Lectures 1-3 Flashcards
Why is neuroscience is considered highly reductionist?
Many areas of neuroscience focus on proteins and ion channels rather than understanding how networks of neurons interact.
Why is understanding emergent brain activity important?
Studying a single neuron does not explain how 100 billion neurons work together to produce cognition.
Why is computational neuroscience becoming more important?
Advancements now allow us to record up to 800 neurons simultaneously in a rat’s brain, providing insights into brain function.
When did cognitive neuroscience emerge as a field?
It became an established field in the 1980s.
What is a definition of cognition?
The mental process of faculty of knowing, including aspects such as awareness, perception, reasoning, language, memory and judgement.
What makes seemingly simple cognitive tasks actually complex?
Tasks like reading seem easy but involve intricate neural processing.
Why is reading considered a difficult cognitive task?
Reading is a recently developed human skill that requires translating visual symbols into auditory language comprehension.
Why is reading an evolutionary challenge?
Humans did not evolve specifically for reading; it requires the brain to repurpose regions for symbol recognition.
What is the the cognitive approach based upon?
Information processing; the transformation of sensory input into memory and/or action.
What does the existence of the brain imply about the memories and cognitive processes?
As the brain has a physical structure, these representation must exist at a physical level (e.g., a distinctive pattern of neural activity within a neural ensemble).
What is the role of action potentials in the brain?
They function as the brain’s communication signals, but their patterns determine perception and cognition.
What does Cognitive Psychology seek to show?
That our knowledge of the world is based upon our biological apparatus for perceiving the world.
AND
Our perception is a constructive process that depends up on both information about the stimulus and the mental structure of the perceiver.
How does perception differ from sensation?
Sensation involves external stimuli input, whereas perception is the brain’s interpretation of that input.
What do behaviorists focus on in cognitive processes?
They study the relationship between sensory input and behavioral output, without considering internal mental processes.
What does cognitive psychology aim to understand?
It seeks to explain the mental processes that occur between sensation and behavior.
What are 5 major factors that established cognitive neuroscience as a discipline?
- The ability to record the activity of single neurons in behaving animals.
- The ability to link these activity patterns to ongoing cognitive processes.
- Renewed interest in the relationship between brain injury and behaviour.
- The development of new recording techniques (e.g., PET, fMRI) that allow the activity of large neuronal populations to be correlated with behaviour.
- The rise of computational approaches to both information processing and modelling of neural networks.
When did neuropsychology contribute significantly to neuroscience?
In the late 1960s and 1970s, lesion studies linked specific brain regions to behaviours.
How do PET and fMRI improve lesion studies?
They provide modern brain imaging techniques that map lesions and their behavioural effects whilst the patients are living; they don’t need to be done post-mortem like traditional lesion studies.
Why is memory a crucial aspect of human life?
Memories shape our identity and influence our experiences and decisions.
How does Alzheimer’s disease affect memory?
It first impairs the formation of new memories before progressing to difficulties retrieving old memories.
Why does Alzheimer’s disease change a person’s identity?
Memory loss alters personal experiences, affecting self-perception and interactions with others.
What methodological change in psychological research did Pavlov and Ebbinghaus champion?
The move from introspection to the experimental approach.
Who was Ebbinghaus and what was his key discovery?
Hermann Ebbinghaus studied memory and developed the forgetting curve, which describes how information is lost over time.
What is the forgetting curve?
The forgetting curve shows how information is lost over time when there is no attempt to retain it.
It demonstrates that memory decline is exponential, with the sharpest decline occurring within the first few hours after learning, followed by a more gradual drop.
What is the spacing effect?
The spacing effect is a learning phenomenon where information is better retained when study sessions are spaced out over time, rather than crammed into a single session, even when the total study time remains the same.
There is improved recall and understanding due to the spacing effect.
What experiment did early behaviorists conduct with problem-solving?
They studied how animals learned to escape from boxes through trial and error.
Who was Edward Thorndike and what did he do?
He was a connectionist and functionalist - precursors to behaviourism - who attempted to develop and experimental method for the mechanical problem-solving ability of cats and dogs.
What was the set up for Thorndike’s Puzzle Box ‘K’?
It was a wooden box/cage that had multiple steps to remove the barricade keeping the animal in.
He would time the latency to escape over time and looked to see if there was learning from cats and dogs.
What was a key finding from early Thorndike’s experiments?
Animals reduced escape time with repeated trials, showing learning through reinforcement.
What was Thorndike’s principle of “Law of Effect”?
He stated that learnt associations are strengthened by use (if ‘pleasurable’) and weakened with disuse (if ‘discomfortable’).
He also thought that all human behaviour could be explained in terms of the development of myriads of stimulus-response associations.
What was the core belief of early behaviourism?
Learning occurs through stimulus-response associations reinforced by rewards or punishments.
How did behaviourists explain learning?
They believed all behaviour results from conditioned responses to stimuli.
What assumption did behaviourists make about human cognition?
They assumed cognition could be fully explained through observable stimulus-response relationships.
How is the ability to learn in an animal measured?
Only by the performance on a task.
What does an animals performance on a task depend on?
Recall.
What are two ways in which recall can be defined (animals)?
The successful use of learned experience.
The expression of a response that was modified by learning.
