Neuro Box 10

The vertebrate central nervous system is composed of the:

• forebrain

• brainstem

• cerebellum

• spinal cord

We have also seen that lower level neural mechanisms within the midbrain play an —— role

instructive

neurons within the cerebellum mediate learning and memory for—-

delayed eyeblink conditioning

it well known that a major function of the spinal cord is to——

relay neural signals between the periphery and the brain.

(a major function of the spinal cord is to relay neural signals between the periphery & brain)

• This capacity depends upon ——

the axons that form the neural tracts that line the outer region of the spinal tissue.

(a major function of the spinal cord is to relay neural signals between the periphery & brain)

• This capacity depends upon the axons that form the neural tracts that line the outer region of the spinal tissue.

  • Because these axons have a ——-, they appear white and for this reason, the outer band of neurons is known as the white matter

myelin coating (a form of electrical insulation that speeds neural conduction)

myelin coating=  

(a form of electrical insulation that speeds neural conduction)

(a major function of the spinal cord is to relay neural signals between the periphery & brain)

• This capacity depends upon the axons that form the neural tracts that line the outer region of the spinal tissue.

  • Because these axons have a myelin coating (a form of electrical insulation that speeds neural conduction), they appear white and for this reason, the outer band of neurons is known as the ———

white matter

(a major function of the spinal cord is to relay neural signals between the periphery & brain)

• This capacity depends upon the axons that form the neural tracts that line the outer region of the spinal tissue.

  • Because these axons have a myelin coating (a form of electrical insulation that speeds neural conduction), they appear white and for this reason, the outer band of neurons is known as the white matter

• When neural conduction in these axons is disrupted by injury, the brain loses the ability to communicate with peripheral mechanisms below the injury, bringing about ——

• a loss in function

• an inability to sense stimuli

• a disruption in the person’s capacity to execute a voluntary response.

What is sometimes forgotten is that there is also an inner region of spinal tissue, a butterfly- shaped region (the ———) composed of neurons and supporting cells (glia).

(the central gray)

What is sometimes forgotten is that there is also an inner region of spinal tissue, a butterfly- shaped region (the central gray) composed of neurons and supporting cells (——).

(glia)

The central gray contains 100’s of thousands of neurons, far (more/less?) than contained within the entire nervous system of invertebrates that can learn

MORE

Neurons within the dorsal (upper) central gray of the spinal cord play a role in—-

processing the sensory signal relayed to the brain

Neurons within the ventral (lower) portion help to ——

organize behavioral responses, including complex movement such as stepping

sensory input to the spinal cord can initiate a behavioral response (a ——-) in the absence of input from the brain

spinal reflex

We know that the spinal reflex response does not require any input from the brain because——-

it can be elicited after communication with the brain has been experimentally disrupted.

Spinal reflexes demonstrate that neurons within the spinal cord can —-

organize unconditioned (unlearned) responses to stimuli.

— —— & ——- were among the first to explore this issue, showing that a spinal reflex becomes weaker (habituates) when a stimulus is repeatedly presented.

Groves & Thompson

Groves and Thompson (1970) were among the first to explore this issue, showing that a spinal reflex becomes weaker (habituates) when a stimulus is repeatedly presented.

In addition, they found that intense stimulation can sensitize behavioral reactivity, providing the foundation for the——— theory of ——

dual process theory of nonassociative learning

Thompson and his students also provided evidence that spinal neurons are sensitive to ——— relations

stimulus-stimulus (Pavlovian)

Grau and his colleagues have shown that neurons within the spinal cord can support ——

a simple form of instrumental learning

Grau Spinal Cord Learning Study:

spinal cord was cut and subjects were trained using a shock that elicited a hind limb flexion respons

• One group (the master rats) received leg shock whenever the leg was extended.

• Subjects in a yoked group were experimentally coupled to the master subjects. Each time a master rat received shock, its yoked partner did too

Grau Spinal Cord Learning Study:

spinal cord was cut and subjects were trained using a shock that elicited a hind limb flexion respons

• One group (the master rats) received —-

leg shock whenever the leg was extended

Grau Spinal Cord Learning Study:

spinal cord was cut and subjects were trained using a shock that elicited a hind limb flexion respons

• One group (the master rats) received leg shock whenever the leg was extended.

  • Subjects in a yoked group were —-

experimentally coupled to the master subjects. Each time a master rat received shock, its yoked partner did too

Grau Study Findings:

— rats quickly learned to hold their leg up, effectively minimizing net shock exposure

Grau Study Findings:

Master (rats)

Grau Study Findings:

Master rats quickly learned to hold their leg up, effectively minimizing net shock exposure. In contrast, the yoked rats, that received shock independent of leg position:

failed to learn

Grau Study Findings:

Master rats quickly learned to hold their leg up, effectively minimizing net shock exposure (see Figure 10.xB). In contrast, the yoked rats, that received shock independent of leg position, failed to learn

This difference between the master and yoked rats indicates that —-

neurons within the spinal cord are sensitive to instrumental (response-reinforcer) relations.

Grau Phase 2 Study:

Master and yoked rats were then tested under common conditions with controllable shock.

Grau Phase 2 Study:

Master and yoked rats were then tested under common conditions with controllable shock.

