Chapter 4bF

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Biology 484 – Ethology
Chapter 4b – Neural
Mechanisms Controlling
Behavior
4.11 Noctuid moth ears
Noctuid moths (owlet moths)
are very large, robust moths
that typically have very well
developed sensory abilities in
hearing.
The specialized hearing
structures in these moths allow
them to detect echolocation
signals used by bats (a major
predator for these moths).
Note that the tympanum
articulates with both the A1 and
A2 receptor cells. The various
air sacs are designed to
modulate the movement of the
tympanum.
4.12 Neurons and their operation
As we see here, the
neuronal interaction is
as described earlier.
This is representing
the classic axodendritic
synapse seen in a
majority of neurons.
Sensory neuron
Stimulus
Integration
center
Receptor
Interneuron
Response
Effector
Motor neuron
Spinal cord (CNS)
Reflex Arcs can bee seen in many aspects of the nervous system. These
are abbreviated pathways that allow a more rapid response than would the
full neural pathway. These arcs are used for a variety of physiological and
behavioral responses in the body of many species.
A common reflex arc of balance…. The Patellar Reflex
The Babinski (Plantar) Reflex which is closely
related to the Crossed- Extensor Reflex.
The Achillies Reflex
The Crossed Extensor Reflex - a
withdrawal reflex that occurs when
the flexors in the withdrawing limb
contract and the extensors relax,
while in the other limb, the opposite
occurs.
The crossed extensor reflex is
contralateral, meaning the reflex
occurs on the opposite side of the
body from the stimulus.
This reflex also occurs in the
forlimbs (arms).
Thought Question…. From a
behavioral perspective, can you
think of some broader uses for
this reflex, especially for
quadrapeds?
4.13 Neural network of a moth
Of special note here are the
interneurons which allow for
a multi-tiered transmission:
a)Typical PNS to CNS
transmission to the brain
and back out to the
periphery.
b)The abbreviated neural
pathway referred to as a
reflex arc which in this case
connects the auditory input
reflexively to the flight
muscles.
4.14 Properties of the ultrasound-detecting auditory receptors of a noctuid moth (Part 1)
The A1 and A2 receptors respond differently. The A1 receptor responds in a more
graded fashion and the neural firing rate varies with intensity of the sound. The A2
receptor, by contrast is responsive in a more “all-or-none” fashion for the stimulus
levels expressed by the bat predator. Only when the intensity gets to a certain level
(suggesting closer proximity) does the receptor begin to fire.
4.14 Properties of the ultrasound-detecting auditory receptors of a noctuid moth (Part 2)
The A1 receptor, however, responds differentially when exposed to pulsatile
sound versus a steady sound. The pulsation shown mimics the ultrasound
pulsation displayed by echolocation in the bat. The steady sound would
represent potential background noise that the moth would initially respond to but
over time would acclimate to the steady sound.
4.15 How moths might locate bats in space (Part 1)
The ability to LOCATE
the position of the
predator (bat) is due to
the differential firing rates
of the A1 cells on either
side of the head. The
cells that are farther away
will receive a weaker
sound signal and will fire
at a slower rate.
4.15 How moths might locate bats in space (Part 2)
Similarly, if the predator is directly behind the moth, the A1 cell firing rate
would be the same on both sides of the head.
4.15 How moths might locate bats in space (Part 3)
Interestingly, the wing position of the moth has an impact on A1 cell activity as
well…. The position of the moth’s wings relative to the position of the sound
impact firing rate. In the example shown, since the predator is above the moth,
the wing down position has a slower firing rate than the wing up position.
If the bat were positioned underneath the moth, the wing down position would
have a higher firing rate than the wing up position.
The theory of how this
position effect works is
that the wings are
serving as a “funnel” to
capture greater sound
intensity when they
face toward the
predator.
Figure 15.25a: Structure of the ear, p. 584.
External
(outer) ear
Middle
ear
Internal
(inner) ear
(labryinth)
This is
similar in
some ways
to HUMAN
hearing.
Auricle
(pinna)
Helix
Lobule
External
acoustic
meatus
Tympanic membrane
Pharyngotympanic
(auditory) tube
(a)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 15.25b: Structure of the ear, p. 584.
Entrance to mastoid antrum
in the epitympanic recess
Auditory
ossicles
Semicircular
canals
Malleus
(hammer)
Incus
(anvil)
Stapes
(stirrup)
Vestibule
Vestibular
nerve
External
acoustic
meatus
Cochlear
nerve
Cochlea
Tympanic
membrane
Oval window
(deep to stapes)
(b)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Internal
jugular vein
Pharyngotympanic
(auditory) tube
Round window
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 5.26: The three auditory ossicles in the right middle ear, p. 585.
