1
Q
What was the impact of Edward Tolman’s experiment? What was the experiment?
A
- Experimented on rats by training them to identify food in a regular maze and then placed them in a sunburst maze that challenged the previous chains of behaviour they had trained on
- It was discovered that even though the rats didn’t know the exact way, internal processes were occurring that indicated they were trying to use their environment to make predictions
- Went against Skinner’s behaviourist claim that we are made up of chains of behaviours that are instigated by stimuli
2
Q
What two major concepts did Tolman develop from his rat experiments?
A
- Cognitive maps - We have internal representations of the spatial layouts of different environments. Later indicated by place cells located in the hippocampus
- Latent learning - Learning can occur without specific training/consequences (i.e., subconsciously storing information)
3
Q
What types of experiments did Karl Lashley perform?
A
- Gave rats lesions on their cerebrum (strictly neocortex) varying in location and size and then tried to train them in a maze
- Was wanting to identify the engram in the brain = the physical change in the brain that forms the basis of memory
- Discovered that the location of the lesion didn’t matter, it was the size that had the biggest impact
4
Q
What two major concepts did Lashley describe from his experiments?
A
- Mass action - Disruption in behaviour is directly related to the proportion of brain damage
- The capacity of any intact part of the brain to carry out the function of damaged areas (i.e., thought there was redundancy in the brain)
5
Q
Between the two major concepts described by Lashley, which one was incorrect?
A
- The idea the functions performed by certain parts of the brain could be carried out by other regions if that one particular area was damaged (i.e., thought brain regions could be multi-faceted)
6
Q
Aside from Lashley’s work with memory, what important experimental contribution did Lashley make to the field of behavioural neuroscience?
A
- One of the first to make the important switch from pure observation to manipulation to understand behaviour
7
Q
What are the three major approaches to manipulating behaviour in neuroscience?
A
- Stimulation (ex. TMS)
- Inhibition (ex. lesioning parts of the brain to inhibit certain behaviours)
- Recording (ex. using electrodes)
8
Q
What major behaviours do rats do in the wild?
A
- Search for food, water, shelter, etc.
- Patrol the home range
- Exploration of new areas (things that are novel)
9
Q
Describe the difference between neophilia and neophobia in rat behaviour?
A
- Neophilia - the drive to explore new things
- Neophobia - a fear of novel things
*Rats have developed to strike a balance between these two extremes. This concept is demonstrated when rats are placed in the residential maze
10
Q
What is a common feature of locomotion?
A
- One of the most common forms of behaviours
- Common feature is the rhythmic and alternating movements of the body
- Very complicated, but simple systems can be used to understand them
11
Q
What’s the step cycle?
A
- A simple way to understand how quadrupeds perform locomotion:
1. Swing: a) Flexion of limb (lifting foot off ground); b) Forward movement relative to body; c) Extended to prepare for subsequent stance phase
2. Stance: d) Limb in contact with the ground; e) Weight support; f) Propulsion - This cycle repeats itself
12
Q
When a rat walks, gallops, or runs, aside from speed, what is a major distinguishing feature of these phases?
A
- The amount of time and how many limbs are in contact with the floor
- As speed increases, the contact of limbs on the ground decreases
13
Q
What’s severe ataxia?
A
- Often seen in Parkinson’s, the individual may have a hard time initiating movement
14
Q
Afferent vs. Efferent?
A
- Afferent - info coming in
- Efferent - info going out
15
Q
What are flexor reflex afferents (FRAs)?
A
- Refer to cutaneous (skin) and muscle afferents
- When the flexor and extensor nerves alternate in activity
16
Q
What does the half-centre diagram attempt to illustrate in terms of flexor reflex afferents?
A
- When a motor neuron is stimulated in one side of a limb, for it to assist in locomotion it must suspend the activity of the other muscle (ex. the extensor muscle)
- This means that when the neuron excites the motor neuron, it also excites an inhibitory neuron, which then inhibits the activity of the other neuron and allows it to act in isolation
17
Q
What occurs when you inhibit an inhibitory neuron?
A
- Similar to pulling the breaks away and letting a the neuron impacted act how it normally would
18
Q
What does reciprocal inhibition refer to?
A
- The idea that two neurons controlling antagonistic motor neurons are capable of inhibiting each other to allow the other one to carry out a behaviour properly
- reciprocal inhibition is a major part of locomotion
19
Q
What role do spinal circuits play in locomotion?
A
- Spinal circuits coordinate movements within and between limbs
- Certain sensory activation can cross to the opposite side in a given spinal circuit
- Also coordinate complementary limb movements like crossed extension reflex and swinging arms when moving your legs
20
Q
Provide an example of a crossed extension reflex.
A
- Stepping on something painful and immediately flexing that leg upwards while weight is displaced onto the extended leg
21
Q
What are central pattern generators (CPGs)?
A
- Neural networks that can produce rhythmic motor activity in the absence of sensory feedback
- Very important in major biological functions such as locomotion, respiration, and swallowing.
22
Q
What do CPGs in the spinal cord do?
A
- They mediate the stepping response?
23
Q
Which animal is used to understand and illustrate CPGs activity in locomotion? Why?
A
- The Lamprey snake
- Locomotion is produced by a wave of muscle contractions travelling down one side of the body 180 degrees out of phase with the opposing side (produces a swimming rhythm)
24
Q
T/F: CPGs can be observed in pre-walking infants.
A
- TRUE, often triggered by placing their feet on the floor
- Illustrates how rudimentary they are to walking
25
How does the rhythmic locomotor pattern of the lamprey snake occur at the neuronal level?
- Reciprocal inhibition and post-inhibitory rebound both occur to allow for an alternating rhythmic pattern to appear between two antagonistic neurons in the spinal cord
26
How do inhibitory L-interneurons work in neural locomotion circuitry?
- When a motor neuron is stimulated by an excitatory neuron in the spinal cord, the same excitatory neuron excites an L interneuron, which after a DELAYED excitation, inhibits the inhibitory activity of an inhibitory neuron, allowing the function to occur on the one side, but then also stopping the inhibitory activity of the inhibitory neuron that was initially stimulated by the excitatory neuron
- This then allows the inhibitory neuron from the other side to shut down the activity on the side that the L interneuron just stimulated but also allows excitation of the other side to occur while it’s in post-inhibitory rebound
27
What other bottom-up afferent signals may impact locomotion circuitry?
Afferent feedback from the limb:
- Muscle spindles (muscle length; stretch)
- Golgi tendon organs (tendon forces, always change with speed)
- Cutaneous receptors (extensor/flexor activity; depends upon phase in step cycle)
28
What does top-down modulation of locomotion entail?
- Descending signals from the brainstem and motor cortex initiate locomotion and adjust stepping movements
29
Which regions in the brainstem are responsible for activating the spinal locomotor system?
- The mesencephalic locomotor region (MLR) and the medial reticular formation (MRF)
- The MLR activates the spinal cord, and these signals are relayed via neurons in the MRF
30
What role does the cerebellum play in regulating locomotion?
- It receives signals via spinocerebellar pathways and works as an error-correction system, correcting movement on the fly
31
T/F: Stimulation of the MLR is insufficient to induce locomotion.
- FALSE, stimulation of the MLR is sufficient to induce motion
- This is cause the MLR is connected to regions like the substantia nigra
- As activity in the MLR increases, rate of locomotion also increases.
32
How do the visual system and the motor cortex work together in modulating locomotion?
- Activity of motor cortex neurons is modulated by visual system input
- Allows for adaptation of stepping movements (ex. skilled walking)
Psychology 478
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