CSB332 Lecture 16
- Explicit learning (e.g., associative LTP, non-associative LTP) occurs in the hippocampus. These
phenomena explain our ability to consolidate explicit memory into LTM stores.
- LTP doesn’t only occur in the hippocampus. LTP and LTP-like processes also occur in different
parts of the brain. The LTP-like processes in different parts of the brain would underlie different
types of memories apart from explicit memory.
- LTP-like processes can occur in parts of the cerebral cortex, basal ganglia (dorsal and ventral
striatum), amygdala, cerebellum, reflex pathways. These phenomena could explain the other
types of memory (e.g., implicit, non-declarative, unconscious, conscious).
- Procedural memory and other types of implicit memory (e.g., classical conditioning, operant
conditioning) are contained in brain structures outside of the hippocampus, or beyond the
medial temporal cortex.
o For instance, motor memory occurs in two motor pathways (e.g., pyramidal pathway
originates from the primary cortex, which contains pyramidal neurons).
The structures involved are the M1 primary motor cortex. The axons of
pyramidal neurons in the primary motor cortex form the corticospinal tract. This
relays or signals to the skeletal muscles. The activity of the primary motor cortex
is modulated by two association areas called the premotor cortex and the
supplementary motor area.
For example, the first time you learn how to drive a car entails greater effort
than after you’ve learned how to drive. There is coordination between visual
input and the location of the different parts of the body. These are all contained
in the premotor cortex. The relationship of your body with the different visual
information in the environment is relayed to the primary motor cortex.
The SMA is also involved, but it produces internally generated motor programs.
The motor program that is contained in the SMA does not have to rely on visual
stimulus because it has to be a memorized program (or internally represented
program). This has to be carried out in order to coordinate complex movement
sequences, such as selecting from the many degrees of freedom involved in
- The premotor area and the SMA contain special types of neurons called mirror neurons. Mirror
neurons become actively firing when the person observes a behaviour and the same neuron also
gets activated when the person engages in that same behaviour that was initially observed. This
mirror neuron system seems to underlie our ability to learn based on observation (e.g., imitation
or visual learning). Slide 10
- Apart from the pyramidal system, there is a motor system located within the basal ganglia called
the extrapyramidal system. The extrapyramidal system contains the caudate nucleus, globus
pallidus, putamen, thalamus, and subthalamic nucleus, and other parts of the basal ganglia.
- This is how the pyramidal system interacts with the extrapyramidal system. The pyramidal
system is located in the primary motor cortex, the premotor area, and the SMA, which are all
located in the cerebral cortex.
- The basal ganglia (or extrapyramidal system) has two pathways.
o The direct pathway originates from medium spiny neurons that are GABAergic located
in the striatum. The striatum contains the caudate/putamen and nucleus accumbens.
The striatum contains GABAergic medium spiny neurons, which are inhibitory neurons.
The GABAergic medium spiny neurons project their axons directly to the output region
of the basal ganglia, which is the globus pallidus interior. It is the output area because it
sends inhibitory projections (shown in blue) to the thalamus, which is the major relay
station of the brain. The thalamus, in response to the inhibition, will send signals to the
primary motor cortex or to other parts of the brain.
Stimulation of the direct pathway stimulates the medium spiny neurons, which
would end up exciting the neocortex stimulating behaviour. It will excite the