Recall depends on the extent to which… (2)
The material was originally stored in memory (e.g., did any learning originally take place?).
The material is still available (e.g., is the memory forgotten?).
How does recall depend upon the timing of events? (2)
Information may be irrelevant at the time and therefore not learned.
Information may have been of use many years ago but of no use now - have you forgotten it or can you just not recall it.
What is a widely held view about learning?
It produces a change in the nervous system - a memory.
It may only be transient (e.g. reverberatory activity) or it may last a lifetime (a permanent physical change).
How does memory retrieval affect memory stability?
Each time a memory is recalled, it is subtly modified.
What does memory retrieval do to identity?
Revisiting memories alters them slightly, shaping a person’s evolving sense of self.
What is required to recall a memory after it has happened?
You need changes in your neural structure to record the details of what the sensations were at the time.
What was Hilgard and Marquis (1940) theory of how memories were stored?
According to Hilgard and Marquis (1940), the reverberatory transient trace is a temporary pattern of neural activity that persists after a stimulus has ended, where neurons continue to fire in circuits or loops for a brief period.
This ongoing neural activity serves as a temporary memory trace that helps bridge temporal gaps between stimuli, making it important for learning and forming associations.
How do neural activity patterns contribute to memory?
Distinct patterns of neural activity encode, store, and retrieve memories.
What are the 3 main types of learning?
Non-associative learning.
Associative learning.
Complex learning.
What is non-associative learning?
A change in response after repeated stimulus exposure.
What is associative learning?
Exposure to 2 or more stimuli that have a particular relationship to each other.
Demonstration of learning is given by expressing evidence of having made an association between the stimuli.
What is complex learning?
Learning that seems more complex than associative learning.
This learning can involve insight or reasoning (e.g., novel routes through mazes, imprinting, bird song-learning, tool use in chimps and imitation learning).
What is habituation?
A reduction in the effectiveness of a stimulus in producing a response when the stimulus is presented repeatedly but with no serious consequence to the animal.
Why is habituation adaptive?
It saves the animal time and energy.
Why is habituation a useful form of learning to study experimentally?
There is only one stimulus.
The relationship between stimulus and response can be quantified accurately.
Why do repeated exposures to stimuli lead to habituation?
The brain gradually reduces responses to familiar stimuli, conserving cognitive resources.
What is required to demonstrate associative learning?
A connection must be formed between two or more stimuli.
What is the name of the model sea slug used to study learning and memory?
Aplysia
How does a sea slug demonstrate habituation?
It withdraws its gill less with repeated gentle taps, showing decreased response to a non-threatening stimulus.
What happens when a stimulus is more intense?
A stronger stimulus triggers a sustained response due to perceived threat.
Why is associative learning useful for animals?
Animals need to be aware of events that produce changes in the environment.
The ability to associate these events and identify the causes, then the animals can take appropriate actions.
The ability to associate these events with positive or negative outcomes has adaptive value (e.g., food availability; production of sickness).
What were the two types of associative learning introduced in the early 20th century?
Classical conditioning and Instrumental conditioning.
What is a unconditioned reflex?
It is an action that occurs when an unconditioned stimulus (US) produces an uncontained response (UR).
It’s a very robust reflex (naturally occurring process).
What is the conditioned reflex?
It is a reflex acquired through experience - thus it is far less robust that an unconditioned reflex.
This is due to the pairing of a previously neutral stimulus to a unconditioned stimulus so that an association builds to the extent that the neutral stimulus elicits a response - a conditioned response.
What is an example of associative learning?
Pavlov’s dogs learned to associate a bell with food, causing them to salivate.
What did Behaviourists such as B.F Skinner and J.B Watson argued about behaviour?
That it could be studied with the same precision as that available in the physical sciences, provided that investigators abandoned the traditional approach of introspection and, instead, turned to the observation of behaviour.
They also thought that all that mattered was an appreciation of physical stimuli and the behavioural responses to them; anything ‘in between’ was deemed to be irrelevant.
What concept did B.F Skinner develop? Outline it.
Operant conditioning.
He developed the Skinner Box, which allowed sequences of behaviour produced over a long time to be studied objectively.
The operant is a behaviour.
The experimenter changes how often the animal displays this behaviour by associating it with a positive or negative reinforcer or punishment.
What is another term for Operant conditioning?
Instrumental conditioning.
What is the “Win-stay, lose-shift strategy”? Why is it useful?
The win-stay, lose-shift strategy task for monkeys is a learning paradigm where monkeys are presented with multiple choices (typically different objects or locations) and must learn to make optimal decisions based on reward outcomes.
If a choice results in a reward (win), the monkey should “stay” with that same choice on the next trial. If a choice results in no reward (lose), the monkey should “shift” to a different option on the next trial.
This task tests the animal’s ability to learn from feedback and adjust their behaviour accordingly, and is often used to study decision-making and reinforcement learning in primates.
What results were found from the win-stay, lose-shift strategy tests in monkeys?
After 100s of trials, Macaque monkeys extract the general features of tasks. They then perform with almost no error.
Who first introduced mazes to animal learning studies and what was their inspiration?
Willard Small (1901) introduced the maze to animal learning studies, inspired by the Hampton Court maze.
What was Small’s key observation about rat behaviour in mazes?
