Yen-Chen (Steven) Huang PhD

Yen-Chen (Steven) Huang


Publications:
2008
  How do visual cues exert stimulus control over hippocampal place cells and entorhinal head direction cells?
Huang, Y-CS, Dudchenko, PA, Van Rossum, M & Wood, E 2008, 'How do visual cues exert stimulus control over hippocampal place cells and entorhinal head direction cells?' Society for Neuroscience Annual meeting, 2008, Washington DC, United States, 15/11/08 - 19/11/08, .
Visual cues help rats to maintain an internal representation of orientation. However, in a changing environment, it is important to choose the most informative cues to guide navigation. We hypothesise that cues are more informative when they maintain stable relative positions with other cues in the environment, as such stability allows the position of one cue to reliably predict the position of another.
To test this hypothesis, we recorded hippocampal CA1 place cells and entorhinal head direction cells in rats as they foraged for food pellets on a circular platform in a cue controlled environment. Four distinct visual cues were fixed onto black curtains surrounding the platform. Three of the cues made up the “stable” cue set, while the other was “unstable”. Between sessions, conflicts were introduced by changing the positions of all four cues such that only the relative relationships between the three stable cues remained fixed. The rats were given five conflict sessions per day for two days, followed by a probe day which included a session where two of the stable cues were removed, and the remaining stable cue was rotated in conflict with the unstable cue (the probe trial). This manipulation sequence was then repeated over the next three days.
CA1 cells showed partial remapping between consecutive cue conflict sessions. The cues that controlled the firing of any individual cell were not consistent between sessions. Thus, a cell might rotate with the unstable cue between sessions 1 and 2, but with the stable cues between sessions 2 and 3. Analysis of the cells that rotated between two consecutive conflict sessions revealed that, within each ensemble, the majority of cells (mean 70%) rotated coherently. For different conflict sessions, this coherent rotation followed the stable cues (44% of conflicts), the unstable cue (10%), the room cues (12%), or to an uncontrolled location (34%). During the probe trials, CA1 ensembles also rotated in a coherent fashion (80% of cells within each ensemble rotated together), but there was no preference for the stable cue.
Simultaneously recorded entorhinal head direction cells rotated coherently with each other during the cue conflict sessions and probe sessions. However, they followed a similar cue control pattern as the CA1 cells in that they followed either stable, unstable, room, or other cues in an unpredictable fashion.
Thus, contrary to our hypothesis, the set of cues that controls the activity of CA1 place cells and entorhinal head direction cells cannot be predicted by the relative stability of cues with respect to each other in a cue conflict situation.
General Information
Organisations: Centre for Cognitive and Neural Systems.
Authors: Huang, Yen-Chen (Steven), Dudchenko, Paul A, Van Rossum, Mark & Wood, Emma.
Publication Date: Nov 2008
Publication Information
Category: Poster
Original Language: English
  How relative stability between visual cues affects cue control of CA1 place cells
Huang, Y-CS, Dudchenko, PA, van Rossum, MCW & Wood, E 2008, 'How relative stability between visual cues affects cue control of CA1 place cells' 6th FENS Forum of European Neuroscience, Geneva, Switzerland, 12/07/08 - 16/07/08, .
Visual cues help rats to maintain an internal representation of orientation. However, in a changing environment, it is important to choose the most informative cues to guide navigation. We hypothesise that cues are more informative when they maintain stable relative positions with other cues in the environment, as such stability allows the position of one cue to reliably predict the position of another. To test the hypothesis, we record CA1 hippocampal place cells in rats as they foraged for food pellets on a circular platform in a cue controlled environment. Four distinct visual cues were fixed onto black curtains surrounding the platform. Three of the cues were assigned as the stable cues, while one was unstable. Between sessions, conflicts were introduced by changing the positions of all four cues in a way that only the relative relationships between the three stable cues remained fixed. The rats were given four conflict experiences in one day for four days. We found that in most cases the place cells rotated their place fields coherently after the conflicts. However, rather than consistently rotating with the stable cues in different conflict sessions, they typically rotated coherently with either the stable cues, the unstable cues, the room cues or to some other locations. In a minority of sessions, they did not rotate coherently, suggesting remapping between sessions. These data do not support the hypothesis that stable cues are more likely to influence the place fields of place cells in CA1, and suggest instead that, during each session, the network is preferentially influenced by either stable, unstable, or room cues in a coherent but unpredictable fashion.
General Information
Organisations: Centre for Cognitive and Neural Systems.
Authors: Huang, Yen-Chen (Steven), Dudchenko, Paul A., van Rossum, Mark C. W. & Wood, Emma.
Publication Date: 2008
Publication Information
Category: Poster
Original Language: English
  The development of prospective goal-dependent firing in hippocampal place cells, and its relationship to behaviour
