Behavioral Neuroscience - Exam 2

What is the visible spectrum?

Light of the visible spectrum is reflected from object surfaces and enters the eye.

What is the major purpose of the cornea?

Bends light toward the pupil

What does the lens of the eye do?

Focuses light on the retina

What are the functional characteristics (sensitivity, acuity, color, location) of rods?

• Located in the periphery

• High sensitivity due to high
  convergence

• Achromatic

What are the functional characteristics (sensitivity, acuity, color, location) of cones?

• Located in the fovea

• High acuity due to low
  convergence

• Can distinguish wavelengths
  (chromatic)

What region of the retina monitors the central field of vision?

Fovea receives light from center of visual field

What is the optic disc? What phenomenon does the optic disc give rise to?

Optic disc area where optic nerve leaves and there are no photoreceptors producing a blindspot

What type of neuron carries information away from the eye toward the brain?

Sensory Neuron

How do we distinguish between the optic nerve and the optic tract?

Nerve - Paired cranial nerve that connects the retina to the brain

Tract - Extension of the optic nerve that carries visual info from the optic chiasm to the brain

What is the general shape of ganglion cell receptive fields?

Circular

What is the difference between on-center and off-center ganglion cell receptive fields? How does stimulation of each affect the activity of the ganglion cell?

“On-Center” - On-center ganglion cells are activated by light in the center of their receptive field and inhibited by light in the surround

“Off-Surround” - while off-center ganglion cells are inhibited by light in the center and activated by light in the surround

What is the purpose of lateral inhibition?

Enables the brain to manage environmental input and avoid information overload.

Which ganglion cells cross at the optic chiasm and which stay on the same side?

Nasal retina axons - cross over

Temporal retina axons - remain on the same side

To what three structures do ganglion cells primarily travel?

Thalamus, visual cortex, and The Superior Colliculus

How do we experience different wavelengths of light?

Color

What is the basic idea of the trichromatic theory of color vision? How does the brain know what wavelength of light is stimulating the retina?

• The three types of cones, S-cones, M-cones, and L-cones, are sensitive to
  different ranges of wavelengths

• Wavelength is coded by the pattern of responses observed in the three cone populations.

• Each wavelength is associated with a specific pattern of relative activity in the three cone types.

What is a scotoma?

A blind spot in one or both eyes

What is retinal disparity? How do we make use of retinal disparity?

The slight difference in the images perceived by each eye due to their different positions on the face

• Depth perception

• Three-dimensional vision

What is the purpose of feedback from the visual cortex to the lateral geniculate nucleus of the thalamus?

This feedback can modulate the gain of LGN neurons, influencing the transmission of visual information to the primary visual cortex. The LGN is also influenced by other sensory modalities, such as audition and touch, which can modulate the processing of visual information.

What are the major functions associated with the dorsal and ventral streams of the visual system?

Dorsal - Processes info about location and visual Layout

Ventral - Processes info for visual recognition and discrimination

What effects would damage to the dorsal stream have?

• Critical for guiding movements

• Damage: optic ataxia

What effects would damage to the ventral stream have?

• Processes information necessary
  for visual recognition and
  discrimination

• Damage: Associative visual
  agnosia

What is prosopagnosia and which visual stream (ventral or dorsal) is likely to be damaged in this disorder?

Prosopagnosia - Face Blindness

Damage dorsal visual stream

What is blindsight?

The ability to use visual information in the absence of visual awareness

What is synesthesia?

Stimulation of one sensory or cognitive pathway leads to autonomic, involuntary experiences in a second sensory or cognitive pathway. “Taste sound or hear color”

What is the difference between flexion and extension?

Flexion decreases the angle between 2 body parts, bringing them closer together

Extension increases the angle between 2 body parts, bringing them further apart

Where is the primary motor cortex located?

Frontal Lobe

What does it mean to say we primarily have contralateral motor control?

Refers to the brain's ability to coordinate movements by controlling the opposite side of the body.

This means that the left hemisphere of the brain controls the right side of the body, and the right hemisphere controls the left side.

How does the amount of cortex devoted to a particular area of the body relate to the control we have over that region?

The more devoted the more detailed the sensory information

What are central pattern generators? What kinds of behavior do they give rise to?

Responsible for producing rhythmic motor patterns that are essential for various behaviors.

Walking, breathing, chewing, crawling, etc.

What are alpha motor neurons?

Motor neurons of the brainstem and spinal cord

What do the axon terminals of alpha motor neurons synapse with?

Muscle fibers

How are muscles connected to bone?

Tendons

What is the Bell-Magendie law?

The anterior spinal nerve roots contain only motor fibers, while the posterior roots contain only sensory fibers, establishing a clear functional distinction in the nervous system.

What is the relationship between location of spinal cord damage and subsequent loss of motor control?

The higher the damage, the greater the extent of paralysis

What brain region prioritizes goals, determining which is most important at any moment?

Prefrontal cortex

What region of the brain appears to be critical for inhibiting inappropriate motor responses?

Prefrontal Cortex

What is the job of the dorsal premotor cortex?

Becomes active when we prepare to make a movement

What is the function of the supplementary motor area (SMA)?

Coincides with the desire to want to move, tends to be a specific movement with a specific body part

What is a readiness potential and from what brain region is it recorded?

Measure of activity in the motor cortex and the supplementary motor area of the brain

What brain region is responsible for controlling voluntary eye movements?

Frontal Eye Field, prefrontal cortex

What are saccades?

Fast, voluntary or involuntary eye movements that redirect gaze from one point to another.

Regarding the basal ganglia, which structures receive input?

Striatum

Regarding the basal ganglia, which structures send output?

Globus Pallidus

What is a looped circuit?

A brain circuit is a network of connections between neurons that form a path for electrical activity to travel within the brain. These circuits are essential for processing information and coordinating actions.

Cortex provides input to the striatum, the Striatum influences activity of Globus Pallidus, and Globus Pallidus sends output to the cortex via the thalamus

What set of structures is critically important for the formation of behavioral habits?

Basal Ganglia

What is alien hand syndrome?

A neurological condition where one hand acts independently, often performing involuntary movements that the person does not intend.

What is the relationship between the substantia nigra and the striatum?

Nigrostriatal Pathway: Component of the basal ganglia motor loop, which is essential for motor control and movement.

Connects the substantia nigra to the dorsal striatum, facilitating the integration and execution of voluntary movements.

What disorder is associated with death of dopaminergic neurons in the substantial nigra?

Parkinson’s

What are the typical symptoms of cerebellar damage?

Damage results in uncoordinated, clumsy movements.

Which region of the brain compares the intended consequence of motor activity with the actual consequence, thus acting as a error detector?

Cerebellum