Brain Flashcards
Brainstem and cerebellum
Little difference between fish, reptiles, birds and mammals
Midbrain and limbic system
Better developed in mammals and birds
Cortex and neo-cortex
Better developed in primates especially humans
Anatomy of brain stem
Lower brain or Neo- or Nigro-striatal
Bulge at top of spine
Connections to sensory and motor neurones
Autonomic nervous pathways such as those controlling heart and respiratory rate
Includes cerebellum which is responsible for motor co-ordination.
Some differentiation into particular pathways.
Light sensitive sensory neurones are associated with cerebellum which may help with co-ordinated movement
Mechanical and Unconscious
Limbic system
Mid-Brain or Mesolimbic System
Includes Thalamus that allows sensory information (e.g. sight, smell and hearing) to be used together
Amygdala which is involved in some emotional responses (e.g. fear) and olfactory memory
Hippocampus which is involved in relational or spatial memory
Hypothalamus which is involved in hormonal responses.
Thalamus
Allows sensory information to be used together
Amygdala
Involved in some emotional responses and olfactory memory
Hippocampus
Involved in relational and spatial memory
Hypothalamus
Involved in hormonal responses
Cortex and neo-cortex
Upper Brain or Mesocorticol
Thin matrix of sensory cells became heavily folded to allow many neural connections to be made with little increase in volume.
Cortex is the skin of this body.
Involved in detection and interpretation of sensory information
Involved in associations between stimuli and in long-term memory.
Responsible for conscious thought, conscious memory, thinking, planning and communicating.
Divisions of cortex
Parietal lobe
Occipital lobe
Temporal lobe
Neo-cortex involving frontal and pre-frontal lobe
Parietal lobe
Touch and motor cortex
Occipital lobe
Vision
Temporal lobe
Sound and language
Frontal and pre-frontal lobe
Speech, thought and decision making
Short term memory
Also called working memory
Lasts short time and information is rapidly removed/replaced
Used in coordination of ongoing behaviour
Long term memory
More permanent reference store
Consolidation of short term memories to long term memory involves repeated exposure and/or rehearsal
Retrograde amnesia
Cannot remember events from before brain damage
Effected long-term memory
Anterograde amnesia
Cannot remember events after brain damage
Effected working memory or process of consolidation
Implicit memory
Includes perceptual, motor and stimulus response learning
May involve sensory or associative cortex
Procedural - no understanding of relationship
Explicit memory
Includes: relational , spatial, episodic, semantic and emotional
Involved frontal cortex and limbic system
Declarative representation of information
explicit memory tasks
Free recall tasks - involve frontal cortex and hippocampus
Eg name your favourite colour
Implicit memory task
Completion task - involve visual cortex
Eg what colour is that
How to study the brain
Human psychiatry
Animal models
Electro-stimulation and detection
Scans
Human psychiatry
Mental illness, brain damage and surgical intervention.
e.g. Korsakoff’s syndrome
Apparent inability to form new memories
Related to malnutrition and alcohol abuse
Caused by low levels of thiamine (Vit B1).
Animal models
Lesions, electro-stimulation and drug intervention
Electro-stimulation and detection
Long term potentiation in hippocampus
Scanning techniques
Computerized Axial Tomography (CAT)
X-ray for looking at soft tissue anatomical features
Magnetic resonance imaging (MRI)
Orientation of unpaired hydrogen in magnetic field
Positron emission Tomography (PET)
Centres of activity located by radio-active labelling
Work on the living brain.
CAT and MRI show structural image whilst PET is a functional imaging technique
CAT vs MRI vs PET
CAT and MRI show structural image
PET is a functional image
Evidence from psychiatry for functioning of memory.
H.M. and Anterograde Amnesia
H.M suffered severe epilepsy which was treated by bilateral removal of temporal lobe
Produced similar symptoms to Korsakoff’s syndrome
I.e. Inability to form new memories
E.g. Location of new home, Identify new people
What forms the limbic system
Cingulate gyrus
Pineal gland
Fornix
Mammillary body
Hippocampus
Amygdala
Hypothalamus
Pituitary gland
Thalamus
Loss of memory
No impairment of immediate memory (E.g. can perform 7 number task)
Little retrograde amnesia
Therefore problem appears to be one of consolidation.
Can learn simple perceptual task (e.g. Priming), simple stimulus response tasks, and simple motor tasks.
But can not remember process of learning.
Therefore no problem with procedural learning, but there is a problem with relational learning.
HM performs as well as normal people on implicit, word completion tasks, but less well on explicit, free recall tasks.
Hippocampal lesions and memory loss
These appear to be necessary for relational memory and the consolidation of short-term memories.
Spatial memory and food caching
Store food in many locations
May locate caches by: cues (e.g. smell or local disturbance), simple rules (e.g. favoured locations) or good spatial memory.
Episodic memory
Time constrained
Activity of hippocampal region during learning tasks
Hippocampus found to be active during free recall tasks (PET scans)
Specific neurones fire during association of events
Appears to be particularly important in placing events in context.
I.e. Single stimuli can be associated via stimulus response learning
Complex rules e.g. Respond to either of two cues, but do not respond when both are present requires more complex circuitry.
Animals modes of memory
Difficult to study declarative learning in animals as they do not declare what they have learnt, so we tend to use models based on relational or spatial learning
Eg radial mazes or Morris
Remembrance of things past
term memories or simple rules
E.g. Rats can remember which arms are baited
But does impair use of working memory
E.g. Rats can not remember which arms they have visited.
And find it harder to locate platform if released from different sites in milky maze.
Synaptic plasticity
Based on connections that are already in place
Changes in sensitivity due to simultaneous activity of neurones.