Hosburn, C, Huang, Y-CS, Dudchenko, PA & Wood, E 2008, 'The development of prospective goal-dependent firing in hippocampal place cells, and its relationship to behaviour' 6th FENS Forum of European Neuroscience, Geneva, Switzerland, 12/07/08 - 16/07/08, .
Hippocampal place cell activity can be influenced by behavioural context, including the task being performed, and past or future locations. For example, Ainge et al (J Neurosci, 2007 27:9769-79) showed that many CA1 place cells had goal-dependent prospective firing as rats performed a serial reversal task on a double Y-maze (where the choice arms of the initial Y each give rise to a second Y). In well trained rats, goal-dependent firing occurred before both the first and second Y choice points. However, it is not clear whether this activity is present from the outset, or emerges only after the task is well learned. To examine this, we recorded from CA1 place cells for the first 12+ days of training on the same double Y-maze. Each day, four blocks of 10-20 trials were run, with a different goal box rewarded on each block. We found that the proportion of place cells with prospective goal-dependent activity on the maze changed across training. On Day 1, different rats showed either little or no goal-dependent firing, and tended to perform badly on the task. Over the next few days, the proportion of cells with goal-dependent activity increased, either gradually across days, or in some cases abruptly. This increase was associated with increasingly accurate performance by the rats both in returning to the correct goal box during a block of trials, and in redirecting their choices to the new goal when the reward location switched. Interestingly, during later stages of training, and after performance reached asymptotic levels, the proportion of cells showing goal-dependent activity often decreased (although goal-dependent activity was still observed). These dynamic changes are consistent with a role for goal-dependent place cell activity during acquisition of the task, in that it emerges as the animals learn. They also suggest either that the neural basis for performance may change, and/or that fewer cells with goal-directed activity are required with overtraining.
General Information
Organisations: Centre for Cognitive and Neural Systems.
Authors: Hosburn, Cassie, Huang, Yen-Chen (Steven), Dudchenko, Paul A & Wood, Emma.
Publication Date: 2008
Publication Information
Category: Poster
Original Language: English
2007
  Resolving orientation in an environment with conflicting directional information
Huang, Y-CS, Wood, E & van Rossum, MCW 2007, 'Resolving orientation in an environment with conflicting directional information' Society for Neuroscience Annual Meeting, 2007, San Diego, California, United States, 3/11/07 - 7/11/07, .
Several populations of neurons recorded from freely moving rats, such as place cells, head direction cells and grid cells, anchor their spatial receptive fields to polarising cues of the environment. Cue rotation usually leads to a matching rotation of the receptive fields of these neurons. Cue conflict experiments provide evidence that different types of cues in the environment can have differential strength in controlling the receptive fields. We hypothesised that a given cue is more useful to facilitate navigation if it is consistent with other cues in the environment. Based on this hypothesis, we predicted that the amount of control exerted by a cue is affected by how coherent it is with other cues in the environment. To explore the hypothesis, we used a computational model of the head direction cell network as described by K. Zhang. 1996, J Neurosci, 16:2112-26. The activity bubble of the network was updated by angular head velocities calculated from the head direction profiles used for the simulations and the direction represented by the network was determined by the vector sum of the units in the network. Additional units representing the cues from the environment were added to the model. These cue perception units connected to all units of the head direction cell network and the weights of the connections were strengthened or weakened by a competitive Hebbian learning rule. The firing rates of the cue perception units were Gaussian functions of the actual head directions of the simulation. We showed that, similar to the cue control experiments, these cue perception units could reset the activity bubble of the head direction cell network once appropriate weights were established by the learning rule. Next, we created conflicts between the cue perception units with comparable firing rates and demonstrated that the largest coherent set of units exerted stronger cue control over the network. We also explored the role of the perception units whose input to the head direction cell network were too weak to affect the position of the activity bubble, in a cue conflict situation. We found that the weak units among a coherent set of cue perception units also facilitated the set to gain dominance on cue controlling the network during conflict resolution. We showed that, with competitive Hebbian learning rule, the network chose the largest set of coherent cues to orient its activity bubble. This demonstrated how the amount of cue control from one cue could be affected by its relationship with other cues in the environment. We plan to verify the model by implanting unit recording electrodes to the freely moving rats and expose them to different cue conflict situations.
General Information
Organisations: Institute for Adaptive and Neural Computation .
Authors: Huang, Yen-Chen (Steven), Wood, Emma & van Rossum, Mark C. W..
Publication Date: 2007
Publication Information
Category: Poster
Original Language: English

Projects:
Hippocampal integration of head-direction information (PhD)