Bio Psych Exam #2: Chp. 11

Afferent somatosensory information_________.

travels from the sensory organs inward via the somatic nervous system.

Movement information

travels out of the central nervous system via a parallel efferent system.

Spinal Segment corresponds to a region of body surface

Dermatome

The motor cortex lies in the______________.

lobe, anterior to central fissure in brain

The sensory cortex lies____________.

posterior to the central fissure and extends into the parietal lobe

Layer IV (afferent) is relatively thick in the__________.

Sensory cortex

Layer IV (afferent) is relatively thin in the___________.

Motor cortex

Layer V (efferent) is relatively thick in the_________.

motor cortex

Layer V (efferent) is relatively thin in the_________.

sensory cortex

Lashley

Argued that movements must be performed as motor sequences, with the next sequence held in readiness while the ongoing one is under way

Motor Sequence

Movement modules are preprogrammed by the brain and produced as a unit

Prefrontal cortex

Plans complex behavior

Premotor Cortex

produces the appropriate complex movement sequences

Primary motor cortex

specifies how each movement is to be carried out

Primary Motor Cortex

Specializes in producing focal skilled movements, such as those of the arms, hands, and mouth

Species-typical behavior

Actions produced by every member of a species

Hess

Stimulated different areas within the brainstem to produce different species-specific behaviors

Cerebral Palsy

•Voluntary movements difficult to make, whereas conscious behavior controlled by the cortex may remain intact

•Caused by brainstem trauma

Locked-in Syndrome

•Condition in which a patient is aware and awake but cannot move or communicate verbally because of complete paralysis of nearly all voluntary muscles except the eyes

Due to brainstem damage

Quadriplegia

Paralysis and loss of sensation in the legs and arms due to spinal cord injury

Paraplegia

Paralysis and loss of sensation confined to legs and lower body due to spinal cord injury

A movement module preprogrammed by the brain and produced as a unit is called a _____.

motor sequence

The _____ organize(s) movement sequences.

premotor cortex

Fritsch and Hitzig

Discovered they could electrically stimulate the neocortex of an anesthetized dog to produce movements of the mouth, limbs, and paws on the opposite side of the dog’s body

Wilder Penfield

Confirmed the role of the primary motor cortex in producing movement in humans

Homunculus

Representation of the human body in the sensory or motor cortex

Topographic organization

Neural spatial representation of the body or areas of the sensory world perceived by a sensory organ

The parts of the motor cortex that control the ______________ are disproportionately larger than parts of the motor cortex that control other areas

hands, fingers, lips, and tongue

Motor cortex represents not muscles but rather__________.

movement categories

Constraint-induced Therapy

• forces use of the affected limb as a major therapy for stroke-induced limb paralysis

• Effectiveness depends on frustration of the good limb, which promotes a concerted effort to use the bad limb and promotes neural plasticity.

Corticospinal tract

Bundle of nerve fibers directly connecting the cerebral cortex to the spinal cord, branching at the brainstem into an opposite-side lateral tract that informs movement of limbs and digits and a same-side anterior tract that informs movement of the trunk

Lateral corticospinal tract

•Branches at the brainstem level, crossing over to the opposite side of the brain and spinal cord

•Moves the digits and limbs on the opposite side of the body

Ventral (anterior) corticospinal tract

•Remains on the same side of the brain and spinal cord

•Moves the muscles of the midline body (trunk) on the same side of the body

Two Kinds of neurons in the spinal column’s ventral

Interneurons, connect to motor neurons, and motor neurons, that connect to muscle

Laterally located motor neurons

control the fingers and hands

Intermediately located motor neurons

control the arms and shoulders

The most medially located motor neurons______.

control the trunk

Extensor

Moves (extends) the limb away from the trunk

Flexor

Moves the limb toward the trunk

The main efferent pathways from the motor cortex to the brainstem to the spinal cord are the _____.

Corticospinal tracts

Corticospinal-tract fibers that cross to the opposite side of the spinal cord form the _____ tracts

lateral

The basal ganglia receive input from:

All areas of the neocortex and allocortex, including motor cortex

The basal ganglia project back to:

the motor cortex and substantia nigra

The basal ganglia functions include:

association or habit learning, motivation, emotion, and motor control

Nuclei forming the basal ganglia include:

•Caudate nucleus and putamen

•Subthalamic nucleus

•Globus pallidus

Damage to the basal ganglia can produce two main types of motor symptoms:

Hyperkinetic and Hypokinetic

Hyperkinetic symptom

Damage to the caudate putamen may cause unwanted writhing and twitching movements called dyskinesias; seen in Huntington disease and Tourette syndrome.

Hypokinetic symptom

Damage to the basal ganglia may result in a loss of motor ability, leading to rigidity and difficulty initiating and producing movement; seen in Parkinson disease.

Volume control theory

• The globus pallidus internal acts like a volume control on the motor cortex.

  • If it is turned up, movement is blocked; if it is turned down, movement is allowed.