Neural explanation of Hebb rule
Seen in Hebb synapse.
Connectionist
Based on formation of new connections
Potential to learn dependant on complexity of neural network.
2 theories for changes in association/memory
Classical conditioning (Pavlovian)
Step 1: Animal performs natural (unconditioned) response to stimulus e.g. Salivate or approach food dish
Step 2: New, unconditioned signal reliably precedes reward.e.g. Buzzer/light
Step 3: With repeated pairing, animal performs response (conditioned) to artificial, conditioned stimulus. Eg. Dog salivates in response to buzzer, even without feed reward.
Neural basis of memory and long-term potentiation
Memories are groups of neurones which fire together in the same order each time they are activated.
Links between individual neurones are formed by a process called long-term potentiation. (LTP)
First described by Bliss and Lomo (1973) in hippocampus
Field excitatory post-synaptic potential
Increased sensitivity (greater likelihood of firing)
Persistence: Increased sensitivity for hours or days.
Synapse Specificity: Not all synapses on neurone are effected
Associativity (Hebb Rule): Association between weakly firing and strongly firing synapses leads to potentiation of the weak synapses
Investigating long term potentiation - persistence
- Single stimulation leads to weak response
- Repeated stimulation leads to enhanced response (e.g. 100 signals in few seconds)
- If LTP has occurred then single stimulation will now lead to enhanced firing.
Association and specificity
- Locate strong synapse.
- Stimulate afferent neurone and record firing (EPSP) in strongly associated neurone.
- Pair strong (CS) stimulation with stimulation from weakly (US) associated neurone
- Leads to strong association between newly conditioned stimuli and recorded neurone.
Molecular mechanism of long term potentiation
Persistence, sensitivity and association can be explained by priming.
This appears to occur through depolarisation of the post-synaptic membrane.
This is mediated by the glutamate sensitive N-methyl-D-aspartate receptor (NMDA).
NMDA receptors act as calcium channels.
Glutamate (an excitatory neurotransmitter) activates NMDA.
But they are usually blocked by magnesium ions
If the post-synaptic membrane is depolarised magnesium ions are ejected so the calcium channels are freed.
Therefore activity of NMDA depends on both activation of synapse (glutamate as neurotransmitter) and post-synaptic membrane depolarisation (caused by activity in other synapses).
Depolarisation and priming
- Activity of strong synapse depolarises dendrite membranes
This primes NMDA receptors on dendrite spines (see above) - Activity of weak synapse releases glutamate
This opens (primed) NMDA receptors - Opening of calcium channels
Leads to entry of calcium ions and strengthens weak synapses.
Long term potentiation in rest of brain
Other LTP events appear to not depend on NMDA receptors
E.g. CA3 area of hippocampus
Other Sites of LTP
Cortex (including pre-frontal, motor and visual areas)
Limbic system: Thalamus and Amygdala
These may or may not involve NMDA
What primes the post synaptic knob in long term potentiation - NMDA receptor
Magnesium ions replaced by calcium ions
Ostensive definition of emotions
Conveys the meaning of a term giving examples, things like anxiety, fear and frustration
Operational definition of emotion
Designed to model or represent a construct, physiological and behavioural reactions associated with a particular stimulus which reflect the personal significance of the stimulus to the individual
Intensional definition of emotions
Gives meaning to a term by specifying necessary and sufficient conditions for when the term should be used
What it needs to have to be an emotion
Emotion
complex reaction pattern, involving experiential, behavioral, and physiological elements, by which an individual attempts to deal with a personally significant matter or event.
The specific quality of the emotion (e.g., fear, shame) is determined by the specific significance of the event.
For example, if the significance involves threat, fear is likely to be generated; if the significance involves disapproval from another, shame is likely to be generated.
Emotion typically involves feeling but differs from feeling in having an overt or implicit engagement with the world. —emotional adj.
Component process theory
An operational approach to defining emotion
Cognitive
Neurophysiology
Motivation
Motor expression
Subjective feeling
Component process theory - cognitive
Appraisal
Information processing
Evaluation of events and objects
Component process theory - neurophysiology
Bodily signs/ arousal
Support
System regulation and preparation
Component process theory - motivation
Action tendency
Executive control
Direction of action
Component process theory - motor expression
General and Specific eg facial, behaviour
Action
Communication of reaction and intention
Component process theory - subjective feeling
Experience
Monitor
Monitoring and co-ordination of internal state relative organism-environment interaction
The triune brain
Emotional state is a reflection of more general
brain state rather than activity in a specific structure
Neocortex- association areas
Limbic brain/ thalamo-hippocampal system
Basal ganglia/RAS
Limbic brain/ thalamo-hippocampal system
Affective responses associated with individual appraisal / encoding value
Neo cortex/ association areas
Behaviour informed by Associative information and concept formation
Basal ganglia/ RAS
Innate behavioural responses
Survival habits
Declarative information
Emotion primitives
Recognising the evolutionary building blocks of emotional responses:
An operational approach
Scalable responses
Valence
Persistence
Generalisation
Panksepp’s affective systems
An intensional approach to defining emotion in non-human vertebrates
- Circuits have a genetic basis for responding to biologically significant unconditional stimuli
- Circuits organise behaviour, through the regulation of effective biologically based subroutines
— autonomic, hormonal & motor - Circuits change the sensitivity of relevant sensory systems
- Activity feeds back on and outlasts precipitating circumstances
- Circuits can come under the control of conditioned stimuli
- Circuits interact with higher cognitive brain circuits
What allows for the recognition of emotional processes across non-human taxa
Operational and intensional definitions
Function of emotions
serve an important function which facilitates individual differences in behaviour in response to the same stimuli and so their basic functional constituents are probably quite widespread within the animal kingdom