Rats would quickly choose shortcut routes to the goal, despite being previously reinforced to run different routes through the maze.
What major controversy in animal learning did Small’s maze findings help establish?
Whether learning could be reduced to simple stimulus-response associations OR if factors like cognition, insight and motivation must be considered.
What did Small’s maze experiments suggest about animal learning beyond simple conditioning?
His findings suggested that animals could demonstrate complex learning behaviours involving insight and cognitive mapping, rather than just following reinforced paths.
Why do naïve animals learn differently from experienced ones?
Some species, like rats, learn by observing others, while others rely on direct experience.
How does repeated stimulus exposure relate to advertising?
Initially, advertisements grab attention, but repeated exposure leads to habituation and reduced response.
What must happen to encode an experience as a memory?
The brain must undergo structural and chemical changes to store the event.
How does retrieval of a memory impact its accuracy?
Each recall slightly alters the memory, reinforcing or distorting details.
How did early experiments demonstrate trial-and-error learning?
Animals in boxes had to repeatedly attempt different actions to escape, gradually learning the correct behavior.
What is the relationship between action potentials and perception?
The frequency and pattern of action potentials determine sensory experiences and cognitive processing.
What is the significance of lesion studies?
They help identify which brain regions control specific behaviors by examining deficits after damage.
How does habituation help organisms conserve energy?
Reducing responses to harmless, repetitive stimuli prevents unnecessary energy expenditure.
How does cognitive neuroscience benefit from technological advances?
Modern imaging techniques enable detailed study of brain activity and cognitive processes.
!!!START FROM HERE!!!
!!!START FROM HERE!!!
What navigation method do nocturnal ants use?
Nocturnal ants use moonlight polarization as a direction indicator.
What is meant by egocentric navigation?
It’s navigation based on internal sensory cues (e.g., proprioception).
What are ants visual systems sensitive to?
Polarised light.
What is the weight of an ant’s brain?
O.1mg
What must ants have, given it is most adaptive for them to take food straight back to their nest?
A system which can compute the resultant vector to head straight back.
How do desert ants determine their location?
Desert ants store information about distance traveled and direction using their visual system, which is sensitive to polarized light.
What is the most adaptive behavior for an ant carrying food?
Taking the food straight back to the nest using a computed resultant vector.
How do ants update their navigation?
Ants update vectors based on their vector maps and celestial compass, using proprioception.
What experiment by Wittinger, Wehner & Wolff (2006) tested ants’ step-counting ability?
METHODS:
- Ants were made to locate food and then take it back to their nests.
- Ants had their legs lengthened (stilts) or shortened either:
A - Once they found food.
B - Before they found the food.
- Accuracy to returning home was measured.
RESULTS:
- Ants with leg length changed once food had been found showed that it affected their return distance, over or undershooting depending on if they were lengthened or shortened.
- Ants with leg lengths altered pre-trip found no difference in accuracy.
This suggests they count steps.
How do homing animals navigate?
They use roads and external cues to create internal maps.
What is allocentric navigation?
Navigation that utilises external cues, such as landmarks, roads etc.
What is path integration?
A method that allows animals to track their position within a known area by integrating linear and angular self-motion.
*Tends to accumulate more errors.
What are local/cognitive maps?
They are detailed local maps based on external cues.
*They are highly accurate.
What are some examples of homing animals?
Birds, ants, and mammals use homing abilities, often relying on environmental cues and cognitive maps.
What are the two types of cues used in navigation (spatial learning)?
Idiothetic cues (aka egocentric).
External landmark cues (aka allocentric).
Describe idiothetic cues.
Also known as egocentric.
Internally generated and provide the basis for navigation by path integration.
E.g., Vestibular input, proprioceptive information and optic flow.
Used subconsciously to compute turns and distance travelled.
Only works in an environment that you know well and can accumulate lots of errors.
Describe external landmark cues.
Also known as allocentric.
Externally generated and range between large scale (buildings/roads) and small scale (pictures on wall/furniture).
They are the basis for a cognitive map.
How does supervised learning differ from unsupervised learning?
Supervised learning involves reinforcement or rewards, while unsupervised learning does not initially have an explicit reward.
In computational terms, what is supervised learning?
It is learning by a system that monitors the prediction error and then adjusts associative weights within a supportive network to minimise this error.
In computational terms, what is unsupervised learning?
Learning that occurs when there is no explicit (at least to the subject) learning outcome, e.g., spatial learning.
What did Tolman’s rat experiment demonstrate?
Unrewarded rats formed cognitive maps of a maze and later used them efficiently once rewards were introduced.
Describe the study by Tolman (1930) into unsupervised learning in rats.
METHODS:
- 2 Groups of Rats.
- One group trained to run for food.
- One group had no food until day 11.
- Measured their deviation from the optimal path from getting to the food.
RESULTS:
- The fed group initially got better as they were being enforced by food.
- The delayed fed group weren’t that good until they were fed, in which they began to outperform the fed group.
- Suggested that the unfed group produced a cognitive map through unsupervised learning in the initial phase.
- Once this map became important, they used it to drive their performance in the maze.
What is a cognitive map?
An internal representation of spatial relationships in an environment, used for navigation.
How do rats demonstrate insight in spatial learning in the detour experiment?
