Motor Cortex executes the actions

Primary motor cortex

Strip of neural tissue with control of skeletal muscles. Left PMC controls right side of body and vice versa. Amount of cortical space devoted to a body part corresponds to the complexity or 'fineness' of movement in that part.

Broca's area

In left frontal lobe only. Coordinates with body parts involved in speech to produce articulate, clear and fluent speech.

Parietal lobe

Behind Frontal lobe, back half but not rearmost. Receives and processes bodily info: touch+temp, muscle movement+body position. Contains primary somatosensory cortex.
Has association areas for spatial recognition and attention, plus taste perception (insula cortex)

Primary Somatosensory Cortex

Cortex strip that receives and processes sensory info from the skin and body parts (inc. tongue). Left receives right and vice versa. Cortical space for each body part corresponds with sensitivity and usage of a body part.

Homunculus

A human-like representation of the disproportionate areas of somatosensory cortex.

Occipital lobe

Rearmost. Almost completely visual receiving and processing. Largest area is primary visual cortex.

Primary Visual Cortex

Receives information from retina in back of eyes. Left side receives info from left HALF of each eye (which gets info on right visual field), and vice versa. Different neurons are specialised to respond to different features of visual info.

Temporal lobe

Around temples. Auditory perception, memory, recognising faces, and emotional response to memories. Contains Wernicke's area, Primary Auditory Cortex and a part of gustatory cortex (taste).

Primary Auditory Cortex

PAC in BOTH lobes get info from BOTH ears. Different areas are specialised for different parts of sound.

Wernicke's area

LEFT ONLY. Speech comprehension. While the PAC in left hemi processes auditory sensation, you can't understand it without the Wernicke's area. Connects with Broca's area. Also involved in production of coherent and meaningful speech.