Neuro Pellis 138-175

What two forms of head scratching exist in birds?

Over-wing scratch (foot passes over the wing) and under-wing scratch (foot passes under the wing)

In swallows and frigate birds, when do they use over-wing vs. under-wing scratching?

Perched → over-wing; in flight → under-wing

Out of 391 bird species surveyed, what percentage showed both modes of scratching?

Only 9.7%

Which bird order accounts for 84.2% of dual-use scratching cases?

Passeriformes (perching birds)

What was the consistency index (CI) for over-wing scratching across bird phylogeny?

CI = 0.14 (indicating high homoplasy)

According to the authors, why is penguin scratching considered truly over-wing despite their flippers?

Penguins press the flipper against the body or rotate the trunk to move the flipper out of the way — the foot trajectory remains over the wing

Did leg morphology (tarsometatarsus length) differ between birds that scratch over-wing vs. under-wing?

No the ranges overlap completely; no significant difference

What happened when a bird wore a leg ring and tried to scratch over-wing?

The ring got caught in feathers; after several failures, the bird switched to under-wing scratching

What is the developmental sequence of head scratching in birds?

Under-wing first → over-wing later (never the reverse)

Do species that typically scratch under-wing ever switch to over-wing?

No — they scratch under-wing at all ages and in all contexts

What is the authors' main conclusion about bird head scratching patterns?

The two patterns represent distinct motor strategies with neural biases, not mere byproducts of biomechanics

In silver leaf-eating monkeys (Trachypithecus cristatus), what body part is always scratched with the foot?

The head

In these monkeys, what body part is always scratched with the hand?

The rump and tail

As the scratch location moves down the body toward the hip, what happens to foot use?

Foot use decreases; hand use increases

Scratching the lower torso with the foot requires ______ postural adjustments compared to scratching the upper torso.

More

Do primates that scratch their heads with their feet also use their hands to groom their heads?

Yes hands are used for grooming, cleaning ears, and placing food, but not for scratching.

What is a key piece of evidence that biomechanics alone doesn't explain foot vs. hand choice?

Monkeys can and do use hands for fine head tasks but still preferentially use feet for scratching.

Why are motor biases needed when multiple equally good motor solutions exist?

To allow quick action without spending time weighing options (especially important for predation)

How does the classical ethological concept of Fixed Action Pattern (FAP) relate to neural bias?

FAPs are movement strategies historically suitable for solving persistent disturbances, allowing quick enactment

What advantage do neural biases provide?

They allow a movement strategy to be enacted quickly when multiple strategies are possible

What are the three types of biasing rules identified by the authors?

1. Fixed movement rule bias

2. Fixed rules for connecting body parts bias

3. Fixed rules for access to similar actions bias

What happens when the hypothalamus is electrically stimulated in chickens?

Antipredator behavior is elicited, with low voltage evoking early phases and higher voltage evoking later phases — all without a predator present

In macaque monkeys, what do higher levels of cortical electrical stimulation elicit?

Species-typical behaviors: protective hand raising toward face, reaching/grasping toward nonexistent objects, placing nonexistent food into mouth

In the dorsal vs. ventral visual stream dissociation, what can patients with ventral stream damage still do?

Shape their fingers appropriately when reaching to grasp an object, even though they cannot recognize or name it

In pigeons pecking at the same disc in a Skinner box, how do food vs. water rewards affect pecking?

Food reward → food peck (bill partially open, eyes partially closed, faster); Water reward → water peck (bill closed, eyes fully open)

When do adult-typical grooming syntax patterns emerge in rodents?

Early in development, before adult body proportions are achieved

What is the "elbow-in" movement in rats during reaching?

Rats press elbows inward toward the body so lower arms are almost parallel with the midline

Can rats successfully reach and grasp without the elbow-in movement?

Yes rats with brain damage or other mammals of similar size can use elbow-out successfully

What are "motor primitives"?

Automatic units of action that can be inserted into various movement sequences

How do male and female rats differ in dodging during food defense?

Females pivot around a vertical axis at the pelvis; males pivot around an axis centered on mid-body

Does the sex difference in movement coordination disappear when body size is controlled?

No it persists irrespective of body size.

Does the sex difference in movement coordination appear only after adult body morphology develops?

No it appears in preadolescent rats before pelvic sex differences develop

In testicular feminization mutation (tfm) male rats, what happens to body morphology vs. movement pattern?

Body morphology becomes feminine, but the male-typical movement pattern persists

Name four behaviors in which the rat sex difference in fore-hindquarter coordination appears.

