192-IgG Saporin lesions of the medial septum or nucleus basalis magnocellularis disrupt exploratory trip organization. D.G. Wallace*, S.S. Winter, M.M. Martin, J.L. McMillin Dept Psychology, Northern Illinois Univ., DeKalb, IL, USA - PowerPoint PPT Presentation

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192-IgG Saporin lesions of the medial septum or nucleus basalis magnocellularis disrupt exploratory trip organization. D.G. Wallace*, S.S. Winter, M.M. Martin, J.L. McMillin Dept Psychology, Northern Illinois Univ., DeKalb, IL, USA

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Title: 192-IgG Saporin lesions of the medial septum or nucleus basalis magnocellularis disrupt exploratory trip organization. D.G. Wallace*, S.S. Winter, M.M. Martin, J.L. McMillin Dept Psychology, Northern Illinois Univ., DeKalb, IL, USA


1
192-IgG Saporin lesions of the medial septum or
nucleus basalis magnocellularis disrupt
exploratory trip organization. D.G. Wallace,
S.S. Winter, M.M. Martin, J.L. McMillinDept
Psychology, Northern Illinois Univ., DeKalb, IL,
USA
90.15
Abstract
Results
Figure 4 Distance traveled on searching segments
(blue bars) did not differ among groups. Each
rats set of homeward segments (red bars) were
divided into short and long segments. No group
differences were observed in the distance
traveled on short or long homeward segments.
Figure 7 Groups did not differ in the standard
deviation associated with the peak speed location
on searching segments (blue bars). Although
groups did not differ in standard deviations
associated with the peak speed location on
homeward segments (red bars), larger standard
deviations were observed on long homeward
segments relative to short homeward segments.
Previous work has demonstrated that rats use
self-movement cues to organize their exploratory
behavior. The hippocampus and several cortical
areas have been implicated in processing
self-movement cues. The current study
investigated whether selective cholinergic
deafferentation of the hippocampus or cortex
differentially influenced the organization of
exploratory behavior.
Figure 2 Coronal sections stained for
acetylcholinesterase are presented for a
representative sham (A), medial septum (B),
nucleus basalis magnicellularis (C). The graph
(D) plots the average optical density for areas
of the cortex and hippocampus. MS lesions
produced selective hippocampal deafferentation.
NB lesions failed to produce significant
reductions in cortical acetylcholinesterase.
A
B
Methods
Figure 8 Groups did not differ in the error
associated with the peak speed location on
searching segments (blue bars). Although groups
did not differ in error associated the peak speed
location on homeward segments (red bars), larger
errors were observed on long homeward segments
relative to short homeward segments.
Long Evans female rats received injections of 192
IgG-Saporin into the medial septum (MS, n5) or
nucleus basalis magnocellularis (NB, n4). Rats
that received saline injected into either
structure were collapsed into one group (Sham,
n7). Subsequent to recovery, rats were placed on
a large circular table with access to a refuge
under complete dark conditions (infrared cameras
and goggles were used to visualize the rat). Rats
were free to explore the table for 50 minutes.
Rats were given five exploratory sessions. All
exploratory trips (up to 25 trips) were digitized
using the Peak Performance motion capture system.
Figure 5 Searching segment (blue bars) path
circuity did not differ among groups. Groups did
not differ in homeward segment (red bars) path
circuity. Long homeward segments were
significantly more circuitous relative to short
homeward segments.
C
D
Conclusions
Figure 3 Quadrant preference (((T-B)(T-C)(T-D))
/3) and total distance traveled were evaluated
for the first exploratory session. Groups did not
significantly differ in either of these general
characteristics of exploratory behavior.
Figure 1Topographic and kinematic
characteristics are plotted for three exploratory
trips. Searching segments (blue lines) of
exploratory trips are a sequence of progressions.
Homeward segments (red lines) reflect the
progression after the last stop. Note that
homeward segment peak speed varies as a function
of progression length.
  • MS lesions produced significant cholinergic
    deafferentation selective to the hippocampus.
  • These lesions spared home base establishment and
    spared many characteristics of exploratory trip
    organization.
  • These lesions impaired modulation of peak speed
    observed across short and long homeward segments.
  • NB lesions produced significant cholinergic
    deafferentation selective to the cortex.
  • No impairments were observed in the organization
    of exploratory behavior.
  • These results are consistent with previous work
    demonstrating a role for the medial septum in
    distance estimation derived from self-movement
    cues.

Figure 6 Peak speeds observed on searching
segments (blue bars) did not differ among groups.
Both Sham and NB groups showed a significant
increase in peak speeds across short and long
homeward segments (red bars). The MS groups did
not demonstrate a significant increase in peak
speed across short and long homeward segments.
Acknowledgments Bethany Barnes, Deirdre Clarke,
Steve Wagner, Jenny Raines, Patricia Wallace,
Adam Sommerfeld, William Mcdermott
Correspondence D.G. Wallace dwallace_at_niu.edu
Web www.niu.edu/user/tj0dgw1 Grant support
NINDS grant NS051218 to D.G. Wallace
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