They adapt to blockages in a maze by finding the shortest route instead of repeating previous behaviours.
This suggests their learning isn’t simply stimulus response, as you have to discern the best route and not simply repeat what you’ve already learnt.
What is the role of the hippocampus in spatial memory?
The hippocampus is essential for forming spatial memories and cognitive maps.
What did Scoville and Milner discover in the 1950’s?
That bilateral removal of the medial temporal lobes in humans (including the hippocampus) produced a profound impairment in episodic memory (anterograde amnesia; the inability to learn new declarative information).
*At the time people thought memory was in the cortex alone and had NOTHING to do with subcortical structures.
Describe the trisynaptic circuit in rodent hippocampus.
It’s a key pathway for memory formation and consists of three major synaptic connections:
- Entorhinal cortex → Dentate gyrus (perforant path): Input from the entorhinal cortex synapses onto granule cells in the dentate gyrus.
- Dentate gyrus → CA3 (mossy fibres): Granule cells project mossy fibres to pyramidal cells in the CA3 region.
- CA3 → CA1 (Schaffer collaterals): CA3 pyramidal cells project Schaffer collaterals to pyramidal cells in the CA1 region.
What is true about the hippocampus between rats, monkey and humans?
The size of it hasn’t expanded hugely over time; its relatively the same size in humans - it’s the neocortex that is bigger.
What happened to hippocampal and entorhinal cortex positioning from rodent to macaque to human?
The expansion of the cortex pushed the hippocampal structures down and round into the temporal cortices.
What methodology did David Olton introduce into research of spatial memory? Explain the concept.
The radial arm maze.
It’s a behavioural test used to assess spatial learning and memory in rodents.
It consists of a central platform with eight equally spaced arms extending outward, each potentially containing food rewards at their ends, and with a random allocation of spatial cues around the outside of the maze.
Animals must remember which arms they’ve already visited to efficiently collect all rewards, testing both working and reference memory.
Performance is measured by tracking errors (revisits) and completion time.
This task is heavily dependent on hippocampal function and relies on the animal’s ability to use spatial cues for navigation.
Within the Radial Arm Maze paradigm, what is reference memory?
This is memory used between trials.
For example, the fact that all arms (or a subset) are always baited.
Within the Radial Arm Maze paradigm, what is working memory?
This is memory used within a trial.
For example, a mental note of the arms already visited by the rodent.
What is the paradigm that Richard Morris made to test spatial learning in rodents? Outline it.
The Morris Water Maze.
It’s a behavioural test that assesses spatial learning and memory in rodents.
It consists of a circular pool filled with opaque water containing a hidden platform just below the surface.
Animals must learn to locate this invisible platform using spatial cues placed around the room.
Learning is measured across multiple trials by tracking swim path, escape latency (time to find platform), and time spent in the target quadrant during probe trials (when platform is removed).
What are probe trials in the water maze paradigm and what did the results of these trials show?
Probe Trial = Recall. Once training has been complete (exposed and found the location of the platform, the platform is removed to watch the rats behaviour.
If the platform is removed, rats spend most time searching in the ‘correct’ quadrant for the platform.
This shows that it remembered.
What is true of cued vs spatial versions of the water and radial arm maze - what will they show about learning?
If the hippocampus IS involved in making maps and spatial memory, it’s lesioning should disrupt memory trials but NOT these cued versions of tasks.
What is the entorhinal cortex?
A major cortical input structure to the hippocampus.
What is the septum.
A major subcortical input structure to the hippocampus.
What is the fornix?
A region that has input/output role for subcortical <-> hippocampal axonal projections.
What is the Fimbria?
A structure that carries the CA3 commissural connections to ipsilateral CA1.
(Associated w/ the hippocampus).
What did lesions across the Entorhinal cortex, Fimbria-fornix, post commissural fornix and the septum in the Radial arm maze show in cued learning vs spatial learning trials?
Showed that you need the hippocampus for spatial but NOT cued learning:
Cued learning was always okay; it actually slightly improved in some conditions (due to no competition from declarative memory).
However, the spatial learning conditions experienced a large deficit.
What experiment into the neural basis of the cognitive map did John O’Keefe create?
The cylindrical open field recording apparatus.
Put an animal in an arena and recorded from single cells in the hippocampus and then mapped where the animal was when certain cells were active.
Used this methodology to show that the hippocampus contains place cells that fired action potentials when the rat entered the place cell’s place field.
What does place fields being non-topographic mean?
It means that adjacent cells in the hippocampus do not encode adjacent spaces in the physical world.
What are place cells?
Neurons in the hippocampus that fire when an animal is in a specific location within an environment; they encode spatial information.
What type of neuron are hippocampal place cells presumed to be?
Pyramidal cells.
When do place cells tend to fire ‘complex bursts’?
As the animal moves through a specific location.
What is a place field defined as?
The area in which a place cell fires maximally - this is the place field of that neuron.
What are 3 key properties of place cells and what are their significance?
Place fields demonstrate remarkable stability and robustness in several ways:
- Temporal stability: Can persist up to 6 months in rats
- Rotational stability: Maintain their firing patterns even when environment is rotated
- Cross-species conservation: Present in both rodent and human hippocampus
These properties indicate that place cells create a reliable and persistent spatial map of the environment.