Dodging, spontaneous turning, rearing, reaching, and righting

Can both sexes perform both movement patterns?

Yes both sexes are physically able to perform both patterns but preferentially use their sex-typical pattern

What is the common rule for head-limb coordination in scratching across birds and mammals?

Use only one section of the body to make target-specific contact (limb moves to target, OR head moves to limb — not both)

What is the "final common pathway" in motor control?

Motor neurons converging on the same muscles used for different behavioral actions

In rat righting, which form of righting remains dominant over all others at all ages?

Trigeminal righting (tactile sensation on the face)

What problem occurs when multiple righting forms are coactivated in infant rats?

Movements compete and can actually retard righting

In the Mabel Stark tiger example, what did the bite to the back of the neck actually signify?

Mating behavior (copulation), not predation

What does the Mabel Stark example illustrate about motor outputs?

Similar motor outputs (e.g., a bite) are controlled by different neural mechanisms depending on behavioral context

In cataleptic rats bracing on a downward slope, which sex performs better and why?

Males their bias gives hind feet a dominant role (pulling), which is more efficient than females' forepaw pushing

Do female rats switch to the male pattern when it would give a better outcome?

No they persist with their sex-typical pattern even when it yields worse outcomes.

What is the consistency index (CI) for hand scratching evolution in primates?

CI = 0.375 (moderate homoplasy)

Once a primate lineage switches to using hands for scratching at least some of the time, what happens?

There is no reversion back to using primarily the foot

How are infantile behavior patterns typically eliminated from the adult repertoire?

By inhibition of their expression (not elimination of the neural circuit itself)

What happens to the rooting reflex in elderly people with dementia?

It reappears because late-forming cortical circuits (which normally inhibit it) are disrupted

In Allen's swamp monkey with a hind leg amputation, what happened to head scratching on the missing-leg side?

100% of head scratching involved the ipsilateral hand (showing the hand is capable of much higher frequency)

In infant spider monkeys vs. adults, what difference in head scratching is seen?

Infants scratch with feet more often than adults (reduced inhibition of foot scratching)

What is the proposed mechanism for switching from foot-typical to hand-typical scratching in primates?

Evolution of an inhibitory mechanism that suppresses the older (foot) pattern

In typical mammals, how are posterior body areas scratched?

Nibbling with teeth

What is the first transition in primate scratching evolution?

Using hands to scratch body areas previously scratched with teeth (lower body)

What is the second transition?

Encroachment onto neighboring body areas (upper arms, shoulders, neck) previously scratched with feet

What is the third transition?

Continued encroachment to include the head

Once a primate lineage began using hands to scratch the lower body, did any revert to using teeth?

No there have been no reversals

What is the consistency index (CI) for body-scratching transitions in primates?

CI = 0.50

In cats, what happens when electrical stimulation of the lateral hypothalamus is increased?

The area of the face in which touch will elicit predatory orientation expands

What is the proposed final stage of transition from foot scratching to hand scratching?

The foot pattern comes under inhibitory control, leaving hand scratching as the sole active pattern

How do Siberian ibex adults scratch their backs?

Using the tips of their curved horns

Do ibex kids use the same horn-scratching method as adults?

No kids are hornless and use hind hooves and teeth.

What novel scratching behavior did a Moluccan cockatoo perform?

Grasped a stick with its foot and used the free end to scratch the opposite side of its head (under-wing approach, but foot crossed midline)

How did a white-fronted parrot with a missing left leg scratch its right head side?

Used its beak to grasp cage bars, freeing its right foot to scratch

How did a chaffinch with half a missing right leg scratch its left head side?

Balanced on right stump, stretched right wing to touch perch for support, then raised left foot

What did a ring-billed gull with a missing right leg do?

Persisted in raising the stump and making scratching movements even though head-to-stump contact never occurred (failed to innovate)

What correlates with the likelihood of developing innovative behaviors in primates and birds?

Increased brain size, especially areas linked with associative and executive functions

When animals develop new movement solutions, do they replace the old ones?

No they add them to their repertoire, using a mixture of old and new

According to the authors, what three factors are sometimes sufficient to produce species-typical behavior regularities?

1. Simple neural rules (maintaining a perceptual constant)

2. Body morphology

3. Environmental context

When are additional neural rules (biases) needed?

When the three factors (perceptual rules, body, context) are insufficient to account for the regularity

What is the function of biased neural rules in evolution?

They allow quick, automatic enactment of movement strategies for predictable disturbances

Can phylogenetic biases ever be overcome?

Yes some species innovate novel strategies (e.g., using tools, body parts in new ways), though others remain tied to inherited biases