[CTN] Special CTN seminar: Dec 10th **10.30am**, Dr. Nathan Insel, PAS 2464

[Matthijs van der Meer]

(Apologies for the double post, for some of you!)

Dear all,

My friend and colleague Nathan Insel will be in town next week, and he
agreed to give a talk. Nate recently received his Ph.D. from the
University of Arizona, working with Carol Barnes and others on the
neural basis of decision making in relation to aging. Title and abstract
of his talk follow below.

Note the special date and time -- 10.30 on Friday -- but the place is
the usual, PAS 2464.

If you would like to meet with Nate, please let me know!

Thanks,

- Matt


Title: Network dynamics and neural coding in the rat medial prefrontal
cortex: implications for speed of processing and goal-directed action
selection

Abstract: How does the brain use goals to select the right behaviors?
Convergent evidence suggests that the dorsal medial prefrontal cortex
(dmPFC) makes an important contribution to goal-directed action
selection. The dmPFC is also part of a network of brain regions that
becomes compromised in old age. It was hypothesized that during
decision-making, some process of comparison takes place in the dmPFC
between the representation of available actions and associated values,
and that this process is changed with aging. These hypotheses were
tested in aged and young adult rats performing a novel 3-choice, 2-cue
decision task.

Neuron and local field potential activity revealed that the dmPFC
experienced different states during decision and outcome phases of the
task, with increased local inhibition and oscillatory (gamma and theta)
activity during cue presentation, and increased excitatory neuron
activity (among regular firing neurons) at goal zones. Although
excitatory and inhibitory activity appeared anti-correlated over phases
of the decision task, cross-correlations and the prominent gamma
oscillation revealed that excitation and inhibition were highly
correlated on the millisecond scale. This “micro-scale” coupling between
excitation and inhibition was altered in aged rats, and the observed
changes were correlated with changes in decision and movement speeds of
the aged animals.

With respect to decision-making, both aged and young adult rats learned
over multiple days to follow the rewarded cue in the 3-choice, 2-cue
task. Support for the hypothesis that the dmPFC simultaneously
represents alternative actions was not found; however, neuron activity
selective for particular goal zones was observed. Interestingly,
goal-selective neural activity during the decision period was more
likely to take place on error trials, particularly on high-performing
sessions and when rats exhibited a preference for a particular feeder.

A possible interpretation of these patterns is that goal representations
in the dmPFC might have sometimes overruled learned habits, which are
likely to be involved in following the correct cue and which are known
to be supported by other brain regions. Thus, in investigating the
question “How does the brain select the right behaviors,” in the context
of an experimentally controlled, slowly-learned, cue-following task,
dmPFC activity was found that might sometimes contribute to the brain
selecting the "wrong" behaviors.