What is the cognitive map hypothesis, originally proposed by O’Keefe and Nadel (1976)?
(As the neural basis for the cognitive map)
The construction of the hippocampal spatial map relies on the availability of external sensory cues to generate an internal map of the environment and signal the position of the animal within this map.
Thus, this theory does not depend on motion or memory.
The major (and perhaps only) function of the hippocampus according to this model is spatial navigation.
What is the path integration hypothesis?
(As the neural basis for the cognitive map)
A proposed mechanism where the brain tracks position by calculating distance and direction from a starting point, even without external cues.
Relies on grid cells (providing spatial metrics), head direction cells (orientation), and place cells (integrating self-motion with landmarks) to form a comprehensive neural framework for navigation.
This allows animals to track position continuously and navigate effectively in both familiar and novel environments.
What is the memory system hypothesis?
(As the neural basis for the cognitive map)
Eichenbaum and co-workers suggested that place cells form part of a more general hippocampal ‘episodic’ system.
This memory system serves to encode the different aspects of any event into an episodic memory (presumably for long-term storage in the cortex.
What information do Place fields provide?
Omnidirectional positional and contextual information (cognitive maps).
What are head direction cells?
Cells in rat, monkey and human presubiculum that fire when the animals face a particular direction.
They fire:
- In a 90 degree arc around their preferred direction.
- To the same direction in different environments.
They may play a role in ‘orienting’ spatial maps in the hippocampus (analogous to a compass).
What two brain regions are associated with Head direction cells?
The presubiculum and the anterior thalamus.
What did May-Britt & Edvard Moser discover in the entorhinal cortex?
They found cells - gird cells - that encode distance; they can keep track of ‘how many nodes’ the animal has been through.
What are grid cells?
Neurons in the entorhinal cortex that fire in a hexagonal grid pattern, aiding in spatial navigation.
Each grid cell has multiple firing fields arranged in a triangular lattice, creating a repeating hexagonal grid pattern.
Different grid cells have different scales of this pattern, with some firing in larger hexagons and others in smaller ones but all maintain the same geometric organization.
This pattern provides a coordinate system for spatial navigation.
In what arrangement are grid cells in the brain?
They are arranged topographically, unlike place cells.
What are some key characteristics of grid cells?
They are arranged topographically.
They are context independent & maintain a constant spacing between peaks in firing rate.
The grid they generate adjusts for speed.
They have more than one node (place cells only have one).
What did recordings from hippocampal place cells show?
Place cells fire at specific locations in an environment, forming a spatial representation.
What is dead reckoning?
A navigation method where one’s current position is estimated based on previous positions, using cues like direction, velocity, and time.
How do rats use cognitive maps in maze experiments?
They find the shortest path by using stored spatial information rather than simple stimulus-response behaviors.
What is the difference between cued learning and spatial learning?
Cued learning does not require the hippocampus, while spatial learning depends on it.
How do head direction cells function?
They fire based on the direction an animal is facing, regardless of position in space.
How do grid cells encode distance?
They fire in repeating patterns, allowing an animal to track its movement through space.
What is the relationship between the hippocampus and the entorhinal cortex?
The hippocampus forms cognitive maps, while the entorhinal cortex aids in path integration.
What experiment demonstrated place cells?
Recording from single cells in a rat’s hippocampus showed that specific neurons fired when the rat was in a particular location.
How do rats demonstrate spatial learning in the water maze?
Rats learn to locate a hidden platform using external reference cues.
What happens when the platform is removed in the water maze?
Rats spend more time in the area where the platform used to be, indicating spatial memory.
What is the radial arm maze used to study?
It assesses spatial memory and learning by measuring how well animals remember which arms contain food.
What does lesioning the hippocampus do to spatial memory?
It impairs spatial memory but does not affect cued learning.
What is the primary function of the entorhinal cortex?
It provides input to the hippocampus and plays a role in spatial navigation and memory.
What happens to spatial learning if the entorhinal cortex is damaged?
It disrupts grid cell activity and impairs spatial navigation.
What is the primary function of the anterior thalamus in spatial memory?
It helps process directional and spatial information.
How does the presubiculum contribute to navigation?
It contains head direction cells that help determine orientation in space.
Why do hippocampal place cells rotate with environmental cues?
They align with spatial reference points to maintain accurate mapping.
How does the hippocampus interact with the neocortex in memory formation?
The hippocampus encodes and consolidates spatial memories, which are later stored in the neocortex.
What is the role of the subiculum in navigation?
It processes spatial information and relays it between the hippocampus and other brain areas.
What is the significance of hexagonal firing patterns in grid cells?
They provide a consistent metric for spatial representation across different environments.
What role do boundary cells play in spatial memory?
They fire in response to environmental borders, helping to define spatial limits.
How do hippocampal lesions affect navigation in open environments?
Lesioned animals struggle to navigate efficiently without spatial cues.
What is the impact of hippocampal damage on episodic memory?
It impairs the ability to form and recall detailed spatial and temporal memories.
What is the Morris water maze?
A behavioral test used to study spatial learning and memory in rodents.
What are the main inputs to the hippocampus?
The entorhinal cortex provides major input to the hippocampus.
What role does the retrosplenial cortex play in navigation?
