PSYC1020
MENTAL PROCESSING
Top-down processing/Mental set: What one already knows and what one presently thinks has a direct impact on
how you absorb, interpret and act upon new information
We have some degree of control over these voluntary processes
Mondegreen: misperceptions of song lyrics
PARADIGMS
Paradigm: a perspective, approach or frame of reference in regards to subject matter, methods or concept
Biological
Subject matter Scientific study of biological basis of behaviour
Specific focus Behavioural and cognitive topics
Methods Experimental, case study, correlational
Language & concepts Biological terms
Root metaphor Biological machine
Intellectual Neuroanatomy and physiology, behaviourism, cognitive perspectives
influences
Cognitive
Subject matter Scientific study of mental processes (as shown in behaviour)
Specific focus Attention, memory, thinking processes
Methods Experimental (mostly human)
Language & concepts Input, output, codes, memory stores
Root metaphor Programmed computer
Intellectual Mentalism, Behaviourism, computer science
influences
Behavioural
Subject matter Scientific study of behaviour
Specific focus Learning
Methods Experimental (mostly animal)
Language & concepts Stimulus, response, conditioning, reinforcement, shaping
Root metaphor Blank state, lump of clay
Intellectual Mentlaism, Darwinian biology
influences
Psychodynamic
Subject matter Study of conscious and unconscious processes as seen in ‘mental illness’
Specific focus Mental illness
Methods Case history
Language & concepts Ego, Id, Superego, Defence Mechanisms
Root metaphor Psychological condition is like mental illness, fluid dynamics
Intellectual Philosophy, Victorian culture, Darwinian struggle
influences
Humanistic
Subject matter Study of conscious human experience
Specific focus Individual awareness, conscious choices, well-being
Methods Case history
Language & concepts Personal growth, self-actualisation, awareness, transcendence, human potential
Root metaphor Growth
Intellectual Behavioural, Existentialism, ‘Eastern’ philosophies
influences STRUCTURE OF THE HUMAN BRAIN
Multi-layered: youngest (exterior) – oldest (interior)
Weighs about 1.36 kg
Complexity of brain is related to its organisation rather than size
Intelligence best indexed by the complexity of the cortical bulges (gyri) and indentations (sulci)
Long stretch of fibre in human brain creates more folds
Neuroanatomical references
Sagittal: lateral view; into left and right down longitudinal fissure (used in MRI)
Coronal: from above; into anterior and posterior (front and back)
Horizontal: axial slice; into superior and inferior (top and bottom)
Basic divisions
Hemispheres are asymmetrical and divided by longitudinal fissure
Hemispheres connected by ‘corpus callosum’ (a bundle of nerve axon fibres)
Cyroarchitectonics: division of brain based on differences in structure of stained tissue
FUNCTION OF THE HUMAN BRAIN
Brodmann’s guess: Structural differences may reflect functional differences
Broca’s area: speech production
Wernicke’s area: language comprehension
Cortexes of the brain
Frontal cortex
Located anterior to the central sulcus
‘Executive functions’
Plays an integral role in:
- Reasoning, planning, problem-solving
- Parts of speech and movement (motor cortex)
- Emotions Phineas Gage: metal pole went through frontal cortex and was physically unaffected but had changed
personality completely
Cerebral cortex
Outermost layer of grey mater (about 3mm)
Divided into 6 layers
Where most functioning occurs
Motor cortex
Located anterior to central sulcus (pre-central gyrus)
Cortical site involved with controlling body movements
Sends signals to other areas of the brain for voluntary movement initiation
Parts of body that require more fine-tuned movement represented more on cortex
Somatosensory (parietal) cortex
Located posterior to the central sulcus (post-central gyrus)
Receives signals from other brain regions for sensory perception of stimuli related to touch, pressure,
temperature and pain
Involved in spatial awareness
More sensitive areas of body represented more on cortex
Occipital (visual) cortex
Located at posterior part of brain
Concerned with many aspects of vision
Processes form
Motion
Orientation
Colour
Dimensions
Integrates into ‘whole’ picture that we see
Temporal (auditory) cortex
Inferior to the lateral sulcus
Contains Wernicke’s area
Concerned with perception and recognition of
- Auditory stimuli i.e. hearing, sound frequency
- Aspects of language i.e. prosody, comprehension
- Links to memory
Cerebellum
Coordinates movement and balance
Coordinates complex movements (via sensory feedback)
Stores procedural memories (fine motor learning)
More neurons than entire brain
The Limbic system
Loosely connected network of structures which plays a role in learning, memory and expression of emotion
Amygdala
Serves a vital role in processing emotional information, particularly learning of fear responses
Learning and remembering emotionally significant events
Hippocampus
Important role in memory, particularly consolidation of new memories
Converting short-term memory into long-term memory
Damage means one may not be able to retain memories
Hypothalamus
Helps maintains steady internal state - Regulates body temperature, appetite, sexual behaviour and electrolyte balance
Thalmus
Brain’s ‘sensory switchboard’
Relays sensory messages to the cortex
Brainstem
Reticular formation
- Controls arousal (i.e. alertness, sleep-wake cycle)
Medulla Oblongata
- Anatomical functions such as heart rate, breathing, blood pressure
Psychopathy and empathy (Meffert, 2013)
Psychopaths have ability to feel empathy but also control it
Empathy activated more strongly when instructed to do so
CELLULAR ANATOMY OF THE BRAIN
Billions of cells (10 )
2 categories: neurons & glial cells
Neurons
Responsible for processing information
~100 billion in adult brain
Soma (cell body) – INPUT
- Contains nucleus and structures for cell function
Dendrites – INPUT
- Unique to neurons
- Receives signals
- Can contact 100+ other neurons
Axon – CONDUCTING
- Unique to neurons
- 1 axon per cell
- Integrates inputs and decides outputs
- Sends signals through nodes of Ranvier
Terminal boutons – OUTPUT
- Form synapses with other neurons
- Secretes neurotransmitters into synaptic space when reached by an action potential Glial cells
Provides physical structure and support for neurons
Astrocytes
- Provide structural integrity
- Create ‘blood-brain barrier’ by sealing off capillaries
- Detect input and regulate neurons accordingly
- Nourish neurons by sucking up nutrients from blood stream to neurons
Microglia
- Protects brain from invading microorganisms
- Engulf and remove dead or damaged neurons
- Activated during inflammatory reactions
Oligodendrocytes
- Produce fatty substance called myelin which wraps several times around axons
- Each can myelinate several axons in the brain
Relay race
Signals pass across synapse in one direction
1. Electrical potential received at postsynaptic neuron through dendrite
2. Action potential generated at axon hillock and transmitted down axon
3. Neurotransmitters secreted in vesicles and passed to dendrites of next axon
4. Presynaptic neuron conducts signal towards a synapse
NEURON COMMUNICATION
Electrical signals (long distance within neurons)
Chemical signals (short distance between neurons)
Membrane potential: difference in electrical charge in cells
Messages transmitted as changes in membrane potential
Channels opened or closed in response to changes in voltage
Resting potential: difference in chemical composition inside and outside cell at rest
Result of concentrations of potassium (K+), chloride (Cl-), sodium (Na+) and negative protein ions
Usually -70mV (due to negative ions inside cell)
More potassium inside cell; more sodium outside cell
Action potentials
Operate on all-or-none principle
1. Regulating ion flow creates a resting membrane potential
2. Excitatory and inhibitory messages from other neurons change resting potential
3. If resting potential exceeds a threshold (~-55mV) action potential is activated
4. Rapid depolarization as sodium ions enter cell
5. Hyperpolarisation returns cell to resting potential following an undershoot
6.
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