Learning performance in dwarf mice

247 D.T.P.'s lateral

into N . T . P . ' s dorsal

corresponding perfusion

in the photic

nucleus visual

of the

cortex.

of one eye with

responses

lateral The

same occurs

solutions

of the contra-

geniculate

body

during

containing

and the

precorneal

norepinephrine

or

~--sympathomimetics. Although structures

the p r e s e n c e

other

established, that

receptors

by means

the pineal

part

Also,

experiments

the p h o t i c

nerve

fibres

which

give

further

of a r e t i n o - r e t i n a l

of the brain w h i c h

res-

of the photo-

the results

in rabbits

but p r o b a b l y

on retinal

reported

influences

of s y m p a t h e t i c

neurons.

some

organ

clock

in the close v i c i n i t y

for the e x i s t e n c e

loop c o m p r i s i n g

endings

has not been h i s t o l o g i c a l l y

from the p r e s e n t l y

- receptors

or retinal

evidence

vessels

the c i r c a d i a n

of the eyes

end on ~

of s y m p a t h e t h i c

blood

it follows

in rabbits

ponses must

than

is d e f i n i t e l y

the s u p r a c h i a s m a t i c

closed not

nuclei.

REFERENCES

i. Bobbert, 307-325.

A.C.

et al,

(1978)

Int.J.Chronobiology,

5

,

2. Bobbert, 327-344.

A.C.

et al,

(1978)

Int. J . C h r o n o b i o l o g y ,

5

,

3. Bobbert, 519-532.

A.C.

et al,

(1978)

Int.J.Chronobiology,

5 ,

LEARNING

PERFORMANCE

BOUCHON,

R. AND WILL,

Laboratoire 67000

B.

de P s y c h o p h y s i o l o g i e ,

Strasbourg,

The which

IN DWARF HICE

(France)

first b e h a v i o u r a l

are c h a r a c t e r i z e d

hypophysis, learning

revealed

and m e m o r y

A) H e b b - W i l l i a m s

maze

T maze,C)passive these b e h a v i o u r a l

7, Rue de l'Universit~,

studies

conducted

by a primary

that

at adult

deficits

age,

these

in the following

learning, B ) s p o n t a n e o u s

step-through deficits

on m u t a n t

deficiency

avoidance

are very

animals

exhibit

tasks:

alternation

learning.

similar

dwarf mice,

of the a n t e r i o r

Thus

to those

in a far,

all

248 characterizing

animals

The dwarf mice environments vioural

did

the

in rats

were

bearing

As

mice,

suggested

previously,

or i m p o v e r i s h e d

lesions

) until

rearing

in a s i m i l a r

beha-

conditions

way

as they

i) : in c o m p a r i s o n g r o u p made

more

often

of p e r f o r m a n c e

to

less e r r o r s in the T m a z e

in the p a s s i v e

with

2) . However,

significantly

these mice

the b e h a v i o u r a l

be explained,

interaction

external

) . These

alternated

level

enriched

at 21 days

the e n r i c h e d

maze,

lesions.

task.

development ment

later

performances

a higher

dwarf m i c e m i g h t creased

in either

hippocampal

dwarf

in the H e b b - W i l l i a m s and d i s p l a y e d

hippocampal

( generally

( one m o n t h

learning

improverished

avoidance

reared

from w e a n i n g

testing

modified

bearing

it a p p e a r e d their

a markedly

environment

at this

deficits

at least,

the e n v i r o n m e n t

affects

display

partly

during

their

that p o s t w e a n i n g

learning

decreased

of the

by their

early environ-

performances

interaction

de-

although

with

the

period.

REFERENCES

1. Kelche, C.R. 935-941.

and Will,

B.E.

(1978)

Physiol.

Behav.,

21

,

2. Bouchon, R.M. and Will, B.E. (1980) B e h a v i o r a l d e v e l o p m e n t of the d w a r f m u t a n t mouse. Ist m e e t i n g of the i n t e r n a t i o n a l society for d e v e l o p m e n t n e u r o s c i e n c e . Strasbourg.

VISUOMOTOR

FUNCTION

BUCHBINDER, MAY,

J.

W.S.

Hunter

Providence,

S.,

DIXON,

Laboratory Rhode

WCIE

The pons midbrain striate

7JG,

cortex,

GLICKSTEIN,

of P s y c h o l o g y ,

M.,

Brown

02912, (U.S.A.)

Mechanisms

}{WANG,

Y.W.

AND

University,

and

of Behaviour,

3 Malet

Place,

(England)

relays

visual

B.,

Island

MRC Unit on Neural London

IN M O N K E Y S

visual

centers area

17,

information

between

and the cerebellum. sends

cortical

In monkeys,

few or no fibers

and the

to the p o n t i n e