Week 9 - topic 3 Flashcards
The supplementary motor area
involved in performing previously learned, automatic series of behaviours
The premotor cortex
involved in motor learning and memory that is guided by sensory information
The ventral premotor cortex
is where mirror neurons are located that facilitate motor learning through observation
Role of cortex in perceptual learning
• Visual perceptual learning = learning to recognize things by sight
• The primary visual cortex receives information from the Lateral Geniculate Nucleus (LGN) of the thalamus and sends it to the extrastriate cortex (sensory association cortex):
• Ventral Stream (projects to inferior temporal cortex)
– object recognition
• Dorsal Stream (projects to posterior parietal cortex)
– perception of object location
• Damage to the inferior temporal cortex = disrupt ability to discriminate among visual stimuli (recognition; agnosia)
Memory and implied movement
- Specific kinds of visual information can activate specific regions of the extrastriate cortex
- MT/MST = movement perception
- Participants look at still photos with or without implied motion
- Implied motion activates MT/MST
- Even though the photos did not move, memories presumably contained info about movements they had previously seen
Amnesia
• Anterograde Amnesia:
Amnesia for events that occur after some disturbance in the brain, such as a head injury or certain degenerative brain diseases
• Retrograde Amnesia:
Amnesia for events that preceded some disturbance to the brain, such as a head injury or certain degenerative brain diseases
Patient HM and learning
- Anterograde Amnesia can be caused by damage to the temporal lobes.
- Bilateral removal of medial temporal lobe in patient HM produced memory impairment.
- More specifically, the critical site of damage in the case of HM was the hippocampus
Conclusions about memory based on patient HM by Milner and colleagues
- The hippocampus is not the location of long-term memories; nor is it necessary for the retrieval of long term memories
- The hippocampus is not the location of immediate (short term memories)
- The hippocampus is involved in converting immediate short term memories into long term memories
Building on Milner and colleagues conclusions about patient HM
• The idea of consolidation relates to Milner and colleagues original conclusions
• If HM’s STM were intact and if he could remember events from before his operation, then the problem must be with consolidation
• It involves the hippocampal formation – a forebrain
structure of the temporal lobe, constituting an important part of the limbic system.
Spared learning abilities in anterograde amnesia
• Patients with anterograde amnesia are capable of three of the four major types of learning
- Perceptual learning,
- Stimulus–response learning,
- Motor learning
Perceptual learning and HM
- Participants are shown sets of broken drawings and asked to identify objects
- HM completed test twice.
- On second test, HM showed considerable improvement
- On a test months later, he still showed improvement = long term retention
Stimulus-response learning and HM
• HM and another patient with anterograde amnesia
showed a classically conditioned eye blink response
• HM was trained on an operant conditioning task where he was given pennies for correct choices in a visual discrimination test
Motor learning and anterograde amnesia
• People with anterograde amnesia could learn a
sequence of button presses in a serial reaction time task
Non-declarative memory and anterograde amnesia patients
- Learning to ride a bicycle is a combination of stimulus–response learning and motor learning, both of which are non-declarative in nature.
- Remembering when we learned to ride a bike is an episodic memory, a form of relational learning.
- Someone with anterograde amnesia might be able to learn to ride a bike, but not remember learning.
• Although patients can learn to perform perceptual, motor, and stimulus-response tasks, they do not remember anything about having learned them.
Hippocampal formation and declarative consolidation
- Hippocampus receives information about what is happening from sensory and motor association cortex, as well as the basal ganglia and amygdala
- Via efferent connections with the same regions, the hippocampus modifies the memories that are being consolidated, linking them together in ways that will permit us to remember relationships among the elements of the memory (e.g. order of events, context etc.)
Functional imaging and the location of stored long-term memories
Functional imaging revealed that the retrieval of the youngest long-term memories activated the hippocampus more than the frontal cortex, but retrieval of older memories activated the hippocampus less and the cortex more = memories initially stored in the hippocampus are transferred to the frontal cortex
Semantic memories
• Declarative memories can be episodic or semantic
• Semantic Memories are a form of declarative memory
that can be acquired gradually over time
• Involve facts, but not information about the context in
which the facts were learned
• Semantic Dementia: semantic information is lost, but
episodic memory for recent events can be spared
• Semantic memories appear to be stored in the
neocortex – anterolateral temporal lobe
Spatial memories
• Although spatial information need not be declared, people with anterograde amnesia are unable to consolidate information about the location of rooms, corridors, buildings, roads and other important information in their environment
• Bilateral medial temporal lobe lesions produce profound impairments in spatial memory, but deficits can occur with only right hemisphere damage
• Functional imaging studies suggest that the right
hippocampal formation becomes active when a person is remembering or performing a navigational task
Spatial learning in animals - hippocampus lesioning
Laboratory animals show problems in navigation following hippocampal lesioning
• Different neurons have different spatial receptive fields — they respond when animals are in different locations. These neurons are place cells
• This doesn’t mean that each cell responds to only one particular location
• Information is represented by particular patterns of activity in circuits of large numbers of neurons within the hippocampal formation
Spatial learning in animals - how this occurs
- Hippocampus receives spatial information from the parietal lobes by means of the entorhinal cortex
- Hippocampal region also contains grid cells, head direction cells, and border cells all found in the entorhinal cortex
- Information provided by these cells reflects the animal’s location and head direction
Place neurons
- A place neuron is one that becomes active when the animal is in a particular location in the environment.
- The place neurons are normally found in the hippocampal formation.
- Nonetheless, it is important to note that there isn’t just one neuron that encodes one particular location.
- > Rather, the information is represented by particular patterns of activity in circuits of large numbers of neurons within the hippocampal formation.
- Place cells seem to encode current location and intended destination
