PSYC550 Biological Bases of Behavior Sense or Senseless?

PSYC550 Biological Bases of Behavior

Sense or Senseless?

The Stimulus

• sensory receptors– A specialized neuron that detects a particular

category of physical events.

• sensory transduction– The process by which sensory stimuli are

transduced into slow, graded receptor potentials.

• receptor potential– A slow, graded electrical potential produced by a

receptor cell in response to a physical stimulus.

The Stimulus

• hue– One of the perceptual dimensions of color;

the dominant wavelength.

• brightness– One of the perceptual dimensions of color;

intensity.

• saturation– One of the perceptual dimension of color;

purity.

Anatomy of the Visual System

• vergence movement– The cooperative movement of the eyes, which

ensures that the image of an object falls on identical portions of both retinas.

• saccadic movement– The rapid, jerky movements of the eyes used in

scanning a visual scene.

• pursuit movement– The movement that the eyes make to maintain

an image of a moving object on the fovea.


• accommodation– Changes in the thickness of the lens of the eye, accomplished

by the ciliary muscles, that focus images of near or far objects on the retina.

• retina– The neural tissue and photoreceptive cells located on the

inner surface of the posterior portion of the eye.

• rod– One of the receptor cells of the retina; sensitive to light of

low intensity.

• cone– One of the receptor cells of the retina; maximally sensitive to

one of three different wavelengths of light and hence encodes color vision.


• photoreceptor– One of the receptor cells of the retina; transduces

photic energy into electrical potentials.• fovea

– The region of the retina that mediates the most acute vision of birds and higher mammals. Color-sensitive cones constitute the only type of photoreceptor found in the fovea.

• optic disk– The location of the exit point from the retina of

the fibers of the ganglion cells that form the optic nerve; responsible for the blind spot.


• bipolar cell– A bipolar neuron located in the middle layer of the retina,

conveying information from the photoreceptors to the ganglion cells.

• ganglion cell– A neuron located in the retina that receives visual

information from bipolar cells; its axon give rise to the optic nerve.

• horizontal cell– A neuron in the retina that interconnects adjacent

photoreceptors and the outer processes of the bipolar cells.• amacrine cell

– A neuron in the retina that interconnects adjacent ganglion cells and the inner processes of the bipolar cells.


• dorsal lateral geniculate nucleus– A group of cell bodies within the lateral

geniculate body of the thalamus; receives inputs from the retina and projects to the primary visual cortex.

• magnocellular layer– One of the inner two layers of neurons in

the dorsal lateral geniculate nucleus; transmits information necessary for the perception of form, movement, depth, and small differences in brightness to the primary visual cortex.


• parvocellular layer– One of the four outer layers of neurons in

the dorsal lateral geniculate nucleus; transmits information necessary for perception of color and fine details to the primary visual cortex.


• calcarine fissure– A horizontal fissure on the inner surface of the

posterior cerebral cortex; the location of the primary visual cortex.

• striate cortex– The primary visual cortex.

• optic chiasm– A cross-shaped connection between the optic

nerves, located below the base of the brain, just anterior to the pituitary gland.

Coding of Visual Information in the

Retina

• receptive field– The portion of the visual field in which the

presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron.

Coding of Visual Information in the

Retina• negative afterimage

– The image seen after a portion of the retina is exposed to an intense visual stimulus; consists of colors complementary to those of the physical stimulus.

Analysis of Visual Information: Role of the Striate Cortex

• simple cell– An orientation-sensitive neuron in the striate cortex

whose receptive field is organized in an opponent fashion.

• complex cell– A neuron in the visual cortex that responds to the

presence of a line segment with a particular orientation located within its receptive field, especially when the line moves perpendicular to its orientation.

• hypercomplex cell– A neuron in the visual cortex that responds to the

presence of a line segment with a particular orientation that ends at a particular point within the cell’s receptive field.

Analysis of Visual Information: Role

of the Striate Cortex

• cytochrome oxidase (CO) blob– The central region of a module of primary

visual cortex, revealed by a stain for cytochrome oxidase; contains wavelength-sensitive neurons; part of the parvocellular system.

• ocular dominance– The extent to which a particular neuron

receives more input from one eye than from the other.

Analysis of Visual Information: Role of

the Visual Association Cortex• extrastriate cortex

– A region of visual association cortex; receives fibers from the striate cortex and from the superior colliculi and projects to the inferior temporal cortex.

• dorsal stream– A system of interconnected regions of visual

cortex involved in the perception of spatial location, beginning with the striate cortex and ending with the posterior parietal cortex.


the Visual Association Cortex

• ventral stream– A system of interconnected regions of visual

cortex involved in the perception of form, beginning with the striate cortex and ending with the inferior temporal cortex.

• inferior temporal cortex– In primates the highest level of the ventral

stream of the visual association cortex; located on the inferior portion of the temporal lobe.

From the retina to other parts of the

brain• Superior colliculus

– Head orientation to movements in peripheral field

• Accessory optic nucleus– Eye movements to compensate for head

movements

• Suprachiasmatic nucleus– Controls circadian rhythms

• Pineal body– Controls circannual rhythms


the Visual Association Cortex• visual agnosia

– Deficits in visual perception in the absence of blindness; caused by brain damage.