• As you would expect, master rats:

learned faster than control subjects that previously had not received shock

Grau Phase 2 Study:

Master and yoked rats were then tested under common conditions with controllable shock.

• As you would expect, master rats learned faster than control subjects that previously had not received shock.

• In contrast, the yoked rats failed to learn.

  • This behavioral deficit resembles the phenomenon of —-

learned helplessness.

Grau Phase 2 Study:

Master and yoked rats were then tested under common conditions with controllable shock.

• As you would expect, master rats learned faster than control subjects that previously had not received shock.

• In contrast, the yoked rats failed to learn. This behavioral deficit resembles the phenomenon of learned helplessness.

As observed in intact animals, exposure to controllable shock also has ——that can protect the spinal cord from the adverse effect of uncontrollable stimulation.

an immunizing effect

Neurobiological studies have revealed that learning within the spinal cord depends upon a form of ——

NMDA-receptor mediated plasticity, the same neurochemical system that underlies learning and memory within the hippocampus

physiological phenomena linked to learning and memory (——-) have been observed in spinal neurons

e.g., long-term potentiation and depression

an analysis of spinal processing has begun to inform learning. At a functional level, it can help reveal——

what is basic—an inherent property of any system that can learn.

Does response-contingent shock cause an increase in flexion duration because a downward movement of the leg coincides with shock onset (——-) or because an upward movement is contiguous with shock termination (escape)?

• This issue can be addressed by delaying either the onset or offset of shock

punishment

Does response-contingent shock cause an increase in flexion duration because a downward movement of the leg coincides with shock onset (punishment) or because an upward movement is contiguous with shock termination (——)?

• This issue can be addressed by delaying either the onset or offset of shock

escape

Does response-contingent shock cause an increase in flexion duration because a downward movement of the leg coincides with shock onset (punishment) or because an upward movement is contiguous with shock termination (escape)?

• This issue can be addressed by——

delaying either the onset or offset of shock

Delaying the onset of shock by just 100 msec:

eliminated learning

Delaying the onset of shock by just 100 msec eliminated learning, whereas delaying offset :

had no effect

the key reinforcer is linked to —-and that the learning reflects a form of—-

(to) shock onset ; punishment

Instrumental learning depends on a —- relation

response-outcome (R-O)

For shock onset (the outcome) to matter, it must ——

occur in the presence of a cue that provides information about leg position (the response).

Physiological studies have revealed that sensory receptors within the muscles and joints provide a sensory signal that indicates current limb position (a form of ——-)

proprioception

proprioceptive cue yields ———-, which would allow for a form of R-O learning.

an index of limb position (the response) at the time of shock onset (the outcome)

proprioceptive cue yields an index of limb position (the response) at the time of shock onset (the outcome), which would allow for a form of R-O learning.

From this perspective, the cue for leg position is linked to shock onset and, as a result of this learning, ——

gains the capacity to drive a flexion response

does Pavlovian conditioning contribute to instrumental learning?

• In the present case, the answer may be yes, for the learning appears to depend upon——

• the relation between a proprioceptive cue (the CS) and shock onset (the US)

motoric effect:

the organism executing an adaptive behavior in response to sensory input

If spinal neurons can encode that there is a regular relationship between an index of limb position (the R) and cutaneous stimulation (the O), this learning could ——

transform the signal relayed to the brain allowing the organism to directly perceive some instrumental (R- O) relations.

(limits of instrumental learning within the spinal cord)

learning is often—-

biologically constrained

we can train a normal rat to perform a variety of behaviors (e.g., pull a chain, press a bar) using a wide range of reinforcers (sugar water, food pellets).

• In contrast, both the response and the range of outcomes available seem highly constrained in ——

• spinal learning

we can train a normal rat to perform a variety of behaviors (e.g., pull a chain, press a bar) using a wide range of reinforcers (sugar water, food pellets). In contrast, both the response and the range of outcomes available seem highly constrained in spinal learning

• the learning appears tied to ——

• pre-existing reflexive behavior

Spinal mechanisms can encode R-O relations, but do so using—-

a simple system that is highly constrained

Brain processes bring a level of flexibility that allows the organism to —-

integrate information across sensory modalities, time, and response alternatives

the —- can support delayed eyeblink conditioning, but to span a gap in time (trace conditioning) requires a hippocampus.

cerebellum

he cerebellum can support delayed eyeblink conditioning, but to span a gap in time (——) requires a hippocampus.

trace conditioning

a common environmental puzzle (e.g., encoding a R-O relation) can be solved in multiple ways, and alternative mechanisms may vary in both their —— & ——

sophistication & operational range

Grau and Joynes have argued for a functional approach to the study of learning (neurofunctionalism), suggesting that —-

a process-level description of the mechanisms can be used to link neurobiological observations to behavior

exposure to uncontrollable stimulation after a contusion injury: 

not only impairs spinal learning, it also undermines behavioral/physiological recovery after a contusion injury (a bruising of the spinal tissue that emulates the most common type of human injury)

contusion injury:

(a bruising of the spinal tissue that emulates the most common type of human injury)

— —- training can foster behavioral recovery after a contusion injury

Instrumental

physical therapy—to retrain the patient to perform some essential activities. The hope is that training will have a last effect, yielding—-

a form of memory that will improve function

Rehabilitation remains the —-

most effective treatment after spinal injury and its aim is to inspire a form of instrumental learning.