It helps integrate spatial and directional information for memory formation.
What are sharp-wave ripples in the hippocampus?
High-frequency oscillations that are crucial for memory consolidation.
How do animals use boundary cells for navigation?
Boundary cells fire when an animal is near the perimeter of an environment.
What is the significance of theta oscillations in the hippocampus?
They help synchronize neuronal activity for spatial navigation and memory encoding.
What is the function of the dentate gyrus in spatial memory?
It aids in pattern separation and the formation of distinct memory representations.
How do hippocampal lesions affect long-term spatial memory?
Lesions disrupt the ability to remember locations over time.
What is the role of head direction cells in navigation?
They provide an internal compass by firing in response to an animal’s orientation.
What is the role of the fornix in spatial memory?
It connects the hippocampus with other brain areas involved in navigation and memory.
What is the importance of the medial septum in memory?
It regulates hippocampal theta oscillations, which are crucial for spatial learning.
How do animals use optic flow for navigation?
Optic flow refers to the movement of visual patterns that help animals estimate speed and direction.
What did experiments on arena exploration reveal about place cells?
They fire at specific locations, forming a map of the environment.
How do grid cells in larger environments behave?
They maintain their hexagonal firing pattern but scale with environmental size.
Who was patient HM and why is he significant?
Patient HM (Henry Molaison) was a famous neurological case who underwent medial temporal lobe resection, leading to severe anterograde amnesia. His case transformed the understanding of memory as previous to him memory was thought to be cortical only.
What was the cause of HM’s memory impairment?
HM underwent bilateral medial temporal lobe resection to treat epilepsy, which removed most of his hippocampus and adjacent structures, causing severe memory deficits.
Ended up having the anterior 2/3 of his hippocampus removed.
Briefly describe the differences between Normal EEG and Grand Mal seizure EEG traces?
A normal EEG displays organised, rhythmic patterns with lower amplitude waves and clear distinctions between different wave types.
Grand Mal seizure EEG shows chaotic, disorganized patterns with high amplitude spikes and waves, characterized by rapid, excessive synchronous firing and spike-and-wave complexes.
After the seizure, the EEG may demonstrate post-ictal slowing.
What is the modern ‘medial’ approach to medial temporal lobectomy?
Create a small temporal lobe resection (small cut in the temporal lobe).
This allows the surgeon to visualise the amygdala and hippocampus for subsequent removal, allowing for much more precision in the tissue removal.
Saves more amygdala and is less damaging.
What type of memory was most affected in HM?
HM had profound anterograde amnesia, meaning he could not form new declarative memories, though his procedural memory remained intact.
More specifically, it was episodic amnesia and he had a strong spatial memory deficit.
What is declarative memory?
Declarative memory refers to memory for facts and events, including episodic (events) and semantic (facts) memory.
What is procedural memory?
Procedural memory involves the ability to learn new motor skills and habits, independent of conscious recall, such as riding a bike or mirror drawing.
What brain region is crucial for declarative memory?
The medial temporal lobe, including the hippocampus, is critical for declarative memory formation.
What is anterograde amnesia?
Anterograde amnesia is the inability to form new memories after the onset of brain damage.
What is retrograde amnesia?
Retrograde amnesia is the loss of memories formed before the onset of brain damage, often affecting recent memories more than older ones.
What did HM’s case reveal about the hippocampus?
His case demonstrated that the hippocampus is essential for forming new declarative memories but not for retaining old ones.
How was HM’s IQ affected by his surgery?
His IQ actually increased slightly post-surgery, indicating his cognitive abilities were largely intact apart from memory deficits.
What is the delayed non-match to sample task?
A test used in animal studies where subjects must select a novel object instead of a familiar one, assessing declarative memory.
How do medial temporal lobe lesions affect memory performance in the delayed non-match to sample task?
Lesioned animals perform worse as the delay increases, indicating a role for the medial temporal lobe in long-term memory.
What role does the amygdala play in memory?
The amygdala is involved in emotional processing and memory but is not essential for declarative memory formation.
How did HM perform on procedural learning tasks?
He improved on tasks like mirror drawing despite having no memory of previous trials, indicating intact procedural memory.
What is perceptual memory and why was it intact in H.M?
Is learning about things rather than what to do when they are present.
It’s dependent on sensory association cortex, not the medial temporal lobe.
What did the Gollins partial pictures task demonstrate about HM?
HM showed intact perceptual learning, recognising fragmented images more quickly with repetition, despite not recalling previous trials.
His deficit was shown in retest trials; controls improved massively but he only had minor performance improvements.
What is the significance of patient RB in memory research?
RB had selective CA1 hippocampal damage, meaning that the specific role of the hippocampus could be measured.
He exhibited severe anterograde amnesia, reinforcing the hippocampus’s role in memory formation.
What did DNMTS lesion studies in macaque monkeys show about the medial temporal lobe?
They demonstrated that more extensive damage to the hippocampus and surrounding cortex results in greater memory deficits.
What is the DNMTS training task?
Delayed non-match to sample task has three stages:
- SAMPLE
Monkeys are presented with a sample object in which there is food underneath. - TEST
After a variable delay (to test memory duration) the monkey is presented with sample object and another object. - NON-MATCH
Over a series of trials with different pairs of object, the monkey learns that food is present under the object that differs from the sample.