Referred Pain

Pain that arises in one of the internal organs but is felt on the surface of the body. Ex. heart attack=upper arm pain

Anatomy of the cerebellum

• Flocculus

• Two hemispheres

  • Homuncular organization

  • Lateral parts

  • Medial parts

Lateral parts (Cerebral hemispheres)

Controls movement of limbs, hands, feet, and digits

Medial Parts (Cerebral hemispheres)

Control movement of face and midline of body

Cerebellum has information about both versions of the movement —_______—and can calculate the error and tell the cortex how to correct the movement.

what you intended to do and what you actually did

The _____ contribute(s) to motor control by adjusting the force associated with each movement.

basal ganglia

The cerebellum contributes to motor control by improving movement _____.

timing

Somatosensory system

•Tells us what the body is up to and what’s going on in the environment by providing bodily sensations such as touch, temperature, pain, position in space, and movement of the joints

•Allows us to distinguish between what the world does to us and what we do to it

Glabrous skin

Skin that does not have hair follicles but contains larger numbers of sensory receptors than do other skin areas.

Nociception(Somatosensory Receptors)

•Perception of pain, temperature, and itch

•Free nerve endings activated by chemicals

Hapsis (Somatosensory Receptors)

•Perceive fine touch and pressure and identify objects that we touch and grasp

•Activated by mechanical stimulation of the hair, tissue, or capsule

Proprioception (Somatosensory Receptors)

•Perception of the location and movement of the body

•Sensitive to the stretch of muscles and tendons and the movement of joints

Rapidly adapting receptor

• responds briefly to the beginning and end of a stimulus on the body

• Haptic receptors that respond to touch (Meissner corpuscles), to fluttering sensations (Pacinian corpuscles), and to vibration (Ruffini corpuscles).

Slowly adapting receptor

• Body sensory receptor that responds as long as a sensory stimulus is on the body

• Nociceptive receptors that respond to sharp and dull pain and those that respond to heat/ cold; Merkel’s receptors (steady skin indentation) and hair receptors (flutter or steady skin indentation)

Proprioceptive and haptic neurons (Posterior Root Ganglion Neurons)

•Carry information about location and movement (proprioception) and about touch and pressure (hapsis)

•Large, well-myelinated axons (fast)

Nocioceptive neurons

•Pain, temperature, and itch information

•Small axons with little or no myelination (slow)

Deafferentation

Loss of incoming sensory input usually due to damage to sensory fibers; also loss of any afferent input to a structure

Ipsilateral

Using/on the same side of your body

Contralateral

Using/on opposite sides of your body, e.g. your right arm and your left leg.

The haptic and proprioceptive axons for touch and body awareness ascend the spinal cord_________.

ipsilaterally

Nociceptive (pain, temperature, itch) nerve fibers synapse with neurons whose axons cross to the_________.

contralateral side

The Posterior Spinothalamic Tract

carries haptic and proprioceptive information via fine-touch and pressure fibers

The Anterior Spinothalamic Tract

Pathway from the spinal cord to the thalamus that carries information about pain and temperature toward the brain.

Monosynaptic reflex

reflex requiring one synapse between sensory input and movement

The ______________ is the main pain pathway to the brain.

anterior spinothalamic tract

Reticular formation pathway

associated with arousal

Amygdala pathway:

associated with emotional responses

Hypothalamus pathway:

Associated with hormonal and cardiovascular responses

Gate theory of pain

A spinal cord interneuron receives excitatory input (plus signs) from the fine-touch and pressure pathway; and inhibitory input (minus signs) from the pain and temperature pathway. The interneuron’s relative activity then determines whether pain and temperature information ascends to the brain.

Within an ear, a vestibular organ contains:

•Three semicircular canals

•Otolith organs (utricle and saccule)

Vestibular organs have two functions:

•Tell the position of the body in relation to gravity

•Signal changes in the direction and speed of head movements

Vestibular System and Balance

When the head moves, fluid (endolymph) located within the semicircular canals pushes against hair cells, which causes bending of the cilia located on top of the hair cells

Vertigo

•From the Latin for “spinning”

•Sensation of spinning when one is not moving

•Dysfunction of the inner ear

Ménière disease

Disorder of the inner ear resulting in vertigo and loss of balance

_____ is the perception of pain, temperature, or itch.

Nociception

The part of the thalamus that carries information about body senses to the somatosensory cortex is called the _____.

ventrolateral spinothalamic tract

Primary somatosensory cortex

•Receives projections from the thalamus

•Brodmann’s areas 3–1–2

•Begins the process of constructing perceptions from somatosensory information

Secondary somatosensory cortex

•Located behind the primary somatosensory cortex

•Brodmann’s areas 5 and 7

•Refines the construction of perceptions, projects to the frontal cortex

Apraxia

Inability to make voluntary movements in the absence of paralysis or other motor or sensory impairment, especially an inability to make proper use of an obect.

The somatosensory cortex plays an important role in_______.

confirming that movements have taken place.

Damage to the secondary somatosensory cortex (SII) produces _____, an inability to complete a series of movements.

apraxia

Hapsis

Perceptual ability to discriminate obects on the basis of touch

Meniere Disease

Disorder of the middle ear resulting in vertigo and loss of balance.

Neuroprosthetics

Field that develops computer-assisted devices to replace lost biological function

Pain gate

Hypothetical neural circuit in which activity in fine-touch and pressure pathways diminishes the activity in pain and temperature pathways

Periaqueductal gray matter (PAG)

Nuclei in the midbrain that surround the cerebral aqueduct oining the third and fourth ventricles; neurons contain circuits for species typical behaviors (e.g., female sexual behavior) and play an important role in the modulation of pain

Position-point Theory

Idea that the motor cortex allows an appropriate body part to be moved to a point in space

Proprioception

Perception of the position and movement of the body, limbs, and head