Malleus
Incus
Epitympanic recess
Superior
Anterior
Pharyngotym- Tensor
panic tube
tympani
muscle
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Tympanic
Stapes
membrane
(medial view)
Stapedius
muscle
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 5.27: Membranous labyrinth of the internal ear, p. 586.
Temporal
bone
Facial nerve
Semicircular ducts in
semicircular canals:
Vestibular nerve
• Anterior
Superior vestibular ganglion
• Posterior
Inferior vestibular ganglion
• Lateral
Cochlear nerve
Cristae ampullares
in the ampullae
Maculae
Spiral organ (of Corti)
Utricle in vestibule
Cochlear duct in cochlea
Saccule in vestibule
Stapes in
oval window
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Round window
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 15.35: Structure of a macula, p. 594.
Macula of
saccule
Macula of
utricle
Kinocilium
Stereocilia
Otoliths Otolithic
membrane
Hair bundle
Hair cells
Vestibular
nerve fibers
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Supporting
cells
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 15.36: The effect of gravitational pull on a macula receptor cell in the utricle, p. 595.
Otolithic
membrane
Kinocilium
Ster eocilia
Depolarization
Hyperpolarization
Receptor
potential
(Hairs bent towar d
kinocilium)
Nerve
impulses
generated in
vestibular fiber
Increased
impulse frequency
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Excitation
(Hairs bent away
from kinocilium)
Decreased
impulse frequency
Inhibition
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 15.37: Location and sturcture of a crista ampullaris, p. 596.
Flow of
endolymph
Crista
ampullaris
(a)
Fibers of
vestibular nerve
Cupula
(b)
Turning motion
Cupula
Position
of cupula
during turn
(c)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Increased firing
(d)
Ampulla
of left ear
Ampulla of
right ear
Cupula at rest
Position of cupula
during turn
Fluid motion in
ducts
Horizontal ducts
Decreased firing
Afferent fibers of vestibular nerve
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
4.17 Is the A2 cell necessary for anti-interception behavior by moths? (Part 1)
The “terminal buzz” phase
of echolocation occurs just
prior to the attack and
represents when the bat is
fine-tuning his final
approach to the prey.
(B- cells are non auditory
(balance) oriented cells in
the moth’s ear and do not
play a role here.)
4.17 Is the A2 cell necessary for anti-interception behavior by moths? (Part 2)
We see that it is the A1
neurons that fire
differentially as the
terminal buzz occurs not
the A2 neuron.
Therefore, there is no
known link between the
A2 neuronal group
related to evasive
maneuvers from bats.
Question to Ponder….
From what we have
described, can you
suggest POTENTIAL uses
for the A2 that could be
studied?
4.18 Avoidance of and attraction to different sound frequencies by crickets (Part 1)
In crickets, the abdominal position is an indication of flight pattern. In a,
when there is no sound, the abdomen suggests a straight flight course. In
b, we have a low frequency sound and we see the abdominal position such
that it shows the cricket will fly towards the sound. In c, the high frequency
sound is associated with the cricket turning AWAY from the sound.
4.18 Avoidance of and attraction to different sound frequencies by crickets (Part 2)
Notice here how the
specific frequency range
is able to fire at a far
lower intensity in this
neuron.
(the int-1 interneuron)
What could this
specificity indicate?
4.20 Escape behavior by a sea slug
Escape behavior like
shown is an involuntary,
reflexive response in the
slug.
The behavior results in a
rapid series of undulating
responses leading to full
ventral flexion followed
rapidly by full dorsal
flexion.
4.21 Neural control of escape behavior in Tritonia
The alternating activity of this escape behavior is seen in the neuronal
tracings.
4.27 The star-nosed mole’s nose differs greatly from those of its relatives
The four
species all,
however, rely
significantly
on tactile
sensation to
find food
(prey).
4.28 A special tactile apparatus (Part 1)
What might you predict about the
specificity of the tactile response of the
multiple projections of the snout in the
species?
Theodore Eimer – German Zoologist from the 1870s who identified the
specialized tactile sensory structures seen in many different mole
species. They have been named in his honor, the Eimer’s Organs.
4.28 A special tactile apparatus (Part 2)
Eimer's organs are sensory organs of
the epidermis modified into bulbous
papillae. These organs are present in
many moles, and are espeically dense
in the star-nosed mole, which bears
~30,000 of them on its snout. They
contain a Merkel cell-neurite complex in
the epidermis.
4.29 The cortical sensory map of the star-nosed mole (Part 1)
Note the
appendage
numbers shown
in (A)
correspond to
the same
numbers in (B)
showing
regions of the
cortex.
4.29 The cortical sensory map of the star-nosed mole (Part 2)
Why would you think Area 11 is so strongly represented?
4.30 Sensory analysis in four insectivores
4.31 Sensory analysis in humans and naked mole-rats
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