What effect do lesions of the amygdala have on declarative/explicit memory?
No effect.
What is the difference between short-term and long-term memory in terms of brain structures?
Short-term memory does not require the medial temporal lobe, whereas long-term declarative memory does.
What is important to consider about memory retrieval?
Information retrieved into consciousness (STM) undergoes re-encoding (re-consolidation) and back to the LTM.
Thus, retrieving a memory changes that memory.
What did studies on monkeys show about memory retention over different time delays?
Monkeys with medial temporal lobe lesions could remember objects for short delays but performed at chance levels for longer delays.
The severity of the deficit was in the following order: (least to most)
1. Hippocampus
2. Hippocampus, adjacent Entorhinal cortex and Parahippocampal cortex.
3. Hippocampus, anterior Entorhinal cortex and Perirhinal cortices.
Therefore, the more of the MTL you remove, the stronger the amnesia.
What is the impact of hippocampal damage on object recognition memory?
Hippocampal damage impairs long-term object recognition, but animals may still retain short-term familiarity-based recognition.
(Based on Monkeys from DNMTS task).
What does good performance in monkeys on short delays in DNMTS tasks suggest that lesioned monkeys can do? (3)
- Attend to, perceive and encode object cues - (the ventral ‘what’ and dorsal ‘where’ sensory streams are intact in MTL amnesics).
- Execute choice responses, are motivated to perform and can acquire and retain the non-matching rule.
- Can also acquire motor skills.
Thus MTL is NOT necessary for STM.
How does depression affect memory recall?
Depression can alter retrieved memories by adding negative affect, leading to a biased recall of past events.
What is reconsolidation in memory processing?
Reconsolidation is the process by which a recalled memory becomes temporarily labile and can be modified before being stored again.
What was the primary finding of the London taxi driver study?
The study found that extensive spatial navigation experience correlates with increased hippocampal grey matter volume, supporting its role in spatial memory.
How do animal studies support the role of the hippocampus in memory?
Experiments in monkeys and rodents show that hippocampal damage impairs long-term memory and spatial learning while sparing short-term recall.
What is the function of the medial dorsal thalamus in memory?
The medial dorsal thalamus is implicated in familiarity-based memory recognition rather than recall-dependent memory formation.
How do lesion studies help distinguish between familiarity and recall memory?
Lesions in different brain regions show that recall depends on the hippocampus, whereas familiarity-based recognition relies more on cortical and thalamic structures.
What is the role of the perirhinal cortex in memory?
The perirhinal cortex is important for object recognition and familiarity-based memory but not for episodic recall.
What is the significance of the CA1 field in the hippocampus?
The CA1 field is crucial for memory consolidation, and damage to it (e.g., in patient RB) results in severe anterograde amnesia.
What does the concept of memory consolidation suggest about long-term memory storage?
Memory consolidation suggests that long-term memories become independent of the hippocampus over time and are stored in the neocortex.
What is the difference between episodic and semantic memory?
Episodic memory involves recollection of specific events, while semantic memory refers to general world knowledge and facts.
Question
Answer
What is the standard method for detecting epileptic seizures?
Electroencephalography (EEG) is commonly used to detect abnormal electrical activity in the brain associated with seizures.
Why was HM’s case initially considered unremarkable post-surgery?
Patients with similar surgeries appeared fine initially, and the specific memory deficits were only detected through psychological testing.
What is a grand mal seizure?
A grand mal seizure is a type of generalized seizure that involves loss of consciousness and violent muscle contractions.
How did intracranial EEG improve seizure detection?
Intracranial EEG provides more precise seizure localization by placing electrodes directly on the brain surface, reducing signal distortion.
How did HM’s memory loss change over time?
His memory deficits remained static over the years, allowing detailed long-term study of his condition.
What is the primary difference between procedural and declarative memory?
Procedural memory involves motor skills and habits, while declarative memory involves facts and events that can be consciously recalled.
How did Brenda Milner contribute to memory research?
Milner conducted extensive tests on HM and discovered his selective memory impairment, shaping modern memory theories.
What does the term ‘medial temporal lobe amnesics’ refer to?
It refers to individuals with damage to the medial temporal lobe, leading to severe declarative memory impairment.
What does the hippocampus integrate to form episodic memories?
The hippocampus combines spatial, sensory, and contextual information to create cohesive episodic memories.
Why is the hippocampus evolutionarily significant?
Despite being an ancient brain structure, it plays a crucial role in complex memory functions, challenging prior assumptions.
What are place cells in the hippocampus?
Place cells are neurons that become active when an animal is in a specific location, contributing to spatial memory and navigation.
What was the key finding in Eleanor Maguire’s taxi driver study?
London taxi drivers had larger hippocampi due to extensive spatial navigation experience, supporting its role in spatial memory.
What evidence supports hippocampal involvement in non-spatial memory?
Some hippocampal neurons respond to contextual cues such as sounds, smells, or specific objects in a memory.
What is the impact of removing the amygdala along with the hippocampus?
Patients may experience additional emotional and social processing deficits, beyond just memory impairment.
What is the role of the perirhinal cortex in memory?
The perirhinal cortex supports familiarity-based recognition and object memory, separate from hippocampal recall functions.