• apperceptive visual agnosia– Failure to perceive objects, even though visual acuity

is relatively normal.• associative visual agnosia

– Inability to identify objects that are perceived visually, even though the form of the perceived object can be drawn or matched with similar objects.

• prosopagnosia– Failure to recognize particular people by the sight of

their faces.

Damage to the parietal lobe

• Critical for spacial perception and locating objects in space

• ocular apraxia– Difficulty in visual scanning.

• simultanagnosia– Difficulty in perceiving more than one object

at a time.• Optic ataxia

– Deficit in reaching for objects under visual guidance

Hearing…

Audition• tympanic membrane

– The eardrum.• ossicle

– One of the three bones of the middle ear (malleus, incus, stapes).

• malleus– The “hammer”; the first of the three ossicles.

• incus– The “anvil”; the second of the three ossicles.

• stapes– The “stirrup”; the last of the three ossicles.

Audition• cochlea

– The snail-shaped structure of the inner ear that contains the auditory transducing mechanisms.

• oval window– An opening in the bone surrounding the cochlea that

reveals a membrane, against which the baseplate of the stapes presses, transmitting sound vibrations into the fluid within the cochlea.

• organ of Corti– The sensory organ on the basilar membrane that

contains the auditory hair cells.• hair cell

– The receptive cell of the auditory apparatus.

Audition

• basilar membrane– A membrane in the cochlea of the inner

ear; contains the organ of Corti.

• tectorial membrane– A membrane located above the basilar

membrane; serves as a shelf against which the cilia of the auditory hair cells move.

Audition

• cilium– A hair-like appendage of a cell involved in

movement or in transducing sensory information; found on the receptors in the auditory and vestibular system.

• tip link– An elastic filament that attaches the tip of

one cilium to the side of the adjacent cilium.

From the ear to…

• Medulla– Cochlear nuclei– Superior olivary nuclei– Lateral lemniscus

• To inferior colliculus• To medial geniculate• To auditory cortex

Audition

• cochlear nerve– The branch of the auditory nerve that

transmits auditory information from the cochlea to the brain.

• superior olivary complex– One of a group of nuclei in the medulla;

involved with auditory functions, including localization of the source of sounds.

Audition

• lateral lemniscus– A band of fibers running rostrally through

the medulla and pons; carries fibers of the auditory system.

• tonotopic representation– A topographically organized mapping of

different frequencies of sound that are represented in a particular region of the brain.

Audition

• place code– The system by which information about

the different frequencies is coded by different locations on the basilar membrane.

• cochlear implant– An electronic device surgically implanted

in the inner ear that can enable a deaf person to hear.

What happens if we give a bilateral

lesion of the auditory cortex?

Can

det

ect p

itch a

nd ...

Can

hea

r, bu

t can

’t ...

Will

be

com

plete

ly d

eaf

33% 33%33%1. Can detect pitch

and intensity, but not “melodies”

2. Can hear, but can’t detect pitch or intensity

3. Will be completely deaf 1010

What happens if we lesion the inferior

colliculus?

Can

det

ect p

itch a

nd ...

Can

hea

r, bu

t can

’t ...

Will

be

com

plete

ly d

eaf





What happens if we lesion the lateral

lemniscus?

Can

det

ect p

itch a

nd ...

Can

hea

r, bu

t can

’t ...

Will

be

com

plete

ly d

eaf





Somatosenses

• cutaneous sense– One of the somatosenses; includes

sensitivity to stimuli that involve the skin.

• kinesthesia– Perception of the body’s own movement.

• organic sense– A sense modality that arises from

receptors located within the inner organs of the body.

Somatosenses

• glabrous skin– Skin that does not contain hair; found on

the palms and soles of the feet.

• Ruffini corpuscle– A vibration-sensitive organ located in hairy

skin.

• Pacinian corpuscle– A specialized, encapsulated somatosensory

nerve ending that detects mechanical stimuli, especially vibrations.

Somatosenses

• Meissner’s corpuscle– The touch-sensitive end organs located in

the papillae, small elevations of the dermis that project up into the epidermis.

• Merkel’s disk– The touch-sensitive end organs found at

the base of the epidermis, adjacent to sweat ducts.

Somatosenses

• phantom limb– Sensations that appear to originate in a

limb that has been amputated.

• nucleus raphe magnus– A nucleus of the raphe that contains

serotonin-secreting neurons that project to the dorsal gray matter of the spinal cord and is involved in analgesia produced by opiates.

When resonance causes the cilia to

move:

It ti

ckle

s

It c

ause

s th

e ty

mpan

..

Sem

icirc

ular c

anal

s ...

Cal

cium

chan

nels

open

25% 25%25%25%1. It tickles2. It causes the

tympanic membrane to vibrate

3. Semicircular canals vibrate

4. Calcium channels open 1010

The neural structure noted for control of

circadian rhythms is the:

Acc

esso

ry o

ptic n

uc...

Supra

chia

smat

ic n

uc...

Pin

eal g

land

Super

ior c

ollic

ulus

25% 25%25%25%1. Accessory optic nucleus

2. Suprachiasmatic nucleus

3. Pineal gland4. Superior

colliculus

1010

PSYC550 Biological Bases of Behavior Sense or Senseless?

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Transcript of PSYC550 Biological Bases of Behavior Sense or Senseless?