How does the hippocampus contribute to memory retrieval?
It reactivates stored information, allowing recall of past events and integrating related details.
What memory impairments result from selective CA1 hippocampal damage?
Damage to CA1 disrupts memory consolidation, leading to severe anterograde amnesia while sparing remote memories.
What are the two types of amnesia seen in medial temporal lobe patients?
Anterograde amnesia (inability to form new memories) and retrograde amnesia (partial loss of past memories).
Why do recent memories tend to be more vulnerable to hippocampal damage?
Recent memories rely on the hippocampus, while older memories become independent and are stored in the neocortex.
What is the key finding from delayed non-match to sample tasks in amnesic animals?
Hippocampal-lesioned animals perform normally for short delays but show severe deficits with longer delays.
What role does the parahippocampal cortex play in memory?
It is crucial for encoding and retrieving contextual associations, supporting both episodic and spatial memory.
How does the hippocampus interact with the neocortex in memory consolidation?
Initially, memories rely on the hippocampus, but over time, they are transferred to the neocortex for long-term storage.
What is the relationship between synaptic plasticity and memory?
Synaptic plasticity, including long-term potentiation (LTP), strengthens neural connections essential for learning and memory.
How does stress impact hippocampal function?
Chronic stress can impair hippocampal function by increasing cortisol levels, which may lead to memory deficits.
What is the role of the prefrontal cortex in working memory?
The prefrontal cortex is essential for maintaining and manipulating information in working memory over short periods.
How do patients with medial temporal lobe damage perform on recognition tasks?
They struggle with recall but may retain some familiarity-based recognition ability, depending on lesion extent.
What was the primary contribution of the RB patient case study?
RB’s case confirmed that selective CA1 damage results in anterograde amnesia, helping pinpoint hippocampal roles.
How does sleep influence memory consolidation?
Sleep, particularly deep and REM sleep, facilitates the reactivation and stabilization of newly acquired memories.
What is the difference between implicit and explicit memory?
Implicit memory involves unconscious learning (e.g., habits), while explicit memory requires conscious recall of facts and events.
Why do patients with hippocampal damage struggle with spatial navigation?
The hippocampus is essential for creating cognitive maps, so its damage impairs the ability to navigate and recognize environments.
What is memory reconsolidation?
Memory reconsolidation is the process where retrieved memories become temporarily malleable and can be modified before being stored again.
How does hippocampal damage affect temporal memory?
Patients with hippocampal damage struggle to place events in the correct chronological order, affecting their ability to recall sequences.
What is the role of the thalamus in memory?
The thalamus is involved in coordinating memory retrieval and supports familiarity-based recognition.
How do hippocampal lesions affect spatial learning in rodents?
Rodents with hippocampal lesions struggle to navigate mazes, demonstrating deficits in spatial memory and learning.
What is the role of the cerebellum in memory?
The cerebellum contributes to procedural memory, particularly in motor skill learning and coordination.
How does aging affect memory performance?
Aging is associated with declines in episodic memory and slower recall, though procedural and semantic memory are often preserved.
What are the symptoms of Korsakoff’s syndrome?
Korsakoff’s syndrome results in severe anterograde and retrograde amnesia, confabulation, and difficulty forming new memories due to thiamine deficiency.
What is the effect of hippocampal neurogenesis on memory?
Neurogenesis in the hippocampus supports memory formation and cognitive flexibility, particularly in learning new environments.
How does synaptic plasticity relate to memory storage?
Synaptic plasticity, including long-term potentiation (LTP), enhances neural connections, strengthening memory storage.
What distinguishes episodic memory from semantic memory?
Episodic memory involves personal experiences tied to specific times and places, while semantic memory consists of general knowledge and facts.
What type of amnesia did HM experience?
HM had severe anterograde amnesia, meaning he could not form new declarative memories, while his procedural memory remained intact.
How does the basal ganglia contribute to memory?
The basal ganglia play a key role in procedural memory, including habit formation and motor learning.
What happens to memory retrieval during stress?
Acute stress can enhance memory retrieval, while chronic stress impairs hippocampal function, leading to memory deficits.
What is source amnesia?
Source amnesia occurs when a person remembers information but cannot recall where or how they learned it.
How do hippocampal place cells contribute to spatial memory?
Place cells in the hippocampus fire in response to specific locations, helping encode spatial environments.
What is the role of the entorhinal cortex in memory?
The entorhinal cortex serves as a hub between the hippocampus and neocortex, facilitating memory consolidation and navigation.
How do lesions in the medial temporal lobe affect future planning?
Damage to the medial temporal lobe impairs the ability to imagine future events, as episodic memory is crucial for future planning.
What is the impact of repeated memory retrieval?
Repeated retrieval strengthens memory traces and improves long-term retention, but also makes memories susceptible to modification.
How does working memory differ from long-term memory?
Working memory holds and manipulates information temporarily, while long-term memory involves the stable storage of learned information.
What is the function of the hippocampus in fear conditioning?
The hippocampus helps contextualize fear memories, distinguishing between safe and threatening environments.
What is the relationship of grid size in mEC cells in relation to their dorsal to ventral locations?
The smallest fields are represented dorsally and they get bigger the more ventral you go.
